This issue just began a couple of months ago. Drove it all last summer with no issues, and in the winter I was worried that I wasn't getting enough heat into it. No changes other than the number of miles on it, but as of a month and half ago the heat started climbing. In a 30 minute drive home or to work it starts pushing 210 degrees. Radiator is hot top and bottom. No leaks. Truck is running just as it did last year - decent power, no backfires, no lugging, no more smoke than there has been previously, it's just overheating now. Need some advice on next steps.
- 73 FJ40
- 75ish SBC, Carb'd
- Stock sized radiator, 4-core, no shroud
- 160 degree thermostat
What I've done:
- Swapped the water pump (minor drip around impeller shaft)
- When I swapped the water pump I checked the radiator for sediment buildup - looked clean
- Put in a new thermostat (used same 160 degree)
- Removed siezed fan clutch and put in new fan clutch
- Replaced spark plugs - cylinder 1 looked ugly, a lot of gray ash buildup, the rest looked fine
- Checked timing - looks okay
- Turned up the fuel mix screw on the carb to run a little richer
- Pulled the York compressor to minimize drag/parasitic loss
- Checked hoses, don't seem to be collapsing
- Replaced radiator cap
- Replaced oil pump - doubled the oil pressure, but seems to have accelerated heat-up
- Flushed and refilled with 50/50 antifreeze/water mixture
What's left to do, other than replace the motor? Could it be water channels plugging up? I could go to an aluminum radiator and/or a shroud, but this wasn't necessary last year. Am I missing something?
Anyone want to buy a truck?