350 piston slap on warm start-up

I'm new here and have not found any discussion on this subject. My 98 pickup with 350 has just started making sloppy engine noises for about 5 seconds after warm restart. This is a cherry engine with 120K miles. I've always been strict with oil changes, etc. I have seen reference to this problem in the past but without any detailed discussion. Some have made reference to an alternate oil filter with check valve to prevent bleed down while parked. Any ideas on this would be appreciated.

What brand oil filter is on engine now?

I have always used Delco filters #1218

I'm new here and have not found any discussion on this subject. My 98 pickup with 350 has just started making sloppy engine noises for about 5 seconds after warm restart. This is a cherry engine with 120K miles. I've always been strict with oil changes, etc. I have seen reference to this problem in the past but without any detailed discussion. Some have made reference to an alternate oil filter with check valve to prevent bleed down while parked. Any ideas on this would be appreciated.

this could be check valve in oil pump where oil filter screws on..ball or weak spring...


did you notice on start up slower oil pressure rise...

Bleed back ( drain back) is not an issue with a vertical mounted oil filter.

Everybody hears the so called piston slap. The dealers are saying it is piston slap due to short piston sleeves. It is realy the wrist pin to piston. Soon your engine will be wiped out. Drive it slow.

Everybody hears the so called piston slap. The dealers are saying it is piston slap due to short piston sleeves. It is realy the wrist pin to piston. Soon your engine will be wiped out. Drive it slow.
A piston pin will be noisey most of the time. If the noise goes away as the engine warms up from a COLD engine start it may be piston slap but it would take more than 5 seconds for the piston to warm up and expand to stop the noise. It is the piston skirt that is short that contributes to the piston slap the dealer is refering to. It may be a lifter that is leaking down a little. Do you have any unusual noises on a COLD start?

There is absolutely no unusual noise on cold start. The noise on warm start isn't like any lifter noises I've had, and beleive me, I've changed out plenty of lifters over the years due to being a noise-a-phobic. Thanks for the inputs.

Kill one cyl at a time till the noise changes or diminishes, this indicates a rod bearing or piston problem, the piston noise usually will not occur warmed up.

There is absolutely no unusual noise on cold start. The noise on warm start isn't like any lifter noises I've had, and beleive me, I've changed out plenty of lifters over the years due to being a noise-a-phobic. Thanks for the inputs.


what is the oil pressure when hot ? is it 35-60psi...... if no oil gauge get one and monitor the pressure.... with that then it will help in finding the problem...

if it is piston problem this is usually from lack of oil/lubrication...



check fuel pressure see if you have no bleed down of fuel pressure maybe a cylinder is getting flooded on shutdown......

eventually with testing probing you will find the problem...