ivai

I have an 86 944 turbo and a couple months ago I noticed a tapping noise one time when i started the car.. it sounded like something rattling under the hood so I popped the hood and it sounded like it was coming from the general area of the camshaft.. I can't tell if its coming from the distributer or the cam or what... It varies in frequency -- sometimes I don't hear anything at all, and others, well, it can get somewhat loud. The majority of the time it doesn't rattle.. Hoping its nothing too major.. Thoughts?

Thanks in advance,
Jeff

RolexNJ

Ivai:

I'm not the expert mechanic on here, but I just had that same problem from what you just described. I'm sure more experienced people will give you a better idea of what it is. However, it sounds to me like your lifters are slowing going or are dead all together. They usually make a tapping sound when you start the car. Sometimes they just stick and the noise stops; and other times if they are totally dead the noise won't stop at all. I just had brand new factory Porsche ones put in mine. For me, the tapping noise was the definately the lifters. A complete set of lifters will go for about $400. Also, if you are going to go into where they are, I would highly recommend replacing all of them, not just the ones that are bad or sticking. With a model as old as yours, I am sure they will all go, it's just a matter of time. Mine went on my 1989, and I only have 28K original miles on it!

Well, that's my two cents. Good luck

Peckster

Take it to someone who has experience diagnosing engine sounds. It could be something serious, or just lifters on the way out.

rhesus

I bet your belts are loose and are slapping against the housing. That happend to me.
If not, how's the oil level?

hosrom_951

That loud tapping noises you hear are the injectors firing. Our cars are known to have 'loud' injectors, but to be on the safe side, have it checked out (the tapping could also be from the camshaft tappets).

ivai

i checked the oil level and have it correct.. currently my oil pressure gauge isn't working but thats a whole other thing i need to mess with sometime.. I ran out to pep boys and got a mechanics stethoscope (sp?) but by the time i got back the noise had subsided.. hosrom, i'm pretty sure its not the injectors.. this noise doesn't always occur.. tomorrow i'll see what i can do about the belts, but it sounds like a metal against metal kind of tapping... i found this other thread https://rennlist.com/forums/showthre...ling+noise+944 and there it was the gear on the end of the cam.. I'm also going to check that. Otherwise, it sounds like I may need to get a new set of lifters.. thats unfortunate cause I'm somewhat tight on money and just got all new brake rotors and pads cause mine were shot. Anyways, from the other threads I've read, it sounds like if its my lifters, they're in the early stages of going, so I may have some time before it becomes necessery

Thanks for all the help

DanR 1201

In my case it was a totally broken weld on the #3 exhaust pipe to flange.

R.B.

Check for metal flakes in your oil. It may be a rod bearing. I went through the same thing a couple of years ago. After replacing the lifters, I still heard the metal tapping and yes it did sound like it was coming from the head. Change your oil and check for metal. If it is clean you can relax a little, if it isn't don't even think about starting your car until you fix it.

HTH
R.B.

Jeff F

Try a can of Rislone. This is common on 928's. You may want to do a search on that list and check threads. If it is lifters/tappets, it will likely cure the problem. Did for me--on both the V8, and on the 968. Good luck.

Jeff

'86 951 2.8. Lots of extra stuff.
'87 928 S4. Some extra stuff.
'92 968 Cab. Mostly stock & staying that way.

JDeitz951

I thought I had a rod knock once, but it was a bad alternator bearing (whew!). I proved it by removing the alternator belt.

vogel

This is similar to my experience as well. Look for metal on the drainplug immediately.

JDeitz951

If you have metal bits on the drain plug, your trouble is much more than rod bearings, since rod bearings are made of bronze, a non-magnetic metal.

UK952

I bet a lifter, is it worse when it hasn't been run for a while?
Put a good qulity oil in there and see if it improves.
Tony

ivai

Well, the noise is continuing even after the car has been running for a long time, but sometimes it goes away momentarily.. I finally got to use the stethoscope while the noise was happening.. it sounds like its coming from the front of the cam housing, around the distributor rotor... I just noticed but I can actually see in the housing through a little hole.. i'm guessing there should be a plug there? I can see the gear there.. maybe somethings gotten in there.. at any rate, I took off my cap and tried taking off the rotor but the 3mm allen bolt looked like it was stripped.. i tried a 1/8" allen wrench but still no luck.. Do I need to take off the rotor to take off the cover of the cam housing to get to the gear, if perhaps its loose or theres something in there? If so, any suggestions about the stripped bolt? I'm going to have the car up on jackstands tomorrow and will check the drain plug too.

Thanks

NZ951

I am guessing belt slap

I have had the same noise for months now... in fact I think it went away last serivce, 2 days ago...