Posted this in the 80 section - thought I'd repost here and see if anybody had ideas.
93 FZJ80, 260K on the clock. I've recently had intermittent issues with the heaters - no heat from the front, very little from the rear. Blowers are fine. Temp gauge reads normal. Eventually it will start working again for no apparent reason. Maybe after a bit on the same drive, maybe after being shut off for awhile.
I've also noticed that if I drive it hard while the heaters aren't working, the temp gauge will climb rapidly until I back off and idle. Temp gauge is stock. If the heater is working, this doesn't happen. This seems like a bad thermostat maybe? But from other reading, if a thermostat fails, it stays failed, usually open. Not likely to cause an intermittent problem.
Other info - radiator is full, though i had to add about half a gallon last week. Top of the core was visible. Drove it skiing this weekend - 300 miles on highway with no problems, no coolant loss. No leaks when parked. But now no heater going to work 2 days in a row.
About 3 months ago the hardline to the rear heater failed. Replaced with OEM, refilled and burped the system.
Radiator is about 5 years old. Good quality 3 core brass, but not OEM. I am running a modified fan clutch.
Had trouble overheating last August in UT pulling hills in 100 deg weather, heavily loaded.
It's also developed a rough idle recently. Going to R&R distributor cap, wires plugs this weekend. Will also check with the block test kit. Oil & oil cap looks fine. Head gasket is original AFAIK - I've had it since 104K.
Any other ideas/suggestions?
93 FZJ80, 260K on the clock. I've recently had intermittent issues with the heaters - no heat from the front, very little from the rear. Blowers are fine. Temp gauge reads normal. Eventually it will start working again for no apparent reason. Maybe after a bit on the same drive, maybe after being shut off for awhile.
I've also noticed that if I drive it hard while the heaters aren't working, the temp gauge will climb rapidly until I back off and idle. Temp gauge is stock. If the heater is working, this doesn't happen. This seems like a bad thermostat maybe? But from other reading, if a thermostat fails, it stays failed, usually open. Not likely to cause an intermittent problem.
Other info - radiator is full, though i had to add about half a gallon last week. Top of the core was visible. Drove it skiing this weekend - 300 miles on highway with no problems, no coolant loss. No leaks when parked. But now no heater going to work 2 days in a row.
About 3 months ago the hardline to the rear heater failed. Replaced with OEM, refilled and burped the system.
Radiator is about 5 years old. Good quality 3 core brass, but not OEM. I am running a modified fan clutch.
Had trouble overheating last August in UT pulling hills in 100 deg weather, heavily loaded.
It's also developed a rough idle recently. Going to R&R distributor cap, wires plugs this weekend. Will also check with the block test kit. Oil & oil cap looks fine. Head gasket is original AFAIK - I've had it since 104K.
Any other ideas/suggestions?
Last edited: