104.992 from 1994 - common issues compiled. - PeachParts Mercedes-Benz Forum

cphilip · #1 11-28-2008, 04:00 PM

Just one post I searched and found goes all around the specifics and seems inconclusive

Tell me what you know about this motor.

Looking at one that I believe has suffered a head gasket issue in the past (maybe but no records) and now has a slight oil leak from up high somewhere around rear of Valve covers (maybe). Still trying to find exactly where its coming from. Very hard to find it but have had it on lift cleaned and run hard a few times but small amount only seen around rear valve cover. But puddle about 3 inches diameter found under it where it had been sitting a while. Perhaps some had collected on the plastic belly pan and leaked afterward but now we have removed the belly pan and can't seem to get it to drip for us.

I say and conclude it may have had a Head Gasket job because it has a brand new Water pump (as well as many new hoses) on it. Some evidence of valve covers and head being removed (tranny dipstick not completely buttoned down the block). Also a dirty line around the inside of the coolant recovery tank but no oil in coolant (currently has wrong coolant in it but it is real fresh wrong coolant). But there is just a grunge line where it probably had some at one time and was not completely cleaned out.

Oddly, and probably not related, it appears to have a new Power Steering box (Remanufacture sticker on it)

Does not smoke, runs at normal temps and runs strong.

Also would like to know what else to look at while in there on these motors.

suginami · #2 11-28-2008, 05:08 PM

The typical head gasket leak is at the right rear corner (passenger side) of the head.

1993 - 1995 M104 motors also have bad engine wiring harnesses. Try the search function to read up on it. You might check your to see if yours is original or not.

Also check the part number of your OVP (Over Voltage Protection relay). It sits behind the battery. Do a search for OVP for the old and new part numbers. They are cheap, so change yours if you have the old part.

cphilip · #3 11-28-2008, 05:21 PM

Thats specifically where we were looking for it. And in the general area we see some oil (we think) but yet it is wet up higher than that around the Valve cover. But we cannot tell for certain due to the small amount that regathered after we removed the belly pan and cleaned it all off good and ran it trying to see if we could see new oil. But we could not see much more than a weep around the valve cover gasket. Even with a good lift and good lights. And the other evidence points to it having a past heat issue and that being done but I cannot tell if the Head Gasket was done or not.

The car is a possible purchase car so I (and the seller) are trying to determine the cause before we discuss price. At this point his mechanic is going to look into it more Monday. And I am going to talk to mine about a general ballpark for doing a head gasket and he and I will then talk again. Any guesses on what a good Indy might end up costing to do a head gasket at 60 bucks an hour?

Not sure exactly how to investigate the wiring harness. I had read about that but it was unclear to me where I would find the problem and what to be looking for...

I will search OVP...

suginami · #4 11-28-2008, 05:26 PM

Quote:

Originally Posted by cphilip

Thats specifically where we were looking for it. And in the general area we see some oil (we think) but yet it is wet up higher than that around the Valve cover. But we cannot tell for certain due to the small amount that regathered after we removed the belly pan and cleaned it all off good and ran it trying to see if we could see new oil. But we could not see much more than a weep around the valve cover gasket. Even with a good lift and good lights. And the other evidence points to it having a past heat issue and that being done but I cannot tell if the Head Gasket was done or not.

The car is a possible purchase car so I (and the seller) are trying to determine the cause before we discuss price. At this point his mechanic is going to look into it more Monday. And I am going to talk to mine about a general ballpark for doing a head gasket and he and I will then talk again. Any guesses on what a good Indy might end up costing to do a head gasket at 60 bucks an hour?

Not sure exactly how to investigate the wiring harness. I had read about that but it was unclear to me where I would find the problem and what to be looking for...

I will search OVP...

An indy might charge $1,400 - $1,600 for the head gasket.

Just put "wiring harness" in the search box. There are pics posted. The insulation flakes off, causing shorts and all sorts of check engine light problems.

cphilip · #5 11-28-2008, 05:34 PM

That seems more like a MB dealer price to me than an Indy!

None of them seem to point to where under the hood or in the cab that this wiring harness problem is best to look for. But there are good pictures of it once you get there. I just have no idea where to start to look yet.

http://homepages.roadrunner.com/infoage1/complaints_nhtsa_mercedes_wiring_harness_failures_images.html

The OVP one is fairly straight forward... I will transfer that here for ease of finding

Overvoltage Protection relay.
MB number 000-540-52-45 are known bad,
replacement number is 000-540-67-45.
Located behind the battery, remove plastic cover & there it is.

suginami · #6 11-28-2008, 05:42 PM

Did you read this thread:

http://www.peachparts.com/shopforum/showthread.php?t=128181&highlight=wiring+harness

cphilip · #7 11-28-2008, 06:03 PM

Yes... I believe thats where I pulled the link for the picture from.

Again... no one seems to indicate WHERE to examine this. Well.. one or two references deep in the NHTSA complaints I found a reference to under the hood over the engine, thats vague as no harness bundle runs over the very top of the motor. I imagine its one side or another.

I can say that this oil leak we have not quite found is very close to or near where you would expect to find a Head gasket to leak oil in this car. I just can't yet be certain as its not showing well. I would think a florescent Die in the oil test would be helpful?

suginami · #8 11-28-2008, 06:09 PM

You can cut away some of the black fabric covering the wiring harness anywhere, like along the firewall. Just be careful.

cphilip · #9 11-28-2008, 06:17 PM

Sounds good. I did see one mention that there was some areas without fabric covering that it could be seen. Can anyone confirm?

Arthur Dalton · #10 11-28-2008, 06:54 PM

Blu . 2 wire sensor on the termo housing...pull back the outer sheathing and look for dry, brittle. cracked insulation...you can cut back there a couple of inches with scissors w/o fear of having to recover/repair the sheathing.

cphilip · #11 11-28-2008, 08:54 PM

Thanks guys...

More inspection to do next week. Will be a shame if I have to pass on this one. I am almost resigned to abandoning looking at the "afflicted years" after this point. These particular years wagons are so nice though. Certainly this one was a cherry plumb without these issues rearing up. But... they may be there. I will have to see. Then its up to him if he wants to take the hit because I won't take it all.

suginami · #12 11-28-2008, 09:52 PM

After the head gasket and wiring harness have been taken care of, these are really really good cars.

Remember that this engine was in continuous use up to 1999 in the W140 chassis S320. This inline-6 engine is really sweet. I prefer it to the next generation M113 3.2 liter V6.

You just have to buy the car at the right price.

Arthur Dalton · #13 11-28-2008, 10:21 PM

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Take an extra 5 min. and access the codes...

crashone · #14 11-28-2008, 10:57 PM

The valve cover gasket is actually 3 piece. There are 2 pieces that are "U" shaped that fit in the block, one in the back and one in the front. The one in the back may be leaking. You could possibly use an inspection mirror and light to see if there is a leak in that area. If you are getting a good deal on the car, have some fun.

deanyel · #15 11-29-2008, 07:38 AM

Quote:

Originally Posted by cphilip

Thanks guys...

More inspection to do next week. Will be a shame if I have to pass on this one. I am almost resigned to abandoning looking at the "afflicted years" after this point.

Not arguing for this car but don't lose sight of the big picture. Where are you going to find an engine less "afflicted" than these? They have bulletproof bottom ends, bulletproof top ends, excellent timing chains, excellent DIY diagnostics, etc. In the bigger picture over the long term the wiring harness is almost a non-issue, and a head gasket should only be a one shot thing too. The only arguably less troubled engine is in the E420 which does has more timing chain risk.