Hey All,

I have a 93-944 with 131K that has developed a "pump" kind of sound coming from the engine area when the engine is running. The sound does not change with the throttle. The sound comes on for about 2 seconds and then is off for about 2 seconds. It sounds like that sound a pump makes when it turns on (like the fuel pump hum). I cannot seem locate it. It definietly is not the fuel pump. I can really hear it loudly if I take off the air filter cover.

I was wondering if it could be the water pump? The A/C is not on.

It is getting a little louder over the last week...I am getting concerned that I might be hurting something else by not figuring this out.

Thanks for any help and will check often for any clarification.

Don

The noise is coming from the Air Box! I did not know it had anything in it to make noise...? I unhooked the throttle body hose and the engine recycle hose and the noise is coming straight from that.

What could that be?

Don

I know the AC isn't on, but that still sounds a lot like the AC compressor cycling on and off (except for it being louder through the air box). Is your defrost on?
--
Andy in St. Paul - '91 745 213K mi, '91 745 210K, '90 744 183K, all Rex-Regina - past 240s

Andy,

I do use the defrost occasionally now, but it is not on very often.

I took off the belt to the A/C to see if it stopped the noise and it did not.

Could it still be the compressor without the belt on it?

Don

Dear Don,

Good p.m. and may this find you well. If you removed the compressor drive belt, the compressor will not turn. In stopped mode, it shouldn't make any noise at all.

Has the timing belt tensioner ever been changed? If it is failing, it could generate an harmonic. If the tensioner fails, the timing belt slips out of place, and the car stops. The B230F/FT engine won't be damaged. However, the car will not run until the timing belt and tensioner have been replaced.

Has the harmonic balancer (aka crankshaft pulley) even been changed? It consists of a steel hub, a rubber liner, and a steel outer ring. Time and heat cause the rubber to fail. Then, the outer ring gets loose. On that ring ride the drive belts for the alternator, air conditioning compressor, and the power steering. If the pulley is not replaced, the alternator doesn't charge properly, as it doesn't get full power from the engine.

A failing pulley can vibrate, and so make noises.

You can test the harmonic balancer as follows. Using "white-out" (correction fluid) draw a line from the center of the pulley out to the face, and then across the flat surface of the face, to the very edge.

Drive the car for 15 minutes (more or less). If the white line has separated into two segments, that do not align, the pulley has failed. You can get a replacement at www.fcpgroton.com.

It is rare for these pulleys to come apart completely. Should that happen, you'll at once lose power steering and air conditioning. When the battery - no longer charged by the alternator - gives out, the car will stop.

Hope this helps.

Yours faithfully,

spook