I have a 86 GMC Sierra 1500 Pickup Truck ; 1 owner, 61,000 miles ( the past 3 -4 years havent put on 1,000) Was considering having it painted, but before I did that , started driving it a bit more- noticed more than usual trouble starting; Was getting some backfireing. Carried it to a mechanic for an opinion–He listened, and listened, and listened (to it running_not to me_) with its occasionl hit,or skip,or backfire. One footnote-he changed my spark plugs 1-2 years ago. His conclusion : the lifters need replacing. Seperately saying the lifters on that yr modle were defective and that he has seen others with the same problem. While that “sounds” like it could "fit " to the problem - It hits me a bit odd that with only 61,000 miles the lifters are just now-all of a sudden not performing right --historically -years back I dont recall ever hearing any backfires, skips-( of course maybe thats why I had the plugs replaced 2 yrs ago- thinking I was hearing one of them skip/miss. I have to decide If its worth replacing the lifters on an 86 pickup (b 4 i paint it)??? But would like to be positive it is the lifters?? Any thoughts -suggestions or confirmations of “bad year for lifters” ???
sbh
I don’t recall lifters being bad on the 86 model GMC’s. I do know however that when the lifters go bad that the camshaft tends to be bad as well on these engines. I would get a second opinion and maybe a third. Have them check the camshaft very carefully if the lifters do have to be replaced.
I never studied the problem in depth and I don’t know if the lifters are wearing out the camshaft or is it really the camshaft wearing out the lifters. It’s a question that I’ve had in the back of my mind for years regarding these GM engines. Maybe someone can enlighten us.
Yes, @missileman, Chevrolet engines sometimes wipe out cam lobes and the most frequent complaint that brings them to a shop is back firing when accelerating.
I think you its cam lob that wore down. Their were some bad cams in those years. I had one on a 85 350. It also could be that one or more of the lifters have gone bad from sitting. A dry start can take out cam lob too. If it was mine I would pull the intake and have look at the lifters and the cam. If you have bad lifter, I would replace the cam too.