Thread: Why? (re: motor mounts) --- long

I've got a weird problem with motor mounts and am looking for ideas --- the issue might end up being obvious, but here's what's going on.

when I first got my car (a 98 gtp close to 2 full years ago) I replaced the motor and trany mounts with napa solid pieces. They cured a world of ills but the motor mount didn't last that long. The napa pieces were the noted crappy ones of the era and the motor mount had collapsed on itself in about 3 months, to the point where the oil filter (long one) was almost on the cradle.

Anyway, I got some plates made for shims to level the motor up and I got a AZ piece, made by anchor. I used a 3/16 plate to shim the motor to level and life was good ---- for about 6 months when that motor mount collapsed on itself. I got the mount replaced under the lifetime guarantee and fixed it again.

So great -- I need to replace another mount now -- about the fifth one in two years. The car had been making strange noises the past week, which I attributed to the mount but I noticed during it's weekly once over the DS dogbone bolt to the rad support was missing ---- which does explain a lot of the weird noises and feels I was getting. I'd found the nut laying down by the crank pulley last week but thought it was maybe from when I did my shocks last summer? So after a stop to home depot I get it all bolted down again. I rocked the motor a little (probably an inch worth) and noticed that both round bushings in the dogbones had quite a bit of play in them. They are new Montana pieces (shorter) from Rock Auto (made by Anchor) but sure look like they need to be replaced again (~ 6 months)

Now to the motor mount issue --- all that seems to happen to them is they collapse. I don't see any sheer or anything but them crushing down to where my spacer place it resting on the pin of the mount. I've got an oil leak down there and the mount gets pretty wet. I'm not sure where the leak is --- but it's not a lot, about a quart in 5K miles. I replaced the front seal when I did the CPS but noticed a groove in the balancer shaft that I'm not sure is supposed to be there. The other is the oil pan --- a stealership replaced the gasket but didn't do a great job on it. I'm just not sure that that little oil can rot a mount in 6 months time though?

the car is mostly stock so it's not a power issue --- lol.

anyway --- any ideas on any / all of this? does the balancer need to be replaced because of that groove? are the anchor mounts just junk (AZ gave me a different brand one this time) or wtf could I be doing wrong?

thanks in advance

Well i have not seen the aluminum mounts so i don't know how there designed.Altough it seems they would be put under more stress without polly uppers.

Under hard acceleration you're motor moves about an inch and a half with all stock mounts. With polly's it moves nearly none at all. So if you think about it, the aluminum mounts are designed to be stationary and give nothing when it comes to movement. To me it would seem the same as far as support wise if you ran without the upper dog bones all the time,with the lower solid mounts being installed becuase your putting a lot of strain on them with the top of the motor not being secured (or you may as well say that since it can move nearly 2'').


If that didnt make sense what im saying is basicly the only mounts you have are what you have replaced with solid aluminum ones,becuase all the other mounts are designed to be able to move to reduce vibration,wich they can't do that because of the soldi aluminum ones. Therefor all the movement that is ''suppose to be happening'' is not causing a LOT of strain on the solid ones.


I can't say that i've ever seen anyone with just solid lower mounts. Most people I belive have polly uppers also. And by having that ''extra'' support that you're lacking could be actually what you need.

Originally Posted by TDCRacing

Well i have not seen the aluminum mounts so i don't know how there designed.

well the plates aren't mounts --- it's a shim that I put between the motor and the mount, like the plates that Vinnie sells.

but let me ask ---- is that groove in the balancer shaft normal --- or is that where my oil leak is coming from?

thanks

Originally Posted by Bio248

groove? i think there is one but i cant quite remember..got a picture?

no, but it's on the outside of the shaft that slides through the front seal.