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Old 07-10-2011, 09:08 AM
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Join Date: Aug 2006
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1987 300 SDL oil leak

I have a 1987 300 SDL that is leaking oil at the vacuum pump. It appears to look more like the leak is coming more from the front of the pump. Does this pump come apart or is it solid? Does anyone have a picture that shows this? The thing is slinging oil like crazy. I searched for information but I have not had any luck. How hard is this to repair? Thanks in advance for suggestions and comments. Jack

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Old 07-10-2011, 09:26 AM
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Join Date: Aug 2006
Posts: 185
I used a mirrow to find leak.
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Old 07-10-2011, 09:35 AM
scottmcphee's Avatar
1987 w124 300D
Join Date: Mar 2008
Location: Edmonton, Canada
Posts: 1,539
Sure it's not the front crank seal going? That is more typical.

If you're driving around the air can push the leak all over the front and bottom of the engine so it's hard to tell where it's coming from... need to clean things up real good, go for a short drive and check.
Scott McPhee

1987 300D
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Old 07-10-2011, 12:23 PM
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I thought it was the crankshaft seal. I replaced that and it was a PITA. The best I can tell it is coming from the vacuum pump. Help please
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Old 07-10-2011, 01:27 PM
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smoke gets in your eyes
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,832
I will assume this is a vacuum pump with crimped on cover rather than the updated style with screws holding the cover. If so, consider replacing the pump for the reduced risk of the pump coming apart and messing up the engine.

The front cover seal is a hokey design, IMO. It relies on the elasticity of the o-ring gasket to press against the crimped cover. Eventually the gasket stiffens and the front cover isn't on tight enough to hold back oil. I'm not aware of a replacement o-ring or seal. Maybe you can make one or use RTV.

87 300D
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Old 07-10-2011, 06:33 PM
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Join Date: Nov 2007
Location: Carlsbad, CA
Posts: 520
Oil Leak - Vacuum Pump (VP)

Like Sixto says you can try RTV if it really is the VP cover. And... if it is the pump is the older version replace the whole enchilada. Replaced mine and no more oil leak.

My SDL story: Similar oil spray pattern particuarly on the dirvers front wheel well, top of A/C Pump, and down around the cranks seal to pan. I too thought it was the VP cover (old crimped style). I pulled the pump and filled the pump housing /cover gap with JB Weld. Installed a new gasket from Dealer made of gasket material for the housing to front cover joint. Still leaked as before. So I figured it must be oil from the front crank seal. While waiting to get in to have a local indy do the crank seal I decided to replace my Vacuum Pump, water pump, etc.

Too my surprise the oil leak was fixed by the new pump and a newer style "metal" VP to Front Cover seal. I put a "dusting" of permatex gasket tack spray on both sides of the gasket and lit it cure for 24 hrs prior to installation.

1986 300SDL 440,xxx
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Old 07-10-2011, 08:11 PM
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Posts: 185
Thanks, I am pretty sure it is the vacuum pump leaking. Has any one took the front cover off with pump still on the car?

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