Some Background

Applicability and Efficiency
This thread would apply to not only the S430, it should also describe similar info for all M113 V8 engines and M112 V6 engines used in various MB platforms. The only practical difference between these modular engines for this job is 2 fewer cylinders and differences in air inlet housings. As such, there are some workshop instructions posted by 43sqd on the ML W163 forum (see post 2 of the link) and a pictorial exploded diagram (see post 9 of the link).

http://www.benzworld.org/forums/w163-m-class/1612771-ml430-valve-covers-oil-leak.html

NOTE: An efficiency gain can be made by combining valve cover gasket replacement with spark plug / wire change outs and / or crank position sensor replacement. If you can replace the spark plugs and reseal the valve covers at the same time, the labor is reduced substantially. During this job, accessibility to the CPS will be greatly improved, such that you can see and touch the CPS at the same time, should you care to complete that preventive maintenance item.

Rubbers
Heat and time will age rubber products so that they lose pliability, creating cracks and causing leaks. This is why periodic replacement is needed. The affected components in this work scope will be valve cover gaskets, the RTV (Room Temperature Vulcanization) sealant for the breather covers, and the breather hoses. All of these components will need replacement at around 100,000 miles or 6 years. If they are not leaking oil or air at this mileage, they will be soon. Oil leaks can get onto the coil packs, spark wires, and drip down to the exhaust manifold. Air leaks in the breather hoses will bypass the filter (think sand in your engine) and unmetered air will bypass the MAF and affect mileage. If you are thinking of just replacing the RTV – it is more than likely that the hardened and brittle breather hoses will crumble in the replacement process and need to be replaced.

Breather System
Evacuation of blow by gases is necessary to prevent an otherwise sealed valve cover system from losing oil. The M113 / M112 engines do not use PCV check valves to reduce crankcase gas pressure. Instead, there is a two level evacuation system for the crankcase and the valve covers. A small diameter hose extends from each breather cover via a barb with a 1.5 mm diameter center hole and connects to a common tee at the aft section of the intake manifold. The connecting tee has a down section that sits in front of the throttle plate and sees intake manifold pressure. This small hose system allows intake vacuum to be applied to the breather covers at idle speed. On the driver’s side, a single larger diameter hose connects to a full diameter barb on the breather cover to the MAF body after the sensor. This larger system allows a vacuum at higher engine speeds to be applied to both of the valve covers and crankcase via the timing chain cover. The breather cover on the driver’s side is longer to separate entrained additional oil from crankcase gases before being sucked into the air intake. For this reason, the driver side breather cover also has 3 oil drain ports to help minimize oil consumption at the intake. Another benefit of a properly working breather system is that formation of engine oil sludge can be reduced by evacuating water vapor from the engine crankcase. Conversely, an engine with sludge buildup can clog the drain ports on the driver's side and result in excessive engine oil consumption. These are simple systems that need to be periodically maintained to keep your engine in working order. Replacement of the breather hoses is a wise and inexpensive investment for your car engine. Witek from the ML W163 forum posted an excellent diagram of the breather system in the attached link on post #11.

http://www.benzworld.org/forums/w163-m-class/1508527-please-help-i-got-oil-coming-2.html

Vacuum Leaks
A poorly running car can often run amazingly well after an afternoon’s worth of work, going through the various rubber boots and hoses around the engine. Vacuum lines, intake boots, seals and many other small gaskets around the engine can be the source of poor running and idle problems. Many times, a lean running condition can be traced back to a cracked or torn rubber in the system. This is another reason to renew your car’s breather system!

Metallurgy
The M113 valve covers and breather covers are made of Magnesium. (So is the intake manifold and several other engine components) The primary benefit of using Magnesium instead of Aluminum is weight savings - a one third weight advantage. However, this tradeoff is not without cost. Although Magnesium has approximately the same strength as Aluminum, it is more brittle. This means that if a breather cover is dropped to concrete or pried up with a screwdriver or pulled up by the breather hose connection – it is likely to crack. (Valve and breather covers are sold together. $100 used replacement with no guarantee of condition - $400 for a new replacement.) Another drawback of magnesium is that it is more susceptible to general and galvanic corrosion. Magnesium corrosion is more pronounced than in Aluminum. Ever hear of someone complain about how their engine looks after degreasing with a mildly acidic bath? Looks like their engine has leprosy. Even worse, some of a degreasing solution will get trapped in the valve / breather cover gasket capture grooves and cause a corrosion cell and completely deform the parallel lines of cast grooves. This will cause a vacuum leak and an oil leak. This type of corrosion makes it hard for a new gasket or RTV to achieve a good seal. Although contact with Aluminum and Stainless steel will not cause extreme galvanic corrosion; magnesium to steel will set up a galvanic reaction. This is why the steel through bolts for the valve cover are painted – to minimize oxidation of the magnesium. One other drawback of magnesium – if you have an engine bay fire that goes above 1000 deg F, the car will be a complete loss because the magnesium will ignite and self-oxygenate when using traditional fire extinguishers. Although it is difficult to ignite a block of magnesium, after it is lit, adding water or a CO2 fire extinguisher will be ineffective and simply add oxygen to the exothermic chemical reaction – just get everyone at a safe distance and call the Fire Department.

Mechanical closure design
The breather covers mate to the valve covers with a ridge and valley. A small amount of RTV sealant should be applied in the valley to accomplish a good seal. Filling the valley is all you need. Too much RTV will result in excess material being transported to the engine oil sump and blocking sump screen flow – partially starving the engine of lubricant. Breather covers are initially fastened to the valve cover from the factory with aluminum cap screws (2 on passenger side, 3 on driver side). These are not reusable, and need to be replaced with stainless steel. Reusing the aluminum cap screws will likely result in their shearing off. Substituting a steel cap screw instead of stainless will result in galvanic corrosion since the cap screws thread directly into the magnesium valve cover. These cap screws are to be lightly torqued to 4-Nm. Over torque could damage the magnesium threads in the valve cover. The purpose of the cap screw and accompanying light torque is to hold the alignment of the covers during installation so that the RTV sealant is not disturbed while curing.

Valve covers have a capture groove for the gasket. A properly manufactured gasket is molded to include side ridges for a tight fit into the valve cover. This means a good fitting gasket will allow you to hold the valve cover in its normal upright position and shake it without the gasket falling out. This design negates the need for any RTV sealant or gasket tack at this sealing junction. Less RTV sealant means less chance to get rubber blocking the oil sump suction. Long steel bolts hold the valve cover to the aluminum head. These reusable steel bolts are torqued to 8 Nm. Some of the long bolts pass through the breather covers. Over torqueing of the long bolts not only brings up the possibility of bolt shear and pulling out the threads from the aluminum head – it is also useless in trying to fix a leaking gasket. At the four corners and each through bolt location of the valve cover mating surface are “crush stops”. These are cast metal ridges that prevent over compression of the gasket and provide multiple points of metal to metal contact between the valve cover and cylinder head (outside of the gasket of course). In other words, you can easily strip out threads in your aluminum engine head, but you cannot over-crush the valve cover gasket. See photo below for two crush stops on the corners of an installed valve cover - the black gasket disappears behind them.

 

Tools, Parts and Supplies

Parts and Supplies

I took the approach of using MB parts through the Mercedes Benz Fort Lauderdale online store.

Home - TradeMotion.com

This site is hard to search, so I used AutohausAZ.com to look up part numbers, and apply them to the MB online store. This was a few dollars cheaper than using AutohausAZ.com. Victor Reintz has a line of gaskets and hoses, but the price difference is so small it made sense to stick with OE. Just over $100 shipped. And for Pete’s sake, don’t buy URO parts!

- 2 Valve cover gaskets (left and right side, part number depends on if you have a M113 or M112)
- 5 stainless steel replacement bolts to replace the aluminum – Old Part number 000912-005010, M5x18 superceded by new Part number 000000004436.
- Spare steel through bolts for valve cover (optional)
- 4 breather hoses and three plastic connectors (same for M113 and M112) 1120180482, 1120180282, 1120180182, 1120180382, 1179901578 (connector)
- Crankcase breather rubber connector tee (same for M113 and M112) 1120180209
- MB sealant Part number 003 989 98 20 10. (same for M113 and M112)
- Brake cleaner – 2 cans
- Cleaning tub
- 1 inch diameter wooden dowel 2 ft long
- 1 inch by 2 inch by 2ft long wooden lever
- Paper clip
- Paper towels
- Lots of latex gloves
- White out / marker paint
- PB Blaster or other penetrant
- Black Zip ties

Tools needed

- Torque wrench capable of 4 to 8 N-m
- You may need a 1/4" male adapter if sockets are 3/4" female
- 3/8 inch universal socket joint
- 3/8 inch ratchet and extensions
- ¼ inch ratchet
- E10 torx
- T30 torx
- T20 torx
- 4mm hex driver
- 1/4 inch socket driver (optional)
- 10 mm socket
- 8 mm socket
- 17 mm open end wrench for fuel line
- Snips for ty wraps
- Pliers
- Flat blade screw driver
- Portable light
- Inspection mirror
- Hydraulic jack (optional to give you a higher work platform)
- Safety glasses
- Shop vacuum
- Caulk gun
- Box cutter
- Garden Shears (that’s right – garden shears)
- Magnetic bowl (Optional for keeping track of screws)

 

Tools, Parts and Supplies

Parts and Supplies

I took the approach of using MB parts through the Mercedes Benz Fort Lauderdale online store.

Home - TradeMotion.com

This site is hard to search, so I used AutohausAZ.com to look up part numbers, and apply them to the MB online store. This was a few dollars cheaper than using AutohausAZ.com. Victor Reintz has a line of gaskets and hoses, but the price difference is so small it made sense to stick with OE. Just over $100 shipped. And for Pete’s sake, don’t buy URO parts!


- 5 stainless steel replacement bolts to replace the aluminum – Old Part number 000912-005010, M5x18 superceded by new Part number 000000004436.

I know this thread is super old, but maybe I could get some help. I have bought most of the tools and parts needed for this project (on my 2002 c240), but had trouble finding the replacement bolts you listed above and understanding what kind of bolts they are. So far I know that they need to be stainless steel to replace the old aluminum ones. Is the correct type of bolt M5 threads size, 18mm in length? Do I need to buy them from an auto store or can I find any correct material/sized bolts to replace? Lastly, do you know the size of the bolt head (diameter and/or head height)? Thanks in advanced!

 

Sequence - Valve cover removal

A MB valve cover gasket should come with a cardboard backing and already be laid out to relax in its final form. If not, spread out the gaskets on a clean surface in the outline they will be installed to give them time to get into form.

Remove the main engine cover that also houses the air filters. It is held on by four pressure clips. You can see the two at the front of the engine, to remove the housing lift it at the front of the engine and once the front clips release the rears will release as well. Because this procedure involves removal of the MAF body, use and inspection mirror to get a sense of how the airbox fits to the MAF body before removal. It may come in handy later on.

Although the passenger side is the best one to start on because it is simpler, go on to the driver’s side and place an indelible match mark (or even better a scribe mark) that can withstand gasoline solvent on the flexible fuel connection. (See photo). Let this dry while you go back to the passenger side.

Disconnect the individual wiring harnesses going to each coil. They simply squeeze in and pull out of the coil. Cut any ty wraps to free the loom. Swing the coil wires back over the intake and secure them out of the way.

Use a T30 driver to remove the coils, one at a time. You do not have to disconnect coil packs from the spark plugs. Tuck them down and out of the way. (Photo)

On the Passenger’s side – move the brackets for the Transmission dipstick tube (8mm socket to valve cover) and Engine Oil dipstick tube (captured by the E10 bolt) is necessary when the long through bolts to the valve cover are removed.

On the Driver’s side - Remove the fuel line supply with a 17 mm open end wrench (see photo). Be ready to catch / absorb the ½ cup of fuel that will come out. (No smoking on this job) This step needs to be done prior to removing the valve cover to avoid getting fuel into the crankcase oil. The driver’s side of the engine also has two breather hoses – the larger one used when the engine is under load. The smaller breather hose may be zip tied to the fuel rail.

Next, remove the crankcase breather hose from the breather cover. If the hose is fairly new it should slide off. If the hose is original or old there is a very good chance it is dry and brittle and you are going to damage it and need to replace it. If you are going to replace the hoses, it is easiest just to cut it with garden shears 2” away from the breather cover. (The driver’s side of the engine also has two breather hoses – the larger one used when the engine is under load.)

This is a good spot to remove the aluminum cap screws (2 passenger, 3 driver) that hold the breather cover to the valve cover. Remove the cap screws in the cover with a T20 Torx. (The replacement screws require a 4mm hex driver.) The RTV sealant will keep the covers together in the remainder of the process.

Next, either vacuum around the top edges of the valve cover to avoid getting debris in the valve gallery – and / or - I used a spray of PB Blaster around each long bolt that helped to capture the magnesium oxide buildup in the valve cover bolt holes.

Use an E10 Torx driver and remove the 11 long bolts ( for M112 engines) holding the valve cover on.

You may have to wiggle the cover around to get the seal to break loose to remove the valve cover. Do not hit the valve cover with a hammer or try and jam a screwdriver between the valve cover and head as this can damage both causing them to leak even more. Magnesium – remember? If needed, use a rubber mallet or wooden pry bar to gently break the valve cover loose. Place the valve cover onto a piece of cardboard on a sturdy surface.

Remove the old gasket and clean the area on the aluminum head. You need to clean off all of the old gasket and clean any areas that mate – no oil or debris.

I liked how good the valve train is in the photo below on my 12 year old 125,000 mile engine. Mobil 1 0W40 is all this engine has seen over the past 100k miles. Not pristine, but pretty good.

 

Breather cover instructions

If the breather hose was cut off and still attached, use pliers to gently remove the remaining hose from the barb. Consider using the box cutter to score the outside of the rubber hose (don’t cut all the way through) to help loosen the old hose. A flat blade screwdriver may also help to loosen the grip of rubber on the barb.

CAUTION - Do not hit the breather cover with a hammer or try and jam a screw driver between the valve cover and breather cover as this can damage both covers causing them to leak even more.

Next, you will need to separate the breather and valve covers. (Ensure the aluminum cap screws have been removed) Use the wooden 1 inch by 2 inch by 2 foot long pry bar to separate. The wood is softer than the magnesium covers, and will not nick them. The forging between the breather cover and the coil pack mounts is strong and should not crack with a little twisting motion to break the RTV seal. In the photo, you can see a string of the old factory installed RTV still hanging on. This is a reminder that using too much RTV can result in debris getting to your oil sump.

NOTE - Key to successful application of any type of sealant is both surfaces must be clean of any old sealant and bone dry. Not a trace of oil.

Once the covers are separated, wipe out the sludge with paper towels. Then use a wooden scraper to pull out the old RTV seal (the wood being softer than the metal won't damage the magnesium). Then use a can of brake cleaner over a tub to clean the channels. For anything that is left, use the scraper again, or unfold a paper clip to do spot cleaning. Use the paper clip to clean out the 1.5mm barb for the breather hose so that this system works - it may have some sludge blocking the port. (see photo). Although the passenger side breather cover has large holes to drain entrained oil, the driver side has several smaller drains. These small diameter drain pipes need to be cleaned out - if blocked with sludge or RTV sealant will cause entrained oil to be sucked through to the MAF body and your engine will burn oil excessively! The brake cleaner did a great job in cleaning the covers of oil and residue, evaporated quickly, and did not corrode the magnesium. The gasket on the valve cover may either pull out upon disassembly, or just pull it out if intact with the valve cover. Check to see if there is any debris in the gasket capture channel.

NOTE – The previous step also includes cleaning the valve cover gasket seating area with brake cleaner.

NOTE - Clean the land area of the valve cover bolt holes of any debris and oil to ensure the most accurate torque values.

CAUTION - Failure to thoroughly clean out the long drains on the driver side valve cover (see last photo) or clear either of the 1.5 mm holes at the hose barbs will result in excessive engine oil consumption. See attached Service Bulletin for causes of engine sludging.

The ventilation chamber (on either side) is attached to the valve cover with sealant and a few bolts, no gasket is required. The oil baffles on the valve covers are resealed with engine sealant 003 989 98 20 10, it is 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 a while to fully cure but that is unimportant to its sealing qualities. An alternate sealant for this application in Loctite 5900. 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. The MB RTV comes with a plunger, but it is hard to use. Place the MB kit into an ordinary caulk gun for an easy dispenser. A 1 inch wooden dowel will help get the last bit of RTV out of the MB kit when placed in the caulk gun.

After you have cleaned both surfaces thoroughly, apply a small bead of RTV compound to the channel and the through bolt connections in the breather cover. The channel should be filled to the top, not overflowing. Remember, excess will be transported to your oil sump. Use the tip of the applicator to shove the compound into the channel. Take the channel into bright sunlight to check for voids that need filling.

CAUTION - The small cap bolts holding breather chamber to valve cover were one time use aluminum. They may snap off on any attempt to reuse or retorque. Replacement screws are stainless steel.

Mate the breather cover to the valve cover and avoid sliding it around too much. Torque the NEW stainless steel cap screws to 4 N-m. You should see a small bead of RTV compound from between the two sealing surfaces. (see photo) If you see a lot, consider repeating this process because the inside of the cover will also have excess RTV sealant that will get transported to clog the engine oil sump.

 

Valve Cover gasket installation

CAUTION - The valve cover is attached to the cylinder head with a gasket and bolts. Do not add sealant to the gasket or valve cover. Doing so will risk RTV sealant being transported to the engine oil sump, and clogging the oil pump suction and ruining the engine.

Install the new gasket into the valve cover. It should fit snugly to the point that it will not fall out when held upside down. Make sure the gasket sits flush in the channel, especially on the rear at the half moon cutout for the camshaft.

Place the valve cover onto the engine head. Thread in long bolts by hand just for positioning. Next, use an inspection mirror to ensure that the valve cover gasket has not become dislodged while setting the valve cover. Failure to inspect at this point with a fold in the gasket will result in crease that will become a vacuum and / or oil leak.

After starting all fasteners by hand, then tighten them in a circular pattern, starting at the center and go around in an ever widening circle. This helps the gasket set better in the groove of the valve cover head. Torque the long bolt fasteners (E10 socket) in two stages, 4 N-m, then torque the E10 long bolts to 8 N-m in the same circular pattern. Remember, this is a metal to metal fit, so there is no chance of gasket over crush; the concern is pulling out the threads in the aluminum head.

For the driver’s side reinstall the fuel line back to the match marks or scribes installed earlier. For the passenger side, torque the 8mm bracket for the transmission tube to 4 N-m. The oil dipstick bracket fits under the lower forward E10 bolt.

 

Breather Hose installation

There are four hoses, one rubber connecting tee and three plastic connectors. The large hose goes from the MAF body to the driver’s side breather cover. Two hoses connect together with a straight piece on the driver’s side. One passenger side hose goes from the breather cover to a common tee with the driver’s side. To get at this connection you have to remove the MAF body.

There is a small 6mm bolt that needs to be removed by where the wiring harness meets the MAF sensor. Also the main wiring loom is clipped to the harness, unclip this as well. At the bottom of the MAF body, there is a latching lever. Push down on this (see photo) and pull the body aft. At the top of the MAF body, there are two plastic catches to the intake manifold. Release these catches and swing the MAF body out and then up towards the passenger side. At this point, the only thing holding the MAF is the sensor wire (since the large breather hose was severed earlier).

With the MAF body out of the way, you can see the rubber tee connection at the throttle body plate for connecting the two smaller hoses. If the breather hoses do not come off easily, then cut the outside of the hose and pry out with a screwdriver. (see photo where green knife is pointing at the Crank Position Sensor and screwdriver blade is peeling back hose at the multi-junction tee.) The tee pulls straight up if you are replacing this rubber connection. Two of the three plastic straight through connections fit into this rubber connecting tee.

Reconnect new hoses to the rubber junction tee, and a new large diameter hose to the MAF body. Thread the small diameter hoses back to their barbs on the breather covers. Both hoses have torturous paths. Be sure the passenger side hose is not sitting high or it will prevent the air box cover from sitting properly. The driver side hose has to be ty wrapped back into place.

Lower the MAF body back down, and thread through the large hose to its connection point on the breather cover. Lock the lower and upper plastic tabs on the MAF body back in place. Use an inspection mirror to ensure proper seating of the MAF body onto the throttle body.

On the passenger side, I installed a ty wrap to act as a hose clamp on the breather cover barb. This was due to a bit of corrosion on the barb that was not resulting in the best seal.

 

Coil Pack and air cover

Coil packs go back on and are torqued to 8 N-m. Reinstall the leads from the loom until they snap in place or the colored weather seal is no longer visible. Lightly tug test the spark plug wires to ensure that they have not been disconnected.

Snap the engine air box cover on. Check it with a mirror to ensure that the MAF body properly engages with the air box.

Wait 24 hours for the RTV sealant to dry, then test run and check for oil / vacuum leaks.

Cheers

atm

 

WOW!

What a great writeup!! Now all in one spot for easy access when the time comes.

Thanks Again, Bob

 

Really nice writeup by our resident atom smasher - added to the Encyclopedia, of course!!

 

You are welcome sir!

 

Great write up. Did mine few months back and definitely some very good points in here.

 

fwiw, no removal of the fuel line is necessary

my 53k mile valve train:

 

Thanks atm for the excellent write up. Car just turned 100K, so reading your post I went under the hood to look around for leaks.

Found none, but discovered that the breather hoses were in miserable condition (driver side). Both had cracks at the nipple, and larger hose was as hard as a broomstick.

It was a pain to remove it from the bottom of the MAF assembly, but following your instructions job is successfully completed.

Thanks again

 

The case of Wholey Vave Covers.

Having read here that the MB 220 valve covers are magnesium. Further comments have been made that these covers are subject to degradation resulting in perforations which are basically terminal parts failure. I dug back in my knowledge bank from salt water boating to being here a refresher in the nobility of metals and the potential for corrosive reactions. (see Below)


Galvanic Table of Nobility Material:

Magnesium
Zinc
Aluminium
Cadmium
Mild steel
Wrought Iron
Stainless steel (Low Chromium)
Lead
Tin
Brass
Copper
Bronze
Copper-nickel alloy
Nickel-copper alloy
Stainless steel (High Chromium)

These metals are commonly used in MB construction in some amount

Metals placed at the top of this table have a higher negative potential will corrode faster than those with lower negative potential. Metals at the lower end of the table are known as passive, and are less likely to corrode.

The greater the difference between two metals on the table, the greater will be the galvanic reaction between them.

So, considering that magnesium valve covers are subject to a variety of metals, metal salts, and electrical currents some thought and consideration in PM actions by owners might be helpful in order to minimize exposures to causes of galvanic corrosion of magnesium components.

First and foremost would be to make certain by inspection that the battery ground connections are clean tight and corrosion free. That the starter and alternator connections are also clean and secure. That all wire harnesses in, on and around the engine are well insulated, secured in looms and off the engine surfaces. Keep oil clean, changing at recommended intervals and change the filters at each oil change.

Oil changes maybe the single most critical issue with respect to corrosion of these magnesium covers. Consider that oil carries copper, cadmium, aluminum, chromium and other lower metals gathered in to suspension from internal wear. These are circulated to the valve covers in a continual bath. While exposures are minute, the frequency of exposure is the killer and a source of damage to the integrity of magnesium corrosion.

One might argue that the engine is "grounded", and they would be correct. Yet autos have a floating ground and are not connected to earth which would drain off the galvanic current. Floating grounded systems require something more called a "Galvanic Isolator" in the system. I do not believe MB pops one of these in each car. That said, the single best protection is to make sure the battery ground is faultless and can provide some protection from corrosion.

W220 owners are blessed in this case by having the battery in the trunk and away from the engine. Hydrogen gas would melt these valve covers as would ozone by the way.

I didn't price the valve covers, but I suspect a the cost of shorter interval oil changes is largely mitigated by the replacement cost of just one valve cover. Those now afflicted by wholey valve covers might experiment with JB Weld as I do not believe JB has any metal scintering for patching. Epoxy patching with metal added should be avoided in this case.

 

Valuable information! Thank you very much, Asureyes.

 

thank you so much for the help, nice write up, thanks again

 

Fantastic write up, possibly the best I have come across yet! I just did my 2003 S500 at 99,800 miles and both valve covers and both breathers had just started to leak. Only small issue was one of the (aftermarket) gaskets I ordered online was slightly too small for the cover, no way to make it fit despite 2 hours of tweaking. No way to get another and needing the car tomorrow, so I had to cut the gasket in 1 place to make it temporarily fit, then seal the 1/2" gap with RTV. I'll have to order a new gasket and reinstall it later. Never buying aftermarket parts again...

I am wondering about the RTV curing time though - all the times I have used it in the past, I have been able to drive the car almost immediately, and all the mechanics I spoke to said it is fine to drive as soon as you reassemble it?

 

Thanks for the feedback.

For the MB RTV product, I did not start the engines (two down one to go) until the next day. In both cases, the RTV was still tacky the next day, but there were no leaks from the breather covers after starting the engine. I did have a little oil that had dripped from the open valve gallery onto the intake that smoked for a few minutes - that made my heart sink until realizing it was residual and there was no new leak. Overall, just follow the instructions on whatever product you use for how long the RTV needs to cure.

The Fort Lauderdale link for parts supplied MB valve cover gaskets for a price lower than AutohausAZ, with a one week turnaround so I have to give them props for service and price. For grins, I had ordered a Victor Rentz gasket to compare with MB. They were identical in appearance and seemed to come from the same mold; but the VR was less pliable than the MB. I suspect that the harder rubber will not last as long when placed in service.

Mike

 

they now have "right stuff" which cures in about 1 minute.

 

Atmsmshr: This is a great post and many thanks for it. It matches up nicely with what I've just observed about my oil consumption: the gaskets are leaking a bit in mine, and that is causing the high usage at high speeds. The dealership quoted me an hour and a half to do both, while they are changing the plugs and wires: so a total of about 4 hours for it all, $400. Since it is work that is well beyond my minimal abilities, I'll pay for it. I just purchased the gaskets and the breather hoses: I think they are likely plugged with grime, gunk, and replacing them will likely eliminate my oil consumption problem. Well on the road to perfection until my next fix

 

Good show in combining the spark plugs and valve covers for a labor savings. Out of curiosity, is the dealer also going to reseal the breather cover chambers with RTV for that price?

 

A picture of the breather cover chambers is shown below, and are labeled part #2. They sit on top of the valve covers, part #3. This black bead joint (Green arrows) usually only lasts as long as the valve cover gaskets (Yellow arrows) and should be replaced concurrently. The RTV that I used was MB brand at $40. Rather extravagant, but I wanted some assurance that this job would last 100,000 miles. The small bolts label #1 are aluminum - and are one time use only or they will break even with a light (4-Nm) torque.

 

You ask good questions that will help me request service. I'll have them replace the seal on the chambers, and replace the bolts: my guess is I'll pay more for those, but I don't mind purchasing small items from the stealership: it is the large items I get elsewhere.

 

add sealant

I know that previous posts have said to not add valve gasket sealant to the rubber gasket, but I would disagree. As long as you're careful, there should be no problem adding a bead to the inner groove or to the top of the rubber. This creates a better seal, and is how they do it at the factory.

 

I know that previous posts have said to not add valve gasket sealant to the rubber gasket, but I would disagree. As long as you're careful, there should be no problem adding a bead to the inner groove or to the top of the rubber. This creates a better seal, and is how they do it at the factory.

Uh, no they don't.

Adding sealant is absolutely not done at the factory, nor is it recommended.

There is zero point in doing so.

Install the gasket properly on a clean surface and tighten the bolts correctly, and the seal will be just fine.

 

Excellent write up -- I am about to do this job and I was already getting a little overwhelmed by the fact this SHOULD be a straight forward job without all these little issues haha.

 

ps2cho - thanks.

For a back saver tip - run the car up on ramps before starting. You won't have to bend over so far.

Watch out for the 4 and 8 N-m torque values - there seems to be a rash of over torques and broken bolts on the W163 forum.

 

Valve cover torque



I thought so. Before replacing gaskets, etc., on a 60,000 '99 ML320, I'd like to try just re-torqueing the bolts to possibly take up some gasket shrinkage. What torque values would be appropriate?

No major leaks, just visible seepage except for the rear passenger side at the bottom corner . . . there is a small drip there.

If this were an American car I would simply do it by feel. Based on what I see with the MB cars you have to not exceed a specific torque.

 

Gud post...

I was wondering...I take it this process is the same for any car with the same problem? Changing out around the 100k point? That's gud advise.

 

NITO - looks like you have the 4.3L engine - which is the same as the M113 engine seen in the post. For best results, take your time, use OEM parts, don't reuse the breather bolts, and don't over torque.

 

ATM: Top Post! You were exceedingly detailed in your Posts. Thank You. For the write up and detailed pictures.

 

Charles - thanks. Mike