over heating

[cruis77er]

Hello to all you cruiser heads. Here is my problem. 1977 2F motor rebuilt just installed with a NV4500. I have an electric fan between the radiator and the motor. Running around town I can run with the fan off as long as the lights are not to long then when it starts to heat up I flip on the fan an the motor runs at temp. Today I took it for a shake-down run on a slightly rough road with a good incline not to steep for 4x4 drive. 2nd gear in 2x4 at about 1500rpms with the fan on an it over heats. But only while going up hill it runs cool down hill. I went up the hill once more just to see if it would overheat again which it did. The road is about half mile long with a good incline. I am running the red anti-freeze in the motor not sure if the 2F likes the red or should I go back to the green stuff. Thermostat seems to work just fine an the rad cap is good. I did open up the heater valve (finally) to get all the air out of the system before heading back down hill. It ran cool even after I turned the fan off when I hit the pavement. I did have to put about a quart of H2O back in the motor once I got it to cool down at the top of the hill.

 

[dgangle]

what is your definition of 'overheat' and exactly how are you measuring it?

stock unitless idiot range gauge? Install a quality aftermarket mechanical gauge and report back if applicable.

new or existing issue?

 

[cruis77er]

stock gauge goes past the 2nd line plus the over flow tank looked like a volcano going off when I opened the hood.

 

[4x4Poet]

Sounds like you need another uphill test run to check how it behaves without the claimed, now resolved air pocket issue.

Otherwise, you can't beat the stock fan clutch with the fan that has the fins on the end of the blades.

Piggybacking on dgangle, did you have the radiator checked/cleaned during the 2F's rebuild?

 

[Pighead]

Yes, you do need a real temp gauge and give us real numbers...
No, a 2F should not overheat unless something is really wrong. Bad timing or a lean mixture can make you run hot. Also may suspect your electrical fan is not working as it should (you got it blowing the right way?).

 

[cruiserbrett]

timing, fuel mixture, bad headgasket, clogged radiator etc? loose belt on the WP?

Ditch the electric fan and get back to what toyota designed to work in the saudi desert.

 

[cruis77er]

Thanks for the ideas. I do have the fan pulling the air so that should not be a problem. I shall check the fuel mixture also before I head out again. I may just put the clutch fan back on just because it did work before I had the motor rebuilt. One thing I failed to mention is that when the mechanic reworked the head he ruined it so I replaced the dome style head with a later model bathtub style head.

 

[cruis77er]

did not have the rad cleaned out but it was working great before the rebuild, Timing is spot on but I will check the fuel mixture may have moved the screw with out knowing it while putting everything back together.

 

[psuknow98]

My 2F was running hot last year. I PUT THE THERMOSTAT IN UP SIDE DOWN!

 

[robtackett]

Well mine overheated really bad the other day and blew the head gasket. I think mine was due to a really loose old belt and floppy water pump. I am going to say its due to a water pump bearing failure.

 

[lostmarbles]

My opinion..........

Could be the radiator. Does it still have all its fins? (Maybe time for a recore if it doesn't.) And the overheating may be showing up now because your engine is putting out more power - and therefore more heat - than it used to.

And stick with just the OEM gauges if you want to. ----- I do myself - because they've worked well for me over the last 30 years. (I don't need to see numbers/values.) And in your case, the OEM gauge correctly alerted you that you were running hotter than normal.

But I think to consider solving the problem by changing coolant-additives is "clutching at straws".

And I agree with the comment here that you should go for another test run before deciding to do anything - Just to confirm it still overheats with all the air burped out.


Then again - you'd get these same symptoms (overheating + purging coolant through the overflow) if combustion gases were entering the coolant through a head-gasket-leak or cracked head for instance. - So don't rule out that possibility either. - Particularly since the motor has recently been worked on.

Cheers
Tom