Front cover leak 103 - PeachParts Mercedes-Benz Forum

lee polowczuk · #1 01-18-2008, 07:13 PM

How much oil would you typically lose through the front cover leak area.

I am still having oil issues with my 103 3.0 on the 300ce.... i have replaced the valve stem seals...but i am thinking this might be a culprit, too..

the front cover is clean from the front side... but when i put my finger behind it... it is very oily..also oily below it...

i have that pesky little gasket...and can do the job when the weather gets better..

i had just expected to see oil in the area where the cover meets the head gasket.

car continues to run perfectly.

JEdwards · #2 01-18-2008, 07:44 PM

my valve cover gasket is leaking and my top timing cover gasket is leaking, and neither of them contribute to any oil loss (oil loss is negligible). There is another thread here where I talk about disappearing coolant with a picture of the front passenger's side of my engine and the oil slick is substantial, but not enough to lose more than 1/3-1/2 of a quart every 2k miles. Perhaps you are experiencing oil loss somewhere else?

I'll also note that my oil drain plug is not long enough, and subsequently some oil weeps out there too.

anthonyb · #3 01-19-2008, 06:20 PM

A little bit of oil from the front cover can cause a lot of mess. Chances are it's not a ton of oil, but the fan is spreading it all over the place. Typically they leak from the bottom of the cover, and it runs down to the passenger side, then down the passenger side of the block.

lee polowczuk · #4 01-19-2008, 08:57 PM

i am going to clean up the bottom of the engine..and see if i can isolate any leaks..

this car does not have the bottom pan in it...so i can see drops on the driveway...

i should have addressed this sooner..but i honestly thought it was a problem with my valve stem seals...but it is a step beyond that....

oh well.... i probably shouldn't have concluded it was the valve stem seals because the car always seems to run perfectly...

Zeus · #5 01-19-2008, 11:19 PM

lee - I had over 300,000 Kms on my 300E when I sold it. The car had the oil leak from this location since Day 1. Consumption would vary. On long highway trips, high revs, I'd have to add a fait bit of oil, say about 1L/800Km or so, sometimes more. Less when city driving, and less in the winter. All of which was consistent with the oil leak. Always carried oil in the trunk.

I never had any issues with the engine other than this leak. Car still have original everything when I sold it - valve stems, etc. All original. Ran perfectly. No visible signs of oil consumption (no blue smoke, etc.) and plugs were clean. Emissions (cat) also fine.

I tried to fix that leak several times - even bought a new timing chain cover piece. Had the gasket sealed several times, also the camshaft seal. Didn't help, it still leaked.

On the plus side, my engine was spotlessly clean inside. The cam/rockers glistened.

Down side, I went through a fair bit of oil. Though I sometimes wonder if adding all that fresh oil helped keep the engine so clean and helped prolong its longevity and remarkable long-term performance.

So long story short, yes, you can lose a fair bit of oil from this leak, especially when the engine is hot and working hard.

Just my $0.02.

lee polowczuk · #6 01-19-2008, 11:29 PM

thanks Zeus...

i am experiencing what you are... I just want to keep the CE for the long run...

ha-ha-ha..keeping a 19 year old car for the long run...

truth be told, i would like to have it as a daily driver for another 4-5 years...

and then restore it..... and keep it for an occasional driver until they put us in the grave.....

riorust · #7 01-19-2008, 11:56 PM

I'm new to MB's, but my 190 2.6 leaks in the same place. Pretty common from what can gather.

I've lost about a 1/2 qt. over the 2K miles/since August 07. It is not much to worry about. It seems to leak out o the passenger side and work its way down along the block, making for some oily sway bars and all.

I will be replacing that seal next weekend because I don't like my cars to leak oil . From what I understand , the leak is a splash type leak, that is, not coming from a high pressure passage, so some seepage can be tolerated.

It seems like an easy fix and it is the right thing to do with the other fixes I had in mind (timing chain tensioner, cam seal and dist. seal). I figure some gaskets, seals, labor, GOJO, a couple of friends and some beer and I'll be done in time to watch the game!

psfred · #8 01-20-2008, 01:53 PM

Here's what I've been told about that leak:

The leak is usually NOT the seal itself, although they do eventually, like all German rubber, get hard and shrink. Leaks a LOT then.

The real cause of the leak is failure of the sealing compound to adhere properly to the front cover/head/seal intersection, and since oil sits on there any time the engine is running, it oozes out.

The correct method of sealing is to clean the groove in the front cover and the bottom of the top cover spotless. Use brake parts cleaner, etc and get any and all old sealant out.

Place a 1/4" spot of Loctite 5910 or 5900 sealant (and only one of these) in the corner and trace 1/8" bead of it around the seal surface on the head.

Wipe a thin trace of silicone grease on the bottom of the top cover.

Install seal DRY into the goove, press home in the corners. The sealant must contact the full corner AND the ends of the seal Seal must be squeaky clean and dry, especially at the ends.

Place cover on camshaft, making sure the camshaft seal goes in place correctly (there is a tool $$$ for this). Press cover down and in to engage locating pins, and then PRESS DOWN while pushing in at the bottom of the cover to fit into place. DO NOT rotate the cover downwards using the locating pins as leverage, this rolls the seal over. The silicone grease enables the cover to slip on the seal enough to get the cover in place without rolling the seal over.

If you do not put the sealant in the corners, use anything but Loctite 5900 series (soft set, high adhesion), or rotate the cover into place rather than sliding it straight on, it will leak.

Check to make sure the seal didn't flip over, too, before you tighten to bolts up.

I would recommend Loctite 5910 -- it's easier to find, and has a set time of 20 min rather than 5 min.

Perfectly installed, it should give you at least 30,000 miles of leak free operation. Probably not more, though... bad design.

Peter

lee polowczuk · #9 01-20-2008, 02:07 PM

Quote:

Originally Posted by psfred

Here's what I've been told about that leak:

The leak is usually NOT the seal itself, although they do eventually, like all German rubber, get hard and shrink. Leaks a LOT then.

The real cause of the leak is failure of the sealing compound to adhere properly to the front cover/head/seal intersection, and since oil sits on there any time the engine is running, it oozes out.

The correct method of sealing is to clean the groove in the front cover and the bottom of the top cover spotless. Use brake parts cleaner, etc and get any and all old sealant out.

Place a 1/4" spot of Loctite 5910 or 5900 sealant (and only one of these) in the corner and trace 1/8" bead of it around the seal surface on the head.

Wipe a thin trace of silicone grease on the bottom of the top cover.

Install seal DRY into the goove, press home in the corners. The sealant must contact the full corner AND the ends of the seal Seal must be squeaky clean and dry, especially at the ends.

Place cover on camshaft, making sure the camshaft seal goes in place correctly (there is a tool $$$ for this). Press cover down and in to engage locating pins, and then PRESS DOWN while pushing in at the bottom of the cover to fit into place. DO NOT rotate the cover downwards using the locating pins as leverage, this rolls the seal over. The silicone grease enables the cover to slip on the seal enough to get the cover in place without rolling the seal over.

If you do not put the sealant in the corners, use anything but Loctite 5900 series (soft set, high adhesion), or rotate the cover into place rather than sliding it straight on, it will leak.

Check to make sure the seal didn't flip over, too, before you tighten to bolts up.

I would recommend Loctite 5910 -- it's easier to find, and has a set time of 20 min rather than 5 min.

Perfectly installed, it should give you at least 30,000 miles of leak free operation. Probably not more, though... bad design.

Peter

thanks.... i'll do this when it gets warmer....

i have actually had the rubber seal for a couple of years... just never did this job.... but it can't be more difficult than the 5 hour water pump job....

psfred · #10 01-20-2008, 02:22 PM

Nothing at all like that waterpump!

Peter

Zeus · #11 01-20-2008, 07:08 PM

lee - another culprit I looked at back when I was tackling this issue (and before I gave up, accepted it, and started buying oil in bulk) was that the camshaft could have worn to the point where it was not sealing properly at the camshaft seal, given the high mileage. Therefore no amount of sealant, etc. was going to stop that. My techs (competent and proven) tried several times to stop the camshaft seal leak and the timing chain leaks (did it a few times, no charge, etc.) but it would end up leaking eventually.

Other than that, that M103 was one hell of an engine!

JEdwards · #12 01-21-2008, 07:54 AM

For the front timing cover seal there is a DIY article that describes the process step by step with pictures - I'd check that out under the DIY Articles tab above.

Kestas · #13 01-21-2008, 09:01 AM

Peter's writeup is spot on - good post. That's exactly how I repaired my upper timing cover leak and it's still dry 5yrs/25K later. One mistake people make is they try to beef up the upper timing cover seal by adding a layer of Loctite sealant with the U-seal. I believe this seal needs to "float" with the thermal cycling the engine experiences. Extra sealant will only hamper this function.

Jackd · #14 01-21-2008, 08:32 PM

Peter's write-up is spot on.
In my 17 year of ownership (1989, 260E) I had this job done maybe 7 or 8 times, by the dealer and by independent mechanics.
Every time, it lasted anywhere from 6 months to 1.5 year....until I decided to do it myself.
There is no magic trick. Disassembly is strait forward, re-assembly is what makes it.
GO SLOW, clean, clean, clean, every surface, every groove, every joint.....and clean again.
When you think your done with cleaning,,,,,,,,,,
clean again.
Reassembly everything s-l-o-w-l-y.
Apply the proper torque to each bolt. Use only Lock-Tire 5910, sparingly
Let it sit a few hours after the job is done.
I've done the job about 4 years ago and there is still absolutely no leak.
Good luck

lee polowczuk · #15 02-28-2008, 08:11 PM

well, i did two jobs.... the horseshoe gasket and the oil level sender o-ring.

500 miles later, haven't lost a drop of oil.

I think it was the horseshoe gasket that was the real issue.

I had replaced the valve stem seals and that didn't cure the issue... although i am glad i spent the 30 dollars to do the stem seals and a new valve cover gasket

When i got the car at 124k i was losing or burning a quart at 1200 miles... it had dipped down to 350-400 miles a quart at 166k even after doing the valve stem seals.

I started to get more of a cue that it was at least the horseshoe gasket when i started to smell oil burning when the car was stopped. oil was leaking onto the exhaust pipes or manifold or something.

i suspect it was more of a horseshoe problem..because very little oil was coming out of the oil level sender. That was a 20 minutes job.

I know 500 miles isn't a real indicator...but a couple of weeks ago , i would have already added an entire quart of oil.

i'll post again at about 2k miles or whenever it is low a quart. My light comes on when it is down a quart.

I could not find the 5910 the day i wanted to do the job. Spent 16 dollars on some red stuff... it seems to be working. If it doesn't i'll get the 5910.

i have one more horseshoe gasket in the parts bin. I may do the sons 300e. He seems to have a small leak there