1980 Other Chevrolet Models Problems with my truck

KATTW8

MEMBER
1980 CHEVROLET
V8
2WD
AUTOMATIC
143,000 MILES

I have a 1980 1 ton dually 2WD pickup truck I purchased to pull my horse trailer. The truck is very clean, was originally a california truck. I noticed a little rough 'miss' every now and then when I first purchased it in the winter. I only use this truck occasionally- soley to tow. On my way to a horse show in June I overheated. Replaced water pump, raiator cap (radiator was pressure tested in jan- was fine) and thermostat. Vehicle still overheated, only when towing. By this time engine has more miss/rough running times, coughing, spitting and sputtering intermittantly. Timing checked, it's fine.
Truck is running rich- can smell gas and let's not talk about what the mileage is. Oh this is a 454 engine.
As of last week the truck is now running so rough I was unable to make it up a hill/driveway w/ trailer in tow (trailer is heavy- 9000 lbs) this is a 1 ton pickup-camper special. I have NO water in the oil/ or oil in the water. No black or white smoke. Am thinking it's a cracked head? Help.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following:, Pressure test the Rad. Cap, Clogged radiator, air lock in the cooling system, Fan clutch, Radiator electrical fan, collaspe hoses, water pump