Motor Mount Inspection and Replacement

Motor Mount Inspection and Replacement

There are several ways to tell if the motor mounts are worn. I think the best way is to measure the amount of free space between the mounts and their safety hooks. If the gap between them is large enough to insert your index finger, the mounts are worn. If the space is too narrow to insert your pinky, they are fine. Anywhere in between, they are wearing.

If you plan to replace them yourself then you will need to do the following.
1) Raise car high enough to work under it comfortably (a foot or so).
2) Support the engine from above with an engine hoist.
3) Drop the steering rack, but do not disconnect the tie rods.
4) Remove the lower nuts that hold the motor mounts to the cross member.
5) Remove the cross member.
6) Remove the engine side motor mount nuts.
7) Install new motor mounts in the reverse order.

However, the way I did it was;
1) Drop car off at repair shop.
2) Pay for parts and labor. (BS with the shop staff.)
3) Take car home the next day.

The job was well done, and (for me) was clean and easy. However, it did manage to dislodge a large lump of green paper in my wallet. Parts alone were about $500.

Merry motoring, Ed.

Replacing the motor mounts is one of the more frustrating tasks that I have undertaken on the 928. It is a hard, dirty and expensive job - but it did make a very noticeable difference in both of my cars.
Some reasons for frustration:
The nine-volume shop manual doesn't even mention this job, and doesn't have a good illustration of it.
The area is dirty.
You have to take off several unrelated items to replace the mounts.
Fasteners are very tight and very hard to get to.
You have to jack the engine.
The mounts are expensive - $210.60 each for '82 - up.

Some tips:

Support the car securely at a comfortable working height. You will be reaching up into the engine compartment 8", so allow for that. You will need a jack to support the engine - a small bottle jack takes up less room under the car.

Replacing the mounts is easy once the cross-member is out, basically impossible without it being out. Removing the cross-member requires dropping the steering rack and the inner lower control arm mountings. If you plan to replace the front shocks, now is the time.

1) Jack the car.

2) I chose to lower the steering rack rather than removing it. You can leave the hoses connected - don't over-stress them. Remove the steering shaft universal joint. There is one nut on top by the shaft that is a pain to hold. Try sticking a flat-bladed screwdriver beside it to hold it.

3) I chose to remove the lower control arm mounts. This shouldn't screw up your alignment. Removal is pretty obvious. Be careful of the ball joint boots and the brake lines - it is easy to damage them by letting the arms swing.

4) Support the engine - be sure to spread the load with a large wooden piece, so you don't damage the crankcase. Drop the cross-member and mounts. There are a few other pieces that are in the way, such as ground cables, etc. Remove what you have to.

5) Replace everything, but first: Snug - don't over-tighten - all of the oil pan bolts; Clean and check everything that you touch, such as ground cables, etc.

6) When you get to the steering universal: Pull the plastic plug found on the front of the rack housing just in front of where the shaft goes in. Look inside the hole, find the dimple in the rack, and center it in the hole. This centers the rack. Install the universal so that the steering wheel is straight with the dimple centered.

I have probably forgotten something - this is the type of thing that you try to blot out of your memory.

Have fun!

Wally Plumley
928 Specialists

Wally's post was almost 100% correct - dirty and hard. Took every bit of 9 hours, only a couple differences:

1) I choose to unhook the power steering fluid lines to swing the rack out of the way rather than the
universal joint - the lesser of two evils?

2) I had to remove the lower control arm mounts as one side goes up through the cross brace

3) I didn't have anything else in the way (cables, etc.)

All these differences might be due to the model year - but just adjust Wally's write up with these notes
for an 86 and you're set.

86.5 928S 5 spd

These were the steps I took, maybe right, maybe not. But It worked ;-)

1. Front end high on jack stands.
2. Drop the steering rack cover plate.
2a. Don't know if you need to. I loosened the stabilizer bar and pivoted it out of the way.
3. Remove the 10mm bolt holding the starter wiring.
4. Loosen and lower the steering rack, drivers side won't drop much due to hoses.
5. Support the engine with a bottle jack, large pieces of wood on the oil pan.
6. Loosen the lower motor mount nuts.
7. Loosen the cross member side bolts.
8. Uh Oh, the cross member is between the lower control arms and the frame.
9. Up the time estimate from 4 hours to the 6 hour figure.
10. Remove the 2 big bolts at the rear of the control arms.
11. Remove the 2 big bolts at the front of the control arms.
12. There's a tow eye looking thing in the way, remove the rear bolt, loosen the front bolt, pivot out of the way.
13. Wiggle the lower control arms loose and forward of the cross member.
14. Cross member won't come down enough, Now What??
15. I wondered at step 4? Remove the PS lines from the rack, Don't forget a drain pan. I didn't.
16. Remove lower bolts on the steering U joint. I marked the rack end with a magic marker for alignment.
17. Now the rack comes down enough.
18. Remove the 4 bolts that hold the motor mounts to the block, each side.
18a. Raise the engine a little to gain more clearance.
19. Wiggle the mounts out of the car.
20. Time estimate goes above 6 hours.
21. Put the new mounts in the brackets. The old mounts were squashed 3/4 of an inch!!
22. Reverse the above to assemble.
Notes: Watch the exhaust shields and the mounts when pushing the cross member back up.
Refill the PS reservoir.
Time was closer to 10 hours.

My oil pan is now even with the cross member, not hanging below it!!!!

Ken Postma '86.5 928S Auto (refreshed motor mounts and other new stuff.)

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