Grrrr.... Valvetrain tapping

Topic: Grrrr.... Valvetrain tapping (Read 755 times) previous topic - next topic

Grrrr.... Valvetrain tapping

July 10, 2006, 08:43:24 AM

Well I got the car on the road for a couple days last week and coming home on the second day it started to TAPTAPTAPTAP. Digging around it looked to be a valvetrain noise. I thought maybe an HLA had gone south, but swapping out all 8 netted no change.

I think the problem though is that this cam and followers are OLD. They were assembled in this head in the 80's or early 90's. They've been run with double springs all that time too, and as a result there is a nice groove worn into the followers.

I don't think it's enough that the HLA is "unloading", but it could be enough to snag the nose of the cam and cause the follower to pop around.

Oil pressure is good, so they're not just running dry. I had no problems with it for 10-20K, but it sat for a couple years off the motor before I reinstalled it recently.

Looks like I'm either going to have to swap out the cam/followers, or I might try a good set of used followers to see if that helps. I guess if it toasts the cam and everything it's not a big loss since I was looking at replacing it anyway.

Grrrr.... Valvetrain tapping

Reply #1 – July 10, 2006, 10:09:44 AM

Buncha TAPS or a little bit??? As long as the lobes are still farly rounded I've not had a problem with noise other than the HLAs, then I haven't run double springs on a 2.3 either... I't been when the lobes get "peaked" that I've had noise problems(and a couple bad HLAs)...

Grrrr.... Valvetrain tapping

Reply #2 – July 10, 2006, 10:17:33 AM

It's a bunch of taps.
It will rattle when warming up, and then lessen when warm until you load the motor. Actually the rattlle is there all the time, but it won't really rattle on a decel. It's a top-end thing though

This cam has kind of an odd asymmetrical profile, and I'm not sure if it's because of wear or intentional. One side has kind of a sharp (at least compared to the other) radius off the nose.

I suppose I could try the other followers and see if it quiets down. Don't know if they'll last though. They aren't new followers though.

Grrrr.... Valvetrain tapping

Reply #3 – July 10, 2006, 03:00:41 PM

So the sharper side is on the opening of the valve right? In theory the cam is "launching" the follower off....Tap.

Grrrr.... Valvetrain tapping

Reply #4 – July 10, 2006, 05:51:33 PM

throw some 90 weight oil in there and call it done

Grrrr.... Valvetrain tapping

Reply #5 – July 10, 2006, 10:19:39 PM

Quote from: CougarSE

So the sharper side is on the opening of the valve right? In theory the cam is "launching" the follower off....Tap.

If it's like the ones I've seen, it is the back side that wears flat... When the rocker is at full lift, it then just falls off into open space causing the "clack" when the valve closes... No it don't make a bit of sense, but every one I've changed for noise had at least some of that trait and the really noisy ones all the lobes were flat on the trailing side..

My most bizarre 2.3 cam ordeal was a '82 Stang(but it had a '75 engine) that would not run over 2500 RPMs when cold... If you tried to buzz it up, it completely died as the HLAs pumped up and held the valves open(too much oil pressure)... Would not restart till it sat 2-3 minutes. To make a long story short, I tried a bunch of different stuff to no avail... Finally contacted the previous owner(I got it at a auction) and asked if he'd ever had that problem. Yep sure have was the reply, the oil holes in the cam are plugged up... No way I said, the cam looks perfect and those things will wipe a cam in a few seconds with no oil... Trust me he says that will fix it, so for the umphteen time off comes the valve cover, and for kicks I started it without the valve cover(A BIG NO NO if the cam is oiling the followers as it should). Just as he said... no oil. After cleaning out the cam it ran perfectly...

Grrrr.... Valvetrain tapping

Reply #6 – July 10, 2006, 11:08:33 PM

Well on this cam, the "flat" spot is on opposite sides for the intake and exhaust. On a couple there is a definite "edge". It's still radiused, but coupled with the trough in the follower, I can see it "snagging". Not sure if that is wear or by design on the lobe profile, and no one at Schneider had much clue when I contacted them a while back about the cam in the first place.

Anyway, I said screw it and have got a RR cam on the way. I'll just retard it 4* and call it good for now. At least I can reuse the followers on another "larger" roller cam in the future. Yeah I'm giving up a few hp, but it's either this right now or the car sits... All my post divorce cash outlays of May and June are catching up with me this month.