84 GM 5.0 liter bucking/surging after totally warmed up

[91waggin]

On my 91 with the double roller you didn't have to pull the pan. Just pull all the accessories off the front and remove the timing cover.
Definitely replace the harmonic balancer while you're there. It's probably split and nasty because it's rubber and also 30 years old. I know there are 2 different balancers, a 28oz and a 50oz balancer. One is for early years, one is for later years, but I don't remember which is which. I'm sure Thain or Scott will tell us in a minute here.

[gadget73]

no, just the timing cover has to come off. It may be a little easier to get the cover back in if you loosen the front pan bolts a bit for extra clearance though. The gear isn't solid plastic, it just has plastic as a coating to make it quieter. Fairly stupid idea really, the plastic chunks off and makes for a sloppy chain and it gets into the pan where it can clog the oil pickup. Its also an interference engine so if it jumps, it smashes the valves. That BS went away for the most part in 1986 when they went to a double roller chain. I'd stick a double roller on the 84 to permanantly eliminate the problem. Might have to ask for a chain for say a 1989 Mustang, but its a direct fit.

The 28 oz balancer was 82 and older. 84 would be a 50. they do go bad, and if you have it off, theres no better time to replace it. At a minimum, inspect it closely. If the rubber is pushed out and cracking, it wouldn't hurt to put a new one on. Replace the front crank seal while the timing cover is off. Its in the cover, and is absolute cake to do with the cover removed from the car. It would also be a good time to do the water pump or fan clutch or any old hoses in the area that need changing.