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Hello All,
I found this outstanding 1979 928 at a salvage yard. The car had been abandon and I am trying to save the old girl. I just replaced the master clutch cylinder and that job sucks. The car does start and runs for a few seconds. Most of the vacuum lines are cracked. I am hoping the vacuum lines are causing the nasty oil in the intake airbox issue. So what is the best case scenario for the oil shooting out of the small airbox hole and what is the worst case scenario? Any advice is welcome and that you for your help.
Thank you, everyone, for your great advice. After more investigation, I have discovered more issues with the vacuum lines. Honestly, I have no idea how or why oil would be circulating back through the air filter box. My best guess is one of my vacuum lines is not working and this is causing the issue. I hope the engine is okay. The engine does start and runs well for 20 seconds then sputters out. I did find a hose that is not connected at all. Any additional advice on how to troubleshoot my problem? Thanks
Crankcase vents vapors back to the intake boot. Lots of oil means blowby or head gasket leak. Do a cold leak down test to get a yardstick feel for blowby. Know that the al block and heads corrode with old coolant. You’ll want to get the heads off if blowby is ok, looking for gasket failure and corrosion at the sealing faces.
The vacuum hoses are the least of the concerns I suspect.
Thanks, dr bob! I feel that the head gaskets are toast. How big a job is it to replace the head gaskets on this old girl. Can't be worse than the master clutch cylinder Thanks again for your help.
With the engine out for the full refresh needed, access for the clutch master cylinder (and the connecting hoses) is a piece of cake. You can sit on the crossmember while engine is in the stand.
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Your local parts store will free-rent a cooling system pressure tester. Fill with system with water, pump to 1bar (about 14 PSIG), see if it holds and if not, where it leaks. Pull all the spark plugs before you crank the engine next, and rotate it by hand to see where water comes out.
It might be physically possible to pull the heads with the motor in the car, but 10x easier to pull it and do it with it out. I would do some leakdown testing first to try to narrow the problem down a bit before you pull (it could, possibly, still be the radiator) The pull itself is pretty easy, more so on CIS cars as there are fewer wires and hoses to wrangle. Also, a 'full refresh' is a bit less of a deal on a CIS car in some ways. Fewer parts, wires, and hoses. But what parts are there are more difficult to deal with. A good plan might be:
-check cam belt timing. if the belt has skipped, compression tests might be deceptive.
-check oil and coolant condition.
-perform compression and leakdown tests to narrow down any head/block issues.
-perform WUR pressure tests, and FD output tests to get baseline on injection system.
-create list of parts you need, start sourcing them
-If needed pull motor, pull and inspect heads.
This can be a lot of fun, but you will want to gather as much data as you can try to make careful decisions. Someone else gave up on this puzzle, so you will have to be smarter than they were.
didn't 79 have that odd "water cooling" pipe for crank case ventilation that went in to the hose that connects to that breather hole?
Correct,
disconnect and block (or better yet bypass) the coolant lines from the larger engine vent hose, it's highly unlikely the engine is spitting oil all the way up through the filler point and back to the airbox
that brown muck will simply be dirty rusty coolant from a leak inside the heated vent hose itself
Thanks, everyone for the great advice. I love that this is a very active and knowledgeable forum. I am going to do the compression test this weekend and based on the data make my next move. This is a very fun project because I have no idea of the background service history. It is like a good Sherlock Holmes novel with plenty of mystery and clues, I will keep everyone posted on my progress.
10-02-2018, 11:01 PM
Porsche 928 spitting out nasty oil
Thanks again for your help.
