Barrman
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- Giddings, Texas
My 1984 former USAF 6.2 powered C20 Suburban was running great. I stopped at the store on the way home from work the other day. I fired it up and even though it sounded ok. There was a noticeable vibration. At idle, in gear and while driving. It ran like normal though. It did make a weird sound and vibration when letting off the throttle at speed.
I got it home and didn't have time to even look at it that night. Which of course left me to wonder all kind of expensive problems. Was the IP going? Did the balancer rubber let go? I really thought it was this one because besides being a known problem, the vibration started right way after starting it back up. Did it eat a valve? Maybe a glow plug tip broke off? etc...
I crawled under the engine the next evening. Balancer rubber was solid, no cracks and no sign of it shifting. While down there I noticed the passenger side motor mount bolt was about 3 inches out. Looking at the other side of the mount I saw where the engine side steel shell was touching the frame. I put a bottle jack under the pan with a block of wood to spread the load. Once the engine went up some, the bolt went right back in. A new nut secured it there.
I checked the other side and the nut was loose. Starting the engine had everything back like it was. Smoooooth.
Checking my two 1009 trucks found 1 of the motor mount nuts hand loose and 2 able to be tightened a good bit with a wrench. That means 5 of my 6 6.2 motor mount bolts on 3 vehicles were loose to some degree. The three vehicles in question came from three different states. Two were GSA trucks and another was GL. No common link besides being mid 1980's GM square body trucks with a 6.2 engine.
You might want to check yours the next time you are down there.
I got it home and didn't have time to even look at it that night. Which of course left me to wonder all kind of expensive problems. Was the IP going? Did the balancer rubber let go? I really thought it was this one because besides being a known problem, the vibration started right way after starting it back up. Did it eat a valve? Maybe a glow plug tip broke off? etc...
I crawled under the engine the next evening. Balancer rubber was solid, no cracks and no sign of it shifting. While down there I noticed the passenger side motor mount bolt was about 3 inches out. Looking at the other side of the mount I saw where the engine side steel shell was touching the frame. I put a bottle jack under the pan with a block of wood to spread the load. Once the engine went up some, the bolt went right back in. A new nut secured it there.
I checked the other side and the nut was loose. Starting the engine had everything back like it was. Smoooooth.
Checking my two 1009 trucks found 1 of the motor mount nuts hand loose and 2 able to be tightened a good bit with a wrench. That means 5 of my 6 6.2 motor mount bolts on 3 vehicles were loose to some degree. The three vehicles in question came from three different states. Two were GSA trucks and another was GL. No common link besides being mid 1980's GM square body trucks with a 6.2 engine.
You might want to check yours the next time you are down there.
