crufone

On a 2.7 engine I have a major oil leak somewhere from the upper front passenger side of the engine. The thermal reactors and the air pump were removed years ago and this car has the external oil cooler up front. I have absolutely no compression loss or blowby between the heads and cylinders. This leak only appears sometime after the car is shut off and parked for a while, like over night. No leak is apparent with the engine running. I can drive 300 miles with no loss of oil.

When the car is parked what amounts to a pint of oil can leak into a catch pan after a few days. Any ideas? Oil tank hoses?, hoses for the external oil cooler?, valve cover gaskets? What else is on that side of the engine up high that could leak that much oil?

Thanks for your thoughts.
Michael

mo_gearhead

Michael, Would be best if you could raise the car and take some pictures of where the oil is dripping from. This may help pin point the source. Although oil can certainly leak at one place and run to another to drip, this will help. You (or a mechanic) should be under there and if not able to get pics. at least describe the area/part it's dripping from. Otherwise all you will probably get online are numerous "guesses".

SeattlePorsche

The other oil cooler is up front passenger side. There are 3 seals in there that can get old, and of course that oil cooler has a lot of oil in there.

JV911

my 2.7 had a few - oil tank hose, oil return tubes and rocker shafts

maybe lay a clean sheet of paper under the car and wait for it to drip to pinpoint where its coming from ?

Droops83

Most likely source is the oil thermostat o-ring that's on top of the engine. The once soft rubber seal gets rock hard and oil will leak past it. Also could be the oil pressure switch, which is located right next to the thermostat. These can basically burst and also cause a pretty good oil leak, but this is often accompanied buy the oil pressure light staying illuminated. Both leaks will drip down from the top of the engine and down the oil cooler, and it will look like the oil cooler seals leaking. This is also a possibility, of course. Get a flashlight and a mechanics mirror and try and peek around the airbox and see if oil is on top of the engine at the rear. If so, replace both the O/P switch and the t-stat o-ring, no matter which is the culprit.

Unfortunately if your 2.7 is CIS like it was originally, you will have to drop the engine to get to that part of the engine---the CIS airbox is simply in the way. On earlier carbureted and MFI cars and later EFI 3.2 Carrras you can easily get to both from the top w/ the engine in, but in CIS cars, no dice. You simply can't get a wrench back there. While the engine is out, however, it is a good time to do bellcrank bushings, breather hoses, and check your clutch/flywheel condition, etc. Good luck.

---Chris A.

mo_gearhead

Just re-read this post. What I find interesting (and most puzzling) is you state the car does not leak at all while running? You can drive 300 miles with no oil loss? But parked overnight it leaks??? I cannot imagine that scenerio.

Keep us posted, I want to hear about this solution.

crufone

Thanks guys for the responses,
When I purchased this car the owner had a dish pan full of cat litter under the right rear of the engine. Said that he had chased the oil leak and could never figure it out, but he was a building architect and perhaps not a mechanic. The engine runs so well that I purchased the car anyway. I have driven 4K miles and not an issue with the engine. Silly me I thought 'how difficult can finding this oil leak be'. To answer 'gearhead' I always checked the oil before a trip and most always added a quart to top up. I have driven the car for 4K by adding a quart to keep full and have not addressed the oil leak. Some trips were 5 or 600 miles and before the return trip I would check oil and top up if necessary. I know LAZY me. Once when taking a sharp curve oil must have poured down onto the exhaust mannifold cuz much blue smoke came from rear of car. I thought that, gosh did I blow the engine. Oil pressure was fine, checked under car and oil was all over the right lower side of engine, drove home, cleaned up the mess and has not happened since.

Droops 83 thanks for the suggestions. I believe that after I clean up engine and inspect with light and mirror that I might have to pull engine to replace seals, gaskets etc. I plan to put car up on jack stands and run until hot and them shut off and wait to see where oil comes from. It is time to fix this. How high off the ground does the car have to be to drop the engine? Is the crank seal a leaker problem also? I know on VW's it was. I thought that I would adjust the valves and replace the VC gaskets if the engine were pulled, cuz it would be easier then. What other gaskets/seals would you guys replace while the engine is out......................I am all ears......................makes sense to do all this while access is easy. Engine runs well so I don't plan to do any mechinical work at this time. After all the car is for sale and I don't want to invest any money that will be 'lost' on potential buyers. Many on this list don't think that a 1977 911S is worth much, or at least is not desireable. All say that it is the WORST possible of all Porsche engines. I believe and many Porsche guys locally have said that the engine sounds great..............................so what do I believe?

Thanks, I really appreciate your input. I am mechanically inclined, but I am unfamiliar with the Porsche. I must admit that I am a bit intimidated to drop the engine. Unlike many sellers I want to be sure the car is fine before I offer for sale, at least mechanical issues attended to.

Michael

Tom Tweed

To diagnose oil leaks, my mechanic adds a fluorescent dye to the oil and uses a UV (black) light to reveal the source. It is much easier to trace the leak and distinguish new leakage from old oily spots that way. There are dye kits available from multiple vendors that are compatible with engine oil.

Good luck,
TT

mo_gearhead

My 69 has to have the rear license pan about 32" high! With the engine/tranny on a jack, the P cars do have to have the butt end WAY UP there to get it out.

Possible leaks in those areas: oil cooler, lines of course, oil pressure sender, valve covers. I think once you have it out and can "see" better, you will find the problem.

porrob

Any luck finding the source of the oil leak? My 87 930 is doing the exact same thing. Based on information in some other post, I changed the oil pressure switch, but it did not solve the problem. I am now considering replacing the gasket on the internal oil themostat. I have been watching this post for more info, I thought I would give it a bump.

Rob
87 Porsche 930

crufone

I took a closer look with a mirror and flash light. The car has not run since the fall and oil is still dripping from the right rear timing chain housing. I think that I will check the tightness of the bolts and nuts to see if they are loose. Valve covers appear dry as does oil cooler. My first 'fix' will be to take apart the chain housings and replace all the gaskets. I will then clean the oil off the bottom of the engine and run it again to check with paper exactly where the leaks appear.

Will keep folks posted on the progress that I make.
Michael

BlackPearl

Something to think about: when the engine is off, all the oil "ponds" in the engine-bottom. If any seals are old/cracking they will "weep" when the engine cools down. When the engine is running, the oil is picked up and sent all over the place, including the tank, reducing the static hydraulic pressure from the bottom of the engine. The heating of the seals + the scavanging of the oil away from the bottom of the engine effectively reduces the leaking potential of the bottom seals. The cold/cracked seals and oil collecting/gravitiy behavior at rest will increase the potential of cold-oil leaking. I'd check all seals below the mid-point of the height of the engine.

Just my musings.....

pjc

Unfortunately these engines do leak oil - and it can leak from many locations. This is made worse by the fan blowing any oil from a leak on the top of the engine down between the barrels etc. The situation is made worse by the air flow as the car travels through the air. Oil can therefore appear from almost anywhere - even a diff seal leak can look like an engine leak. However, the symptoms do look similar to a breather tube leak on the top of the engine; there is little or no pressure at this point but a spray of oil is deposited on top of the engine which runs down between the barrels towards the back of the engine compartment on the RHS (looking from the rear). A typicla view of the top of the engine where this has happened is shown. Only real option is to remove engine to fix.

PJC

Jase007

Was searching and came across this thread. You don't have to pull motor ... remove CIS and a partial drop will work. Thought some pics might help:

OIL & CIS work thread on another board:

What I first saw with CIS off...



What everything is ...



What motor looks like with CIS removed and partial drop ...



CIS on the bench ...



After putting it all back together [one afternoon] I still have a leak from the cooler. But, I know the rest of the parts aren't leaking anymore Will get it pressure tested ... I'm sure it will fail and then will be in the market for a used [&tested] cooler or a aftermarket one.

theiceman

looks easier to just drop the engine really !