Any common oil leaks on 300e's? - PeachParts Mercedes-Benz Forum

#1 05-15-2002, 08:55 PM

Well my girlfriend is finally bugged me to the point where I have to look at her car.

She says there is an oil leak but from where she has no clue. Is there a common place on a 89 300e for oil to leak.
thanks

chupr98 · #2 05-15-2002, 09:47 PM

tkamiya is right, head gasket, timing chain cover, plus valve cover gasket and if you are as unlucky as me, the transmission leaks as well.....german engineering???

good luck!!

#3 05-16-2002, 06:54 AM

The '89 has the single cam M103 engine which does not exhibit the head gasket oil leak as does the twin cam M104 engine.

The upper timing cover is, however, a common source of an oil leak. If so, you will see oil at the corner of the head/block/upper timing cover. It is usually a seeping leak, not a "pee on your driveway" leak.

If this is where you find the leak, it can be fixed relatively easily, but you need to use the correct sealant on the U seal at the bottom of the upper timing cover. The correct sealant is slick enough to allow you to push the cover rearward to put the shaft seal in place without disturbing the location of the U seal.

As far as the transmission leaking, I would be surprised if this automatic is any more prone to leaking than any other. The only way I know how to prevent having an automatic transmission that leaks is to buy cars with a manual transmission.

Good luck,

Mike Murrell · #4 05-16-2002, 11:11 PM

Passenger side corner of cyl. head on SOHC M103 motors is indeed are spot where oil is known to leak out of. Get a strong flash light and take a look in this area. Once the leakage from this area picks up, you'll begin to see oil dripping off the cross-member that covers the tranny torque converter. Some believe this is not a situation you want to ignore for too long. I forget if it's a feed or return line(oil) that's in the vicinity of the right rear corner. Either way, once the gasket gives way, you can loose alot of oil in a hurry.

yal · #5 05-17-2002, 12:34 PM

Yes 103 and 102 single overhead cams exhibit the headgasket leak at the back of the engine block around 100k on the clock.

autozen · #6 05-17-2002, 09:58 PM

Dan,

I'm throwing in with Mike and Yal. The 103 develops a classic leak at the right rear of the head gasket. There is a Tribeca area where the oil pressure, the oil return, and the coolant passages are in close proximity. Be sure to use an MB or Elring head gasket. I may get some opinion on this last statement, but that's good. That's how we all learn.

Good luck,
Peter

Gilly · #7 05-17-2002, 10:19 PM

I'm with Larry on this as far as the tendency for 103's to leak mainly from the front cover lip seal. My experience has been that the 103 rarely has a external oil leak from the head gasket itself. A failed headgasket on a 103 almost always is an internal leak from oil pressure into the cooling system, gives you the appealing "butterscotch in my coolant tank" effect.
On the actual repair, i have to disagree (if I understand his recommendation correctly) with the repair recommendation.
When reinstalling the lip seal (the U shaped seal Larry mentioned) only a thin film of oil is applied to the top of the lip seal. The ONLY sealant to use on this job is Loctite 5900, it's applied to the mating surface between the front cover and head (on the cover) and also prior to installing the lip seal a dab of 5900 is applied to the back of each side of the groove on the lower cover (the groove the lip seal squeezes into).
The 104's also leak from the front cover lip seal, but also from the right front corner of the head gasket (hard to tell between a front cover leak and a right front head gasket leak) and also the 104's will leak from the right rear corner of the head gasket. I've never seen a 104 mixing oil into the coolant like a 103 or a 102.
Gilly

autozen · #8 05-18-2002, 12:48 AM

Gillybenztech,

I think you need to regroup and think again. You are shooting from the hip. My guess is that the other professionals are chuckling from the sideline.

Peter

#9 05-18-2002, 06:55 AM

Yep it is the Head gasket. I told her it was more than what I would do on her car and took her to see the mech.
The car runs and drives fine so it is not that bad.

Mike Murrell · #10 05-18-2002, 03:12 PM

I'm not a pro, but a 30 yr. vet by the name of Stu Ritter(Ritter-Easley List) is. He's mentioned more than once that 103 SOHCs do indeed begin to leak from the right rear corner as time goes on.

Just went thru this myself.

#11 05-18-2002, 05:24 PM

I'm sure if she tells her parents they will probley just buy her a new car.

Gilly · #12 05-18-2002, 09:07 PM

Peter:
Pretty much all advice given here can be considered "shooting from the hip" when it comes right down to it. No one should consider all of this advice as 100% accurate, I would be hesitant to have anyone have a repair done based solely on someones advice who has not looked at the car.
I stand by my comments that usually a 103 engine head gasket failure displays itself as oil getting into the coolant, not an external leak----I said "usually", and 104's usually have external oil leaks as being discussed here.
If other technicians want to disagree, they are free to voice their opinions. Maybe southern Wisconsin is just some Bermuda Triangle of 103 head gaskets, and that's why this external leak from the gasket itself seems to be non-existent. Lip seals, tons of those.
Peter, so you've never seen a 103 with oil in the coolant, is that what you are implying?
Gilly

blackmercedes · #13 05-18-2002, 09:28 PM

Knowing lots of M103/102 owners, and being an ex-M103/102 owner myself, I would comment that they have a lower incidence of head gasket failure than the M104 engine.

However, the front cover is quite failure prone. Follow Gilly's advice on that repair, and it'll last much longer than it did from the factory.

I've seen some M103 engines with leaking main seals, front and rear. On further inspection, found severly overfilled crankcases.

Overall, I wouldn't characterize the M103 engine as a "leaker." Sure, they can, and do, but I think overall the 103 is pretty good.

Gilly · #14 05-18-2002, 09:59 PM

Yes in general the 103's are pretty darn good motors, and the head gaskets do fail slightly more often on the 104's. It also seems to me that we see more 103 engine cars than 104's (where I work, the Bermuda Triangle), so yeah, maybe the 103 is quite a bit better in this regard.
It still baffles me why anyone would say that 103 engines don't have gasket failure which only leak oil into the coolant, that's really the only reason we replace them, and you end up replacing the coolant tank, overflow tank, and usually a bunch of coolant hoses, plus flush it 2 to 4 times to get the oil out of the cooling system. Yuck!
Gilly

haasman · #15 05-19-2002, 12:14 AM

My '91 300E is leaking a little oil from the front of the engine. I pressume this is the cover leaking as Gilly spoke about. It leaks high, but doesn't look like the head gasket.

If it is the cover, how long does this repair take?
Should I just follow the repair suggestions here or are there other threads to look up as well?

Thanks