964 leak diagnosis

I took off the cars underside engine panel. It looks like the oil is leaking from the rear of the engine (towards the rear of the car) from between a vertical black plate? and the lower part of the engine. There is a bolt visible on each side. Should I tighten them down to see if it stops. It also leaks above the muffler pipes on both sides from somewhere. It also looked like oil was seeping from the two right rear valve cover nuts. Should I just start tightening stuff to try to stop the leaks? Also, I'm not sure if I'm going to put the bottom panel back on, I need to clean it first somewhow. I know the opinion is that it holds in too much heat, but since heat disappates upward how does that make sense. It is not airtight. It did keep the bottom of the engine pretty clean (except the oil leak). What if I modified the pan and cut in some vents? Any suggestions would be appreciated.
Thanks

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Daryl 964 Targa

[This message has been edited by Planter91C2 (edited 05-22-2001).]

Well guys, I was hoping for some input. I'll try and tighten those nuts down more to see if it helps.

I also thought I would take that panel to a do-it-yourself carwash and just put it on the ground, spray some degreaser on it and hose clean.

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Daryl 964 Targa

Daryl,

Those 964 valve covers use a rubber gasket/seal ... so, you may want to try getting a replacement set, as 10 years may be long enough to expect without leaking.

If tightening the nuts does not work, you may want to replace the sealing rings and Nyloc nuts before replacing the rubber seal at the next oil change or valve adjustment.

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Warren Hall
1973 911S Targa

do take off/remove the engine sound tray. BA highly reconmend this mod. try to tighten down on the bolts/nuts in the suspected area but not with force. however, if the nut just turns without much force the stud might have backed out of the engine case. this happened to me and the local P dealer thought it was a stripped stud and wanted to drop the engine and heli-coil it... $3000+ for labor. well, I did not want to spend that much money just to stop a minor leak (drops) and thought it would be a good idea to have the heli-coil done when the engine does have to be dropped for other repairs. a week later, I decided to take a peek at this and... well, I backed out the nut along with the stud and luckly no matal shavings came out of the hole. Replaced the stud and tighten down the nut... no more leaks.

Daryl,

Yikes! Your posts were only a few hours apart. . .patience is a virtue. . .especially on a work-day!

Anyway, be careful tightening various nuts indescriminately as you could over-torque something and really create a leak. I like to go around occasionally and g-e-n-t-l-y check various fasteners to be sure they are secure but if it takes reasonable effort to tighten something, you're better off not to do it. The key word here is "gently".

Have you changed your oil recently? The reason I ask is that when you (or your mechanic) removes the oil filter, oil runs out pretty quickly all over the right side of your engine compartment. . .I don't care how fast you are screwing on the new one. It can drip for a few days (or more) around the right side of the engine/exhaust, depending on how diligent you are in cleaning up the spillage.

I removed my pan last summer and will never put it back on. You will notice that the inside is lined with fairly dense insulation that actually comes in contact with your heads. Heat is held in and can only cause excess exhaust valve wear. If you look up from underneath, you'll see that there is really no escape, above or below, for the heat or for air to get in. With the cover off my engine has not gotten dirty. Actually, I can now better keep an eye out for new leaks and do a bit of occasional cleaning when the mood strikes. During hot weather, the temp guage seems to stay a bit lower also. Not much down-side. I cleaned my cover and put it in a large plastic bag with all the bolts in a small zip-lock for the next owner.

Have fun,

Mike 94 C2 cab

Daryl,

I too have a 91 C2 and had pretty much the same experience. When I took the pan off there was a bit of oil on it and some oil on the underside of the engine. It was hard to pinpoint exactly where it was coming from -a little here, a little there. I replaced the valve cover gaskets and (thankfully), all leaks stopped. My engine surfaces are now bone dry. If the gaskets are old, I'd certainly start there - it's one of the easier fixes to try.

Oil leaks can be tricky, particularly if they aren't really leaks. Before going around tightening stuff, I would clean the areas in question (maybe even the whole engine) and then start addressing the sources of the leaks one by one.

Your car is, like S-Man said, 10 years old. I owned an '85 Toyota MR-2 as a project car a few years ago and that thing leaked in so many places it wasn't even funny (and it had less than 100K on it). A lot of the rubber on various seals and gaskets became brittle. On that particular car, a rubber seal around the distributor leaked (it was as brittle as a dry piece of wood when I pulled it out) but it gave the impression that the valve covers and/or cylinder head were leaking. I wouldn't see any reason a Porsche would be any different. My own observations about the 964 series is that when they approach 100K miles they tend to develop leaks (like any other car).

My point is, find the sources of the leaks first. Another poster on this site is now in the process of doing some major repair work on his engine because of a busted head stud. It's entirely possible (although speculative) that a mechanic may have tried to fix a suspected cylinder head leak by just tightening the stud down, and then breaking it in the process.