compression tests

LtUSMC · 08-15-2000, 03:49 AM

I'm bringing the post I made on "Owners Ages" thread to here, not to clog that one up with something not related to owners ages.

Hoff said his compression check gave him 180 PSI. Mine had 120. And the Haynes manual suggest 145+ is what's expected, though too high is also bad.

Is 120 too low? It was 120 in all 4 cylinders. Is 180 too high? Haynes manual says a high pressure tends to indicate carbon buildup in the combustion chambers.

hoff944 · 08-15-2000, 10:02 AM

Well as long as your hitting 120 on all four I'd say thats good. Did you read my last post on the ages? I've talked to two 944 mechanics (One that has worked on them since they were introduced.) and they said that 180 on all four was excellent. I take it would have to be around 200 to be bad maybe.

porscheboi928s/c944t/n · 08-15-2000, 10:11 AM

how did you check the compression??? is there any smoke(blue smoke)coming out of the pipe?? did you do a leak down test too?? did you try pouring oil on the cylinder and did a compression test again?? try this and keep us informed...

LtUSMC · 08-15-2000, 12:12 PM

I had the compression test done as part of the pre-purchase diagnostic work. So a mechanic did the check. The Haynes manual does describe how to do it though. Don't know if I would play with it though unless you have a reason.

Hoff, it probably is a good sign of what those mechanics told you. I'll ask my mechanic about next time I see him. But don't always accept things for what they are. Before I found the good Porsche mechanic I did, I went to the only guy who worked on Porsches within 20 miles of here. He had a great reputation too. When my car overheated, he put his "best" mechanic on the job... a mechanic that owns a 944! Long story, those incompentant baboons ripped me off by about $500! Worst of all, they made me really worried for a while when they couldn't diagnose a noise from the front of the engine compartment. They said I was screwed and should just drive it "till she blows up." Those idiots didn't realize it was just new timing belts on there which had to be tensioned, that's all. What a bunch of freaking idiots. And the "best" mechanic owns a 944! Shameful!

Just shows you, don't go trusting too much...

944Driver · 944Driver's Garage

LT: I have a similar story of a mechanic who owns a 951. When I found out this guy owned a 944, I thought: great! I don't need to go out of town for servicing anymore. Over the space of a few months, I had the struts, steering rack, and heater controls replaced at this shop. I went back a couple of times to complain that I kept losing coolant after he worked on the cooling system. Well... the last time I went back in, as I waited in the front of the shop, I heard the guy say to his partner: what the f*** does that jerk want this time? Needless to say, I left faster than a 959 on the autobahn. It turns out this 'fine gentleman' had not bothered to properly tighten a hose clamp on one of my heater hoses, hence the loss of coolant. (It's a real ***** to get to, but isn't that why I'm paying him??) I daignosed it and fixed it myself.

LtUSMC · 08-15-2000, 08:16 PM

Don't you hate that?

Charlie has 30 years of experienced, as he proudly advertised. When I asked him why I was overcharged for towing over the phone (calling from HIS shop) he started yelling at me that if I didn't pay I wouldn't get my car back. He then said how he didn't "just stick my car in the corner, but actually worked on it." He treated me like I was ***** and his work reflected.

He caused my radiator to leak, and after overcharging me to replace it, had his POS 944 owning mechanic improperly clamp the hose too. I was losing coolant for months until I figured it out.

What's the moral of the story? Well, I think all you gentlemen in the crowd can figure that one out.

todd951 · 08-15-2000, 08:41 PM

Damn, looks like I've been pretty lucky. I always take my 951 to SportsCar Clinic in Christiansburg, only about 5 or 10 minutes from where I live. They do good work, their prices are reasonable, and I've never been disappointed with them. And they don't charge to fix something again if they didn't get it right the first time (like when I had them install my new brake lines and replace the fluid recently, the car had a very soft pedal when I got it back, and they re-bled the brakes for free when I took it back to them). They have a shop in Roanoke too, but I've never been there. If anyone is really having trouble finding a decent mechanic in VA, I can definitely recommend SportsCar Clinic if you're within a reasonable distance.