Piston slap causing oil consumption?? pic inside
11-23-2009, 05:46 AM
#1
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Piston slap causing oil consumption?? pic inside
Have very high oil consumption so I took off the heads to look at the cyl walls. Wanted to take the heads off anyway to get them even more ported by LE.
All 8 cylinder walls look alike, intake same as exhaust side of the walls. Looks like piston slap to me and can't be fixed through new rings as I see it.
These are forged 4032 SRP pistons with standard tension 1/16, 1/16, 3/16 rings
Need some advice on this before I continue.
All 8 cylinder walls look alike, intake same as exhaust side of the walls. Looks like piston slap to me and can't be fixed through new rings as I see it.
These are forged 4032 SRP pistons with standard tension 1/16, 1/16, 3/16 rings
Need some advice on this before I continue.
11-23-2009, 08:50 AM
#3
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I haven't done anything to the pistons except wipe the walls clean to take some pictures.
The intake is really soaked from oil on the inside. It's probably coming through the PVC valve because of too much blow by.
The intake is really soaked from oil on the inside. It's probably coming through the PVC valve because of too much blow by.
11-26-2009, 12:35 PM
#5
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Don't know what that means.
Pulled pistons today, none of the rings are broken and overall the pistons don't look to bad.
Three pistons have undersize though.
#2 0.0016"
#3 0.0012"
#5 0.0024"
The scuffed areas/walls are about 0.0004"--0.0012" larger. The clearances are otherwise in tolerance.
Piston #1 looks worst to me, here are two picture of piston #1.
Pulled pistons today, none of the rings are broken and overall the pistons don't look to bad.
Three pistons have undersize though.
#2 0.0016"
#3 0.0012"
#5 0.0024"
The scuffed areas/walls are about 0.0004"--0.0012" larger. The clearances are otherwise in tolerance.
Piston #1 looks worst to me, here are two picture of piston #1.
11-26-2009, 02:51 PM
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11-26-2009, 04:22 PM
#7
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The scoring starting directly below the oil control ring + the clean almost pitted look at the outside edges of the pistons indicates detonation as the cause. The chicken and the egg principal can get confusing here as oil in the cylinder can cause detonation independent of timing, compression, and fuel so if those factors were borderline to begin with and oil consumption started due to bad ring seal or PCV issues, that could have been a tipping point leading to detonation.
If it was not detonation, the most common things to look for with scoring like that would be dirty assembly, dirty oil, or a spun bearing which flings babbit up onto the cylinder walls in that cylinder causing the scoring.
Just simply from lots of motors being torn down that I have seen with known detonation problems + the known accepted symptoms of detonations makes me believe without much doubt that is your problem, plus a little bit of dirty assembly and oil as indicated by the little independent streaks of scoring on the piston separate from the main patch of side loading wear that is shown.
I'm not exactly sure what you mean by your comment earlier about "three pistons have undersize" but I assume you mean that the skirts are collapsed which I can basically see from the pictures.
If it was not detonation, the most common things to look for with scoring like that would be dirty assembly, dirty oil, or a spun bearing which flings babbit up onto the cylinder walls in that cylinder causing the scoring.
Just simply from lots of motors being torn down that I have seen with known detonation problems + the known accepted symptoms of detonations makes me believe without much doubt that is your problem, plus a little bit of dirty assembly and oil as indicated by the little independent streaks of scoring on the piston separate from the main patch of side loading wear that is shown.
I'm not exactly sure what you mean by your comment earlier about "three pistons have undersize" but I assume you mean that the skirts are collapsed which I can basically see from the pictures.
11-26-2009, 04:44 PM
#8
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Yes, I mean the diameter of the piston measured 1/2" from the end of the skirt.
# 1 4.0272
# 2 4.0256
# 3 4.0260
# 4 4.0272
# 5 4.0248
# 6 4.0272
# 7 4.0272
# 8 4.0272
I drove now and then using my DataMaster and noticed very seldom knock retard. When it appeared, it was in the range of about 4000--5500 rpm.
Questions are though:
must I buy new pistons or can I reuse these pistons and just buy new rings??
Would not like to go to 4.040" bore.
# 1 4.0272
# 2 4.0256
# 3 4.0260
# 4 4.0272
# 5 4.0248
# 6 4.0272
# 7 4.0272
# 8 4.0272
I drove now and then using my DataMaster and noticed very seldom knock retard. When it appeared, it was in the range of about 4000--5500 rpm.
Questions are though:
must I buy new pistons or can I reuse these pistons and just buy new rings??
Would not like to go to 4.040" bore.
11-26-2009, 05:24 PM
#9
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Posts: 228
u need to measure the cylinder bore it looks excesive piston to bore clearence and u had some piston slap with some very dirty assembly or airfilter seal leaking and leting dirt in.
sometimes with certain pistions you have to run your piston to bore clearence a lil tighter .
who built your motor?
sometimes with certain pistions you have to run your piston to bore clearence a lil tighter .
who built your motor?
11-27-2009, 03:30 AM
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Thanks for the replies fellows.
I think I will have it bored and honed to 4.035 and use 2618 alloy instead of the 4032. This might help to prevent the pistons from collapsing. Even though I don’t like the idea of going to 2618 alloy because I drive it mostly on the street.
BTW, the clearance is ok 0.00335--0.00394 it’s a little on the large side but still not bad. The piston to wall clearance using the collapsed pistons is of course larger, because the pistons diameter is smaller. Clearance 0.0050--0.0058
See if I can find a place that sells 4.035 pistons and maybe some better rings to a reasonable price. Can anyone help me out here.
I think I will have it bored and honed to 4.035 and use 2618 alloy instead of the 4032. This might help to prevent the pistons from collapsing. Even though I don’t like the idea of going to 2618 alloy because I drive it mostly on the street.
BTW, the clearance is ok 0.00335--0.00394 it’s a little on the large side but still not bad. The piston to wall clearance using the collapsed pistons is of course larger, because the pistons diameter is smaller. Clearance 0.0050--0.0058
See if I can find a place that sells 4.035 pistons and maybe some better rings to a reasonable price. Can anyone help me out here.
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