300CE - 24 oil leaks

[joconey]

Hi, new to this club and wondering if anyone can help me with a couple of pointers.

I recently bough a 1992 300CE-24 Sportline. It drives very nice but it has an oil leak from the front of the engine that's is running over the alternator and down the chassis. It is not a head gasket as water is fine and not milky; there is no smoke coming from the engine (smoke from the exhaust and manifolds, of course) and still pulls strongly. I drove it 400 miles to get it back here stopping about three times to check and top it up.

I have seen that it may be the front timing cover seal leaking. Does this sound right? If so, is it a big job? Any other ideas?

Also, the auto box clunks when changing (worse when cold). Vacuum or Diff?

Cheers

John

 

[mattc]

use the search engine; you will find it probably is as you describe. the seal is a u shaped gasket and is a typical weak point (though I am no expert - I get someone esle to do my oily stuff) from what I read.

So the question is how handy with the spanners are you and do you want to do the job yourself? As a matter of interst how much oil did you use in that 400 mile journey?

with regard to the clunking gear box is it a 4 or 5 speed one? Could be simple vac line has come off or is it the prop shaft where they are jointed. Could be as simple as ATF fluid levels - have you checked this, when was it last changed?

Also just to give us all an idea what mileage and history do you have with it?

 

[kth286]

joconey

mercedes acknowledged the fill capacity of this 104 engine was too much and issued a bulletin back in 1995 stating not to fill more than half way between min and max.

This action cured my leak over the alternator side of engine.

 

[EDZ649]

It will be the 'H' seal at the front of the head behind the camchain cover. Common problem and it's a head off job to rectify I'm affraid, just had my V12 done at PCS. Your looking at about £500 labour plus the head kit and stretch bolts!

Clonking could be prop shaft couplings or rear subframe mounts or..........

 

[joconey]

Hi Matt,

I guess I used about 2 litres in all. It has a FSH, all documented and mostly Merc or accredited. Used to be quite handy under the hood until everything started to get a bit complicated. Has 133K on the clock and the rest of the car is almost concourse so it has been looked after.

Tranny levels look fine, it is a 4 speed.

Cheers

John

 

[Apial]

The original head gasket has been modified to prevent leaks from oilways that are near the edge on the manifold side. This is a very common problem on the M104 and once replaced, the head gasket does not appear to cause anymore trouble.

With this type of leak you only get the oil running out down the side of the engine and it does not always affect the oil or the compression.

 

[joconey]

Thanks for that. Pardon my ignorance but not familiar with the M104 motor - is this a big job in terms of labour/cost?

Cheers

John

 

[kth286]

It will be the 'H' seal at the front of the head behind the camchain cover. Common problem and it's a head off job to rectify I'm affraid, just had my V12 done at PCS. Your looking at about £500 labour plus the head kit and stretch bolts!

Clonking could be prop shaft couplings or rear subframe mounts or..........

NOT a head off job on the 104 straight six engine to do that U-shape seal, which is indeed a common problem on higher mileage cars.

However, lots of oil being used and therefore suspect that maybe the front crankshaft oil seal may also be gone, as that is also a very common problem on these engines (unless the oil is being burned of course).

 

[joconey]

Thanks KTH,

I really don't think the oil is being burned - there is no burning or smoke when the oil cap is off and the oil dropping is very clean. Think it may be going straight in and then coming straight out again.

Cheers

 

[EDZ649]

NOT a head off job on the 104 straight six engine to do that U-shape seal, which is indeed a common problem on higher mileage cars.

However, lots of oil being used and therefore suspect that maybe the front crankshaft oil seal may also be gone, as that is also a very common problem on these engines (unless the oil is being burned of course).

So how do you replace the seal then? It is sandwiched between the head and the block.

It's not a mileage related problem, its due to the age of the seal, they harden with heat and age. The seals on mine were like stone! My car has only done 76K.

There will be a new crankshaft seal in the head kit.

 

[lynall]

SEALING THE FRONT COVER

One of the last steps is sealing the front cover that caused the whole problem. Unfortunately, the front cover has to come onto the pin on the driver's side horizontally and, in that position, the gasket won't fit. As a result, the whole thing has to be assembled very carefully. (It's a problem that's similar to the seal on the top of Volvo four-cylinder water pumps.) Care must be taken as the cover is pushed down and back, not to roll the seal out of the indentation in the lower cover.

The process of sealing also has been covered in updated information from Mercedes. There are two recommended sealants: The first,M-B p/n 002 989 47 20 10, is used sparingly on the vertical metal-to-metal surfaces. At the point of convergence between the head, head gasket and the cover seal (see Photo 10 with the head removed),

Remember doing head gasket on wifes e320 m104 and sticking the head back on the and doing all the timing gear afterwards so must be possible.



Lynall

 

[Apial]

Thanks for that. Pardon my ignorance but not familiar with the M104 motor - is this a big job in terms of labour/cost?

Cheers

John

Its a big job. I can't remember how many hours, but the head gasket bill came to around £1k for parts and labour.

 

[kth286]

That U-shaped seal is the seal for the UPPER FRONT timing chain cover.

It is in front of the engine and therefore in front of the head.

This top cover is sealed at it's lower front and lower sides with that seal, and it is glued to the front of the head on its upper sides.

There is a fair bit of dismantling to do, like head top cover, and top chain guide and chain tensioner etc, and various small seals need to be renewed, but the most difficult part is getting the top guide rail pin out from the this top timing chain cover, so as to remove the cover.

Also some coolant needs to be removed to avoid a mess when the front coolant pipe running across the front of the engine behind the fan is undone.

 

[lynall]

Pulled my pin out with an m6 bolt and a few washers and sockets to act as spacers.



Lynall

 

[Ian B Walker]

Quick tip for fitting this seal. Run a file over the back edge of the housing to remove the sharp edge as it drags the seal in when re fitting. Also use some silicone grease on the seal. Dont be tempted to glue it in as it will cause you loads of grief later.

 

[davidbilyk]

My previous 124 used to clunk from cold, my local indie did the diff mount for me and all was quiet again! Does it clunk from the rear, middle or front of the car?

 

[joconey]

Hi David,

It comes from the rear - I think.

Cheers

John

 

[joconey]

Thanks all - turned out to be the Cam Shaft Oil Seal so no head (gasket) aches

Added tranny oil - still thumping a bit but hope it will calm down and the thermostat is ok (still don't know why it runs cool, though).