Piston Slap?
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From: Maryland
Piston Slap?
I bought my V-10 6 months ago and over this winter have noticed a phenomenom which occurs only after an initial startup in the morning. When I start my beast the first time that day I always allow the engine to idle back below 1k rpm before driving away, just to allow the oil to circulate through the heads. I've noticed that if I let it idle longer than that I start to get a knocking sound from under the truck. I've tried to isolate it but I can't tell if it's from the Torque Converter or Engine. Also, its a singular knock, once per full engine revolution. It's not loud and it goes away when I drive off and won't do it again throughout the rest of the day.
My truck is a 2001 and has 75k miles on it. All the service is up-to-date and it runs great. The oil pressure runs 3/4 on the gauge with no oil burn. I know the previous owner specified 5w20 because it's written in big letters on the radiator cover inside the engine compartment. The transmission is also very strong and shifts well, locks the TQ solid.
I don't think this is a big deal, I would just like to know what it is. Has anyone else had experience with this?
My truck is a 2001 and has 75k miles on it. All the service is up-to-date and it runs great. The oil pressure runs 3/4 on the gauge with no oil burn. I know the previous owner specified 5w20 because it's written in big letters on the radiator cover inside the engine compartment. The transmission is also very strong and shifts well, locks the TQ solid.
I don't think this is a big deal, I would just like to know what it is. Has anyone else had experience with this?
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From: Laramie, WY
My 2004 V-10 with 17k had what I thought was a lifter tap that would last for 1.5 - 2 minutes; after 1 minute it would go away at idle, but it would come back if you gave it a little gas for another minute. As with your truck, once p/revolution. Kind of a thunk; not really a tap. Could it be we had the same problem; the noise of start-up/higher RPM on your truck would mask it until the RPM went down? My V-10 was a 6-speed. BTW - I DID think it was a big deal - new owner of an '06 - 6.0 PSD... 17000 miles the engine is making noises... One more problem - GMC here I come!
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From: Long Island USA
That almost sounds like someone else's problem who had a cracked flywheel - not that I think it's that major!
I'd get underneath to figure out where it's coming from.
These things were known to have a few piston slap issues, but they were the "if it was going to happen, it happened right away" variety. And usually happens right away, not after the idle comes down.
Let others comment too, but let's work on this...
I'd get underneath to figure out where it's coming from.
These things were known to have a few piston slap issues, but they were the "if it was going to happen, it happened right away" variety. And usually happens right away, not after the idle comes down.
Let others comment too, but let's work on this...
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From: Vancouver Wash USA
Originally Posted by mdpopo59
I bought my V-10 6 months ago and over this winter have noticed a phenomenom which occurs only after an initial startup in the morning. When I start my beast the first time that day I always allow the engine to idle back below 1k rpm before driving away, just to allow the oil to circulate through the heads. I've noticed that if I let it idle longer than that I start to get a knocking sound from under the truck. I've tried to isolate it but I can't tell if it's from the Torque Converter or Engine. Also, its a singular knock, once per full engine revolution. It's not loud and it goes away when I drive off and won't do it again throughout the rest of the day.
My truck is a 2001 and has 75k miles on it. All the service is up-to-date and it runs great. The oil pressure runs 3/4 on the gauge with no oil burn. I know the previous owner specified 5w20 because it's written in big letters on the radiator cover inside the engine compartment. The transmission is also very strong and shifts well, locks the TQ solid.
I don't think this is a big deal, I would just like to know what it is. Has anyone else had experience with this?
My truck is a 2001 and has 75k miles on it. All the service is up-to-date and it runs great. The oil pressure runs 3/4 on the gauge with no oil burn. I know the previous owner specified 5w20 because it's written in big letters on the radiator cover inside the engine compartment. The transmission is also very strong and shifts well, locks the TQ solid.
I don't think this is a big deal, I would just like to know what it is. Has anyone else had experience with this?
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From: Maryland
I guess it sounds more like a piston rod or bearing than a valve or lifter. If I pop the hood you can't hear it from the to side. If I had a bearing going bad would I see evidence through loss of oil pressure? Also, it doesn't make the noise initially, only if I let it idle for more than 2 or 3 minutes. Once I drive it the noise goes away and it's quiet at idle. I think this next weekend I'm going to see if I can get it to do it and crawl underneath and try to "feel" where it's coming from.
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From: Long Island USA
The oil pressure gauge is a glorified idiot light. If there is ANY pressure, the gauge goes to that "just above half" point.
I'd get a long screwdriver and do the "touch it to the bone in front of your ear" to locate the noise (or use a mechanic's stethescope).
If the tranny's ever been serviced (or even if not), it's possible the torque converter bolts are loose where it bolts to the flywheel. Remember to check around the bell housing with the stethescope.
I'd get a long screwdriver and do the "touch it to the bone in front of your ear" to locate the noise (or use a mechanic's stethescope).
If the tranny's ever been serviced (or even if not), it's possible the torque converter bolts are loose where it bolts to the flywheel. Remember to check around the bell housing with the stethescope.
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From: Maryland
I fixed that housing cover that commonly vibrates but havn't paid much attention to access to the TC. I also replaced the valve body with a Factory Tech body and did a full service, the old fluid looked good and there was not much shavings on the magnet in the pan. Is there an inspection plate that allows access or does the bell housing need to be separated from the engine?
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From: Maryland
OK, well I think It's going to have to wait until Saturday when I have time to crawl underneath. Hopefully that's all it is and I can just tighten up those bolts. That makes sense for the type of noise it's making. Thanks to all you guys for your help, I'll let you know what I find.
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From: NORTH CAROLINA
Are you sure its not a diesel??
Just kidding...
It would be good to actually get a true numbers oil pressure reading when you first start it and also read the oil pressure number when the problem noise begins to be audible.
It could be one of alot of things but,by having a true oil pressure reading you could possibly islolate the problem as internally or externally and whether its,lifter,lifters,oil pressure related, etc.
Another checks /check would be to see if its a vacuum leak(sucking)or actual ignition/timing problem..
Good luck just some food for thought..
I would venture to say it may likely be a faulty/collapsing lifter or your hearing a clicking from compressor..
Just kidding...
It would be good to actually get a true numbers oil pressure reading when you first start it and also read the oil pressure number when the problem noise begins to be audible.
It could be one of alot of things but,by having a true oil pressure reading you could possibly islolate the problem as internally or externally and whether its,lifter,lifters,oil pressure related, etc.
Another checks /check would be to see if its a vacuum leak(sucking)or actual ignition/timing problem..
Good luck just some food for thought..
I would venture to say it may likely be a faulty/collapsing lifter or your hearing a clicking from compressor..
Last edited by jaybird; Mar 6, 2006 at 06:42 PM.
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From: Home Base Nebraska
Originally Posted by D-Driller
My 2004 V-10 with 17k had what I thought was a lifter tap that would last for 1.5 - 2 minutes; after 1 minute it would go away at idle, but it would come back if you gave it a little gas for another minute. As with your truck, once p/revolution. Kind of a thunk; not really a tap. Could it be we had the same problem; the noise of start-up/higher RPM on your truck would mask it until the RPM went down? My V-10 was a 6-speed. BTW - I DID think it was a big deal - new owner of an '06 - 6.0 PSD... 17000 miles the engine is making noises... One more problem - GMC here I come!
Denny
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From: Northern Va
Originally Posted by D-Driller
My 2004 V-10 with 17k had what I thought was a lifter tap that would last for 1.5 - 2 minutes; after 1 minute it would go away at idle, but it would come back if you gave it a little gas for another minute. As with your truck, once p/revolution. Kind of a thunk; not really a tap. Could it be we had the same problem; the noise of start-up/higher RPM on your truck would mask it until the RPM went down? My V-10 was a 6-speed. BTW - I DID think it was a big deal - new owner of an '06 - 6.0 PSD... 17000 miles the engine is making noises... One more problem - GMC here I come!
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From: Maryland
Originally Posted by jaybird
Are you sure its not a diesel??
Just kidding...
It would be good to actually get a true numbers oil pressure reading when you first start it and also read the oil pressure number when the problem noise begins to be audible.
It could be one of alot of things but,by having a true oil pressure reading you could possibly islolate the problem as internally or externally and whether its,lifter,lifters,oil pressure related, etc.
Another checks /check would be to see if its a vacuum leak(sucking)or actual ignition/timing problem..
Good luck just some food for thought..
I would venture to say it may likely be a faulty/collapsing lifter or your hearing a clicking from compressor..
Just kidding...
It would be good to actually get a true numbers oil pressure reading when you first start it and also read the oil pressure number when the problem noise begins to be audible.
It could be one of alot of things but,by having a true oil pressure reading you could possibly islolate the problem as internally or externally and whether its,lifter,lifters,oil pressure related, etc.
Another checks /check would be to see if its a vacuum leak(sucking)or actual ignition/timing problem..
Good luck just some food for thought..
I would venture to say it may likely be a faulty/collapsing lifter or your hearing a clicking from compressor..
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Posts: 398
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From: NORTH CAROLINA
Originally Posted by mdpopo59
I'ts not a noise from the top end but from under the truck, and it doesn't start until after the oil has a chance to circulate through the engine. It almost sounds like someone taking a wrench and lightly tapping against the side of the oil pan or transmission housing. Can the engine or transmission oil pump make a noise like that? It's definitely not a lifter or a vacuume leak.
These are all just areas of concern since the problem area has not been found yet..
Does the engine smoke?Do you see any unordinary exhaust smoke like excessive white or black smoke?
Is the noise definetely in the oil pan or in the tranny?Do the screw drive sound to ear test like someone suggested.
I would still suggest :FIRST buy an aftermarket oil-pressure gauge and get true oil pressure readings before during and after the problem sound..
Its cheaper to spend on a oil gauge then later find out that you had a oil pump problem.....
good luck
Last edited by jaybird; Mar 7, 2006 at 07:30 PM.