How to ID failed engine mount in a 964.

[axl911]

I asked the question of how to identify a failed rear engine mount. I took my engine mount out and compared to one that I ordered. The difference is obvious as shown in the photo below. The failed mount on the right sagged by .5 inch. Keep in mind the mount are shown up-side-down. When shaken, the failed mount has fluid sloshing around. These are liquid filled mounts.



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anthony

[robert plante]

Hi Axl911....,

Now that you changed the motor mount.....did you feel any difference between the old and the new ones?
Why did you changed the motor mounts?

[Porschedude]

A point to clarify your photo Anthony. The threaded stud points down and the engine hangs from the threaded studs via. the rear engine carrier (lt to rt brace). The flange interfaces with the body.

Thanks for the picture, now I know what to look for...

Keith

[axl911]

I haven't have a chance to complet the change yet. Will do that this weekend. I will report back on how it felt.

But currently, the car has the engine is separated and dangling feel. When you go over a bump, you can feel the suspension settle, then you feel the engine settle. I also noticed notchiness in shifting under high rpm or load conditions.

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anthony

[robert plante]

Anthony....,

Yesterday i finally took off the motor mounts out of my 964 1991.They are completely shot.They are looking exactly like the pic's you post except mine are empty i mean ther are no more coolant inside and some rubber parts are missing....
The biggest symptom is vibration.The engine shake all the time and when you depress the gaz pedal you can feel a light vibration.
Thanks for your post it finally help me a lot.....
Thanks

Robert

[Porschedude]

Robert, I believe that the coolant you refer to is actually a dampening fluid.

It would be interesting to know the weights of the new and old engine mounts. Not that this would be criteria to change them out, only wondering how much mass is actually gone on a failed mount.

I have a '91 C2 Targa and soon will have the eng/trans out for a clutch and flywheel, I think that I'll pick up some motor mounts before I start.

Thanks for the thread,

Keith

[robert plante]

Keith....,

I will weighted them and i'll let you know....not sure that there will be a huge difference between them....maybe just a few onces.

Robert
964 1991

[daring]

Another way to check is when you take the mounting stud and can move it all around with your hand.... Hehehe!!

I just changed my mounts yesterday, but I need some information before I put too many miles on my engine.

1. I assume that when you change them you should jack the engine up slightly to take pressure off of the mounting nut and get the proper tightening... Please correct me if i am wrong.

2. What is the required torque on that lower nut. I set it at 80 ft-lbs. but I based that on the torque requirements for the crossmember bolt/nut combo. on the 3.2 Carrera's...(84-89) different setup!! Please let me know the correct spec.

Thank you...

BTW - Major difference in eliminating engine vibration, shifting "notchiness" (As axl911 referred to) went away, and even eliminated my clutch drag which all seems fairly obvious in hindsight.. eh!! Saved me slave cyl. bleeding.

DG

[daring]

Stupid Me!!!!

BTW - I need this info. for a '90 C2 Cab.

Thanks in advance. DG

[robert plante]

Torque needed for the lower nuts:85 Nm
upper nuts:25 Nm

Good luck

Robert

[daring]

Thank you Sir!!!
I guess I torque'd it TOO tight. When I took out the old one the force I had to put on the lower nut seemed like it was under a lot more pressure. I guess engine weight must account for a lot of that over time.

Thanks, Darin