siscogts

Hi! I want to check how much themotor mounts are flattened after 21 years.....Is there a trick to understand this?engone distance from crossmember? Distance between airbox and upper edge of firewall ? Distance between intake manifolds and the strut brace ?
Do you have suggestions?
Thanks a lot!
Francesco

Jim M.

There are several ways to tell if the MM are gone. The top of the intake should be even with the cross brace. If it's about 3/4" below it the MM are gone. Or rev the engine to 3-4000 RPM if the motor doesn't rock the MM are gone. Or crawl under the car and check the distance between the two safety hooks on the MM's. If you can't get a pinky finger between them the MM are gone.
Lastly, after 21 years I can almost guarantee they are gone!

siscogts

Not 3/4" to be even with strut brace. ..but almost 5/8!
I was biying volvo mounts...then i thought:am i pretty sure i need to change them?maybe the previous owner changed mounts....
As a real proof, before this reply, looked at under the car:engine is sitting so low that previous stupid mechanic put spacers between body and the belly pan...!!!!
Thank you!
I really need new mounts. Asap....
Francesco

Hilton

In the meantime, if you can jack up the engine and remove them, I'd get the spacers out of there. You have the whole weight of the engine sitting on a pretty thin aluminium oil pan, and the chances of it cracking are high.

The simple test of engine mounts is:

1. start the engine
2. stand by the engine and use your hand to tweak the throttle arm.

If the engine rocks as you tweak it, the mounts are fine and flexing. If the engine doesn't rock, your mounts have collapsed and its sitting on the crossmember, vibrating the whole car.

(if you're not sure if the engine rocks, then it is not - its *very* noticeable).

siscogts

When i pish throttle arn the engine rocks about 1centimeter or so....
Definitely gone.

siscogts

Anyway i will lift the engine from the trunk and i will put only a safety support for the engine under the car,no bottlelift or other stuff under the car in order to work as easy as possible ....

danglerb

Doesn't sound safe, one of these frequently on sale fender lifts works well, or can be fabricated in wood.

http://www.harborfreight.com/automot...bar-96524.html

siscogts

I use a winch attached to the top of garage by a steel subframe. ..i lifted up to 450kgs in the past,i think i can liift also 270 kgs of 928 engine. ..

Mrmerlin

^^^ you will probably have to remove the hood first^^^

siscogts

Yep....i know....

siscogts

ok....
Ready to replace motor mounts....
cross fingers for me.....
Francesco

Bill Ball

Small correction. The hooks separate as the mount collapses. With new mounts you cannot get a pinky between the hooks. With collapsed mounts, more than a big finger will go between the tips of the hooks. Conceptual diagram:

siscogts

Changed mounts.... The Old ones were so flat the pan was 2,5mm from the crossmember...
Francesco

siscogts

thanks to jim M, Mmerlin, Bill ball,danglerb, Hilton, dwayne's garage info and stan, Mr Pirtle.....and so on...
From this thread up to their 928 pages I learned how to swap motor mounts with big ease....

I opened the window, started engine...and nothing.no vibrations and no problem at all ....since I turned on starter motor till I got home,my 928 experience changed drastically, before the chassis and me were rocking at idle and under acceleration in neutral....now the engine does rock instead.
I opened wondows, and I felt like It's not me starting the car but a 928 owner near my car....the engine is now really "insulated" from the body.....
The engine: it was at 2-3 millimeters from the crossmember, mounts were heavily flattened, not the oil pan is about 3cms higher....

I always thought this car was so brilliant and so expensive that also 21st century owners must go to the dealers or porsche service centers to have problems sorted....here I found very prepared guys, with a ton of know how....

and with good 928-dedicated pages to read....and I will read for sure every page about their experiences....I like to work on my cars, and my 928 is not the exception, not anymore.

Thank you!
Francesco

PS: i overhauled also automatic gearbox, lsd differentials, i repaired bosch ECUs(jetronic or motronic),i repaired stuff usually considered a PITA to repair....but after this motor mounts swap, everything seems to be easier....not the worst dirty place to work in this car, but it's incredible how many bolts nuts and ancillaries you've to take apart to work on those mounts....
anyway, It took me 7 hours with my father working on the other side of the car....4, 5 to change mounts, the rest to clean everything or repaint something ruined....