Packard Forum Index » V-8 (1955-56)

most likely an excessively worn valve guide. Probably worn .012 inch or more. THIS IS DANGEROUS especialy on big valves like the PAK V8! The valve head is closing way off centre, cocked to one side and hitting the SIDE of the valve port due to the slop in the guide. It's closing off-centre and then snaps down into the seat. This will eventualy break the head of the valve off.


BUT FIRST!
Check for a bent pushrod, broken valve spring and ABOVE ALL look thru the coils of the spring to see where the umbrella seal is. The seal should be HIGH on the stem of the valve. If it has slipped down the stem of the valve and against the head then it has prevented oil from getting to the guide.

Two things here don't add up for me:

1. I've never seen a Packard V8 with .012" valve guide wear. May be common, I've just never seen it.
2. That sort of valve guide wear noise wouldn't come on suddenly. It starts soft and gets progressively louder over a long time.

Wonder if it could be rather a sticking valve which is hanging open and then closing with a clang? Could even be sticking open enough to be hitting the piston. I've seen pistons with valve marks on them, but attributed that to over-revving and lifter pump up.

thnx, jack vines

Jack Vines- i was kinda thinking along your lines. this happened very suddenly, within 50ft or so.

Go buy a quart of Marvel Mystery oil and pour it into the engine oil, then vary the RPM's of the engine, going no more than 3000 in park. If the noise goes away, take it for a drive around the block a couple of times, but take it easy. If it is a valve that's sticking, the MMO will get it loose.

My low mileage Exec had .006 - .009 inch clearence at 34K miles.

Try the ez stuff first. If the ez stuff fails then the spring can be removed WITHOUT removing the head for closer examination and solvent cleaning/soaking.

What's the verdict???

i pulled the rocker shaft, but i could not see any problems. i reinstalled the shaft, and restarted the engine with no noise. after the engine warmed up, the noise moved to the next cylnder back, but was much less intense. A test drive about an hour later, and it ran perfectly with no noise.

i have oil pan gaskets on order from kanter, and i will be droping the pan as soon as I can. i think the detergent motor oil has loosened up sludge in the pan thats getting pumped up and clogging the lifters.

the noise is back, worse than before, and is now coming from the passenger side cylnder bank. this time there seemed to be a slight loss of power. the gaskets still havent come in, so the pan hasnt been dropped, but it was running so well in the garage this morning i thought id take it for a test drive. mistake. oh well.

Don't drive the car until you find out the problem before it is too late.

mikec -

That the noise is travelling from place to place in the engine suggests to me that you have a lot of varnish or sludge in the engine oil circuit that's beginning to break losse and move around.

A mechanic once recommended, for the noisy engine in my late model daily driver, that I add a quart of ATF and let the engine idle for 20-30 minutes - then change the oil and filter. Since I was at a point where I was considering engine overhaul or replacement, I gave it a try, but monitored the sound of the engine as it idled in case I needed to shut it down quickly. I had no problem, but you wouldn't believe all the lumpy schitt that came out of the pan when I drained the oil.

The ATF will clean things you could never reach without a complete teardown, but you have to be careful that the stuff that gets flushed out doesn't get sucked back up into the oil circuits or plug the oil pump pickup screen.

So, BEFORE trying the ATF, you might want to drain the oil, then form a loop on the end of a piece of coat hanger wire that you can insert through the drain hole, and use that tool to "sweep" the bottom of the pan and "tickle" the pump pickup to make sure it isn't stuck, but will float. Also, replace the oil filter element and clean the sludge out of the bottom of the canister.

Good luck and keep us posted on your progress.