scottz

Recently purchased a 86 944 turbo. Been great so far, greatly exceeding my expectations. I was reading the rod bearing failure thread and now I'm worried. I think this noise is just a noisy injector (I hope!), but any expert advice (amatuers welcomed as well) as to what this noise is would be appreciated. The noise I am mostly concered about is the clicking/nocking noise. It is seems loudest above the "S" of the PORSCHE on the engine.

There is also the turkey gobbler noise in there as well, correct me if I'm wrong here, which is a heat shield vibrating or something like that. Not to worried about that one unless someone tells me I should be. Thanks.

The file is 256K and is 12 seconds long. Hope I'm not breaking any rules by posting mps here.

http://www.xmission.com/~szolling/ENG.mp3

Hmm, HTML code is off, so I'm note sure I can make a link to the above. Sorry, you'll have to cut and paste the above.

Ski

If its an injector it IS very loud. You may have an exhaust leak on the exhaust manifold(s). How many miles on your car and does your #1 exhaust manifold have the expansion bellows in it or is it just a straight pipe? It might also be a lifter,,was the loud "clank" you letting go of the throttle?

Laust Pedersen

I find it difficult to hear whether it is the injectors or lifters.
You can go through the steps for injectors in my last posting here:
https://rennlist.com/forums/showthre...hreadid=105731
If it is the lifters, then a better oil could solve the problem.
The other noise does sound like a rattling heat shield.
With respect to the rod bearing failure, just keep an eye on the oil pressure and keep the oil level slightly above max if you are driving fast.

Laust

scottz

"was the loud "clank" you letting go of the throttle" - Yes, that was when I released the throttle.

"How many miles on your car" 140K miles.

"Does your #1 exhaust manifold have the expansion bellows". Not sure what expansion bellows are. I'll do some more research and update when I find out.

Lifter huh? Well, that sounds better than a rod bearing.

scottz

Laust - thank for the link. It is very possible that an injector is making contact with the fuel rail. I replaced a leaky injector 3 weeks back, but it was injector #1. Since the other injectors were not modified, they were not suspect. I will check the injectors with the "move each injector up and down at least ±0.5mm" tomorrow. Thanks.

Songzzz

I think the rapid, rythmic clicking noise you hear are from the lifters. Same problem with mine. Recently, I bought a complete set of lifters and will be making the swop in the next few days, hopefully the sound goes away.

Initially I was quite sure the lifters are shot. After hearing you guys mention the possiblilities of injectors fault, leaky headers etc.. I am anxious to know if I had bought the wrong parts.... again.

87951

Another cause of a noise like that is a sticking intake or exhaust valve. As valve guides wear and excessive oil seeps down past worn guides and stem seals, it bakes onto the valve stem and guide and causes the valve to hang open enough to cause a clicking noise like that. You may need a head rebuild.

Ski

Scott, with regards to the #1 exhaust manifold...the 1-4 exhaust manifold had a Porsche recall. Your #1 should have a small accordian looking(expansion joint) section in it, just as the manifold turns down coming out of the cylinder head. IF your car happened to miss the recall, these were prone to cracking under heat expansion over time. When they cracked and started to "move", they also broke the welds on the heat shields as well. As Laust said, it may very well be an injector and that would be the easiest thing to check first. Then exhaust leak, then lifters, then valves if you haven't solved it by then, good luck.

http://www.clarks-garage.com/

You may find this helpful if you don't know about the site.

badass951

The fluttering sound that is constant throughout seems like it would be an exhaust leak at the manifold. A tiny pinhole in the manifold could definately cause this noise, as I have had a similar experience. Not sure what the louder clanking sound might be...

Tom M'Guinn

It sounds like there is no noise at the very beginning of the clip. Does it not make this noise at idle and/or does it do it when the motor is hot and cold? I'g guess exhaust leak, but I rarely guess right.

A mechanics stethescope (cheap) will help you figure out if its a lifter or injector. The mechanical clanging/vibration sounds like something (exhaust pipe?) is loose/broken. Did the two sounds start happening at the same time?

scottz

You guys are great. Thanks for the list of things to check. Since no one is telling me to park the car and not drive it, I will tinker at it little by little and post back when I figure it out.

Songzzz - let me know how your turns out. Good luck.

Tom - It seems to always make the noise. It may be louder when it is hot, but it could just be subjective hearing by me.

I have some spare injectors, so I'll try swapping them out and hope this is the case. Again thanks.

Tom M'Guinn

I may be easier just to pull the connectors on the injectors one at a time and see if the noise stops on any particular cylinder. (I assume this is safe for the DME and motor). If it goes away on one, re-arrange the injectors to see if the noise moves with the injector. If it does, then the injector is the culprit. If not, then probably an exhaust leak. If pulling the injectors wires changes nothing, then I'd guess lifter or an exhaust leak after the headers.

badass951

That is definitely NOT my recommendation. If you think it is something with the engine then you are really risking it big time. Not that these threads do not help in solving problems with our cars, but I know by experience that it is not likely to determine a problem like this over a forum.

emilysgranny

Scotty ; if you believe it is an exhaust leak , take a strip of paper and move it around the flange , the bellows and where the Y section of the pipe is . It will flutter. If you are brave , carefully move your finger around the pipes, but be careful as this could burn you if you actually touch the pipe. Bad injectors have a rythmic sound somewhat like the old mechanical wristwatches ,but obviously louder. Take a long handle screwdriver and put the butt end to your ear, you be be amazed at what you can hear.

MHT

it sounds very much like an exhaust leak, are any of the studs that secure the manifolds to the head broken or missing? The usual culprit is the rear most one. The other rattling noise sounds like a broken heat shield. It definately does not sound like a rod knock, that is a much hollower sound, and at least at first you will hear it most as you snap rev the motor.

Good luck