To rebuild or not - just for some leaks

[Navaros911]

Guys,

Need some advice here on what to do next.

My car has developed some oil leaks and my mechanic is suggesting an engine out rebuild. So he asked me to have the under side of the engine cleaned and check where the leaks are developing from. A week later I took these engine pics (ignore the one with the bumper off - that one was taken before cleaning the underside of the engine).

The history on the car is as follows: purchased in Dec 1993, it's a C4 with no mods and no cat. Oil it's running on right now is a 50/50 mix of Brad Penn 20w50 and 0w30. She had an engine rebuild at 93k km in 2005 and I can see the piston rings along with other parts were replaced. This was at the official Porsche dealer. The car now has 127k km on her.

This I find very strange... why would a car need a rebuild some 30k km later?

What I'm planning to do is: perform a compression test myself (the tester is on its way) and "read" the spark plugs.

Below you can see one of the oil leaks that is coming from the hard pipe that connects to the oil filter housing (or whatever that part is called).


Below is the right side of the case. The good thing is that the case does not leak. There is a darker spot towards the front of the car on the right part of the case that may be the indication of a leak in that vicinity. Circled in red.


Now here it gets interesting... left side of the car, picture taken from back to front underneath the car's rear bumper. Below is a clear area that is very wet (circled). It seems to come from the chain tensioner covers or so (where they bolt front to back)... or where they bolt to the case (side to side nuts). You can also see some oil coming from the exhaust ports in the background as well. Not sure if it's from there or higher up. I presume the latter.


This is the right side of the case... where there is barely an oil to discover. But in the back circled in red, there seems to be a bit of a leak.


Below is the last one and the worst one. Seems like there are multiple leaks. Taken from the left side of the engine... not sure exactly where all that oils is coming from.


Please give me some advice gentlemen... I don't want my car to catch on fire because there is oil all over the place, but then again if these leaks are not too serious I don't want to head into a rebuild when there is no real reason to.

Thanks in advance!

[Navaros911]

The compression test was done yesterday... results are pretty consistent. So I'm somewhat convinced the engine rebuild wasn't a bad one and the powerplant isn't tired (yet).

Interesting were the spark plugs... one was bridged... ash and carbon build up I guess. I "unbridged" it and they will be replaced soon anyway, just decided not to only do half. This is my daily car and I did the compression test at 10 PM, when at 9 AM I needed to be back at work.

So there is something to look at... more in the next post.

Compression tests:

Cyl 1: 195 psi


Cyl 2: 200 psi


Cyl 3: 195 psi


Cyl 4: 180 psi - this was my first cylinder test, so perhaps it would've been a little higher if I retried, but since not too far out I let it go since it wouldn't have made me change my thoughts on the results


Cyl 5: 190 psi


Cyl 6: 205 psi on go 1, 195 on the second go

[Navaros911]

The spark plugs don't look too good for 20k KM... there seems to be some carbon build up and ash deposits on the plugs.

I'm not sure where this comes from... yes she probably runs a little rich. Since I have not managed to find a tailpipe "sniffer" to measure how the mixture is I can only assume. But there may be something more going on.

Any advice experts?

My unexperienced opinion below. Only based off comparison pictures from a Haynes manual with my pictures.

Cylinder 1: Looks like some carbon build up



Cylinder 2: This one has a lot of what looks like ash deposits. It was also bridged. As can see in the third and fourth shot.





Cylinder 3: Normal looking - perhaps very little carbon build up



Cylinder 4: Looks normal

[Navaros911]

Cylinder 5: Looks normal



Cylinder 6: Looks normal to me - little carbon perhaps

[Navaros911]

So with all this info, here's where I stand:

1/ Chain cover housing leak on the driver side needs to be addressed
2/ Oil line oil filter housing to engine address leak at both ends
3/ Power steering pump - I think it's leaking


Now I need some advice on two things:

A/ What can be told about the spark plugs?
B/ What about the leak below? It's not clear to me what would be leaking, since it doesn't seem to be coming from above.

[RSTarga]

put some decent NGK plugs in and get rid of those 3 pronged Bosch. They don't look oiled at all.
If I lived in Bahrain I'd use a straight 15-50 synthetic. Motul or Mobil 1 or other high quality synthetic oil. No way would I use 0-30 in any combination, even with Brad Penn. Synthetics can take high heat better than any Dino oil.
Take care of the easy leaks, change the oil and plugs and wash it down and observe.

[iamtheari]

See this thread for a fantastic overview of leaks that can be fixed with the engine in the car (a couple are a stretch, but still doable):

964 Oil leaks & fixes thread.

Note that the leaks included are the power steering pump, the oil pipe (see later in the thread as Perelet decided to replace it instead of just tightening up the ends), and the chain housing covers.

[plymouthcolt]

Ash fouled deposits from burning oil and/or fuel additives during combustion. Worn valve guides/seals, rings....

Change the plugs and check again in another 1000 miles. If the same I would do a leak down test.

Left side leak may be coming from top. I had a leak from the thermostat on top that leaked down the side.

I second the use of NGK.

[Navaros911]

RSTarga: thanks for the advice... do you have a reference on the plugs? I have this BCPR7ET as reference. Would this be correct?

iamtheari: thanks for that link... I did see it and it is a great write-up

[Navaros911]

RSTarga: thanks for the advice... do you have a reference on the plugs? I have this BCPR7ET as reference. Would this be correct?

iamtheari: thanks for that link... I did see it and it is a great write-up

[Alpina740]

Not to thread jack but what NGK's do you guys use?

[plymouthcolt]

Originally Posted by Alpina740

Not to thread jack but what NGK's do you guys use?

NGK BPR6ES 911 Carrera/911 Turbo (1984-89,91)
NGK BP7ES 911/911S (1974-77), 911 (1980-83)
NGK BPR5ES 911SC (1978-79)
NGK BP8ES 911 Turbo (1976-89)