My daughter's 300D still puts a small oil puddle underneath when parked.

When I got the car the air cleaner mounts were broken and the air cleaner to manifold seal was bad. I replaced the mounts, cleaned everything up, and finally figured out how to put the seal in the bottom of the air cleaner correctly. I replaced the hose from the top of the valve cover to the cannister, that hose no longer leaks. The o-ring on the nipple at the bottom of the canister is in good shape. The engine is strong, has shown no signs of oil usage or blow by.

It still continues to puddle. HELP ! ! ! !

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

[This message has been edited by LarryBible (edited 04-20-2000).]

Hard to tell from here Larry, be sure the bottom of the aircleaner isn't cracked.

The usual problem with finding these leaks is the mess they create. We have started using the florescent dye additive and a black light to pinpoint the origin.

After pinpointing the exact source you must take into consideration the amount of blow-by in the engine. That goes two fold here as the general pressure causes leaks plus it vastly changes the operation of the oil separator that is being drained here. The volume of oil can be significant at highway speeds with excessive blow-by.

A comparison would be the shingles on your roof. They seal perfectly in the rain but probably wouldn't hold out long under water.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

If you have not thoroughly washed the engine, it would help to isolate the leak. My 240D seemed to be leaking everywhere when I bought it, but after a good pressure washing the leak turned out to be the gasket between the oil filter housing and the block. Another leak that was more difficult to stop was the connection of the rubber hose from the vent trap (cannister) to the intake manifold. I finally had to seal the connection with some sealer, although the leak was more of a seep than a leak, and it never produced a puddle.

vince,

The engine is clean and I know that the leak is coming from below the air filter housing.

This is a problem which is somewhat unique with the normally aspirated 300D crankcase vent system. My 240D is simply a line at the intake manifold that draws on the connection at the top of the valve cover. The 300D is alot different. It has a line from the valve cover to a cannister in the air filter housing that separates the oil by letting it run through a tube back to the crankcase. I wish there were an easy way to put a connection on it like the 240D and use a 240D Air filter, and abandon the oil seperator inside the air filter. Now that I think of it, hhhmmmm.....

Thanks for the replies,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

My '83 240D leaks in the same place, as well as around the oil filler cap. The service advisor at the dealer said it was probably a case of blow-by causing excessive pressure in the crankcase.

The tubes going to and from the oil separator are in pretty bad shape, anyway, and I suspect the O-ring underheath it is as well. I'll get around to replacing those as soon as this semester's over (about 2 weeks).

Is the oil separator something that needs to ever be replaced? Can it become clogged or otherwise contaminated? Is there a reasonable way to test it?

Thanks.
- Nathan
'83 240D, 250k miles

ncarter,

There is no oil seperator in the air filter on the four cylinder. The seperator seems clear on this car, and the engine is strong with no blow by.

Your 240D can probably be fixed be making sure that the tube from the top of the valve cover to the manifold is sealed.

Good luck,


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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles