Pre Purchase Inspections (PPI)

What is a Pre-Purchase Inspection, and why would you want one?  The names says it all.  An inspection made before purchasing a car, to help point out the pro’s and con’s of the car you are about to purchase.  The inspection should be done by someone who really knows the car being inspected.  In other words, having a Honda mechanic inspect a Porsche, might not be the best idea.  He might catch some obvious things that need attention, but might miss others.  Now, a PPI is not going to guarantee failure of certain mechanical items, but it can give you a piece of mind of the general health of the car, especially if you are buying the car sight unseen.  Also, note the “PRE” part of the name.  PPI does not mean Post purchase inspection, done after buying the car, lol.  Not always, but a lof of times a post purchase inspection results in the new owner crying about all the repairs needed on the car.  If you do the inspection before purchasing the car, and it turns out to be a rat, you can easily walk away from the sale, and you are only out the few hundred dollars for the inspection.

What is involved in a PPI?  A very basic PPI will go through the entire vehicle from top to bottom, checking to make sure all the items function on the car, that body panels line up appropriately (misaligned panels typically indicate previous body work), checking the condition of the paint on the entire car, are things present like the spare tire, owners manuals, etc.  A step above the basic PPI would be to add a leak down and compression test, which will check the health of the motor, and give you an idea if the engine is good and solid, or if maybe the rings or valves are starting to have issues.

Once the inspection has been completed, the information is compiled into a report complete with pictures of the car, and the areas of concern are noted.  After reviewing the information with the potential buyer, then that buyer can either make the decision to go ahead with the purchase, or continue to look for a different car.  A good PPI can weed out a really bad, and potentially expensive purchase, and is money well spent.  Expect a basic PPI to range from $150, and one with leak down and compression results anywhere from $300 to $500 depending on the car.

This 993 Twin Turbo came through last week.  A prospective buyer 400 miles away was interested in purchasing the car which is local here in the Kansas City metro.  After a few phone calls, we arranged for the car to come down to me for a full PPI.  Since the 993’s are known to have some top end issues with things like valve guides, we made sure to do the leakdown and compression tests.

Checking the leakdown on one of the cylinders…..a pretty healthy cylinder…….

A leak down test is done by placing the cylinder on Top Dead Center, removing the spark plug, and installing the leak down tester.  Compressed air is then put into the cylinder at 100psi, and the gauge will tell you if the air is able to leak out of the cylinder (at TDC, the valves are closed, so the air should be trapped in the cylinder).  This cylinder is the in the 1-2% leakage region, which is near perfect.

The joys of a 993TT is that the engine is not a twin plug engine, which means getting to the #6 spark plug requires removal of part of the exhaust and engine tin to gain access from below.  Not an easy chore.

The results of the PPI?  Well that is private information for the guy that paid for the inspection 🙂

A parting shot. 🙂

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Jonathan Lackman

November 13, 2009 at 9:39 PM

Pretty nice! I know Lessman, so I followed some links to your site. One day I hope to need a Porsche mechanic!

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