Help! Squealing 951 - Dying alternator?...

todzilla · 08-22-2014, 10:50 PM

OK so here's my dilemma. When my car is started (intermittently, but seems to be getting progressively more common) - she has a bad squeal that builds as revs rise and especially if you create any draw, such as headlights on/fan on/rear defrost, etc...It will eventually go away after about a minute of driving, and used to not come back til the car cooled overnight...but a few times, it made the same noise after being shut down only a short time.

It sounds like a belt that is slipping, but with the plumbing on these 80's turbo cars - and my relative lack of wrencher knowledge - who knows? I do know that about 3-4 months ago I had my car in to a shop for control arms and had them check my charging system as the gauge needle was in the lower 1/3. Not in the red, but I wondered if it was something to worry about. He did say - to my recollection - that it was only putting out 12 or 12.5 volts? I honestly forget, but he did say 'he'd like to see it higher' (I think 14 is where it should be?) It did have a very slow crank one day after I had the radio running while washing my car (about 20 minutes...hatch was open too) It just barely started, but did. It's never let me down, but I think it's a matter of time.

Now I should say the battery is only 5 months old. But bottom line, I suspect the alternator is on its (quick) way out, and this is my warning? Seeing as how the squeal worsens when there is any draw of power, it would seem to make sense?

Or am I off base? For what it's worth, I do have an appt. to get it looked at, but not til Sept. 2nd...and I hate to drive it if I'm either doing damage, or risking getting stranded!

Any advice is (as usual) MUCH appreciated!

944 Ecology · 08-23-2014, 04:22 AM

Your multirib belt is too loose. Adjust it to factory specs, using the factory tool. IIRC, it is 9.5, then one full turn of the turnbuckle.

Jfrahm · 08-23-2014, 05:17 AM

Careful, it is easy to break the struts or the mounting ears on the accessories if you adjust them improperly. If you pay someone to adjust the belt make sure they loosen, adjust and tighten everything properly. Some people just crank the adjuster with the pivots still tight, which is strong enough to break the mounting points or the tensioner strut (if you are lucky). This often leads to the broken AC pump falling out while you are driving.

Yes, the belt is probably loose, the factory spec is very tight.

todzilla · 08-23-2014, 10:39 AM

The multirib belt? That is the accessory belt (serpentine, I believe it's called?) That was done in March - about 5000 miles ago. Can it loosen over that short a time? I suppose this isn't a diy job without the proper tool(s)?

sausagehacker · sausagehacker's Garage

Just feel the belt, if it has any flex in it you should tension it, that belt should be pretty snug (tighter than the timing belt).

todzilla · 08-23-2014, 11:41 AM

I will - only problem is - as dangerous as it sounds, owning a 951 - I'm an entry-level wrecher and unless it's a minor tune or brake pads, I'm in over my head even knowing how to get to it. I haven't actually popped the hood to look for the belt yet, so for all I know, it's 'right there' to get to, but any pointers where to look? haha I know how snug belts should be based on old V8s from the 60's - I've had a few - but I'm assuming the serpentine belt on these is shrouded in secrecy. so sto speak?

And if this makes any difference - seeing as how this belt is 5 months/5000 miles old - is it possible it got contaminated by spraying oil? I had a dislodged vacuum hose (the big one that runs to the intercooler at the front of the engine bay/drivers side) - and for a week or so (til I even noticed) it was seeping out oil, even as far as actually creeping thru the hood/fender crack (gap) to get on the fender! Is is possible that any boil got in there and ruined the belt prematurely?

Jfrahm · 08-23-2014, 12:40 PM

Not only do they loosen up a lot in the first few hundred miles as the belt wears to match the pulleys, they most certainly can absorb oil and get slick. Personally I'd clean it with brake cleaner and re-tension but I am sure some people would want you to replace the belt.

Modern cars have constant tension gadgets (dampened spring or spring piston) that keep the belt tensioned properly over it's life but all the 924-944-968 series cars have no facility for this, so it's up to you to install the belt, run it in and then re-tension it. Fight the urge to install it 'stupid tight' and let it wear to the appropriate tension as this will trash AC and alternator bearings and seals and stuff. It's a common lazy mechanic trick (who would also make a boat payment when you come back to have him replace your AC compressor that he wrecked with a too-tight belt).

944 Ecology · 12:44 PM

Yes, oil contamination will cause the belt to slip.

So, adjust the belt the proper way, and if that doesn't solve the problem, replace the belt with a new one and adjust it properly.

If it was installed 5 miles ago or 5000 miles ago, and it wasn't adjusted properly, it will squeal. There are a lot of "Porsche Specialists" out there who do not have the proper tool, since it is out of production, and thus do not adjust belts properly. Chances are that your multirib belt is not the only one that is not properly adjusted, but it is the only one that will squeal as a warning. The others don't give a warning before they fail. The results of those failures can be quite a bit more expensive.

The Porsche spec is for it to be very tight, as it drives the alternator and the AC compressor.

Bradical · 08-23-2014, 03:49 PM

If you jack the front of the car up and creep up from the front bumper, to your left is your power steering (single belt) and to your right is the multiple-rib belt for the AC compressor and the alternator. There is an arm that is a tensioner that goes from the bottom of the motor to the bottom of the AC compressor, you loosen the bolts on the tensioner (one is reverse thread) and then turn the tensioner body, as you turn it with your wrench it unthreads the two eyelits at either side and pushes the compressor further away, causing the belt tension to increase. You don't have to remove anything beside the oil drip pan if you actually have it.

Be prepared to buy a new tensioner if it's rusted out.

todzilla · 08-23-2014, 08:04 PM

Looks like the general consensus is it's a belt. I'll wait for the official assessment when it goes in. Can't tackle it at my place...plus not really sure I have the tools to do it right. Just hope that's all it is.

Thanx guys!

DannoXYZ · 08-23-2014, 08:43 PM

All you need is 2x 17mm open-end wrenches to adjust the pulley (the Japanese would make it a 17mm & 16mm). Takes all of 60-90 seconds. As Bradical mentioned, the part you're interested in is this:

ebay - 944 alternator tension rod

See those lock-nuts at the end? The two 17mm wrenches lets you hold the middle part steady while you unlock the lock-nuts (one of them is right-hand thread, the other left-hand thread). They both unlock in the same direction.

Then using the other 17mm wrench, twist the middle rod to lengthen the distance between the eyelets. You can tell it's the right direction because you'll increase the distance between the locknuts and the rod. Turn it about 1-full turn and you'll see an extra 1.5mm gap. Then tighten down the locknuts on each end and you're done.

Jfrahm · 08-24-2014, 02:54 PM

That is how you break stuff. Just monstering the adjuster without carefully loosening the pivot points and eye bolts first.