Am I looking at a rebuild?

[RC76]

I recently purchased an 82SC, with 105000 miles on the clock. There was a broken head stud in 1998 w/ about 75,000 miles on the clock, at which time the PO replaced all the studs with Divilar studs, put it timeserts, replaced the piston rings, shaft bearings, chain rails, did a vavle job on the heads, replaced oil return tubes, a 24 stud crank case, and some other stuff. I am basically writing down everyhting on the shop invoice. Sum total of all the work, a little over $8000.00.

Now, I took it to the shop yesterday b/c of an oil leak, come to find out it is, as the mech stated, a small leak from the "oil cooler area." The problem, I am averaging about 250 - 350 miles before I need to add a quart of oil. Of course the mech says it could be time for a top end rebuild. But wasn't that just done. Am I missing something? He could do a compression but recommended that I wait until my next major service, which is in March, b/c it is included, plus the car is running well. Sorry if I am not to educated in this area, hope I don't sound too lost.

[kstylianos]

Timecerts in an aluminum case, replaced the faulty Dilivar with Dilivar...hmmmm The fault prone Dilivar studs are usually replaced with early steel or ARP and the timecerts are usually reserved for the magnesium cases...unless the threads in your AL case were damaged somehow.....just an FYI. If that's really what they did, maybe they did some other 'unconventional' things during the rebuild.

Max oil consumption should be around 1 quart per 600 miles, but with a 'recent' rebuild you should be in the 1000+ mile/quart range. I'd have your mechanic do a leak down w/ compression test to see if valve guides or rings could be your problem. Unless your oil leak is BAD, you are probably loosing oil by the rings or guides. Let the tests be your guide.....post your compression and leak down results if you get them.

[Groesbeck Hurricane]

RC,

I agree with Charlie, but want to add the following before you spend tons of money:

I think your issue might be an oil leak above the oil cooler. There are several little items up there that tend to leak. A partial engine drop can be performed at home during your next oil change (a complete DIY job).

the O-ring at the thermostat pressure switch
the O-ring at the motor oil cooler
check intake hoses if puffy replace them
the oil pressure switch
the seal at the oil breather
and the seals at the internal oil cooler can easily be replaced at this time also

[ChrisBennet]

Tell us more.
Does the motor smoke a lot when you start it up in the morning? (Rings)
If you accelerate and then let off the gas abruptly, doe you (or someone following you) see white smoke come out the tailpipe? (valve guides)
Are there drips under the car and where are they?

I've Timecerted (had machinist) some wobbly head studs so it's not unheard of. It isn't hurting anything to do them all.
Porsche was probably still selling Dilivar studs when the PO had the motor done though the mechanic should have know better than to use them.
David covered the most likely culprits but in the interest of completeness here are some others:
The last motor I did had a leak behind the oil cooler in the case. that sort of thing is rare though.
Another possibility is a leaking rocker shaft seal on the oil cooler end of the motor. Someone who didn't know enough to use non-Dilivar head studs might not have know to use rocker shaft seals.
-Chris

[Wayne 962]

Yup, a lot of what you said doesn't add up. I spent a lot of time working on the Engine Rebuid Book, so I'm not going to repeat myself here, but you definitely need to invest the $35 and read Chapter 1: "When to Rebuild" to determine if you actually need to rebuild. Your oil consumption might be due to excessive oil leaks...

-Wayne