Bkresse

1988 Porsche 911 Carrera Coupe 3.2

I was driving steady at ~3000 RPM's in 4th gear, when I immediately began hearing a chunky grinding noise from the engine. It was on and off for the first 20-30 seconds while the motor seemed to still be able to rev appropriately, then the noise became continuous until I shut it down.

I quickly grabbed my phone and recorded this video for reference.


I'm anxiously awaiting news of its condition; however, the shop won’t be open until Monday. In the mean time, does anybody have any idea what this problem may be? Cost? I'm almost too afraid to ask.

I've always enjoyed reading the information that’s posted on this forum and I'll appreciate any feedback while I wait.

Thanks!

Caferacer

I don't have a clue but the experts will probably want to know if you have done any work on it lately. Did you have oil pressure? Was there smoke? Good luck!

Bkresse

Thanks Caferacer. I did have oil pressure; however, it was bouncing up and down a bit. I was slightly tapping the throttle to check if the noise matched in intensity to the RPM. The RPM and the noise didn't seem to sync up. so in the small amount of time I couldn't assess the noise source.

No, no smoke at all. No engine work done recently. And although, I run it up to 5500 K once or twice a week, I was being very gentle on this particular drive. Additionally, I hadn't noticed any odd noises leading up to this condition either.

Ed Hughes

You can't diagnose something like that via cell phone. Plus, I was getting nauseous trying to follow you moving all around with the camera.

But, it looked (in brief glimpses) like your main fan belt was tracking strangely. You could have a shot alternator bearing, or a loose pulley?

Don't run it any more, until you know.

ivangene

its like giving a haircut to you over the interwebs...difficult at best!

anyhow...as Ed said could just be the alternator or fan blades hitting the housings....you could remove the belt and spin the fan by hand, easy enough to do

could be something else...

Bkresse

I appreciate the feedback. At least you guys have given me some hope that it could be something minor.

ivangene

She's a beauty by the way - I hope for a simple fix

911 Crazy

Nope. Sounds like she'd dead and it's the end of the road. Better give her to me!

911 Crazy

Better yet, send her to me and I'll pick up the towing bill for you!

jakeflyer

The observation about the fan was my first thought. If the belt was removed and the engine run for a short time, (seconds), and the noise stops then you are where the noise is and can proceed from there. If the noise does not stop then, then it is not good.

Bkresse

Excellent advise guys. I think I'll run up to the shop and try these suggestions before the they open tomorrow.

ivangene

take your 24 mm wrench and spanner tool with...belt comes off in 10 seconds!

make sure to pull ALL the washers off for your test, then make sure to put them ALL back on in the right order when done - rotate the fan by hand to get the belt on right...and IMO no need to start it before spinning the fan...it might be obvious right there..if it is then you have a better feeling starting it will not cause any additional damage

Bkresse

Very good, I agree i would hate to start it again if I didn't have to. I'm excited to give this a try. Thanks

911 Crazy

No, no. Way too risky. Send her to me!

Bkresse

Well... Incredible news for me and terrible new for 911 Crazy. I'll be keeping the car for now.

I took everyones advice and headed to the shop to try a few things.

First I removed the Fan Belt and rotated the fan. Upon counter-clockwise rotation it made a noise but in the clockwise direction it didn't. Although I was very encouraged that this was probably the problem; I wanted to test it further.

Second, I removed the A/C belt, the Fan Belt, and the Fan from the alternator shaft. I cranked up the motor and prayed. No noise!! I shut it down ASAP.


Third, I rotated the alternator shaft to reveal the noise. And as you can see this is a fairly new alternator that was installed two months ago. Given my lack of experience, I discounted the alternator as a source of the problem because it was fairly new. In hindsight, it should have been my first suspicion.


I can't thank thank you guys enough by setting me on the right track. I was convinced this was a catastrophic failure. I feel a little silly for jumping to such a conclusion; however, I've never felt better about being wrong.