PPI Protocol? What do I do now?

Kaivball · Jan 17, 2011

Aiden said: ↑

I believe that it is up to the buyer to pay for the first PPI, which shows genuine interest in the car. If it "fails" or requires additional for a retest, it should be on the seller to show he has done his part to rectify the problems. You have invested in a car you dont even own, and should not be expected to pay multiple times. Or have the seller discount the car twice the price of the second PPI.
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That's what I thought.

Buyer already showed the problems.

Seller now wants to demontrate that it's not an issue any more. Seller should pay for second PPI.

If not, just walk.

There are plenty of nice cars out there looking for a good home.

Kai

population485 · Jan 17, 2011

WCCoffey said: ↑

I don't understand what you mean by failed a PPI and requiring a retest. Unless you mean it failed a State Inspection.

Those numbers seem a little off to me.. Do you mind me asking who did the PPI for you?
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I trust the guys who did ppi.. Norwood of Dallas is no slouch. Based on the reputaiton alone.. this is my first dealing with them.. The car had a major 2 years ago and was only driven 1700 miles since that time.. Had to have a problem just from sitting no? We shall see.. fingers crossed

population485 · Jan 17, 2011

348SStb said: ↑

I would question the validity of these engine test results.

Those compression numbers taken by themselves look at the very least decent. I am not talking about the greatness of the numbers (i.e., that they are over 200.) I am talking about the fact that the worst cylinder -- #4 -- is within 10% of the best cylinder. Different people will tell you different things, but typically within 5% from worst to best cylinder is desired but within 10% is not awful.

Then the leakdown #s indicate pretty not-so-good results. Cylinders 2, 3, and 4 exhibit substantial leakage.

Only problem is, the leakage numbers tell us that the compression test was not done properly. Cylinders with that much leakage will NOT exhibit compression results that good -- that is, an engine with good compression MUST have good leakage numbers. I will illustrate the logical relationship below. Again, cylinder #2 having 210 compression and a whopping 20% leakage does not make sense if cylinder #8 has a 224 compression and 4% leakage.

The logical relationship between compression and leakage is as follows:

Good compression numbers --> Good leakage numbers

This is a true statement. If an engine has good compression #s, then it must have good leakage numbers. You cannot have poor leakage results but have good compression results. That would be a spurious test.

Good leakage #s --> Good Compression #s.
This is a false statement. If an engine has good leakage #s, that doesn't mean the engine will yield good compression #s. This is why we do the compression test first. The trick is to use proper methodology.

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On another note: I would not disclose the results to the seller until you perform the second PPI, if you so desire. Oh, and that will be on your nickel. You do not want to give the seller or anyone else the opportunity to pepper the car so that the results will be better next time. A little squirt of oil in the cylinder, you know, fixes a compression test.

That said, I have never heard of doing a "second" PPI.

I would also get a new shop for the second PPI. Seems they do not know how to perform the compression test. This leads me to question their competence in checking the other vital areas. Then again, many so-called "mechanics" don't use any scientific basis whatsoever for performing compression tests. There is a specifically scientific approach that must be followed to keep variables isolated and spuriousness away. Sure, there can be some variation in the conditions under which the test is performed, but the approach is the same. You can't just crank each cylinder till the needle stops moving and write down the final pressure # and call that a compression test. A 6th grade science teacher would be appalled at that use of the scientific method.

Either way, the leakage numbers do not lie. If it leaks, you've got some issues.
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Thanks Dave! I appreciate the advice and the well thought out information.. I will digest this and keep all posted with what happens.. The car had a major 2 years ago and was driven just 1700 miles since that time.. I am not sure what to expect but the guys at Norwood of Dallas have an excellent reputation, it is however, my first dealing with them.. Look soon for a new post this week early... Stay warm on the Island! I was just there on business several times.. Hamptons, Farmingdale, and Newburgh.. BURRRRR!

Eric

348SStb · Jan 17, 2011

population485 said: ↑

Thanks Dave! I appreciate the advice and the well thought out information.. I will digest this and keep all posted with what happens.. The car had a major 2 years ago and was driven just 1700 miles since that time.. I am not sure what to expect but the guys at Norwood of Dallas have an excellent reputation, it is however, my first dealing with them.. Look soon for a new post this week early... Stay warm on the Island! I was just there on business several times.. Hamptons, Farmingdale, and Newburgh.. BURRRRR!

Eric
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No problem. Good luck and keep us posted.

KKSBA · Jan 17, 2011

Rifledriver said: ↑

The compression and leak down tests are invalid.

Someone did not know what they are doing or used faulty equipment.

Find someone who knows how.
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+1

Brian knows what he is talking about!

WCCoffey · Jan 18, 2011

I know the guys over at Norwood's pretty well, and you are right they are respectable and knowledgeable guys. But those numbers don't look right.

However if you want a second opinion, we would be more then happy to take a look at it for you. We are located in Addison. I am in process of doing a major on a 355 right now, but we can work you in if you give us call. 214-269-1572

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