Hi everyone!

I just got the results back today from a PPI that I had done on a 1988 930 Turbo with 83,000 miles and a four speed transaxle. The mechanic that did the PPI and I, both agree that the car is in above average condition for the mileage both inside and outside. I have agreed on a price with the seller contingent on a PPI not finding anything major. Here is the rub....

Below are the negatives that I was not aware of before the PPI.

1. air conditioning needs at minimum a re-charge.
2. needs belts and adjustment
3. both cam oil lines starting to leak / minor leak at cam towers & oil scavage line. Does not yet drip oil but is showing signs of weeping oil just now.
4. some surging at cruising speed - shop said that it probably needed a timing and vacuum advance adjustment.
5. compression: 125, 125, 120, 125, 130, 130
6. leak down: 6%, 12%, 40%, 8%, 4%, 6%

The leak down on #3 was done twice - same result.

I understand that anything less than 10% for leak down is considered normal. For the compression on a 930 Turbo???? I have no idea if these numbers are good.

I am not worried about the all the other items but I am worried about #3 cylinder. The shop that did the PPI said that it was possible that the poor leak down for #3 was due to carbon buld up on the valve and all the engine needed was an autobahn tune up. [I used to say Italian tune up....but thought that wasn't appropriate for a Porsche ] I asked him where it sounded like the leakage was going....He responded by with the intake system. Carbon on the intake valve makes les logical sense than on the exhaust valve.

This would be my first Porsche and as such, I do not have enough experience to make this decision alone. Hoping that you can help me out.

Thanks for your thoughts!

Dan

 

My own car was nursed almost to death by it's elderly formal owner. It had some running issues etc, but after a VERY good freeway blast it seem to come good. Have had it for almost a year now and had more issues with people ' fixing ' it than the car itself. It still surges while cruising but only low revs in 4th at say 50-60kmh. As for the air-con, HA.
These cars were never really designed for day to day traffic. If your after a compliant Porsche, a 3.2 Carrera is the way to go. But if your after a *****-out, in-your-face road warrior the 930 is it. It is still the best looking 911 ever made, but it comes at a price, as most of us here know all too well.

 

Compression numbers are OK, remember the 930 is a very low compression motor---7.0:1. As for the leakdown results, your shop could be correct, I suppose enough carbon on the intake valve could cause it to not seat all the way, causing leakage, but there would have to be a lot of carbon. We always put a fuel additive which cleans out the intake system w/ every service, I have personally never seen this on a customer car. Carbon deposits on the back of intake valves and in intake passages/cylinders are pretty common, especially on cars that have been pussyfooted around and/or poorly maintained. These deposits could be from oil or fuel. I am wondering if the valve guides are ok, does the car smoke excessively on startup and/or on decel? I am a bit confused, however, since in theory massive carbon deposits will raise the engine's compression ratio, and thus compression numbers . . .

An Italian tuneup may be in order, but do it in conjunction w/ a good intake system cleaner like BG and a can of BG 44K in the tank (I swear I do not work for them or get paid, we use their stuff at my shop w/ good results though). Try this and see what happens. The other stuff seems relatively minor. If you get the car, have the shop check your mixture and all your fuel pressures, as well as the timing/advance, to make sure everything is in spec. Good luck!

---

Chris A.

 

When you say done twice, was the engine reassembled and driven before the second test ? Sounds as though you need to budget for some engine work to me though.

 

Are there any maintainence records with the car. Has the turbo been replaced/rebuilt? Has it had a valve job? The other question is how long do you plan to keep it. If it's short term they you may be able to drive it like this for awhile. If it's long term, your going to need to deal with the leak down numbers and the "while your in there" theory.

Chris: Is BG 44K similar to Swepco 503 gas & diesel improver? If not, what does it do.

Harold
'79 930/DP935
soon to be reunited with it's motor

 

Thanks for your thoughts. Sounds like it would be prudent to negotiate some reduction in selling price to share the cost for a valve job. Then when I get the car, try the BG intake cleaning products, a long highway tour and then enjoy the car until I know for sure that valve work is required.

 

VERY unusual to have one cylinder so out of whack? Take it for a hard blast then try it again...

 

Carbon….. my left foot. There is a real problem there. If anyone is doubt have them rerun the test HOT and tab on the valve when doing it. If the number drops then it is carbon, if it doesn't then you have issues.

At 83K the car needs the guides done. I would bet the cost of the rebuild on it. It will probably need exhaust valves and needs at least to be reringed. All this is typical of this mileage.

40% is not considered good and provokes a response normally like "RUN".

 

Damn if you don't learn something new every day!! I'd listen to Stephen...the man knows his stuff.

 

Yes, they do the same thing, but the BG is a bit more powerful (and expensive). Funny you bring the Swepco up, we add a bottle of that at every minor service and the BG at every major service. The stuff does work, the engines that I have seen apart of regular customer cars have hardly any carbon deposits, both Porsches and BMWs. It's not a miracle cure though, just a good product for maintainence.

I would listen to Stephen as mentioned, he probably knows more about these cars than anyone. The carbon deposit thing is a remote possibility, but I have not seen it like I said before and it seems like Stephen has not either. If you can get a real good deal on the car and split the cost of the top end rebuild like you said thatd be great but if not look elsewhere . . . .

---Chris A.

 

Yeah, run tank after tank until the exhaust valve splits and pops its head off and wedges into your piston just before you are shifting from 3rd to 4th... Turns you good day into a expensive nightmare...

Forget the compression numbers.. Look at the leakdown.. You are looking at a sick engine at 80K it will most likely need the topend and most likely pistons and liners..

 

Well.....I bought the car yesterday afternoon. I was able to use the leak down results to re-negotiate the price although not as much as half of a valve job. It was interesting to see how both possibilities were represented in the thread mimicking the tug of war in my head. Technical decision or emotional decision.....I have to say that the emotional side won - I have been dreaming about this car since I was 14 years old (1980). I will go ahead with the intake cleaner, some spirited driving and some luck.

I was thinking of driving it until things deteriorate to where a top end needs to be done, but Kevin has added a new dimension to this thought!

Thanks for the information everyone.

 

Good luck with the car. Hope it turns out well for you.

 

Pics?

 

trying to figure out how to upload some pics.....I saw the "upload photo" button on the top right of the rennlist site but my member number won't log me in there. Will post as soon as I can figure this out.