Engine noise
 

Stock '76 2.0 with FI. Went to start it after sitting for over a week and heard a loud tapping sound from the left side of the engine bay that varies with RPM. It did not go away after warming up. Sounds terrible but there is no noticable performance change during a very short drive. I have been told previously by a competent Porsche shop that I have hydraulic lifters. Do I have a stuck lifter? Any ideas?

If you do have hydraulic lifters (per your mechanic), than I can guarantee it's a dry lifter(s) trying to "pump up".

I've personally witnessed a "sitter" (1+ week) with hydros come to life, and could NOT believe all that noisy fuss for the sake of (assumed) zero maintenance and zero valve adjustments.

Try letting it warm-up and idle until the lifters crank up with juice. Hopefully, it'll revert to its zero-lash self in no time.

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How can one tell if his car has hydraulic lifters anyway? I got myself a stock (I think) '76 with the original FI at the end of the summer and this is one of the things I have been curious about.

Aaron

Hydraulics that sit for a long time do need to pump up and can make a God awful racket while they are doing it.

On my 1.7 with hydra lifters, after a lengthy repair period of sitting which included playing with valve settings... it took a good 10 - 15 minutes for the clatter to stop... very loud... very scary. If I let the car sit for a week or so I can get a mild clatter for the first 30 seconds to minute after start up... then gone.

Push rods on solid lifters are aluminum except for the ends. Push rods on hydra lifters typically are narrower, (someone else has the dimensions), and not aluminum. Take off a vavle cover, clean oil off of a lifter rod and check it out to see what you have.

- Dave

I used to run a hydrolic 2.0 in my 914 untill one gave and tharashed my motor. after letting it sit a week or so mine would tap too occasionaly. warming it up didnt make it go away. i had to get the rpm's up with a load on the motor.. in short, drive it around the block real quick. see if that helps. if not, tighten the lifter a turn

If you have hydraulic lifters, you will have no valve lash when operating properly. If you have lash, you either don't have the above or you have a problem.http://www.pelicanparts.com/support/.../eat_arrow.gif

"They aren't operating properly" is what happens to hydraulic lifters in most Type IV engines that use them. Particularly after they sit for a while. In some cases, only a day or two; in some cases, sitting for a month will do it.

The really fun part is that you can't tell for certain if an engine has hydraulic lifters or not. There are some "clues", parts that are "usually" used with hydro lifters, but they can be fitted to solid-lifter cars too! Things like the solid spacer between the rocker arms (versus a spring), the thinner steel pushrods (versus fatter aluminum), and so on.

The only way to tell for sure is to remove a pushrod tube, then remove the lifter. Solids will be one piece, while hydros will be larger and multi-piece. Often the hydros will come out in separate pieces--if they do, they've been junk for a while.

--DD

Good news! I warmed the car up and this time the lifter noise finally went away after about five minutes. The engine sounds normal again. Thanks to all for your helpful replies!