|08-21-2009, 10:15 AM||#1 (permalink)|
Date registered: Aug 2002
Vehicle: Black 2005 ML 500
Location: Galveston, TX
Mercedes Repair/Maintainance Transmission, etc... Tips
Found the followng Mercedes repair article and thought many of you will be interested in reading it too. It contains some useful transmission tips on the W163.. There is a limit of 15,000 characters, so I will break this article in three sections/parts..
Mercedes Repair/Maintainance Tips
Recommended service intervals:
M104 every 45,000 mi or 4 years
M111 every 45,000 mi or 4 years
M119, M120 every 60,000 mi or 4years
M156, M275 every 60,000 mi or 5years
M112, M113 motors every 100,000 mi or 5 years
M272, M273 motors every 91,000 mi or 5 years
Some years have slightly different intervals, your owner’s manual will have the best information. Or call us and we will confirm it.
It helps to lubricate the threads with anti-seize as you don't want to gall the spark plug bores on removal or installation. You can also use light oil if you prefer but anti-seize is a better thermal conductor and is preferable in the interface. Galling occurs when the aluminum cylinder head threads seize and stick to the plated steel spark plug threads. Many spark plug manufacturers specify installing plugs dry as the anti-seize can increase the torque and cause thread damage. This is probably not the case but you should decrease the torque to compensate if desired, approx 20%. Just be careful the anti-seize doesn't get on the electrode as it is contains metal particles and is conductive and the spark will find the lowest resistance path to ground. Avoid the use of air tools until you are sure the spark plug is moving freely, and use a torque wench to finally install. The correct torque is important as it controls the rate of heat transfer, too loose and the plug will run too hot. A hot plug can cause pre-ignition, this occurs when the fuel air mixture ignites before the optimum piston position. This can cause peak cylinder pressures to occur before the piston is at TDC and if this occurs over time the engine pistons can be eroded and damaged. If the plug is too tight the threads may be damaged and hard to remove later. If the plug cannot be inserted and tightened all the way finger tight the threads may need to be chased with a thread chaser. This has to be done carefully lubricate with penetrating oil if you are cutting carbon, and grease the recesses in the tap if you are removing metal it will catch the shavings from falling into the cylinders. Fortunately, overheating plugs and galled threads are extremely rare on a Mercedes if you follow the tips in this section.
Replacing plugs on the M112 and M113 engines is much easier with the special tool to remove the wires without damaging them. This 17mm wrench was designed to adjust valves back before hydraulic lifters were common, this tool is now more commonly used as a spark wire removal tool. It gives you the proper fork like opening and leverage to make an difficult removal job easy. Hose pliers and boot removal tools are other less preferable options but do work. The correct tool is 110 589 01 01 00 if you do these a lot you may want to order one. Reproductions of this tool are available but the original design is open on both ends and twists in different directions, it helps when doing the back cylinders. Some copies I have seen are not quite the same, they may work well, but I haven't tried them. You may also want a spark plug installer it's all rubber tool that allows you to insert and and finger tighten plugs, cross threading is not something you want on a back cylinder where you have barely enough room for a hand. There are many different deigns the all rubber one from Mac tools works well. Be aware the most common source of ignition problems on these two engines are the spark plug wires. At the dealer the price of one spark plug wire is over $50 when you have 16 on a M113 it gets expensive quickly, may times to accommodate a budget only a few cylinders are done at a time. Iterating repairs and diagnosis time can get even more expensive. We can sell an OEM wire set for a M113 for around $400 while our labor to install is also substantially less than the dealer. Replacement of spark plug wires isn't that common but if you need to do several cylinders consider doing a set. The labor to replace the plugs and the wires is substantially less than doing them separately so if your dealer is using menu pricing make sure you ask for them to adjust for the labor overlap.
One other issue on The M112 and M113 engine is that the oil baffles at the top of the valve covers seep oil, changing the valve cover gaskets alone won't stop the oil seep. The reason it appears in this section is that if usually occurs after 5 years on on most of these vehicles the plugs also need to be replaced. If you can replace the plugs and reseal the valve covers the labor is reduced substantially. The seep when it gets bad covers he coils and wires in oil and dirt and although it can be cleaned up its something that can be avoided if you inspect the valve covers for the need or resealing at the same the plugs are replaced. The oil baffles on the valve covers are resealed with engine sealant 003 989 98 20 10, its the RTV type sealant that is used for most Mercedes engine assemblies that have no gaskets. This is an outstanding sealant that forms a very strong bond when fully cured, has a 10min work time and skins over quickly so it can be put into service within 30min. It takes awhile to fully cure but that is unimportant to its sealing qualities. Be aware it is critical that the surfaces to be bonded be cleaned of all old adhesive and dirt or any oil. Any oil and the finished assembly will leak. It is a labor intensive repair but it doesn't have to cost $1000. I recently resealed two valve covers both baffles and replaced the plugs on a CLK 430 and the total repair was approximately $800, the dealer estimate was $925 just for the valve cover gaskets. You could pay as much as $925 and would be amazed that in many cases the valve covers go in the spray cabinet washer the gaskets get replaced an the baffles are never touched. Technically, the oil baffle reseal is not part of the valve cover gasket operation so it may not always be done. It is an additional operation and is the most time consuming part of the job if done correctly. If you are in need of this repair make sure you do both the baffle and the gasket reseal, and if you are near 5 years or 100k miles do the plugs also. The labor overlap is considerable so its not unreasonable to ask if this was considered when preparing the estimate. At Foreign MotorWorks you can be sure all labor overlaps will be considered when preparing any estimate, so you don't double pay labor charges. For example if I need to remove the coils to remove valve covers or the plugs and I am doing both the total labor needs to be reduced to reflect the reality that the coils were only removed once, it is common for the labor amounts to be summed and no overlap considered.
A note on plugs in older engines before 1990, it is not uncommon to find the incorrect spark plugs in vehicles with distributor type ignition systems. If you plan upgrade sparkplugs you need to carefully inspect or replace all the secondary electronic parts or the end result may be carbon tracking, current leakage and misfiring. It is not practical or beneficial in many cases to do this. Use the OEM plug recommended for the motor. Some high energy plugs may last longer, but often have larger gaps and need more voltage to fire. If your coil cannot provide this voltage or the spark plug wiring insulation is poor, that voltage will find another path to ground. As a result the car won’t idle smoothly, making them a poor choice in this case. With sparkplugs only use the OEM parts or the results may be less than desirable even if the plugs are made of superior materials. Beyond issues of gap are subtle variations of heat range and resistance that make the choice of the correct spark plug best left the design engineer. It's best to keep to the OEM recommendations, there is little evidence to suggest that changing spark pugs from the OEM specification would have any benefits.
Use caution when replacing plugs on Mercedes motors produced between 1991-1196 as the insulation on the engine wiring harness can be brittle. On a M104 engine this is very common but may of these have already been repaired by replacing the engine harness. Check the insulation on any of the exposed wires in the engine harness, on the engine. The heat causes the insulation to crack and flake off, this may be visible. If the insulation is cracked don't touch anything unless you are committed to replacing at engine wiring harness because it may not start after replacing the plugs, or may misfire or backfire into the intake which can damage the throttle valve.
A common cause for misfires is a no spark or weak spark condition. For anyone interested in diagnosing a weak spark condition consider this. In a vacuum the voltage required to jump a gap is high, but the voltage drops with increasing pressure reaches a minimum and sharply increases again. This is called a Paschen’s law. If you use an ordinary spark plug to diagnose a no-spark condition you may mistakenly think the spark is normal and present, but when in the high pressure environment of an engine cylinder the spark may be absent. Use a high energy spark tester, these have very large gaps to compensate for the decrease in the needed voltage at atmospheric pressure. The reason for this is that in a high vacuum ionization of a gas cannot assist spark generation, gas presence is sparse in a vacuum therefore this ionized conductor not being present results in higher energy sparks. At high pressure ionization of a gas in inhibited by electrostatic forces caused by crowding of the ions in the gap, that’s why at lower pressures like atmospheric where an ionizable medium air is present but its concentration is still small that a minimum spark energy occurs. With this mind it also helps to explain why some misfires only occur under load, this is where cylinder pressures are highest and the needed spark energy is also the highest. Weak plug wires may not show up at idle but may turn on the CEL under hard acceleration. A high energy spark tester simulates the higher load condition where the misfire occurs. Most OBD II code scanners can also be helpful locating the problem cylinder if the vehicle was built after 1997. Beyond this ignition scopes provide the best window into cylinder ignition condition and compression, but they are seldom needed on OBD II vehicles because the on board testing is so comprehensive. Misfire recognition is very sensitive, and in case where a leaking valve may be suspected a relative compression check can be performed electronically on some engines with a scan tool which can monitor starter draw current. The relative current draw for a leaking cylinder will be low, this in many cases is much faster than a conventional compression check which can be performed after if needed. If the problem can be uncovered quickly with the correct equipment the corresponding diagnosis cost to you will be the lowest. If you are doing the repairs yourself or at a shop without diagnostic technicians consider the cost of replacing unneeded components, it may be better to have it professionally diagnosed by a specialist before replacing any parts. You can then choose to repair it yourself if desired.
Modern timing chains can be expected to last the life of the engines but some engines such as the M119 have reported failures, bent valves, mostly due to plastic guide failure although this is uncommon if you have any abnormal engines noise you should have it checked. Broken oil tubes on the M119 can also cause loud lifter noise. If your engine has more than 150,000 miles on it and you have done all the scheduled maintenance chances are the timing chain is fine. If it's an older engine from the 1970's or 1980's or has a single roller chain it may be needed. The bottom line is the only way to know for sure is to check it, if it’s fine leave it alone. It would be rare to break without wearing out first. To check it, with the valve covers off rotate the engine at the crank bolt manually clockwise to TDC, either the cam timing marks line up or they don’t. Don’t rotate counterclockwise if you miss TDC, that’s when plastic rails snap. Regardless, you need to take up the chain slack to get a valid measurement so always only rotate in the direction of normal engine rotation.
If the timing marks don’t line up you have chain stretch, installing an offset woodruff is one solution for small corrections, but for anything more than a several degrees you are inviting disaster. On an interference engine loss of the chain is loss of the engine in many cases, unless it occurs at low engine speeds even then valves will be bent on several cylinders. If you replace the chain check the sprockets if blunted or rounded they should also be replaced, a worn sprocket will quickly wear out a new chain. Consider chain and sprocket wear fitted parts. If they are worn replace them both. Realize that the labor to pull the front cover and replace all the sprockets is considerably more than feeding a new chain in, but it won’t last long if your sprockets are worn. For do a chain if its needed unless then make sure its done correctly or it will need to be done again.
If you remove the timing chain you removed the chain tensioner, don't forget to reset it is the ratcheting hydraulic type or you may end up with a chain that's far too tight. You'll hear the chain noise if you missed this step and risk snapping a camshaft or braking the chain if driven like that. You need to dismantle the chain tensioner, to do this remove the allen nut then the spring and spacer. Pull the pin out fully, it only goes one way. Then insert the pin in through the back so it not extended. Install the tensioner with the 27mm nut and the allen nut installed, the chain should be properly installed and timed. Then insert the spring and spacer, compress the spring and install the allen nut. Replace the aluminum seals if they look at all compressed or damaged. Installing the allen nut while compressing the spring is most easily done with an air ratchet, if you use air tools to start the job make sure to finish with a torque wrench.
2005 ML 500
Black, 18" AMG Wheels, 285/60R18 Yokohama Geolander HTS + Bi-Xenons(+ Drew's e-code mod, though the reflectors rusted off and do not give out much light anymore), Yakima roof bars, Akebono pads all around. Former vehicle 2001 ML 320 with 108K miles, when traded, and a large repair/defect history. After all these years of owning my current 2005 ML 500, it is a major unreliable vehicle with a very large/expensive repair/defect history and has been like this since brand new.
Last edited by AC_ML; 08-21-2009 at 10:20 AM.
|08-21-2009, 10:18 AM||#2 (permalink)|
Date registered: Aug 2002
Vehicle: Black 2005 ML 500
Location: Galveston, TX
Springs are difficult to look up in a Mercedes parts catalogue, it takes good parts advisor a few minutes to look at all the footnotes and make sure you have the correct ones. If you are sure you have the factory springs installed note the paint marks colors and number of marks, provide that info to the Mercedes-Benz parts advisor it will simplify the process and prevent mistakes. Be careful because you may not have the original springs in your car, if the ride height looks off at all best to have it double checked. Springs do fatigue with time, they become weaker and compress more for a given force to be applied. In New England with all the road salt it is very common to see coil springs broken on the bottom ends, this drops the car down slightly but this is not always noticed. Broken springs will be noisy over bumps, they sound different than most other worn components. Sacrificial zinc anodes were available for some chassis to prevent this type of corrosion damage, these parts are not commonly installed and may not be readily available. If your front end drags on parking lot curb stops you might have broken front springs. C class W203 chassis commonly have broken rear springs, you may hear a broken coil rattle around inside the rear control arm over bumps. ML W163 trucks have broken rear coil springs on the struts, these are replaced as an assembly. E class W210 chassis have spring perches that break off the body due to broken spot welds and corrosion, replacement perches can be welded on once the spring is removed. Surprisingly, with this type of failure the spring is usually contained against the shock but it could come free eventually if ignored. Use caution with springs, coil springs can expand with lethal force if the correct spring compressor is not used to remove them or the tool fails.
If you are removing any head, open the block drains to drain the coolant below the surface of the head or coolant will leak into the crankcase when the head is removed. If the engine has a V configuration it can have two drains one for each side. When removing the head follow the reverse of the tighten sequence and do it in stages to prevent warping of the head. In most cases the exhaust manifold can be removed attached to the cylinder head.
M104 engines from the 1990's are very commonly leaking oil from the back right hand corner. The failure was partly due to dissimilar metal expansion and the original head gasket design, an aluminum head expands faster than a cast iron block, this combined with the placement of the oil passage very close to the edge on the block. The head gaskets now have an updated design but still repeat failure is all too common. Careful surface preparation is crucial to having a good seal, often repeat failure is the result of corner cutting and poor preparation of the surface. The using of abrasive disks that are too aggressive and cut into the aluminum head surface. Mercedes-Benz does not recommend the use of abrasive disks they prefer gentle scraping or chemical removers, in the trade abrasive disks are used everywhere. If you are worried about bits of abrasive getting into your oil passages and later embedding in a bearing this is a reasonable concern either plug the open holes or be cautious of material falling into them. A vacuum can help remove dislodged material while scraping with the other. In practice using sharp scraping blades works well for poorly adhered material when done at shallow angles gently, don't gouge the surface. If not done carefully you can cause damage that can require cylinder head resurfacing. I prefer a combination of gentle scraping and scotch brite pads all done by hand. Finish the surface prep with 3M bristle disks available in three grades, white 120 grit, yellow 80 and green 50 grit. Use the lightest grit possible on aluminum, and only very light pressure and keep moving. You can plug any open oil feed passages but if the surface is already relatively clean this can be avoided, if you do don’t forget to unplug them later or you will have bigger problems than leaving then open could ever cause. Bristle disks are somewhat expensive unlike roloc disks they have have an abrasive embedded in plastic fingers and produce very little fine debris, if you use an air die grinder most of the material is spun off radially and you can polish the surface and remove any material from small pockets. Use low speeds. light pressure and shallow angles to prevent gouging. Another problem with inexpensive abrasive pads is that some of the fines that remain can pass through the oil filter and may continue to circulate in the oil increasing wear. With the abrasive embedded in plastic the particle is larger can get lodged in an oil filter, using disks for final surface prep can be a good idea the problems arise when they are used to remove bulk material.
When the two surfaces are prepared if you haven't done a it already check the surface for any deviation from flatness, with a machinist bar even over its length to 0.0001" check longitudinally, transversely and diagonally in two directions noting any deviation. Its a good idea to check before cleaning because it may need to go to the machine shop for resurfacing anyway, it must be clean enough for for the straightedge to lie flat. If you can see light from a led flashlight under the bar check with a feeler gauge and quantify the measurement, make sure it is within specification. If not it has to be stripped and sent to a machine shop for resurfacing, you can leave the valves in. If the surface is corroded it may also need to be resurfaced as this can inhibit good sealing, depending on where the damage is. It is not necessarily a good thing to have a head surfaced, only do this when needed. When ready for assembly make sure both surfaces are totally clean, if oil is dripping out of the head wait until that has stopped before proceeding. Clean it just before assembly, both surfaces need to be clean and oil free. Its a very good idea to chase the headgasket bolt bores in the block to insure the bolts turn freely. Make sure you blow out the holes, any liquid in the bores will cause the bolts to hydrolock. A hydrolocked bolt will and stop turning and start twisting before the gasket is tightened completely because the fluid trapped in the bore is incompressible, the resulting assembly will fail very quickly. Most head bolts today are stretch bolts, they have a torque specification and then an angle of rotation specification. This is typically done in three stages. The bolts stretch each time they are installed, so they have an overall maximum length specification above which they are discarded. If the bolts are loose or the head was overheated consider replacing the bolts as a precaution. Make sure the bolts threads are clean and lubricated with motor oil. Tighten only in the specified order and in stages or you may warp the head. If the surfaces are clean and oil free don't apply any engine sealant unless it is specified in the work instructions, use only as directed. If your work is done correctly it will seal on the first warm up, as the cylinder gasket compresses over time the stretch bolts maintain tension and the seal. The first warm up is critical as the gasket really isn't sealed yet, don't install the coolant pressure cap until it is at operating temperature and fully bleed the air with the heat on. If you pressurize it before it is fully warm one problem you can encounter is coolant forced between the gasket faces and this can inhibit proper sealing as the gasket face has temperature activated sealants on it. Run it up to operating temperature and let it cool off then install the coolant pressure cap.
A common timesaver on M104 head gaskets involves blocking the chain tensioner with a wooden or soft wedge, so the tensioner is not removed or reset. Avoid this technique because the tensioner is a ratcheting type and even if wedged it could slip outwards slightly and the chain will end up too tight, upon reinstallation. A tight chain it will be slightly noisy, it can wear and stretch causing the timing to be off. Avoid that short cut removing the tensioner should be done when removing the heads, make sure to reset it on installation or the chain will be way too tight. It has to be dissembled to be reset, see description in the timing chain section. If this is done correctly you will hear the chain tensioner advance on first start and oi pressure is applied as it is hydraulically driven, the sound of the chain will quiet as soon as this happens.
Early transmissions such as the 722.3 have recommended service intervals usually every 60k. The fluid used should carry the correct specification i.e. MB 236.7 which is Dexron II D. You can call us if you want an estimate on a transmission service or need information on the service interval. We will look up and use the correct fluid unless you request otherwise. It is common to use Dexron III but be aware fluid with the correct MB specification should only be used, in most cases Dexron unless it is marked on the bottle with the MB specification being met may not be approved. If possible we always drain the torque converter, omission of this step leaves 4 liters of transmission fluid in the vehicle. With the onset of lifetime fill electronic transmissions in the late 1990s the torque converter drains were omitted. These transmission are controlled by vacuum and modulator pressure, they can be adjusted and have some weak areas where vacuum leaks are common.
The 722.6 has been a very reliable electronic transmission and is much more simple to repair than its predecessors. One problem that was ongoing with this transmission are leaks at the plug adapter for harness connector. There are various versions of this adapter and o-rings, some have tabs, the adapter is best replaced complete with o-rings. If the adapter o-rings should be black, red or white o-rings are prone to leak, connectors with tabs will also leak. The electronic transmissions are lifetime fill in most cases and have a lock on the dipstick. If you replace the adapter you need to adjust the fluid level, the transmission dipstick is a special tool. The fluid used is not Dexron III but a variant of it, don’t use ordinary A/T fluid in an electronic transmission with lifetime fill. The correct fluid is 001 989 21 03, MB 236.10. This fluid is backward compatible with all earlier transmissions. The dipstick is a special tool and the dipstick cap has an anti-tamper plastic lock. The fluid after MY 2006 is the same in a 722.6 as a 722.9, don’t use the 722.6 fluid in a 2006. The newer fluid is slightly purple in color. The newest fluid is backward compatible with all Mercedes transmissions. Some late model 722.6 transmissions have a scheduled transmission service, oil and filter, at 39k. For all others even if its not required a transmission service if done with the correct fluid could only be beneficial, even if it isn't called for.
Early 722.6 transmissions had a poor valve body conductor plate design, this part has the starter lock out switch and transmission VSS sensors built into it and powers the shift solenoids. If it fails you may have an intermittent no-crank no-start condition and the transmission may shift irregularly because the speed sensor signals needed for calculate smooth shift adaptations are faulty. This part can be replaced with the transmission in the vehicle and the valve body removed, this is good to do if considering a transmission service on an older vehicle. If you are experiencing shifting concerns or start delay, please contact us for details as we can scan for codes that would indicate you need this repair or other transmission repairs.
One note on torque converters and transmissions, there is considerable variation in these parts and the best repair is installing and Mercedes-Benz remanufactured unit as it will be an exact match. Used parts will in most cases not match and may be problematic even if they are good, control units can be very specific and may not work correctly. Dealer remanufactured is the highest cost option but is the best and fastest turn around. Alternately, we can rebuild your transmission, and have your existing torque converter rebuilt depending on the extent of the damage. A torque converter may be rebuilt. They are sent out for this repair. They are punch marked, cut in half by a dedicated machine and cleaned of any debris. Inspected and the lockup clutches replaced if needed and welded back together on a dedicated machine. We don't recommend replacing one with an aftermarket remanufactured one, you are best to have the one from the vehicle rebuilt. There are too many variations of these to expect you will get the correct one, although it will fit, internally it will have a different design and stall characteristics. A new unit from Mercedes is the best repair but it may be over 3x the price of having yours rebuilt. In many cases the torque converter is replaced simply because it may be contaminated with material from the failed transmission and if it is reused the new transmission may be damaged, having it opened inspected and rebuilt eliminates this concern.
Another issue with the 722.6 involves transmission fluid wicking up the harness into the control module and causing the module to malfunction. Usually, the harness from the transmission to the ETC module is replaced and the module is replaced provided the leak is repaired. In some cases this may be more than is actually needed but it usually fixes the concern. Transmission fluid does not actually damage the module and can be flushed away with board cleaning solvent or electrical contact cleaner as a first attempt. Always repair the leak before replacing a module.
|08-21-2009, 10:18 AM||#3 (permalink)|
Date registered: Aug 2002
Vehicle: Black 2005 ML 500
Location: Galveston, TX
Another issue with the 722.6 was in Valeo radiators leaking coolant into the transmission fluid, this causes and harsh engagement followed by a droning vibration. There is a glycol test to determine if this is the case. If strongly positive the radiator, torque converter are replaced and the transmission and lines flushed. The dealer used to replace the transmission also but no longer does this commonly. If the contamination is slight the radiator only is replaced and the lines and transmission flushed. Consider having the transmission clutches replaced if the contamination is high, i.e. visible contamination. The clutches are very sensitive and it may not be fully repaired unless the radiator, torque converter and transmission are replaced or rebuilt. If you have this complaint and the glycol contamination is not present you may need a new transmission control unit, the newest software can correct an adaptation issue with the torque converter than can also be the cause. This should be diagnosed by a specialist. The transmission control unit is replaced and adapted to repair this because the transmission software is not flash updatable as it is on the predecessor.
The next transmission in the series is the 7-speed 722.9. It has no dipstick tube and can only be filled or checked from below. If your vehicle has a 7-speed you may have noticed that 722.9 transmissions have no hill holding capacity, they roll backwards with your foot off the brake. Some have a hill holding feature where they use the brakes to hold briefly. The reason is this, when the 722.9 was designed it had to fit into the same envelope as a 722.6, as it was going into vehicles already designed and in production. If you change or modify the transmission tunnel you have to repeat all the crash testing as it is a crumple zone. Since, the 722.6 has five gears and the 722.9 has 7 gears, the extra Ravigneaux gear set that makes this possible that has to fit into the same package something non-critical had to be omitted. From the 722.6 design two sprag clutches were omitted, these are essentially freewheel elements, they spin in one direction but lock up in the other. Without them a transmission will not lock up when it rolls backward in 1st or 2nd gear. If you have ever wondered why a 7-speed automatic doesn't hold a hill like the 5-speed automatic does that’s the reason, it's not broken.
There are numerous issues with the 722.9 particularly the early ones. Contact us if you are having problems with one. These as the 722.6 can rebuilt and repaired readily.
Use these as a guide, specifications from WIS converted from liters. These quantities are for an oil and filter change only. Please consult your owner’s manual to confirm they are correct for your application. If changing the filter make sure you change all the o-rings and use a good quality filter. On the M112, M113 and M272 and M273 motors use a fleece filter.
112, 112.975 8.5qts
112.916, 112.953 7.9qts
156 in W164 10.3qts
156 in W204 9.0qts
156 in W209, W211, W219 9.3qts
156 in W221 10.0qts
156 in W230 8.5qts
156 in W251 10.15qts
M273 9.0qts note GL is about 10.0-10.5qts
I’ll add diesel engine capacities if there is interest, please email me with omissions or corrections.
Use the Mercedes-Benz coolant MB 325.1 it is only slightly more expensive but it is worth it. Dilute 50/50 with distilled water. Don’t use tap water if you can avoid it as water has dissolved ions, hard water can cause precipitates with corrosion inhibitors such as phosphates common in many antifreeze products, causing deposits and decreased flow and heat transfer. Mercedes coolant is formulated without phosphates so hardess is less of a problem. Deionized water has sodium in it, use distilled its preferable because it has negligible ion content. Antifreeze corrosion inhibitors packages are not all alike and considering the cost of a radiator or engine it is cheap insurance to use the OEM formulation. Mercedes uses silicates and is formulated to protect the metals in the system, particularly aluminum. Additionally, brazes, plastics and gaskets are also a consideration. If you mix two types of coolants equally, even if the second is a universal coolant, you just halved each corrosion inhibitor concentration now neither is any longer adequate to protect the system. Universal coolants can be mixed with any type of coolant without immediate damage to the cooling system, but don't ignore the fact that you are reducing the long term protective benefits of both coolants if they are formulated differently so you are inviting long term damaging effects.
For the most part, vehicles MY 2002 and later specify a cooling flush every 15 years or 150,000 miles. MY 2001 and earlier are every 3 years. There are exceptions in the transition years. Later production vehicles with 15/150 service interval have a silica gel packet in the coolant reservoir that constantly replenishes the silicate concentration in the MB coolant helping to promote the long life. If you top off with another type of coolant such as OAT (organic acid) or phosphate based you are contaminating the factory coolant system. Ignore color when trying to differentiate coolants, these are added dyes and don't indicate anything specific about the components. Coolants compatible with MB coolant would be typically labeled G-05. Consider how unfortunate it would be to have to replace the aluminum heater core if it started leaking, although uncommon when it occurs often this is the result of poor maintenance or ignoring the use of the correct coolants. The repair is costly and involves complete removal of the instrument panel to the firewall. The silicate formulation in the MB coolant offers very quick protection of the water pump from cavitation damage, OAT coolants are much slower to protect. When cavitation occurs at high temperatures under load the fluid boils in low pressure areas generated by the pump blades, when these bubbles collapse under pressure they cause tiny shock waves that blow the oxide coating off the metal. The metal can then erode and corrode since it is unprotected, the silicates quickly form a coating the protects the metal and heals quickly if damaged by cavitation. The benefits of using the factory coolant make a long list, it is worth the small added cost. Regardless of the vehicle brand, it is always best to use the OE specified coolant and follow the manufacturer guidelines for dilution.
Mercedes-Benz black cased batteries are Valve Regulated Lead Acid (VRLA) and have no maintenance. White cased lead acid batteries should be serviced regularly. With every service, top off the electrolyte with distilled water but don’t overfill. Only use distilled water in a battery. Make sure the terminals are clean, and wipe it down. Use baking soda solution if you have acid on it otherwise plain water is fine. Although these routinely receive no maintenance even during services, they have a surprising ability not to dry out and still last 5 years ignored. We don't recommend overlooking battery maintenance, and the electrolyte level should be checked with any service and the battery tested. Midtronics battery testers are now routinely able to indentify a battery that needs replacement without doing a load test, they use inductive tests to check conductivity and calculate theoretical output. Its quicker and more accurate, dealers use only this tool for warranty replacment.
Mercedes-Benz batteries are expensive but they are very heavy duty. Hold an aftermarket replacement in one hand and the factory in the other you can feel the weight difference. The plates on the OE battery are thicker and have more surface area, they hold up better longer subject to shock and thermal cycling and don’t dry out easily. If you have to buy an aftermarket battery buy an exact fit as they can be unsafe if not secured in a collision. Interstate supplies Mercedes batteries so they are an excellent OEM source. We can order either for you.
Another overlooked point is the battery vent tube. The vent tube discharges any battery vapors or gas out of the vehicle. Without the vent tube gases collect in the vehicle or flows over delicate components such as the vehicle wiring harness. Don’t forget to connect the vent tube if present, there are two outlets on each end. One is plugged, don’t forget to take the plug from the old one. The other attaches to the vent tube. If you replace the battery you may want to use a vehicle memory keeper or you may have to normalize the windows, roof, steering angle sensor, code the radio and set as many as two clocks on some models.
Last edited by AC_ML; 08-21-2009 at 10:21 AM.
|08-21-2009, 10:26 AM||#4 (permalink)|
Cigarros Finos Aficionado
The transmission Fluid Spec for a 722.6 is now 236.14, not 236.10.
2005 S430 4Matic 'Morton' W220.183 • 722.671 Transmission
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