Hole in piston or bad valve?
03-23-2008, 07:17 PM
#1
Hole in piston or bad valve? I have an idea that it may be both, but haven't finished trouble shooting. Sprayed a 200 shot at the track, AFR was fine on the dyno, but went lean at the track. Burned the electrode off of #1 and #3 plugs and was making a ticking sound. It sounded like a lifter or an exhaust leak, I am certain it is not a lifter b/c sounds like it is coming from the header (not an exhaust leak either, exhaust is welded even the collectors). I haven't put new plugs in yet to test. The sound could almost be like the cylinder is pumping right through the exhaust valve and making a ticking sound. This is the first time this has happened and I know it only takes one time. Oil pressure is good, no abnormal engine noises other than ticking sound, car just felt down on power (not terrible), 2 burned plugs. Would I be able to tell if the piston has a hole by starting the car with the oil fill cap removed and getting excessive blow by?
What are your thoughts?
What are your thoughts?
03-23-2008, 09:22 PM
#5
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if you have a leak down tester try that. take all the plugs out, put the cylinder up at TDC that you want to check, turn motor over until the exhaust and intake are both closed and hook the tester up. you will know right away of a hole in piston or valve.
03-23-2008, 10:47 PM
#7
Not a bent pushrod, they are moly, not a head gasket and doesn't run hot. I pulled a valve cover and the rockers on the side with the burned plugs and couldn't tell anything from that. I guess hooking an air hose up with the valves closed will tell the story.
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03-23-2008, 11:01 PM
#8
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it is very easy to burn a hole in the stock cast aluminum pistons with a good dose of nitrous and a lean afr but u would know it for sure, test for signs of oil or coolant comsumption, use a timing light to determine where the sound is coming from, if it makes the noise once for every time the light comes on it is ur rods or pistons, for one noise for every two lights it is in the valvetrain. do wet and dry compression tests and a vaccum test.
Last edited by bdford; 03-23-2008 at 11:07 PM.
03-23-2008, 11:13 PM
#9
I was tinking that since I drove it home from the track that if there was a hole in the piston, wouldn't the plug or plugs have oil on them. The car wasn't smoking either.
it is very easy to burn a hole in the stock cast aluminum pistons with a good dose of nitrous and a lean afr but u would know it for sure, test for signs of oil or coolant comsumption, use a timing light to determine where the sound is coming from, if it makes the noise once for every time the light comes on it is ur rods or pistons, for one noise for every two lights it is in the valvetrain. do wet and dry compression tests and a vaccum test.
03-24-2008, 04:02 AM
#10
I doubt it ran lean, you probably had too much timing and detonated. If you tuned on a dynojet, that would probably be why. It doesn't load the car like the street does, you can get away with more than you can on a 1/4 mile pass.
03-24-2008, 08:27 AM
#11
I have HPTuners and logged the run. I am not a newb to nitrous. My total advance is set to 25* on the jug, KR pulled 4*, so I was running 21* of timing. It went lean, a 200 dry shot with a stock fuel pump. It made 469 rwhp on a 150 shot. I am looking for advise on trouble shooting from people that have had similar issues (not to sound like an ***). I don't necessarily tune for AFR either, if you have 0 KR and you know how to read your plugs, then you can run closer to the edge. One little hiccup running on the edge can cause catastrophic failure, on a side note, you'll never know how fast or quick your car will go unless you run it on a fine line.
03-24-2008, 08:34 PM
#14
