Engine just started to give a loud tapping noise form drivers side heads. I know it is NOT the lifters (recently changed), nor low oil level, nor pressurizing lifters (heard that noise before). Recently had a compression test done (all good), so suspect the valves are not burnt.

could there be a damaged inner valve spring? Anyone experienced such a thing? Will the engine still run if a valve spring (say the inner one) failed?

 

Dave,

No experience to answer any of your queries, but a generic comment. How recent was the work done on the lifters? Is it possible that the noise you are experiencing now is a result of an error/mistake/oversight in recent work?

Good luck with the fix

Nol

 

Dave,

Assuming the tapping you're talking about is loud and offensive (i.e. anyone who hears it thinks something sounds wrong), I wouldn't be so quick to rule out a failed lifter(s). A broken valve spring not only is far less common than bad lifters, but I don't think it would make that noise, either. The noise would be something like "BAM, CLANK CLANK..." and all the other horrid requisite noises from your piston smacking into a valve that didn't close because of a failed valve spring. And you would certainly have other issues as well such as loss of compression/power. A weak (or failing) spring might also cause the valve to "float," creating noise but this would typically occur at high RPM, and agin could result in piston/valve "meeting" one another.
I also don't see how a burnt valve could cause noise, and this too would probably result in low compression in the offending cylinder.

Sorry if this was long-winded. Get a pro to diagnose the sound, but if the car is otherwise behaving normally, I'd personally bet on lifter failure or something lifter related as that is the most common (AFAIK) source of tapping noise that I can think of. Good luck

Edward

 

 

Dave;

Yes, your engine will run with a broken valve spring. I would recheck the lifters, it is possible to get a defective lifter.... Have it checked. Another option would be the allen fastners holding the rocker shaft could have backed out or broken, and or broke a rocker arm.

 

thanks for the replies. The lifters were replaced by a very reputable guy, and they made a different sound before replacement.

I'll have it checked out - in fact it's going in soon to have the auxiliary airways unblocked - don't think I can claim on the emmissions warranty however as the check engine light isn't on

 

I had a broken valve spring in a 944 many years ago and it felt like the car was running on 3 out of 4 cylinders up to 4k rpm, then it ran fine. There was not alot of "clanking" sounds.