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YOUR RESEARCHNoisy valve lifter???
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Run nhra s/g (9.90 index)
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Same in our '55 Chevy, roller lifters in a 388" small block, we ran NHRA S/G (9.90 index).
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I just noticed an unusual noise coming from the right side underneath the engine. It is an irregular rapid knocking/tapping/rattling sound. Sorta like morse code. It is present at idle, and disappears immediately coming off idle. I also have a loose segment of the exhaust pipe, that last piece where the exhaust tip attaches to, but the sound does not disappear when I put pressure and hold that segment steady.
I had the Porsche tech listen to it, and his comment was "Hmmmm, that's unusual"
. He wants to fix that exhaust first and see what happens to the sound. That part is coming from Germany and won't be here 'til next week.
I think it's one of three things. It's a rattle, and I can live with that. Or, its a leak in the exhaust system, and that should easily be fixed. The worst it could be is a loose valve lifter, and that's a bummer on a 1 year old car. I wonder if the it's-not-a-true-dry-sump thing had anything to do with it?
Anyone have anything like this happen? If it is a valve lifter, would tracking it this weekend grenade the engine? I have a three day DE coming up.
Thanks!!
It is not unusual for hudraulic valve lifters to clatter upon start-up. If they quit within a minute or two, ignore it. Porsches, with opposed engines, are more prone to it than in-line or V engines. This is because the lifter is in a position to more easily allow oil in the lifter to seep out.
You may find that somedays they clatter and some days they don't. This is based on how the lifter comes to rest when the engine is stopped. If the oil port on the lifter happens to be facing down, it is more likely that oil will seep from the lifter, requiring it to pump up when the engine is started.
Lifters rotate in their bores so the oil ports may end up pointing in any direction when the engine stops.
Again, if it stops within a minute or two, it is not a problem at all.
My lifters only ever sounded off once, after my one and only autox, as Mike said it went away after a few minutes. In my situation I would have to think it was an oiling issue, that's the reason I never autox anymore. If there is any oil starvation, which may occur under high Gs, you can get sort of an air lock in the oil passages and this in turn leads to a noisy lifter. After a short period time the noise usually goes away. At least that's my theory.
Unless you have solid lifters, then they make noise all the time, but that's another subject- one that us old drag racers know about...right Mike
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Ahh yes, solid lifters, I know them well! Used solids (roller lifters, actually) in my SS/F Challenger (10.40 ET)and, of course, in the SS/AA Hemi Barracuda (9.15 RT) that I wrenched for many years.
