LOUD Rattle... Help please

[FlyinAh944]

I've got this God awful rattle. This is an annoying (hopefully not costly) problem... Needing some help figuring out what it is though...


Ok, whenever, and I do mean whenever, my foot is not on the gas there is this loud loud rattle/knocking noise coming from under the hood. All it needs is the tiniest bit of gas to take the rattle away too, i can have it at 1,100rpm in first with my foot on the gas and no rattle. Ive tried to figure it out but no luck... the noise sounds as if it is coming from the underside of the engine, from the middle area. On the drivers side of where the exhaust pipes are.. If it helps the car is an early 85 automatic.


Thanks much

------------------
Kirk
85' 944

[Rollins]

Could it be something to do with the flex plate? I don't know much about the autos, but that's a guess. Also, what about your exhaust? Maybe it's rattling and you simply don't hear it when you rev the engine. I would make sure the exhaust is hooked up tight. I had that problem on my 944.

[Cebu]

85.5 944na, Automatic. I had the same rattle problem. Found Transmission rear top mount loose.Verfied by noting the Engine to xmission torque tube housing resting on the rear suspension torsion bar housing (I used two rubber brake pedal pads). Jack up vehicle..support on ramps or Jack stands. Place Jack under Transaxle and jack transmission up slightly,,place rubber pads between torque tube housing and Rear torsion bar housing. This got rid of the rattle.I got the transaxle rear mouut secured later with xmission overhaul.

[lm6y]

If it's not the trans mount, look for a loose o2 sensor. it took me forever to find this on my car. While you are under there, look for any loose heat sheilds.

Good luck with it.

[Morrie]

My 87 924S was similar, loose bracket for wiring on the O2 sensor according to shop. Just adding for others doing searches.

[porschetub]

Engine mount, they turn to mush due to heat/oil or old age.
Trans rubber coupling,they do wierd stuff when they start to self destruct
Exhaust rattle (as mentioned) try shaking the tailpipe and listen for contact under the car.
Best of luck.

[ckelly78z]

I second the heat shield idea, and might add the catyletic converter, that can fall apart inside and rattle.

[rodham]

Had the same thing happen last summer with my 944 85 automatic, at lights or stops whenever just idling it would rattle to death. Turned out to be the spare wheel and bolt weren't snugged up the last time I used the scissor jack.

Turned out to be a real cheap repair.

But now I'm looking for a fix for my transmission... DIY reman (if possible) or buy another.

[mytrplseven]

Exhaust pipes on the drivers' side? I had to look to see if you were in the UK. Did this just start suddenly or come on gradually? I took my exhaust system off to do a clutch job and found 3 of the 6 bolts that hold the exhaust pipes (2 down pipes) loose, even though the threads were rusted. Catalytic Converters will do that when they're shot inside.

[Autobahnkid]

Unfortunately rattles in our automatic transmission Porsche's tend to equal trouble.

I will list several things you should check for, starting with the least expensive. Do read all the posts( search for "rattle"). At Pelican, rennlist, 924org, pca, etc.

1. Heat shields, check at manifold, starter , catalytic converter and exhaust.
2. Exhaust and catalytic converter hitting body.
3. Transmission bolts and mounts.
4. Torque converter bolts loose.
5. Bad torque converter. expensive implies taking down transmission.
6. Torque tube bearings gone bad. ( doesn't sound like this is the problem)
7. Torque Dampner located at front of the car next to the engine( aka the doughnut, rubber damper) very expensive. Take a peek through the inspection port. Look for cracked rubber ring or metal in the housing. $1200 to $1500 part.
You can install a clutch kit to replace (cheaper solution $200+)
Sounds like this is your problem unfortunately.

Good luck. I do hope it is something simple