Temperature Issues

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I been having some temperature issues over the last year and a half or so.

Here is a summary of what has been going on.
1982 FJ45 Troopy with the 2F engine, and basically the original set up for a foreign (Australia) market.
For several years it run with the temp gage right at the middle (or slightly to the right in temps over 95 deg F). No matter if going up hill or flat or towing a small trailer.
Starting around June of 2020 I notice that it was running a bit higher, but only at temps above 95 deg F.
Later in the summer of 2020 I started to notice that it was running higher (3/4) even at temps around 75 deg. F

This summer I notice that it was running at 3/4 any time I pushed the engine a bit, even at temps below 70 deg F.
Also this summer I notice that the radiator was leaking (but any time I looked at the temp gauge, the radiator had just been topped off)
Last week I needed to travel with it, as my Sequoia with 340K miles hit a deer the week before, so I changed the radiator with a new CSF 2888 4 row radiator and new Aisan Thermostat.
Running around town it stays below half. On the highway it got to about half, but going up hill it got past 3/4 and the outside air temp was around 65 to 68 deg F.
When I hit a gravel road pass, it climbed to 3/4 while in second (18-25 mph or so) gear without pushing the engine and temperatures below freezing, maybe 30 deg. F
Once on the other side of the pass it cooled down to between 1/8 and 1/4 and stayed there while going downhill (probably too cold).

When running at 3/4, if I pull over and leave it idling, it cools down to about 1/2.

My concerns are if its running at 3/4+ on hills with temps below 68 deg F, how hot will it get at temps over 90 deg F.
Also my concern is, why did it cool so much when going down hill, I would have expected it only cool down to about 1/2.

Any ideas? Bad new thermostat? Blockage on the cooling system? Engine tuning?

Thanks

Guy
 

rkymtnflyfisher

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How long has it been since the cooling system has been flushed?


My needle stays right about the 1/4 mark on my factory gauge and 190ish on another analog Autometer gauge I have installed.
 

Hugh Heifer

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My BJ73 did the same thing. The radiator was a clogged mess. I had it cored since a BJ7X radiator is not easily acquired.
Verify your temp issue with a laser thermometer to ensure it is not the gauge or sending unit giving you erroneous readings (happened in my 40). Ensure your fan clutch is still operating properly. If they are good I would try a flush as stated above. Then my guess would be a thermostat (which I believe is a service item) and then the radiator. As you mentioned it is leaking, my best guess is it has trash throughout and is clogging the core and interfering with the flow.
 
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How long has it been since the cooling system has been flushed?


My needle stays right about the 1/4 mark on my factory gauge and 190ish on another analog Autometer gauge I have installed.
Thanks. No, I have not done a flush through the engine. What would be the best way to do this?
Guy
 
Joined
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Messages
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Montana
My BJ73 did the same thing. The radiator was a clogged mess. I had it cored since a BJ7X radiator is not easily acquired.
Verify your temp issue with a laser thermometer to ensure it is not the gauge or sending unit giving you erroneous readings (happened in my 40). Ensure your fan clutch is still operating properly. If they are good I would try a flush as stated above. Then my guess would be a thermostat (which I believe is a service item) and then the radiator. As you mentioned it is leaking, my best guess is it has trash throughout and is clogging the core and interfering with the flow.
I'll try to check temps with a laser this weekend. Radiator and T'stat are both new.
 

Hugh Heifer

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I'll try to check temps with a laser this weekend. Radiator and T'stat are both new.
Well.... Where did the radiator come from? I have heard of water jackets getting clogged with rust and stuff but I think that is exceedingly rare. My next best guess is the fan clutch. How is the water pump?
 
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Well.... Where did the radiator come from? I have heard of water jackets getting clogged with rust and stuff but I think that is exceedingly rare. My next best guess is the fan clutch. How is the water pump?
Thanks for the help.

The Radiator is a 4 row CSF 2888. Water pump is pretty new as well and is a Airtex 9493.

Just realized that I put the new pump in, on late November 2019. Curious if it could be the pump, as I started noticing the higher temps the following summer. Hmmmm.

As far as the fun clutch, I'll have to check, but it does cool while idling when I assume the fan would be more critical. At speed you should get sufficient airflow through the radiator (or is my thinking not right here?).
Thanks
 
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This happened to me after I changed my radiator without flushing the engine also.

Turned into a hard lesson learned.
Did you flush using a radiator flush product like hyper-cool or something from Prestone or something similar?
 
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I’m thinking fan clutch. I had very similar experiences and I replaced the fan clutch and then it was perfect.
 

John in Utah

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I'll try to check temps with a laser this weekend. Radiator and T'stat are both new.

Use the temp gun to check various parts of the radiator and look for dead spots. Check temps along the rest of the cooling system too for any clues. I fought a very similar issue on my old 3L Hilux after I turboed it. Went through a “new” radiator and a couple thermostats chasing it down. Cooling down past operating temp while coasting downhill typically points to the tstat or a flow issue. Consider putting an aftermarket gage in if you can.

Not sure if it’s been mentioned but make sure you have good belt tension on the water pump too.
 
Joined
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Use the temp gun to check various parts of the radiator and look for dead spots. Check temps along the rest of the cooling system too for any clues. I fought a very similar issue on my old 3L Hilux after I turboed it. Went through a “new” radiator and a couple thermostats chasing it down. Cooling down past operating temp while coasting downhill typically points to the tstat or a flow issue. Consider putting an aftermarket gage in if you can.

Not sure if it’s been mentioned but make sure you have good belt tension on the water pump too.
 
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Thanks. I will be checking temps with a temp gun. I will also check the belt tension.
Thanks for the info.
 

pb4ugo

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Id clean/back flush the fins of the rad with a hose. There could be a lot of bugs a debris wedged in it. I'd look at the fan clutch and probably replace the rad cap too. Pressure test the cooling system. You can borrow a tester at an a/p store Leave pressure on it and see if it drops. You can also test the cap with it too. Flush the rad and block out if the system is still acting up. The cooling system has to hold pressure. Check you timing, too much timing or running lean will build heat.
 

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