1981 22r 4 speed runs warm -- radiator, fan clutch, or both?

Hello Master Wrenches, I could use some advice.

I have a 1981 Toyota pickup (with a heavy camper conversion on it) with a 22r and a 4 speed manual. I purchased it in October with about

120,000 miles on it.

The truck runs without a hiccup but the temperature gauge rises to about 80% when cruising at highway speeds for any length of time. It stays at an acceptable range in stop-and-go traffic and at 40-50 mph on rural byways.

I have already flushed the radiator -- it was a nice healthy green color with no observable rust or engine oil contamination. I have replaced the thermostat for good measure (hey, why not try the cheap 'n easy thing first!).

To no avail. The condition appears unchanged.

This morning I played around with the fan clutch. It turns pretty easily when I push on it, but it doesn't keep spinning after I take my hand away. A hot or cold engine doesn't seem to make any difference.

What does the gang think is the likely culprit here? Insufficient flow through the radiator, a failing fan clutch, or both?

Thanks in advance for your input!

Eric

Reply to
Strollingbones
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If it overheats at slow speeds, think fan clutch, here are some ideas to test it:

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If its overheating in hot temps and high speeds, then its likely a partly clogged radiator, or a faulty radiator cap, collapsing coolant hose (usually the lower one) or a water pump that is worn out. I had the exact same problems on my '85, would orverheat in temps of 80 or higher with speed > 65 or RPM > 3500. Drop the sprred/RPM below that range and it ran perfectly cool. Dropped in a new 3-row radiator and all was fine:
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Reply to
Roger Brown

Reply to
Nathan

Thanks, gentlemen. The process of elimination is pointing to the water pump as the likely culprit here.

Dumb question -- water pumps can fail gradually, not just suddenly?

Eric

Reply to
Strollingbones

they fail gradually, then suddenly. :oD

Reply to
Celica Dude

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