What do pistons look like that have experienced a lot of detonation?
03-17-2003, 12:49 PM
#1
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What do pistons look like that have experienced a lot of detonation?
Just like the title says, what do they look like?
I just pulled the drivers side head off my motor and 3 of the 4 pistons have this "battlefield" pock mark look to them, and the 4th pistom head is covered in carbon thats kind of the consistency of very gritty oil.
This is my new motor, it has 7000 on it. What the **** happened?
I just pulled the drivers side head off my motor and 3 of the 4 pistons have this "battlefield" pock mark look to them, and the 4th pistom head is covered in carbon thats kind of the consistency of very gritty oil.
This is my new motor, it has 7000 on it. What the **** happened?
03-17-2003, 01:16 PM
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Yeah, you were into detonation for sure- that's what it looks like- like someone took a tiny hammer and whacked away on the top of the piston for a while. The "oily" piston you might have something wrong with the rings in that cylinder (detontion can destroy rings and piston ring lands) or possibly the intake valve guide/seal was really gone.
03-17-2003, 04:12 PM
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Damon, the motor had about 6000-7000 miles on it I think. Brand New Rebuild as of last May.
The oily pistons did not have the detonation marks when you scraped the oily stuff off. they were nice and smooth like they were when installed new.
Uhm... what do I do??
The oily pistons did not have the detonation marks when you scraped the oily stuff off. they were nice and smooth like they were when installed new.
Uhm... what do I do??
03-17-2003, 05:46 PM
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Originally posted by RedIrocZ-28
Uhm... what do I do??
Uhm... what do I do??
You state your compression ratio is 10.3:1 Not only is that marginal for pump gas, but I bet the actual ratio is a litter higher. How did you calculate it?Once you have the source found and fixed, then replace any damaged parts.
03-18-2003, 11:15 AM
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Later I am gonna try to post pictures.
The pistons that showed the detonation marks were 1 and 3. Is it possible that I accidently plugged the wrong injector plugs into the wrong injectors since these 2 cylinders are right next to eachother and this is what it did?
8-7
6-5
4-3
2-1
The pistons that showed the detonation marks were 1 and 3. Is it possible that I accidently plugged the wrong injector plugs into the wrong injectors since these 2 cylinders are right next to eachother and this is what it did?
8-7
6-5
4-3
2-1
03-18-2003, 04:08 PM
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gyhyjg
I say have your cylinder head guy do some combustion chamber work or at least polishing and run a thicker gasket when you put it all back together. I'm not sure if I would leave those pistons in there since I don't see how bad they are looking. Sounds like they've been beaten on pretty badly and possibly they're a lot weaker now. With this new intake and ported heads, possibly a new cam(no?)...the engine will wnt to see over 6000 RPM if I'm not mistaken and I wouldn't want brittle or weak pistons in an engine like that. How much would it cost to buy an identicle set of pistons? If you're still confident enough you could install them yourself. new rings also if the old ones look bad. Goodluck ****! We'll talk about it later.
03-18-2003, 10:37 PM
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ok update time
pistons 1 and 3 had solid carbon buildup on them, they are not detonation damaged like I thought they were. The rest of the pistons have a more oily buildup on them. I don't know why.
Anyway, they are all fine, I just need to tune the car... better. Getting a bit too much fuel or too much spark I guess... too much advance and the gas doesn't get burned right? Then it ends up as carbon buildup on the pistons and in the exhaust.
Guess I shoulda scraped a little harder eh? lol
pistons 1 and 3 had solid carbon buildup on them, they are not detonation damaged like I thought they were. The rest of the pistons have a more oily buildup on them. I don't know why.
Anyway, they are all fine, I just need to tune the car... better. Getting a bit too much fuel or too much spark I guess... too much advance and the gas doesn't get burned right? Then it ends up as carbon buildup on the pistons and in the exhaust.
Guess I shoulda scraped a little harder eh? lol
03-19-2003, 10:57 AM
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My plugs all look good so I doubt that there is oil getting past the rings. At idle there is a definite burn your face and eyes emission coming from the tail pipes... translation.... unburnt fuel and a bunch of it.
I'm gonna have to lean it out a bit. I'll still try to get pictures here in a little bit.
I'm gonna have to lean it out a bit. I'll still try to get pictures here in a little bit.
03-19-2003, 12:09 PM
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Re: What do pistons look like that have experienced a lot of detonation?
Originally posted by RedIrocZ-28
What do pistons look like that have experienced a lot of detonation?
What do pistons look like that have experienced a lot of detonation?
Sorry I couldn't resist
03-19-2003, 05:29 PM
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Brother Chuck, I did NO tuning to the fuel table. NONE.
Those guys over there at the thirdgen.org board were not helpful at all. Every time I would ask what you need to tune on the MAF cars for fuel they told me to go read old poss. Well after about 8 months of reading old posts and comin up with ZIP that was useful, I gave up.
If they would just say, do this here, it would have been fine but they wouldn't have even given me that much... they were no help. AT ALL...
Those guys over there at the thirdgen.org board were not helpful at all. Every time I would ask what you need to tune on the MAF cars for fuel they told me to go read old poss. Well after about 8 months of reading old posts and comin up with ZIP that was useful, I gave up.
If they would just say, do this here, it would have been fine but they wouldn't have even given me that much... they were no help. AT ALL...