Engine mounts on a 996 C4

[The Baron3]

My exhausts were hanging low so decided to swap out the engine mounts, what a minefield, any way ended up with the below from Design 911 code no.
99337504908,

I think hey are the 993 stock mounts from the number, got them for £220 including PCGB discount.

It took me about an hour to swap out, would have been much quicker but the bottom bolts were rusted in place and it took lots of WD40 and breaker bar to get them released.

The old ones I think were the originals and totally buggered.

It's transformed the gear change and driving feel of the car.

Easy DIY job with a big result

 

[photek]

Thanks for the write up and the motivational speech

I've had a set sat mocking me for the last month...I'll get it done. My car has done 180,000 km and I suspect from the state of the bolts underneath is on it's original mounts

Just out of interest, any particular reason you didn't go for some semi-solid mounts?

 

[The Baron3]

Thanks for the write up and the motivational speech

I've had a set sat mocking me for the last month...I'll get it done. My car has done 180,000 km and I suspect from the state of the bolts underneath is on it's original mounts

Just out of interest, any particular reason you didn't go for some semi-solid mounts?

Yes, I heard you can get some harsh vibrations and wanted it as close to stock as possible. My car has done 180,000 miles so my mounts have got a few more miles than yours, mine were completely shot

 

[martin t]

I have the semi solid's on one car and have just replaced the mounts on another with standard ones.

I prefer the standard ones as the ride is smoother compared to the semi solid.

With the semi solid, and a short shift the car is a pleasure to drive but having driven both this week i do prefer the standard mounts.

As for fitting, the job is straight forward but do expect to have the long bolt unscrew from the mount leaving a siezed nut on the thread, TADTS

 

[gizlaroc]

Careful not to over torque them too, the more you torque them up the more 'play' you take out of the mount.

I think it is around 60-65 ft/lbs.

 

[Space Cadet]

There are 2 sizes of top nuts used, if they're M8 then tighten to 17 ftlb, if they're M10 then 23 ftlb.

Bottom are 63 ftlb.

 

[Robertb]

One thing putting me off doing the mounts is if it ends up with the exhaust tips and pipes ending up too high, or wrong in some other way, and having to enter the nine circles of hell of replacing all the exhaust bolts and clamps... did yours end up looking OK?

 

[martin t]

Fear not, there is only 1 bolt on each exhaust tip that would need adjusting should the worst happen.

Next thing to consider is why would the exhaust tips be in the wrong position after fitting new mounts?

As for replacing rusty nut/bolts on the exhaust: I am doing that exact job now on my 997. I need to replace the vaccum pump and rather than struggle i have removed the cats which means 6 x rusty siezed nuts and bolts. They will be replaced by stainless bolts or studs and copper flashed nuts.

With them out of the way i will support the engine and remove the engine mounting bracket (the whopping big thick alloy section that the engine mounts bolt onto. This will give me clear daylight on the scruffy lookung fixings that hold the pump in place. I hate struggling as much as i hate removing rusty nuts!!!

Changing engine mounts is straight foreward

 

[The Baron3]

Yes I bought new nuts to go on the bolts underneath as I had anticipated that they would be seized and indeed they were and the whole bolt unscrewed rather than just the nut.

The exhaust sits much higher and looks how it should, I wouldn't worry to much about the exhaust tips they should just position higher rather than become out of line.

 

[Robertb]

Thanks fellas, that's reassuring. What sort of height movement up are we talking... a CM or so on really worn mounts?

 

[martin t]

I would suppose it to be about 1/2 inch.

Yesterday and today i removed the cats, then supported the engine and removed the engine support bracket.

I am now on my 2nd beer of victory having removed the whatsit pump, of which all the screws were mangled by previous persons unknown and required drilling out and the use of an extractor. But i got there, the new pump is in, the cats with flexi pipes are back on, the flanges are now stainless steel and copper nutted.

Do not worry about the positioning it is obvious how to adjust and will bring much pleasure as a 997 owner.

You can see the beers are working :floor:

 

[The Baron3]

Thanks fellas, that's reassuring. What sort of height movement up are we talking... a CM or so on really worn mounts?

I would say between 10-20mm, but the thing I found more shocking was the rubber had completely perished meaning the bolt flopped from side to side, it was completely shot.