Failed motor mounts? Any experience?

Drivetrain discussion including Transmission, Differential, Driveshaft, and related items.
9C1fanatic
Posts: 430
Joined: Tue Dec 30, 2014 8:58 pm
Location: Texas Hill Country

Failed motor mounts? Any experience?

Post by 9C1fanatic »

Last week, I was run off the road by an elderly lady who felt more comfortable driving in the middle of the road than the far right as is usually the custom. The result was my car going into the ditch and over an unforeseen missing section of the edge of the roadway causing my right front wheel to drop into the hole violently and my engine cradle impacting the edge of the roadway asphalt. It was a very violent strike.

The cradle seems find. Its pretty tough but I do have a vibration now at 65 MPH and above. Put the car up on the lift later on and saw that the inside of my RF wheel is very bent and the driver side motor mount has been leaking fluid. I am not sure at this point if the vibration is the wheel, the motor mount or both but at this time, I have no other symptoms of a broken mount such as clunking on acceleration or excessive movement of the engine under load.

I have yet to see what her insurance company will do as this is a non contact traffic crash but if I am on the hook for this financially can anyone advise if leaking fluid is cause alone to replace the mount and if so, are they difficult to change. They look difficult to get to.

This has me re thinking my tune. I have altered the throttle response to mimic that of a car with a mechanical throttle connection for better response but that combined with my shift quality has my car chirping the tires into 2nd gear on hard acceleration. Don't know if this caused the failure or the impact or both but it was the passenger side of the car that hit the ground and the driver side mount is the one leaking. Our police Tahoes at work are always having driver side engine mounts fail but not so much on our Caprices. My car only has 25000 miles and I bought it new (no police service) I may return the programming to stock except for the DOD delete.

Any thoughts?
Garner Ames



1975 Pontiac Grand Am L77 - 14.82 @ 92.89
1991 Chevrolet C1500 L31 Vortec/5 Speed
2002 Chevrolet Suburban 1500 LM7
2014 Chevrolet Caprice 9C1 L77 - 13.60 @ 105.87
2019 Chevrolet Express 3500 L96
CrashTestDummy
Posts: 2300
Joined: Sat Feb 07, 2015 2:31 pm
Location: Pearland, Texas

Re: Failed motor mounts? Any experience?

Post by CrashTestDummy »

Motormounts on late-model GM vehicles are weak across the board. I guess it's to further isolate the mechanicals from the passengers, but failed mounts are a common complaint. You just about can't keep one in a NNBS Tahoe. I think we have a bad one in our '10 PPV, but haven't really looked around. I get a slight thump when accelerating off a light/stop sign, and we have a vibration that's felt at idle when stopped.

We do not, however, feel the vibration at speed, or my wife would certainly let me know about it. I am about 99% certain your vibration is due to that dented wheel alone. I think what you'd feel from the motormount would be a thump upon acceleration or hard braking, and maybe increased vibrations in gear at a light.

Let us know what you go back in with. I've seen some threads that have been hinting at the neoprene Camaro or G8 fitting a Caprice, but haven't seen anyone come back with a 'yes' or 'no'.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2018 Tahoe PPV (her car)
1995 DGGM Impala SS
1985 Firebird - 310 LS1 C Prepared autocross car.
1980 Bluebird Wanderlodge
And some others
Do YOU have my SPID?
9C1fanatic
Posts: 430
Joined: Tue Dec 30, 2014 8:58 pm
Location: Texas Hill Country

Re: Failed motor mounts? Any experience?

Post by 9C1fanatic »

Yeah it sounds like your driver side mount is out on your Tahoe.

I agree, I'm thinking that the dented wheel is most if not all of the vibration problem but the leak from my motor mount has only recently come up as I change my own oil everytime and I know it was not like at the last oil change. The fluid is now dry but has left a stain all over the motor mount and down the side of the oil pan.

I will look into those after market mounts for the future by I can already tell you that whether its insurance pay or warranty claim, the GM mounts will have to go back in for replacement. Too bad they cant leave alone what they get right. I have NEVER had to replace an engine mount on a RWD GM vehicle even on all of the high mileage B Bodies I had. Trans mounts yes sometimes but never engine mounts.
Garner Ames



1975 Pontiac Grand Am L77 - 14.82 @ 92.89
1991 Chevrolet C1500 L31 Vortec/5 Speed
2002 Chevrolet Suburban 1500 LM7
2014 Chevrolet Caprice 9C1 L77 - 13.60 @ 105.87
2019 Chevrolet Express 3500 L96
fuzzkill
Posts: 152
Joined: Sat Feb 04, 2017 4:19 pm

Re: Failed motor mounts? Any experience?

Post by fuzzkill »

My mounts are holding up fine so far, ~60k of police duty and 10k since. Last 5 months have been with the manual trans, which surely puts them under a lot more stress day to day than the auto.
CrashTestDummy
Posts: 2300
Joined: Sat Feb 07, 2015 2:31 pm
Location: Pearland, Texas

Re: Failed motor mounts? Any experience?

Post by CrashTestDummy »

9C1fanatic wrote:Yeah it sounds like your driver side mount is out on your Tahoe.

I agree, I'm thinking that the dented wheel is most if not all of the vibration problem but the leak from my motor mount has only recently come up as I change my own oil everytime and I know it was not like at the last oil change. The fluid is now dry but has left a stain all over the motor mount and down the side of the oil pan.

I will look into those after market mounts for the future by I can already tell you that whether its insurance pay or warranty claim, the GM mounts will have to go back in for replacement. Too bad they cant leave alone what they get right. I have NEVER had to replace an engine mount on a RWD GM vehicle even on all of the high mileage B Bodies I had. Trans mounts yes sometimes but never engine mounts.
Garner, same here. In fact, I was quite surprised when our transmission guy said one of the motor mounts was bad on our 68 Cadillac. :shock:

Before we got the Caprice, when I was talking to the reseller that had it, they mentioned they were having to replace one of the motor mounts, so I think our car needed one at 88K miles before we got it. I do need to get to that Tahoe mount, but figured I'd do that when I replaced the front control arms.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2018 Tahoe PPV (her car)
1995 DGGM Impala SS
1985 Firebird - 310 LS1 C Prepared autocross car.
1980 Bluebird Wanderlodge
And some others
Do YOU have my SPID?
9C1fanatic
Posts: 430
Joined: Tue Dec 30, 2014 8:58 pm
Location: Texas Hill Country

Re: Failed motor mounts? Any experience?

Post by 9C1fanatic »

Update on this. I replaced the right front wheel which solved the vibration I was feeling. Everything seems fine but I still wonder if that engine mount needs replacing since it leaked. So far, I'm not feeling the usual symptoms of a broken motor mount. It seems the mount is not broken at this time, just lost its filling.
Garner Ames



1975 Pontiac Grand Am L77 - 14.82 @ 92.89
1991 Chevrolet C1500 L31 Vortec/5 Speed
2002 Chevrolet Suburban 1500 LM7
2014 Chevrolet Caprice 9C1 L77 - 13.60 @ 105.87
2019 Chevrolet Express 3500 L96
CrashTestDummy
Posts: 2300
Joined: Sat Feb 07, 2015 2:31 pm
Location: Pearland, Texas

Re: Failed motor mounts? Any experience?

Post by CrashTestDummy »

I bet it will eventually settle some and you'll start getting more NVH, but I'm speculating here. The mounts on our Caprice still seem okay, but I do need to replace the one(s) on the Tahoe.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2018 Tahoe PPV (her car)
1995 DGGM Impala SS
1985 Firebird - 310 LS1 C Prepared autocross car.
1980 Bluebird Wanderlodge
And some others
Do YOU have my SPID?
CHEVEN
Posts: 107
Joined: Mon Jan 16, 2017 9:38 pm

Re: Failed motor mounts? Any experience?

Post by CHEVEN »

I took apart a V8 -2012 caprice w/87 k on it and I was surprised at how busted up the mounts on it were...they were separated split and down right disappointing. I guess that 2 less parts I get to harvest.
CrashTestDummy
Posts: 2300
Joined: Sat Feb 07, 2015 2:31 pm
Location: Pearland, Texas

Re: Failed motor mounts? Any experience?

Post by CrashTestDummy »

CHEVEN wrote:I took apart a V8 -2012 caprice w/87 k on it and I was surprised at how busted up the mounts on it were...they were separated split and down right disappointing. I guess that 2 less parts I get to harvest.
Other than using it as a go-by to see if any aftermarket units match, yes, pretty mush something for the recycle bin.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2018 Tahoe PPV (her car)
1995 DGGM Impala SS
1985 Firebird - 310 LS1 C Prepared autocross car.
1980 Bluebird Wanderlodge
And some others
Do YOU have my SPID?
Maxspeed96ct
Posts: 89
Joined: Fri Jul 21, 2017 6:27 am

Re: Failed motor mounts? Any experience?

Post by Maxspeed96ct »

At 89k both of my motor mounts where shot, I'm surprised it wasn't more noticeable. I just happened to swap them when installing my headers, and glad I looked at them.
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