groovzilla

had PPI done today on the 1995 993 w/99K miles in SF

here is compression test results...my concern is the #4 cylinder

cylinder
#1 200
#2. 203
#3 190
#4 160 ***
#5. 195
#6. 200

how much of a issue is a 20% difference in compression?...cylinder was tested 2x

ed devinney

That's a whole lot of difference - have always heard 5-10% variance to be OK.

I'd want a leakdown test before I'd buy.

chris walrod

Or, a leakdown on #4 at a minimum to pinpoint the source of the leak.

BlkC4S

I wouldn't buy the car as-is. Something's not right in that cylinder.

You've already paid for a PPI so you might as well try getting more information and negotiating.

Personally I'd get another PPI including a leakdown but ask the seller to pay. No one is going to buy that car without a PPI and the next guy will see this same result.

As part of the PPI, have them include an estimate for the repair. It could be $$$ in this case.

At least then you'll have a much better idea on a reasonable price for the car.

Not sure who did your PPI, but I'd recommend RMG (realmeangarage.com) or S-Car-Go (http://scargoracing.com/)

centerpunch

That's a 20% difference, not 40%.

In the old days we'd squirt some oil into that cylinder, and run the test again. If the compression goes up, the problem is rings. If it doesn't, the problem is valves.

groovzilla

i discussed compression results with the owner of the car...both he and a friend of mine (who is a porsche mechanic) suggested driving the car hard for the afternoon tomorrow and owner also will add techron to fuel to hopefully loosen any carbon deposits if this is in fact the problem

shop will retest cylinder#4 in the afternoon when car is brought back to shop

hopefully this solves the problem

NP993

It could also be carbon lodged between a valve and seat causing poor sealing. Definitely worth running the car hard and re-testing.

MarkD

+1
This is why a leakdown is needed in a PPI...

Rob's suggestion of getting the seller to have some skin in the game and fund a leakdown is a good one, IMO.

wayne993

THere are thousands of 993s in the US. You've found one that may need a top end rebuild at least.
Why are you bothering with it?

NP993

I can answer that one -- because it might not need a top end rebuild. The leakdown number might simply be a very common occurrence, such as carbon lodged under a valve because of the removal of the spark plugs. That's why you drive it and re-test. Elementary stuff.

Knute

The rest of the story...

The solution: a full bottle of Techron into half a tank (labeled for use w/ 14 gallons), supplemented with some 100 octane (76 station on Woodside Road in Redwood City has it on a pump) to get the crappy California gas up to an average of 93 octane, followed by 2 hours of GLORIOUS throttle stomping up and down the mountain roads on either side of Skyline (the ridge down the peninsula south of San Francisco). After this, it was definitely "breathing" more freely, and the idle was dramatically smoother. Back to the shop for a retest of the #4 cylinder and the adjacent #5 cylinder for comparison, and both tested at 195.

Nothing like a good Italian tuneup to help these beasts purr like they are supposed to.

(Note: this was immediately followed by an oil and filters change, so whatever crud the Techron flushed into the oil won't be hanging around.)

It's nice to have stories with happy endings!

-Knute
(Former owner of William's '95 993)

95C4VanIsle

Congratulations, glad it worked out so well, and perhaps a learning experience for others.

Texas993

Good ending to the story. Sounds like both sides are happy. William must be a happy guy!

groovzilla

and i must say, knute, who sold me the car couldn't have been more patient, helpful and willing to remedy the situation...it really makes a difference when a seller takes the time and energy to explain the car fully and answer as many questions as an excited buyer may have.

can't wait to pick the car up on 9/10...

if i can't bend over and down to get in the car because of my syurgery, at least the service techs can shoe horn me in!

wm

wayne993

Interesting..... interesting.