Wierd noise from head. Collapsed lifter sound?

[Martin Raska]

I got it tonight, pulled over and used my hand to raise the engine speed under the hood to see what it was.  It's a ratting sound that occurs sometimes between 1500 and 3000rpm, under low load.  It's a noisey rattle, sounds like it's coming from the number 1 cylinder area, but I haven't used a stethascope to verify yet though.  Pressing the gas, going into boost, etc makes everything very quiet again.  I've never heard a known collapsed lifter, so is this what it sounds like?  Any other ideas?

[Martin Raska]

It's rpm dependant in that range, but slow rpm, like 1 per 2 revs would probably be about it, so as far as I can tell it's a lower oil pressure problem with one cylinder, and probably just one valve with bad lash.  It does sound quite a bit like it does when you first put decompressed lifters in a head and start it up to a lesser extent since it's only one.  So I think I know the problem, but if anybody wants to chime in, feel free.

[Sarah Hancock]

change your oil and drive (the warmer temps are fucking viscosities)

[Mike Meron]

valvoline 20w50

[Scott Girvin]

I had this problem once on a rebuilt head with upgraded lifters. It turned out to be a worn tensioner arm that had to be re welded. I would change the oil first tho, as Mr. Meron mentioned.

[Martin Raska]

Oil is 12 hours newer than my post here.  Mobile 1 20W50 always in the warmer months definitely.  It just purrs at idle or anything, no lifter tick but this rattle still comes back after sustained 1500-3000 rpm cruising.  I'll be cruising for a bit then just hear it come in then give some gas or shift to neutral and dissapears.

I'm worried about the tensioner anyways.  I'll hopefully have time to check that out and replace this week.  I have the parts sitting around anyways.

[Martin Raska]

For the record, been driving on a new tensioner for a week, without re-occurance.  Thankfully I still have all valves properly intact.