my M1 experience in GM 5.3L piston slapper

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Originally Posted By: OVERK1LL
Originally Posted By: HangerHarley
Originally Posted By: typ901
The Rod looks different as well...


I digress they look a LOT the same, and the lighting on the older Piston is dark on the area with the words. I can not tell a difference between those two except that they are orientated differently, the one has the words facing "up" the other "to the side."

Maybe some engines from 1999 to 2003/2004 dont have slap on the 5.3 because the Pistons arent all that different?

Im thinking an analysis of WHY PS develops is in order, since it appears to be a random thing, and engines in fleets w same engines and oil, some develop it and some dont.

Might make a case for driving habits? Should those with the heavier foot use the thicker Oil?


You need to take a closer look. There is a BLACK COATING on the piston skirt on the 2nd piston, and the one I just posted above. This is the "updated" design. The skirts are coated in Teflon (common in the aftermarket, and Ford has been using it for a long time in the Modular engines) which helps to reduce or eliminate the noise caused by piston slap. It is also low-friction, so it apparently has an emissions benefit as well.


I would not have known that. One piston looks "Cleaner," namely, the second one. (I also dont have the trained eye.. those pistons looked super same. Im not the expert, though, and i dont doubt what you are saying.)

Also, RE Dupont's Teflon: So they took it out of Oil, but its still on Pistons? And i thought they were coated with "Molybdenium Disulfide," or Mos2..............

Having had an Engine drop a valve once and me looking high and low and in years-old warehouses for ANY Piston, i can tell you pistons from different years probably are NOT interchangeable.
 
Originally Posted By: SteveSRT8
Remember my expertise is in trucks, not cars. And I seriously doubt that all GM V8 vehicles are using coated pistons. Probably just the Hi-Po versions.

There are two distinct types of trucks, vans and pickups.

I can assure you the vans are WAY behind the pickups in terms of technology, and as late as 05 did NOT have any coatings on their pistons. I have an 06 6.0 V8 block on the bench right now for rebuild, I'll be sure and let you know what kind of pistons it has when I tear it down.

As an example of the vans being the '[censored] stepchildren' note that the weren't even DBW throttles in 06!!! Pickups had been for years.


Yes please do, I would be interested in your findings for sure! My understanding of their "fix" was that they had moved to coated skirts across the board. Would be nice to see if there are exceptions here!

-Chris
 
Originally Posted By: HangerHarley
Originally Posted By: OVERK1LL
Originally Posted By: HangerHarley
Originally Posted By: typ901
The Rod looks different as well...


I digress they look a LOT the same, and the lighting on the older Piston is dark on the area with the words. I can not tell a difference between those two except that they are orientated differently, the one has the words facing "up" the other "to the side."

Maybe some engines from 1999 to 2003/2004 dont have slap on the 5.3 because the Pistons arent all that different?

Im thinking an analysis of WHY PS develops is in order, since it appears to be a random thing, and engines in fleets w same engines and oil, some develop it and some dont.

Might make a case for driving habits? Should those with the heavier foot use the thicker Oil?


You need to take a closer look. There is a BLACK COATING on the piston skirt on the 2nd piston, and the one I just posted above. This is the "updated" design. The skirts are coated in Teflon (common in the aftermarket, and Ford has been using it for a long time in the Modular engines) which helps to reduce or eliminate the noise caused by piston slap. It is also low-friction, so it apparently has an emissions benefit as well.


I would not have known that. One piston looks "Cleaner," namely, the second one. (I also dont have the trained eye.. those pistons looked super same. Im not the expert, though, and i dont doubt what you are saying.)

Also, RE Dupont's Teflon: So they took it out of Oil, but its still on Pistons? And i thought they were coated with "Molybdenium Disulfide," or Mos2..............

Having had an Engine drop a valve once and me looking high and low and in years-old warehouses for ANY Piston, i can tell you pistons from different years probably are NOT interchangeable.



Hey, nothing wrong with learning something new
grin.gif


BTW, it would likely depend entirely on the brand and engine family as to different years being interchangeable. Ford used a variety of different pistons in the 302, but IIRC, the same rods. So any of the pistons would be interchangeable. Of course you would affect compression and would have to ensure you didn't have any piston to valve clearance issues (86 had flat-tops, 87-92 had forged dished TRW slugs in the HO) and the like.

As far as the coating goes, the idea is that it stays on the piston. The issue with the Teflon in the oil was that of course it would settle in low-flow areas, being a solid. So it provided no real benefit in that application and could potentially cause issues. Think of the piston skirt like a non-stick frying pan. The Teflon isn't supposed to come off
wink.gif
LOL!
 
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