Very scary compression numbers on my turbo car
10-04-2011, 05:10 PM
#63
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Yes, this is correct. You cannot dispute the howling air on the leak test through the exhaust. I was hoping to get a baseline number where the numbers were close on more than one cylinder, it's clear the engine is blown.
I'm also thinking I had detonation or something although I never heard it on the dyno. That's basically the only excuse for eroded, leaky valves.
I'm also thinking I had detonation or something although I never heard it on the dyno. That's basically the only excuse for eroded, leaky valves.
I'm with mgeoffriau, you need a proper compression tester before you do anything like pull the head.
It's bonkers to be worrying about something when there's no evidence other than a tester which gives funny readings on more than one car.
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10-04-2011, 05:12 PM
#64
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I don't understand, aren't exhausts supposed to leak? If they didn't engines wouldn't run...
I'm with mgeoffriau, you need a proper compression tester before you do anything like pull the head.
It's bonkers to be worrying about something when there's no evidence other than a tester which gives funny readings on more than one car.
I'm with mgeoffriau, you need a proper compression tester before you do anything like pull the head.
It's bonkers to be worrying about something when there's no evidence other than a tester which gives funny readings on more than one car.
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10-04-2011, 05:20 PM
#67
I don't understand, aren't exhausts supposed to leak? If they didn't engines wouldn't run...
I'm with mgeoffriau, you need a proper compression tester before you do anything like pull the head.
It's bonkers to be worrying about something when there's no evidence other than a tester which gives funny readings on more than one car.
I'm with mgeoffriau, you need a proper compression tester before you do anything like pull the head.
It's bonkers to be worrying about something when there's no evidence other than a tester which gives funny readings on more than one car.
if he had serious detonation, there would be broken rings/ringlands, before any valve problems. there would also be a hammertone finish on the pistons, which could be verified by putting #1 at tdc and shining a light in there.
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10-04-2011, 05:30 PM
#69
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Comp TDC on every cylinder. I'm going home to check lash again. The exhaust side is a little tight for my taste.
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10-04-2011, 05:35 PM
#70
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It's been a while since I **** blood as a physiological symptom of stress. Maybe I'll get back there this weekend at the track when I think about the bill to tow my car home from the track incessantly while not enjoying the weekend.
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10-04-2011, 10:56 PM
#79
You may just have some worn valve springs that aren't pulling the valves shut firmly enough.
EDIT: I recall a story similar to this from my auto mechanics class in high school. The car would drive normal, but the compression test or whatever would show a leak. It turned out that one of the valve springs actually cracked/broke so that it had enough spring to pull the valve shut, but not hold it shut very tightly.
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10-04-2011, 11:07 PM
#80
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FWIW, when I've done leakdown tests, I often see the valves leaking slightly. I think it's due to bits of carbon or something getting stuck between the valve and the seat and preventing a complete seal. If you crack the exhaust valve open with pressure in the cylinder, that'll usually blow it loose, then go back and it will seal.
--Ian
--Ian
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