Magdaddy

ummm, what am I missing here? $1200 for a ppi with leakdown and compression...and you need new plugs after doing this-why?

Ask this forum for an independent EXPERIENCED 993TT mechanic to PPI the car in your area, not the next door neighbor DEALER to the seller. If these guys maintained the car, like they're gonna tell you it need $xxxx amount to make it right. Makes them look like incompetent mechanics to a customer, and neighbor.

Get an independent and impartial PPI at some place with experience with these cars. Bad enough going into the unknown with a NA version of these cars..let alone a TT.

Good luck

OverBoosted28

DON'T take it to the same place that told the seller a PPI is not needed! If the seller will not accomodate you to taking it to a qualified indy, walk away. Sorry to say but in the long run it was not meant to be. Again, if you don't mind spending money go ahead and buy it. Then start saving for the inevitable. Todays market for these cars will bring out the greed to make a buck anywhere that someone can be had. Sorry, like I said before, I don't trust many humans.

OverBoosted28

Another quick thought. Research the dealer before you let them do the work and/or PPI. Alot of them just don't have much experience with air-cooled cars and even less with AC turbos. They have to have someone that's probably older than say maybe 35-40, and has been working on pre- H2O cars for a couple of decades. If so go ahead, if not... walk.

dombeau

Like he said, I wouldn't trust the Porsche dealer who already or will sale a car to their customer (your guy). I had a similar experience in Toronto. The seller was a good client of Porsche there... The PPI was good be the car showed piece a crap. You were right Danny and still are today! Paint meter, leakdown and old mechanic familiar to 993s. Good luck and take your time...

hillsdonsmith

Agree with comments below. An honest (and yours probably is) seller should always encourage a PPI at a shop of YOUR choosing, to aid you, but also to protect his/her butt against issues that they may not even know about themselves so they can sell with a clear conscience. I bought mine sight unseen from Houston, had PPI done by Callas - $500 incl leakdown, and he's got a great rep, esp on these cars, so $1200 seems a lot. Good luck - fun times!!

Mike J

As a point of reference, I had a TT in the shop a few months ago for a PPI - ran strong, no codes, no misfires, but one piston had 18% leakdown - the PPI failed, and the purchaser pulled out. Angry mechanic, but I am only reporting the measurements on the gauge SIR. (sound indicated a valve leak - compression was down on that piston too).

BTW, this was a car with 50 miles on a full rebuild, the mechanic who did the work said I did not know how to do a leakdown test or it was carbon (on 50 MILES since a rebuild??). Not sure what happened to the car in the end, likely was sold to some poor slob.

So, get a GOOD experienced mechanic (not the guys in the dealership - most did not have pubic hair when these cars were built) who believes that a compression and leak-down are mandatory when spending this kind of money.

I will not perform a PPI for anyone without those key steps, and its the first thing I do. If that does not pass, no point to look at the rest of the car.

I have also been told by mechanics and the dealer that you can rely on the computer readings - BS. The car I cited above I had scanned with a PST-2 - it was clean as can be.

A compression/leakdown is NOT absolute proof the engine is sound, but a failure means problems, and a pass means its more than likely good.

Cheers,

Mike

Kein_Ersatz

^^^ What he said ^^^ know what you are buying and what it may cost to fix someday.

billswim

Is the $1200 for just the comp and leak down or for a complete PPI? For a complete and through PPI including a comp and leak down test of a TT, that's actually not that bad. I just had Tony Callas's shop do a PPI for a customer in the bay area on a car in LA. They charged $1000. It was just a 1987 g50 911 but it was VERY through.

I'm of the mind that you don't need a leak down test unless the compression test revealed something bad. If the compression test revealed something bad, you don't want the car anyway, walk away.

In the example Mike J posted the cylinder in question revealed low compression on that cylinder already. In my experience, 20+ years working on air cooled porsches, once a compression test reveals a problem in a PPI the buyer should walk away or get the car for a significantly reduced price.

In short, leak down test is just a tool to pinpoint WHERE the problem exists. Compression test is a tool to point out THAT you have a problem. OBDII is yet another tool but one needs to understand how to use it and the data one can get from it. OBD won't tell anything about the mechanical state of the engine as its mostly for emissions and by default the whole motronic system but it can log mis-fires and the knock sensor stepping in and retarding the timing for any number of reasons.

Quadcammer

Disagree.

Leakdown and Compression are both useful and meaningful tools. Not to mention, once you have the plugs out, its just a matter of rotating the crank and hooking up the tool.

$1200 for a PPI is ludicrous.

Shawn O

My gut hurts with all the horror stories. Makes me not want to even buy the car.

I should get the PPI today. I guess the key is be willing to walk away right.

Mike J

The piston compression was not super low, it was a bit more than 10% out of range from the others. I was running leak downs on all the pistons anyways.

My opinion is slightly different (and perhaps a bit more OCD .. ), if you have the spark plugs out, and access to do a compression, it only takes a bit more effort to run a leak-down. its pretty easy work. I think there is a difference between a 2%, 5%, 8% or larger than 10% leak down. Some engines are so tight that my gauges are hardly registering, some are a bit more so are showing a bit of leaking seating (which may be carbon or wear), some are worse. I know it's only an indicator, but having both even compression and 6 pistons at 3% or less is a good feeling, better than just even compression. Having the numbers and repeating the tests over the years can also give indications.

But that only my opinion but I know most guys I deal with like that sort of detail - but they are all enthusiasts.

cheers,

Mike

Mike J

Hardest part. It's not hard if the car is a wreck, it's those cars that are good but have perhaps a bit low compression on just one piston, or just one bad panel repair but the rest is pristine - those cause waffling and judgement calls - buy, negotiate, or walk...

Have fun though!

Cheers,

Mike

Shawn O

The plugs are good way to analyze what's going on in the combustion chambers. I asked them to label which cylinder each plug came from and plugs aren't too expensive relative to many other maintenance items on a 993. The tech could grab some old plugs from another car if he's a dirtbag and show them to me but hopefully the request implies to the tech that his work will be inspected and maybe it will provide some evidence that all the plugs were pulled to validate that a compression test was completed.

Thanks for everyone's input!

nrubenstein

That and because if you are going to pay the labor for a plug change (which is 90% of a leakdown test), it is pretty stupid not to put new plugs in.

Turbodan

changing plugs should ensure that they have done all 6 cylinders, and is a bonus for the owner and you if you buy the car.
the search should be fun. relax these cars require patience to get a good one.