ZePorsche

Hey everybody, new porsche owner here. Proudly just purchased a black '87 944 S a few days ago. Did my homework, got the previous owner's maintenance history and receipts, and had a PPI done. All checked out as 'good' considering the age and mileage of the car. Two things i've noticed need investigating is 1) there is a general vibration that occurs while engaging first gear AND when getting above about 3500 rpm and 2) there's a "buzzing" in the gearbox when I reach around the same rpm. I believe that #2 is contributing to the overall noise of #1 so it is independent, but related - hope that makes sense. My question is: how do i go about zeroing in on what is causing the vibration noises around the car? Furthermore, how much 'play' can i expect from my gearbox? When im in gear (no matter the gear) there is quite a bit of movement side to side. Sorry, this post kinda rambled. Any help or insight would be appreciated.

thanks again.

Mr. Toasty

Congrats on the car! How many miles on it? Vibration of some kind is normal at idle, but that doesn't sound like the issue here. And have you checked the trans fluid level/condition? Hopefully the buzz isn't from worn gears. Is the 3500 rpm buzz present regardless of gear selection, and is it a high or low pitch? Could be worn out bearings in the torque tube or clutch, or maybe even early signs of a rod bearing giving up the ghost. Play in the shifter should ideally be minimal, but if your linkage is original, it's likely that the rubber has dried out and is allowing excessive play. Check out the options at only944.com; they have a couple upgrades for the shifter and linkage.

ZePorsche

Thanks, man! Long-time dream to own a porshe. It has 136K miles. I'll have to check the fluid and get back to you. Buzz at 3500 and above is at any gear and it's hard to describe the pitch. I'll listen again and see if i can explain it. Just sucks because I've hear/read these cars are happiest scooting about around 4k RPM. I also need to take a look at the glove box and rear hatch because i think those places are also causing some of that vibration noise. Thanks again for the response and i'll check out that website as well.

Mr. Toasty

Fingers crossed it's just a trim piece or the hatch resonating with the engine somehow. 136k miles should mean that your torque tube is pretty much fine and shouldn't be audible unless it's had a hard life. Mine is just getting to the point that I'll rebuild it when I pull it for other jobs, and it's at 209k. If your clutch is old and/or is the OEM type with the rubber center, that could be the source. Good news is that it sounds like your transaxle is fine since gear selection makes no difference. My money's on trim/body panels (what about dried up gaskets?) or clutch. Hopefully others will chime in, so keep us posted!

Angus Shaw

This might sound crazy but check the windsheild seal, we looked all around the engine only to find the vibration at certain RPM's were coming from a loose windshield. Easy fix

irishfan007

I have the same issue. I have an 88, and the original owner with 230K miles. The first clutch was replaced 18 years ago and I have been running on the second one so far. With regards to the 3500RMP issue. I started noticing mine vibrating excessively during shifting around 3500 RPMs. What I can tell is the rubber peice the clutch is dependent on is cracked and worn out. I am also noticing some softness in the clutch itself. I plan on taking it in to my repair shop to verify, but am leaning very hard towards it being the clutch going out. Do you know if the clutch has been replaced on the car you bought? They usually last 100-125K. Let us know if you find anything out.

ZePorsche

hey irish, yeah, after reading posts here at Renn and doing some youtube research as well i definitely think my gearbox needs some repair/replacing. Possibly clutch as well because i believe its still on the original clutch. Additionally, i believe my rear hatch is causing some vibrating so i dont know if its the hatch bolts or what because i can tell the glass was resealed.

But another issue has creeped up - getting some funny revs lately and then last night it stalled out. It immediately started back up without hesitation. I've read around and maybe its an Idle Stablization Valve (ISV) or Air Flow Meter (AFM)??? Not sure, but i dont know how to repair/replace either myself so... we'll see

Thanks for your reply

jblobner

With respect to the funny revs. Check your main ground strap that goes from the battery to bell housing. My 87 had all sorts of crazy revs, stalls, and even some odd noises thanks to some friendly replies to my post I replace the ground strap and everything went away. Check it good. My look in good shape, but it wasn't.

indes

AFM is pretty accessible in the front of the engine bay. Clarks garage has an interesting write up on testing it...

The ISV is under the intake manifold - easy to clean out with some carb cleaner and bench test with a 12v source / battery - but a bit of work to get at. (I recall the fuel rail coming off.. some threads claim you can get it out without manifold removal on an S2?? I didn't try...) If you spend the afternoon, also check out the seals/tubing leading to and from for vacuum leaks.. (Rubber mounts may crack, ISV may vibrate, which (I assume) won't be good for proper operation or the rubber tubing attached)

1933beer

Replacing transaxle oil with red line made a big difference in my car yours ago. With 90k then. These shifter get worn and can be replaced to take care of slop. I once had my balance shaft belt slip out of alignment a bit and was causing some vibration. I didn't figure it out until the next belt change. This may not be your issue but I had vibration in all gears about 3 to 4 k.

Emefef

The vibration I had between just over 3200 and just below 3500 was most definitely the clutch. Big chunks of rubber fell out when we took it apart. No way was that balanced!

1933beer

So you still had the original rubber clutch at 130k? I have not heard of one for a few years now and most are done before 100k.

indes

Lost my rubber clutch at 52k.
Just did new motor mounts - that fixed an incredible amount of vibration.

1933beer

I replaced a mount on the exhaust side when I replaced my bearings. I did not notice a difference. The original was not bad yet. It was brittle and when I was removing it it tore. I did not replace the other side because it was still good and does not get the heat. It should be something that is inspected.

indes

My original rubber mounts were the NA-discontinued style ones. Afterwards, I noticed the passenger side (with the heat guard) makes a sloshing sound when shaken. The driver side doesn't. Not sure what they're supposed to sound like... i.e. if there's missing fluid in the passenger one and it makes noise now, or if the driver side is completely empty... ?
They're also the same size if you take an eyeball measurement. I'd stick with the turbo style ones anyway after the test drive..... So smooth.