1986 560sl oil leak

[Rob Thomas]

I have had an oil leak that is hard to detect. Been going on for a few years. Only drive the car about 5k miles per year. Oil does not leak until engine warm. drips right behind oil pan when engine off after driven. had it on lift and hard to see anything. Changed valve cover gaskets and did not help. When sitting still, smoke comes out under left side of car, oil probably dripping on exhaust. About 150K mileage. Any ideas?

[SunGuy]

What brand and viscosity/weight oil are you using?

[Rob Thomas]

5W20 and 5W 30 Castrol or Pennzoil

[SunGuy]

Originally Posted by Rob Thomas

5W20 and 5W 30 Castrol or Pennzoil

For the last 8 years I owned my 560 w/160K on the odometer, I ran high end 'Dino' oil, 20W50, year round. IMO, 5W20 or 30 is too thin.

Re the leak...to find it, you can add a LeakTrace fluid to your crankcase after first cleaning the underside of the engine and transmission. Run your car as you normally would for a couple to several hundred miles. Get the car on a lift and shine a blacklight on the engine and follow the LeakTrace material to the leak origination point. Most progressive shops have blacklights already, so you may want to let them do the trace work

[Rob Thomas]

Can you see the leak trace definatively with how crammed in everything is in that engine? I will try the heavier waighted oil? Is that weight oil ok for here in nc which gets into 30's in winter.? Is there anything typical about this engine and maybe where leaks have developed in the past for others?

[SunGuy]

Originally Posted by Rob Thomas

Can you see the leak trace definatively with how crammed in everything is in that engine? YES, just follow the instructions on the bottle/can.

I will try the heavier waighted oil? Is that weight oil ok for here in nc which gets into 30's in winter.? 20W 50 is safe into the teens temps.
That said, for peace of mind, you can drop to 10W 40, or 15W 40 without issue in the winter..

Is there anything typical about this engine and maybe where leaks have developed in the past for others? Engine seals mostly, sometimes valve cover gaskets. Note, if it does turn out to be a seal, simply running a heavier weight oil may minimize or eliminate your leak. Again, if it is a seal(s) don't be tempted to add a 'StopLeak' type of product to your oil; you'll end up doing more harm than good.

Good luck

[rowdie]

Have you read your owners manual?

[ChiefRider]

Check the "back corners" of your cylinder heads. Head gaskets are famous for developing a leak at the outer corner on this engine.

[SunGuy]

Originally Posted by rowdie

Have you read your owners manual?

In the 'I wish I'd thought of that' category, the link below will take you to the complete Manual Series for the '86 560SL published by Mercedes.
The series includes the Owners Manual, Engine Manual, Climate Control Manual, Body & Chassis Manual, and much more. Hat's off rowdie...

Untitled Document

[Walrus]

Originally Posted by SunGuy

Good luck

Originally Posted by Rob Thomas

Can you see the leak trace definatively with how crammed in everything is in that engine? I will try the heavier waighted oil? Is that weight oil ok for here in nc which gets into 30's in winter.? Is there anything typical about this engine and maybe where leaks have developed in the past for others?

Originally Posted by rowdie

Have you read your owners manual?

I don't recall what the manual sez... I use 20W50CAS Dino and am well pleased with it. Probably not quite as cold as you, here in NE Alabama (1050ASL), but I am at the edge of the anticline and 6F this morning, so climate may be similar enough to compare. Didn't bother the car during this "vortex"...