Chirping idle

[djnolan]

My 87 944S 16V has a chirping at idle. It is a mid range tone, not real high in tone.

I can't seem to pinpoint where it is originating from. I have tried using a hose as a stethescope. If anything it seems to be louder towards the front of the engine, but if you put your head next to the valve cover there is so many conflicting sounds between the cam chain, injectors, plugs, etc I can't be sure if I have a problem with the cam belts or chain or maybe just a rouh idle due to vacuum leaks in the ICV.

I did change the plastic chain guide, but not the chain tensioner and the PO (former Porsche mechanic) told me the belt was just changed.

Any advice on how to check this noise out?

Thanks!

[rb101]

A lot of time the chirping sound is from a bearing starting to go bad. I would pull the belt covers and see if the sound is more pin-pointable. I think you have a bad pulley in the timing system. Needs to be fixed now before it cost you way more $'s

[white944cup]

Timing belt or balance belt idler rollers or tensioner rollers.......possibly water pump beginning to go. I've got he same noise.....I've replaced both idler rollers so far. They were both going bad (rough rolling and noisy), but it did not get rid of the noise. Mine makes an intermittent chirping noise that goes away after it's warmed up. I'm due for a timing belt change in about 10K miles, so I will be replacing the water pump and tensioning rollers then.....sooner if the noise gets any worse.

[djnolan]

Mine gets worse when warm. The noise is most noticable coming from the opening between the airbox and right fender where the belt cover is. If I estimate the frequency of the noise (About 25-30 chirps per 5 seconds at idle or 1 chirp per rpm) can anyone predict which roller is bad? Anyway to replace a roller without removing all of the belts? Belts and wp were just replaced.

[Rasta Monsta]

Timing tensioner roller has the most stress on it, right?

[djnolan]

I guess I will need a p9201?

[djnolan]

After removing the cover I determined the squealing noise is the balance shaft tensioner pulley, so I will replace it and see what happens. The balance shaft belt looks new but the cam belt looks a little more worn. Exactly what should I be looking for when inspecting the cam belt? Obviously the tension but it has a spring tensioner. Are there any rules of thumb for wear?

Thanks-

[djnolan]

OK. Here is what I think happened. Chirping/squeling/whistling noise heretofor mentioned. Pull off belt cover. Cam belt A OK. Balance shaft belt is loose as a goose, the tensioner pulley has slipped and is not holding the belt tight. So I tighten it back up and it squels like a stuck pig. Conclusion: pulley is shot. Obtain new pulley from local parts house. Install (another thread needed to cover the details.) Squeals like stuck pig as verified by stethosocope method. Lower balance shaft bearings maybe? Well after having lunch, I began to think I should experiment with the belt tension before causing myself further agravationm. Loosen up the belt a touch and noise lessens. Conclusion:

[rb101]

If it is the lower balance shaft bearings, you might have other problems as I don't remember ever hearing of a balance shaft bearing failure. You can pull the rollers one by one, pull the dust cover from them and regrease, then reinstall and see if the sound goes away. I am sure it's a roller and adding some grease would only move a bearing failure down the road a little bit. Personally I would replace ALL the rollers and belts.

[M758]

The balance belt should be a little losser than the t-belt. Otherwise it will make noise. Even so check all the rollers just in case. The actual balance shaft bearings are oil fed plain bearings just like the crank. So if those make noise it is due to oiling problems the motor is getting ready o blow. (so probably not the source of the noise)