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Discussion Starter #1
Just bought a '91 300E with 227k miles for 1500, upon a trip to the mechanic oil was discovered in the coolant reservoir, the sellers mechanic swears the changed the radiator leaked tranny fluid in the coolant tank and to just flush it. Merz benz dealer over the phone said just replace the coolant reservoir since there is NO coolant in the engine it doesn't seem to be the gasket. Tire pros also said the same thing oil cap was fine and just flush the coolant. MY mechanic said to do the head gasket and valves. German auto specialist said gasket too. 3 guys said gasket 3 guys said it's not.

Am taking it to get flushed and bloc tested for what type of oil in there tomorrow. I just bought it and didn't expect problems but if it is the gasket I can get the valves done too for 1500 and likely will. Coolant oil temp was 100C yesterday 85-90C (because there's oil in there its hotter on the sensor? Here's what it looks like. Hopefully that is rust only. Cheers
 

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W124
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Lesson number one. Mercedes dealerships are populated by young people with no experience on 25 year old cars.

Clearly the one who told you there is no head gasket issue doesn't know these cars. The primary causes of head gasket replacements on these motors are oil seeping into the coolant and oil leaking at the back of the engine/cylinder head parting line. Your German specialist is right.
 

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1995 W124 E320 Cabrio
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You should sell your car if you're listening to what people at Tire Pros are telling you about the engine on your W124 (god I'm turning into sbaert!)

Who is your mechanic? How old is he? Is he factory certified by MB and Bosch? If not, go straight to the German specialist. I'm hoping he's over 50, and if you're lucky there will be a wall of accolades and qualifications with decades of certifications on one of the walls in the office.

Anything less is like having open heart surgery performed by nursing students at an urgent care center.

This is serious. If you expect to get significantly more miles out of the car, you need a valve job and head gasket replacement, including machining the head, as it's likely warped.

That's just to fix the consequence of whichever neglected part(s) caused the overheat to begin with. Viscous fan clutch is usually fried by now, I'd also have the German specialist test the radiator and the aux fans + all components, thermostat, coolant temp sensor, etc.

After I had a full valve job done on my 95 Cabrio, I had him install a relay that turns on the aux fans anytime the climate control is on, whether the compressor is on or not. You can also have the viscous clutch adjusted to "kick in" at lower temps. May affect your takeoff off the line but will keep your engine cooler.
 

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Current, 90 300CE, 92 400E (Sold 95 E320,70 250C, 91 190 2.6, 91 420 SEL, 95 300D, 87 TD)
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^
"You should sell your car if you're listening to what people at Tire Pros are telling you about the engine on your W124 (god I'm turning into sbaert!"

:ROFLMAO: :D:ROFLMAO:
 

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95" W124/ E220 MasterPiece and 01" W210/ E200 KOMPRESSER
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Both gasket failure and a leak of the transmission circuit line in the radiator are possible causes as shown in your pics .

If I were u, I will detach the bottom main big coolant hose and flush and flush with running water for several times and last for several mins.
This just intends to remove the contaminated coolant in the cooling circuit and verify the source of the leak.

After the flush, go for a drive ...if the oil comes back and its color seems like the engine oil...
You will need a gasket service for sure. Good luck.

PS. Given the pic you post, the gasket failure is the most likely cause IMHO.
 

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Discussion Starter #6 (Edited)
Thank you all for the comprehensive responses. The block chemical test was inconclusive for engine oil no reaction whatsoever and he deemed it rust because mainly water and no coolant was in the reservoir. (Triple A mechanic former Merz tech) (no reaction chemical block test) , then deemed the drive belt, tensioner , shock, idler pulley as time to replace (Got out of there quick after $1700 quote and 150 for this today). Took it to German import specialist and he said little oil leaks from the engine are fine dont worry about the gasket on these but sniffed and tasted (wow) the oil in coolant. Said let's flush it tomorrow and monitor it for a week to see if more comes back. ATF good (nice job he said) oil good. (radiator?) pressure test tomorrow as sometimes it is a transmission line leak(?). So I went and bought a top hose (only one needed changing) for radiator, temp sensor(fail safe) , coolant (Peak euro 50/50) and went to a radiator guy who said we will flush monitor it as well. Drive it and check it tomorrow. Find a leak if there is one.
Maybe air pockets still in the temp as it bounces and then settles back down but is around 100C , German import specialist (old guy) (different from German auto specialist (young) said that's the operating temp is fine a little hotter on these and that if it is the head gasket a better price for buying it would have been 1000. Eagle rock auto import says run from the triple A guy and do the head and valve job asap. I'm inclined to do so just so I dont get stuck w out a car soon as the funds become available. Radiator changer guy swears it was from his job changing the radiator and says see I told you so the block test chemical didn't react. Tapping on the dash makes the needle stop bouncing.
EGR passage blocked when smogged but he still passed me and said get that fixed.
 

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My advice; stop getting advice. You have more than enough opinions. It could be the cylinder head gasket but take the least expensive option first. Flush the system with a citric cleaner then run water for a couple of days and then do that same process two or three more times. Give the coolant reservoir a really good cleaning (remove it to do this right). Then refill with Zerex Z05 or equivalent coolant; you need something that plays well with aluminum. Run the car for a few weeks and see what accumulates.
 

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^Yes, indeed, try the easy solution first and I hope you get lucky, but oil in the coolant, air in the coolant, and running hot are all classic signs of a failing head gasket.
 

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Head gasket is common on these so those telling you you need to get it addressed are more likely to be correct.

Flush your coolant. Several times. Change your oil immediately after the last flush. Observe.
Budget for a head gasket and valve job in the meantime.
 

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Discussion Starter #10
German import specialist is German auto specialists father, took it to the father and he flushed again and said there was rust in coolant in engine flush. Monitor for 600 miles and bring it back later. Note: this car was parked in a driveway for a while not being used and the sellers indy mechanic says he used water and coolant (which would rust sitting there). but if it was 50/50 coolant and water that would explain the high water concentration in the reservoir. Still setting aside money in case I can do the head gasket and valve job anyway in the future to make this car last a good long while.
Question: with another coolant flush is the mechanic able to tell if the radiator trans line was leaking ATF or any radiator leak. It's a BEHR and I'm not aware of it having a trans cooler.
 

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Discussion Starter #11
After two flushes there is still a light brownn film developing in coolant tank that hangs around the top outer edges in tank. Mechanic wants to monitor the oil levels after 600miles of driving. I want to go ahead and change the radiator which was changed to a behr but maybe was used at the time from sellers indy mechanic. Trans heater exchange side in radiator hoping.
 

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You should definitely expect problems with a 29-year-old MB with 227k, especially one that’s been sitting (why would it have been sitting if it was running well). Personally I would be very reluctant to throw a lot of money into a head gasket for this vehicle
 

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If the car had rust in the coolant, that radiator is already shot from that so you need to be changing it for that as well as the potential of it leaking
 

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Discussion Starter #14
Not sure if any mechanics i went to did a compression test on the spark plug areas. Going to bring it in again and see what comes up, thank you for the responses, highly appreciated
 

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Just be aware that there are two common failures of the head gasket:
1. The rear most oil return galley leaks oil to the outside of the engine. This is observed at the parting line between the head and block on the exhaust side, at the rear of the engine - number 6 cylinder.

2. The head gasket fails between an oil passage and a coolant passage. With oil pressure higher than coolant pressure, the oil leaks into the coolant.

Neither of these will be proven through a compression check as long as the compression rings on the gasket are in good shape. If you want to test out whether or not you have a transmission cooling loop leak in the radiator, remove both lines, make up a test rig with a couple of fittings and rubber hose. Put 16 lbs of air pressure on the transmission cooling loop with coolant in the radiator and look for and listen for bubbles. No bubbles/no leak.
 

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Discussion Starter #16 (Edited)
Ok back from the German import specialist and coolant still looks good after 600 miles post flush, (minimal brown stuff around top outer edge of coolant and some random specs)
water pump was wobbly and could have been the rust issue as the bearings may have been wearing down some. Drive belt cracking
idler pulley tensioner replace and water pump is what he wants to do for 900 and then I can sock away for front struts which are weakened and gasket(if needed later) he says use conventional oil instead of 5W-30 SAE
Autozone says 0-40/5-30
Oreillys says 5w-40
I'll ask previous seller if it was synthetic or conventional oil

Is it a hassle to have the mechanic fix the water pump and belts initially separately from the gasket and valves or should I save up for the following
Wish list - Repair in order of importance or all at once
Fan clutch (check it out or change) (might be the wobbly thing near the water pump instead of pump)
Water pump wobbly
Drive belt cracking
Belt tensioner
Idler pulley
Head Gasket Valve job
Front Struts
EGR passageway blocked valve(passed smog but he looked the other way on test, engine should stumble when vacuum line is applied and it didn't)(600$ to clean (wow) ? much to replace altogether)
 

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Interestingly, you can do the head gasket job without touching the water pump, tensioner, or serpentine belt. So in essence, you CAN do the pump, belt, and tensioner now and not worry that all this will have to be removed or even touched once the HG job is done. The only point at which both jobs "intersect" is at the short hose connecting the pump to the head. You would be best served to replace that $6.00 hose each time you touch it.
 

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Second that! The front end work (water pump, PS pump, fan assembly, radiator, timing chain guides, serpentine belt etc) is very decoupled from head gasket / head machining work.

Maybe there is the overlap of a couple of gaskets and the short hose, that is it, like tuttebenne already posted.

I have re-done the head 1-2 years ago and am still waiting to do the front end work which will involve:
(1) Timing Chain
(2) Chain guides and tension-er guide
(3) oil pump chain
(4) Serpentine Belt
(5) Water pump
(6) Belt tension-er and dampener
(7) Pulley seal
(8) Etc. Etc

None of the items has failed yet (completely), but once one does all will be replaced, parts in hand.

- Cheers!
 
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