Can engine mounts be bad even if they are not visibly worn?

[sugarwood]

I was having a minor issue with the shifter enthusiastically popping out when shifting from 1st to 2nd under acceleration. When I replaced my tranny mounts, they almost looked brand new. The rubber was not flaking or cracking in any way.

The problem still seems to exist, however sporadically, but don't know if there is some placebo impacting my perception. So, I am wondering if I should now change my engine mounts. But, I assume they will also appear to look fine. Should I bother?

Often, people are advised to change their mounts just because they are old. Can rubber "go bad" even if there is no visible sign of wear? Can it get softer and more pliable, thus allowing more movement?

[CCM911]

Since rubber is a petrochemical, it most definitely can get old and brittle. For the price of new mounts, I would not even give it a second thought. The advise I received was that they are over thirty years old, so yes, it is time to change.

Crack open the wallet and treat yourself to a new set of engine mounts.

[boyt911sc]

If I were you, I would focus on the shifter mechanism and shift coupler alignment first. Are the shift coupler components in good working condition? How old are your synchronizer? Are you doing the alignment correctly? If the engine and transmission mounts are still the original ones, time to replace them. I had the driver side engine mount collapsed while I was driving and a very scary experience. Keep us posted.

Tony

[stormcrow]

Could be a shifter linkage issue. After I installed my engine I was having the same problem - but mine was popping out of 1st. Did a re-adjustment and the problem went away.

[sugarwood]

Originally Posted by CCM911

Since rubber is a petrochemical, it most definitely can get old and brittle. For the price of new mounts, I would not even give it a second thought. The advise I received was that they are over thirty years old, so yes, it is time to change.

Crack open the wallet and treat yourself to a new set of engine mounts.

Well, it's not about the money, it is about employing correct logic.
"It's old, therefore it must be broken" is what I'm trying to question.

What if my mounts are NOT brittle?
What if the rubber is 30 years old yet looks brand new?
Can the rubber look perfectly good and still be bad?
My tranny mounts looked brand new, and I suspect my engine mounts are even better. (hidden from elements)

[sugarwood]

The PO had the shifter stuff refreshed. Bushing kit? Coupler Kit? I'll check the records.
That said, it can't hurt to learn more about adjustment.
I will post a video of the mechanism under the tunnel flap this week.

[john walker's workshop]

If the shifter hits the front of the tower before it's completely in gear, that can happen. A slight lengthening of the shift rod at the coupler is the fix.

[javadog]

The stock shifter coupler bushings allow a little fore-aft play. Many of the replacements have round holes that don't. One more thing to ponder if you have worn mounts, or a less-than-perfect adjustment of the linkage.

JR

[stormcrow]

here is a link on the proper way to adjust the linkage - this is the method I used and it worked out great. The tranny never shifted so smoothly.

Pelican Technical Article: 911 Shifting Improvements

[DanielDudley]

Don't drive it too hard until you get this fixed. If they pop out enough times, they start to like it.