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  #1  
Old 09-02-2004, 02:22 PM
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Question 300E - Persistent camshaft seal leak - Opinions?

Hey guys,

I need some advice/options. I have a persistent oil leak originating from the camshaft seal inside the timing chain cover/housing. Thus far, I have replaced the camshaft seal numerous times, I've installed a new timing chain cover/housing and I've replaced the valve cover gasket as well.

My mechanics have replaced the camshaft seal three times for me (last 2 times for free) but the leak persists. Over time, the oil will foul the distributor cap and rotor enough to cause a noticeable rough idle (the engine runs perfectly otherwise). I periodically remove the cap and clean the cap and rotor but this is obviously not a desirable remedy. There was also a leak coming from the timing chain cover where it mates to the engine block, along the lower part, but the new cover and some MB sealant cured that leak. The volume of oil lost has gone down dramatically since I fixed that, but some is still leaking via the camshaft seal.

I'm at a loss as to how to cure this problem. I'm guessing perhaps the camshaft itself has worn down such that it no longer fits the timing chain cover smoothly and no amount of new seals is going to stop the leak? The engine does have 300K on it and everything is original.

Short of buying a new camshaft (and hence probably rockers, etc. may as well do the entire head while I'm at it) is there anything I'm missing?

Any advice would be appreciated.

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2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired


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  #2  
Old 09-03-2004, 01:09 AM
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Chris:

300K on the motor.....

Time for some work I suspect.

Not sure if the cam end rides in a journal type bearing? If so, some basic head work and a new cam might do the trick.

I think I'd give up on the fix it over and over thing and pull the head, then find a good machine shop and let them go over it.

My 2 cents.
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  #3  
Old 09-03-2004, 01:40 PM
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Chris,


I'd inspect the camshaft when replacing the seal- Look for a groove or obvious wear. I doubt that's your problem.
Review the installation proceedure in the manual carefully- perhaps you are not getting it installed straight(?). Not uncommon to re-seal the front cover- use the factory sealant stuff!


Michael
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  #4  
Old 09-03-2004, 03:07 PM
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A light polishing of the cam surface that the seal rides on may help. Material to use is an extremely fine "crocus" cloth. It polishes more than cuts.
Hope this helps.
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  #5  
Old 09-03-2004, 06:18 PM
LarryBible
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On many cars, a common leak is the timing cover seal. This happens because the harmonic balancer sealing surface gets a groove worn into it that prevents a good seal. The cure is what is known as a "speedy sleeve." This is a very thin polished nickel sleeve that you press over the harmonic balancer sealing surface. It works very well.

If you get measurements, you might find the correct size speedy sleeve at an industrial supplier such as MSC.

Since the seal has been replaced multiple times I doubt that this could be the problem, but it is relatively easy for this seal to "fold under" when installing it. MB makes a special sleeve tool that can be used to slide the seal in place without it folding under. I don't own such a tool, but have had good success by simply running my fingernail around the seal as I push the cover rearward and just see that it does not fold.

Good luck,
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  #6  
Old 09-03-2004, 06:45 PM
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There is a possibility with your mileage, that the overpressure from weak rings, etc could be all it takes to make that little seal leak (plus the wear groove in the cam certainly doesn't help). You can check this out by loosening your oil cap; if it wants to "blow off" when loose, then you have a possibility here. You can check your air filter return line and your valve cover to make sure there is no blockage, if this is the case.
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Old 09-03-2004, 10:08 PM
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I'd be worried that maybe they don't have the mandrel tool to install the cover. Larry doesn't think so, but I think it's important to use that tool. Maybe they aren't being as careful as Larry when they are installing the cover.

Gilly
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  #8  
Old 09-03-2004, 10:17 PM
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Check the cam for wear at the point the seal rides -- if there is a groove, the only real cure is a new camshaft ($$$$). Also inspect the old seal for scores or cuts -- if there is a burr on the end of the cam, you will snip little bits out of the seal as it goes over, and it will always leak. Big problem on torque converters if you don't file the burr off the "fingers" that drive the pump, they slice the new seal every time!

Make sure the seal is in right -- the seal lip should go in, so that any pressure will push it down tight on the camshaft, not out.

I'd check the cam for play, too -- if the rocker carriers are worn, and the cam is moving a bit, it will leak.

Peter
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  #9  
Old 09-03-2004, 10:22 PM
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The radial seal can be driven in to a different depth (usually slightly raised out of the bore) to get in front of the worn groove, instead of buying a different cam for a 300,000 mile engine.........

Gilly
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  #10  
Old 09-03-2004, 11:25 PM
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Not to be picky here but this is a 300k km engine - about 186k miles.
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  #11  
Old 09-04-2004, 10:24 AM
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Oh, OK, 300,000 miles CANADIAN, doesn't get you quite as much as in US MILES.....hmmmmm sounds familiar.

Gilly
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  #12  
Old 09-04-2004, 12:10 PM
LarryBible
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Don't get me wrong. I'm not saying that the tool for installing the seal is a bad thing. It would always be a good idea to use it. All I'm saying is that I have done this several times by oiling the seal and carefully sliding it over the end of the cam while using my fingernail to ensure that it does not fold. I have yet to have one leak using this method.

Have a great day,
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  #13  
Old 09-04-2004, 12:14 PM
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Since I have never seen a failure here and since MBs are usually forgiving, I'm looking for a bigger answer. How much blow-by do you have?
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  #14  
Old 09-04-2004, 08:46 PM
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Larry
Hopefully the shop doing this is familiar enough with MB to either have the tool or can install it as carefully as you. I'm not saying it's a requirement either, but it may make a difference, especially if they're not being careful enough. I've never seen an engine having any significant leak in this area either. Just a little dribble when replacing a lip seal, replaced the radial seal and no repeat concerns at all. If it's a case of a groove in the camshaft, then by all means just us a little different depth on the radial seal, either a little deeper or shallower so the seal doesn't run in the groove any more.

Gilly
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  #15  
Old 09-08-2004, 12:54 PM
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Some excellent advice here guys, thanks.

To sum it up, so far the cause could be:

- improperly installed camshaft seal (didn't use correct tool or just poor installation)
- increased pressure from worn valves, etc. causing leak
- damaged/scratched camshaft allowing leak

My shop is quite meticulous and they pride themselves on their work. They've been around for over 20 years and they know Benzes. My tech in particular knows his W124s so I don't think the first option is the problem. If a special tool is required, he would have used it. Nonetheless, I'll follow up with them and ask about it.

I'll take things apart as soon as I can and inspect it all closely and see if I can narrow this down. I'd really like to avoid doing the head just now - I know that job is in the mail, but if I can put it off until spring it would help!

Would posting a digital pic of the area/camshaft seal help diagnose it?

Thanks again!

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2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired


"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon
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