Help finding burning oil leak

After I come to a stop with moderate braking in my 78SC I get a big cloud of oil smoke(I can tell its oil hitting the exhaust from the burning smell) coming up the passenger side of my car from the rear Ive looked underneath repeatedly and can't really see where the leak is coming from
Any ideas where to look?
It seems to do this (the smoking)when I am in stop and go traffic I drove a few hundered miles through some back highways at sustained speeds and tried stopping fast to get it to smoke but it doesn't

PS This is smoking so bad for a few seconds Im afraid someone is going to call the Fire dept to put me out!



[This message has been edited by jryerson (edited 01-07-2000).]

Sounds like you have a oil leak on the top
of the engine near the firewall. Could be the breather hose may have a crack in it, or it could be the oil pressure sending unit on top of the engine near the firewall. It may be collecting there while you are driving and when you break it runs down the engine. Get a telescoping mirror and use a flashlight to look back there to see if that may be the problem.

Regards


Steve

I think it is almost certaintly the oil pressure sender on the front top of the engine (behind the CIS unit, by the breather hose on the case).

You can check and replace this without taking the engine out or dropping the engine down. Just take the CIS boot off, and you will have enough access to feel it to see if its leaky. You can also use a flashlight and mirror to see it. It does not take much dexterity with a socket and extension to get to it.

This is a part that I have had very bad luck with over the years in my 914 and 911. Between the 2, I replace about 1 sender per year on average.

Brian

Thanks for the replies I'll buy a mirror to check it out
I thought it could be one of my return tubes but it seems it would be smoking consistently while driving if that were the problem ,oil must be collecting somewhere and when I brake it runs out to the exchanger

Ps Brian.this sender is for the pressure light ,the druck guage sender is by the fan?

Regards
Jeff




[This message has been edited by jryerson (edited 01-08-2000).]

I agree with Brian. When I rebuilt my engine, there was oil all around the sending unit. I installed a new one before I put the engine back in. Then I had a problem with the oil temp thermostat. I removed the intake box - it splits in half - the screws are difficult to get at in the rear. Anyway, I managed to replace it without pulling the engine. You have to be careful to make sure you have all the screws removed before you try to remove the air box half. Once you get it out of the way, you can access the pressure sending unit.

Steve

Jeff, you have the function of the 2 senders correct.

I reread your post, I didn't originally notice the part where you said it did not smoke on a long drive. This is curious, as I would suspect that the sender would leak during that time. But you may be correct, it is either building up or running down, and hitting the exchangers when you brake.

Anyways, the switch is easy and a good first place to start.

I don't really understant the advice above about splitting the airbox. This is a lot of work that isn't really necessary (although you do need to take the top and the air filter off for better access, maybe this is what you mean).

Brian

With regard to splitting the air box. I had to remove my pressure sending unit and found it a lot easier to remove it by splitting the air box. Even though it may be a little more time consuming the amount of room gained to work on that part of the enging was worth it. If the engine has never been removed, there is a good possibility that there is a lot of crud and oil build up in that area and may need a good clean up. In addition, the wire going to the sending unit may have to be replaced. I had to replace mine because the wire was brittle and bare. No telling what else will be found when he looks back there.

Regards


Steve

Did you guys drop the motor to change the switch?I took my CIS boot off today and the inspection mirror I bought was so small it was useless I felt around the back of the motor for the switch and it seems everything is covered with thick greasy crud it was hard to tell how fresh the oily crud is which is all around the switch and general area Its very tight back there when you replace the switch there appears to be a stud it screws into that looks like it has a gasket between it and the case did you replace that also?
One other thing I noticed which may or maynot be contributing to the burning oil is in the holes on the heat exchangers (I guess where to put the hex wrench to tighten or loosen them) their was small amounts oil dripping down in the center of my drivers exchanger, any ideas where to look for the source?
By the way it appears the Po replaced all the return tubes at some point with the expandable replacements and they have no leaks

Jeff



[This message has been edited by jryerson (edited 01-08-2000).]

I got the pressure sender unit out like you suggested Brian. The problem I am having now is getting the new unit in. I can not quite get my fingers down far enough to get the treads started. I tried a socket and a socket extension, but that didn't work either, couldn't really tell where I was at. How do you get the new treads on the new unit started?

To get the new one in, either squeeze your hand back there, or tape the new one into the socket (or stick some tape in the socket enough to hold the sender in), and use an extension. Be careful not to crossthread it, though. Using a mirror may help.

Also, on the subject of the mirror, I use one that is about a 5inch by 5 inch square. Any smaller would be tough.

Brian

FollowUp
Brian and Steve absolutely correct,after cleaning the motor for the 20th time I found the trail of oil coming from the shroud/top of oil cooler it would then drip to the EGR lineon my exhaust then to the heat exch
when I braked So this time I'll try again with a decent mirror I assume its the oil sending unit or gasket for the thermostat
Thanks for the help
Jeff

The oil thermostat is sealed by both a gasket and an O-ring, but try replacing the oil pressure sender first, as it is a lot easier and is probably 10 times more likely to be the culprit.

Brian

Up Date
Replaced my sending unit ,it took me about an hour problem solved.
I find it interesting that I called several shops to see how much they'd charge average was 5 hrs labor to remove switch @ 65.00/hr and they also said that may not solve te problem the only way to be sure is remove the motor remachine thermostat housing at 11 hrs labor
This is why I never have shops work on my car unless absolutely neccessary they are a freaking rip off!
350.00 just for this switch which took me 50 minutes?or 750.00 for engine removal I am in the wrong line of work

Yep, replacing the oil pressure switch is a "gravy" job for lots of shops, that's probably where the "remove or lower engine" myth got started, and why it keeps going. For a shop to charge someone hundreds of dollars to change the switch is roughly equivalent to them reaching into your wallet while your not looking.

It took you 50 minutes this time, but will only take you 20 minutes next time!

Brian

Hey Porsche Repair Facilities:

Are you guys listening?......Andras