4.7L piston slap noise - engine noise

[gundogger]

I was a manufacturing engineer on a production line that produced the GM L18 connecting rod. The 8.1L former (454) big block engine. We made a running change that obsoleted all previos L18 con-rod/piston assemblies....REASON.....COLD START PISTON SLAP - customer dissatisfaction.

Previous design had a press-fit wrist pin. The redesgn included a press fit bronze bushing in the wrist pin bore and a slip fit between the con-rod wrist pin bore (bronze bushing) and the pin which was floating in the piston and changed to a press fit.

We shipped the con-rod assemblies to Zoelner piston and they assembled the pistons I know the have to change there process to include a press fit pin but as far as any other changes such as skirt shape or diameter i am not sure.

I owned a chevy colorado and switched to a tundra because of a list of issues including year. I heard the piston slap and was concerned at first. Once I read and confirmed that i do in fact have piston slap i feel a whole lot better about this issue with my truck.

piston slap NEVER produced an engine failure on the L18 prior to the floating pin design change - In fact there are a ton of them in offshore racing boats and are prefered by offshore engine mechanics.

Our complaints came from private owners and some Uhaul applications

DOE WERRY 'BOUT IT!!! It is just noise

[Johnny_5]

alrighty then...

[kerryman71]

Where's the link to the DVD sales?

John

[Johnny_5]

or purses?

[YOTAtoy]

I was a manufacturing engineer on a production line that produced the GM L18 connecting rod. The 8.1L former (454) big block engine. We made a running change that obsoleted all previos L18 con-rod/piston assemblies....REASON.....COLD START PISTON SLAP - customer dissatisfaction.

Previous design had a press-fit wrist pin. The redesgn included a press fit bronze bushing in the wrist pin bore and a slip fit between the con-rod wrist pin bore (bronze bushing) and the pin which was floating in the piston and changed to a press fit.

We shipped the con-rod assemblies to Zoelner piston and they assembled the pistons I know the have to change there process to include a press fit pin but as far as any other changes such as skirt shape or diameter i am not sure.

I owned a chevy colorado and switched to a tundra because of a list of issues including year. I heard the piston slap and was concerned at first. Once I read and confirmed that i do in fact have piston slap i feel a whole lot better about this issue with my truck.

piston slap NEVER produced an engine failure on the L18 prior to the floating pin design change - In fact there are a ton of them in offshore racing boats and are prefered by offshore engine mechanics.

Our complaints came from private owners and some Uhaul applications

DOE WERRY 'BOUT IT!!! It is just noise

GunDogger!

Greetings from a fellow Traverse City, MI member. You might want to check and make sure, my truck sounds like it has piston slaps ESPECIALLY on cold starts. However it is just a common leaky exhaust manifold, is much quieter after metal warms up and expands a little bit. Does sound an awful lot like piston slap though.

Lets see some more info on your Tundra!

YotatoY

[havasubud]

The cylinder walls on a 4.7 are concave and change shape when it heats up. It will sometimes make noise on cold start ups. My 04 started doing that at 27k miles, and I talked to one of the engineers at Toyota and thats what he explained to me. Nevertheless I put a new shortblock in and the noise went away. It now has 130k and I noticed it is starting again. Oh well, not going to worry about it since he said it will not cause a failure.