1988 GMC 4.3 engine vibration
Question:
My S-15 extended cab vibrates worst than anything in the history of modern civilization! I am on my second engine. Both have gotten worse with miles. Are there any miracle cures, like special motor mounts?
Response:
Does it do this even in neutral? Possible the harmonic balancer has slipped or something. — Robert Hancock Saskatoon, SK, Canada Home Page: http://members.home.net/hancockr
– Hide quoted text — Show quoted text -> My S-15 extended cab vibrates worst than anything in the history of > modern civilization! I am on my second engine. Both have gotten worse > with miles. Are there any miracle cures, like special motor mounts?
Response:
Most of the old version 4.3 were not balanced due to an offset crankshaft. * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * The fastest and easiest way to search and participate in Usenet – Free!
Response:
> Most of the old version 4.3 were not balanced due to an offset > crankshaft.
Care to explain that?
Response:
Sure, the 4.3 was based on the 5.7 or AKA 350 V8. All GM did was chopped off two cylinders off of the 350 and called it there new Vortec V6. Now the crankshaft was balanced two the V8 and not two the V6. GM wanted this engine ready for production in 1985 sine the EPA was jumping down their backs for a smaller and not so fuel hungry engine that would produce less emissions. So they rushed the engine into production knowing that it vibrated some what. Instead of redoing the crankshaft design they just added an extra jounal and put more weight into the flywheel. It smoothed the engine out to a certain extent but it was not as smooth as the V8. The crank was so unbalanced when it frist came out that at idle it would shake its self to death. Over the years they improved the engine and in 1992 but in a counter balancer on the Enhanced Vortec V6 and had all the Vortec V6s have the counter balancer standerd in 94. * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * The fastest and easiest way to search and participate in Usenet – Free!
Response:
> Sure, the 4.3 was based on the 5.7 or AKA 350 V8. All GM did was > chopped off two cylinders off of the 350 and called it there new Vortec > V6. Now the crankshaft was balanced two the V8 and not two the V6. GM > wanted this engine ready for production in 1985 sine the EPA was > jumping down their backs for a smaller and not so fuel hungry engine > that would produce less emissions. So they rushed the engine into > production knowing that it vibrated some what. Instead of redoing the > crankshaft design they just added an extra jounal and put more weight > into the flywheel.
Bull Shit. The 4.3 has split journals like the 3.8 Buicks. Always did. It smoothed the engine out to a certain extent but – Hide quoted text — Show quoted text -> it was not as smooth as the V8. The crank was so unbalanced when it > frist came out that at idle it would shake its self to death. Over the > years they improved the engine and in 1992 but in a counter balancer on > the Enhanced Vortec V6 and had all the Vortec V6s have the counter > balancer standerd in 94. > * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * > The fastest and easiest way to search and participate in Usenet – Free!
Response:
> Bull Shit. > The 4.3 has split journals like the 3.8 Buicks. > Always did.
No it didn’t. I should know I have a 4.3 in my truck. Plus the 3.8 is a very different engine than the 4.3. * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * The fastest and easiest way to search and participate in Usenet – Free!
Response:
Hello All I have a 1988 gmc s-15 4*4 with the 4.3L 6 cyl.. It seems that as I drive at a constant speed the engine will downshift or change rpm’s.. I then need to step on the gas harder to maintain speed.. It also seems to shimmer when maintaining speeds also… Any insight would be great.. I though it was a tranny problem. Steve Before you buy.
