HELP! The Cert Porche Tech said...

[tsuter]

Originally posted by speeder
Any drunken monkey should be able to tell when a motor has a dead hole, he should have told you for free.

Amen to that Bro!!!

[Grady Clay]

Guys,

A properly done PPI is a sequential process. You do the most productive and least expensive things first. Then on to step two, three and so on.

An ignition scope and tail pipe CO & HC check will give some valuable initial information at almost no cost. If there was impaired cylinder(s), a visual of the cap & rotor may eliminate that possibility. We had a test set of wires and plug connectors for a quick swap.
Next would be a sump plate/ filter inspection.

First decision point, do we continue? At this point there is labor, sump gaskets and oil & filter.

Next would be a combined cranking compression and cylinder leak test. Sparkplug inspection is a very important part.

Second decision point, do we continue?

Remove the intake valve covers and check the intake valve clearance properly and the exhaust with a long feeler (not the way to set valves, just a rough check.) Measure the cam timing. It is remarkable how many engines can still run with the cam timing off.

Of course the mechanic is inspecting and testing many other things here. The point is there is a progressive sequence. Only some shyster would continue when major problems were found in the first or second steps.

The other issue is communication. I would insist that the buyer be readily available by phone so we could report the findings and get directions. The critical part of the loop is what the buyer wants. It is up to the PPI shop do accurate testing and to give good advice and council as to what is worthwhile or a waste of money. Many times the buyer wants all the info to negotiate an appropriate price.


A few years ago I spent $600 for several PPIs finding Karen another $4500 early Land Cruiser. Money well spent to find the right ‘84. We started with 119K and now have 330K with very few repairs.

Best,
Grady

[Nine9six]

Thanks Grady for your input! Also very helpful.
Paul

[Wayne 962]

Originally posted by speeder
And Wayne, we all understand that other causes can give a bad HC reading, the point is the converse: a motor w/ bad leakdown could not give good HC #s. No matter how many cool collars are installed. An expensive LD test could be eliminated on most of these turds by a simple sniffer. And I agree that a compression test is sufficient. I wouldn't even bother w/ that unless it passed the sniffer. (With mixture adjust/etc..).

You completely misunderstood what I said. A simple leaking injector (which is an easy problem to fix) would give poor exhaust gas numbers and wouldn't be a useful test of the mechanical components of the engine. In other words, it may filter out an otherwise good car with only a simple problem.

In general, there's tons of misinformation in this thread. There is no such thing as a bullet-proof test. Simple carbon build-up may skew leakdown tests for a single test, then clear up on the highway. Ditto for the compression check. You must evaluate all of the circumstances together as a whole and not depend upon a single test.

Again, read this article - it's the best intro on how to evaluate your engine's condition:

http://www.pelicanparts.com/techarticles/mult_Engine_Rebuild/mult_engine_rebuild-1.htm

-Wayne

-Wayne

[speeder]

I understood what you said perfectly.

What I said, on the other hand, is that a clean sniffer test would pretty much eliminate the need for a leakdown test, IMO anyways.

Yes, many other factors could cause high HCs, (or CO), but take the logic in the other direction: could a car that fails a LD test post good HC #s?

I think that compression tests are more useful in general, unless you already have determined a leakage issue from the CT and want to investigate further. If it was my PPI, and the car had less than excellent compression numbers, I'd factor at least a future top-end job into the price, or walk away.