overheating possible causes

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Jan 18, 2011
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I took the kids to a pool party today, and they love to ride in daddy's truck. I guess riding in moms 11 sequoia gets old. I have a 95 80 and it was high 90's today. First I let the cruiser run for a minute so the a/c could cool the cabin, then drove about 15 miles to fill up with petrol. I never shut off the engine, wanted to keep it cool in the cabin. I then proceeded to drive the next 15 or so miles to our destination. When I arrived I was greeted by the beloved smell of coolant, and a gurgle coming from the overflow resevior which was full. Temp guage( non modded) never mooved, and a/c never quit. You guys think tstat, fan clutch, or something else?
 
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After it cooled down was your radiator full of coolant/water mix? Flow into the bottle is normal if it was really cookin' Any numbers from a Scan Gauge or Ultra Gauge?

I'm fighting a fairly new OEM radiator cap problem right now and found that it was not letting coolant back in at cool down which is attributed to a questionable third seal going bad or compromised. Also - in my case, the draw tube in the reservoir got disconnected and was allowing the reservoir to pull in air (before cap intermittent failure) which caused an air pocket.

Fairly easy to test the fan clutch with a newspaper or other stought paper tube (xmas wrapping paper, etc.). Do you get roar at startup? If yes - then let it warm up. The fan clutch should start seeing some real resistance at around 185F-193F. Mine is nearly impossible to stop. If you can stop it, bad clutch and time for a new one, especially if it's not OEM (search the threads on recommendations, everyone has one).

You can check the FSM and test the thermostat accordingly.
 
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Lots of threads on heating issues… but that didn’t stop me from starting a new one either when I was having problems.;)


Like robertaleon suggested, checking the fan is an easy place to start, fixing a week clutch pretty much solved my problems. A close inspection of the radiator cap and seat is another easy one and a problematic cap seems to fit your symptoms. I have read threads about heating problems related to plugged radiators. How many miles on your cruiser, and how does it look inside with the cap off? Like you mentioned, the t-stat could also be the culprit. Worse case scenario is a blown head gasket. I think that is why robert is suggesting you look in your overflow for residue. Milkshake looking engine oil is also an obvious sign of a bad HG.
 
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When my HG blew, I had similar simptoms, but my AC did stop working when overheating.

I did get resedue in the coolant reservoir bottle, it looked like old rusty dirt. Could have been from the PO's lack of maintanace. But never got any milky oil mix, but I did notice that after a few minutes of running I did have a some water condensation in the top/inside of the oil refill cap.

Looking at the coolant level left in you radiator would be a good idea. I went through half a radiator worth of coolant everytime it overheated and the reservoir would be empty and the boiling sound would come from the radiator. Here's were you differ, you had the reservoir full, so there might be hope still. :)

I hope is not your HG, do go through the steps mentioned above to check your Fan clutch, radiator clog or thermostat, if these all check out, you might be in for a HG job.
 
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94SRUNNER

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PIG PUNISHER...when was the last time you did any coolant system maintenance? Do you know the maintenance history?

It sounds like it might be time. At the very least do a complete flush and fill of the coolant system. Like others have mentioned the fan clutch might be an issue as could be the thermostat, or radiator.

A little more troubleshooting seems to be in order.
 
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Not to hijack this thread but :rolleyes:.... I'm having similar problems w/my 95. HG done about 60,000 miles ago, new blue fan clutch, losing coolent somewhere (new red :mad:), new hoses, new PHH (x3), new heater hoses, radiator looks clean!, just changed very old plugs and they were all consistently worn but clean, but it still gets over 210 degrees on hot days here in Phoenix, according to my scangauge (best thing ever) and will easily go to 225 especially when hill climbing. I'm thinking it's time for a new radiator.
Apologies for hijacking. :D Ned
 
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Jan 18, 2011
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Coolant looks good and clean, rad is fairly new but aftermarket, oil looks good and no residue in overflow tank. Truck has 154*** on the clock. Gonna replace tstat fan clutch and rad cap to see what happens. Thanks guys.
 
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Replaced the fan clutch with a blue hub, replaced tstat, and rad cap with toyota parts from acc, while I was in there, i did a good tune up, plugs wires, cap, rotor, ect. All with parts from acc, Will is a good man. Plugs looked okay, a little white crust, but they all looked the same.
I drove the truck a little, ran the a/c the whole time and everything seems okay. I think it may have been just the cap.
 

chap79

Wheel. Break. Fix. Repeat.
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When I replaced my thermostat, before I set the new one in I bench tested both of them. The old one wasn't opening nearly as much as the new one. Decreased my average running temp by 10 degrees, stays around 185 according the ultra-gauge... In any case, I'm glad to hear the truck is running cooler now. Thanks for following back up.
 

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