How to tell if engine mounts are bad...

Lucky · 06-27-2002, 07:07 PM

Now that I have nice quiet tires on my car, I get to hear all sorts of new noises. One that has me stumped is an occasional clunk from the rear. And psuedo-random shifting difficulty. Maybe my engine/tranny mounts are on the way out?

How does one go about checking engine mounts and determining whether or not they are still good?

GeorgeM · GeorgeM's Garage

That occasional clunking sounds like it might be a broken sway bar mount. That's what mine sounded like.

As far as the pseudo-random shifting difficulties go, there's one sure solution: G50.

Good Luck.

Chris Bunker · 06-28-2002, 06:50 AM

I believe what you want to do is jack up the rear of the car with the floor jack under you engine case and watch the mounts as you lift. If the engine moves first before the body lifts, you need new mounts. If they move together as one, they are OK.

Chris Bunker
78 SC with good engine mounts that I checked yesterday.

Vipergrün · 06-28-2002, 07:29 AM

Poor shiftng is definately a symptom of bad mounts. I installed the *club sport* mounts, aka the cab mounts. They are the same part# as stock, but with a 7 at the end. This has really made a substantial change in the way my good 'ol 915 shifts.

You should be able to get a set of 4 for $160.00 thru Pelican. I swapped mine out in < 1 hour doing them one at a time..

cheers
-Brad
80SC

APKhaos · 06-28-2002, 08:39 AM

John,
Unless your engine has been rebuilt, strong chance that the mounts are original.....and tired. When they get soft, the motor and trans can move quite a bit under cornering and touque loads, which can compromise the shifter alignment under these conditions.

Brad is right on the money - the cab mounts are a nice middle ground between the softer coupe mounts and the track type solid mounts.

GeorgeM · GeorgeM's Garage

Okay... no one appreciated my G50 comment.

I've been looking at he club sport motor mounts as well. It seems that post '86 or thereabouts, the engine mounts and tranny mounts are not the same. I've been told that I can only get the club sport versions for the engine, not the tranny.

I don't have access to my car, I'm just going by the photos in Wayne's book. Do the '87-'89 cars have different mounts for the tranny? If so, then it appears that I'll have to mix and match club sport and stock back to front.

Anyone with a G50 out there that can shed some light on this?

Thanks!

Doug E · 06-28-2002, 02:27 PM

John - do I sense a project coming up that you might need some local Pelicanhead support for? If so, just let us know!

marcesq · marcesq's Garage

John:

The tranny mount for the G50 are different than the the mount for the 915. The mounts for the 915 are the same as the mounts for the engine. The engine mounts where the same until '89.

Changing mounts are a snap. If you want to change them out next weekend, let me know and we can knock it out in an hour. There is one caveat, when we pulled Richards 3.2, the bolts in the engine bay that went through the mounts and into the brace were frozen and bent the brace. So I would suggest soaking with carb cleaner.

Let me know.

89911 · 06-28-2002, 08:07 PM

The tranny mounts on a G50 are part of the tranny strap that supports the engine. The whole unit has to be replaced rather then the individual engine mounts. We are currently doing this to his 87 clubracer.

Lucky · 06-30-2002, 05:37 PM

... I went sailing for a few days, so I appologize for not seeing your replies sooner. It was beautiful, but I still missed the Pelican Forums!

My anti-roll bar mounts have been replaced and are seriously beefy. I know they aren't the cause of the noise. I'm 90% sure the engine mounts are failing as they are original. My engine was out at 48 Kmi for a top end rebuild (premature valve guide wear) under warranty, but the mounts were not replaced then.

I'll try the jack under the engine trick next time I see the car... it's 250 miles away

Then I'll know for sure.

Marc & Doug. I'll take you guys up on the "clinic" offer. I won't have time to do the work, however, for many weeks. Summers are just too busy!

Take care, all.

marcesq · marcesq's Garage

Hey John:

You could always just drop her off at Dougs (he has been known to store fellow 911ers cars for short periods of time) with the keys, and we'll take care of her . . . I think there is a DE event in a couple of weeks great place to test the new mounts.

Doug E · 06-30-2002, 06:01 PM

Marc - You know me too well! The minivan has already been pulled out of the garage and a space always awaits anyone who feels the need to leave their 911 (and the keys) for awhile.

John - just let us know when you are ready, all we need to do is make sure we get your work completed before our next NoVa Pelican fun run.