3F-E running hot after 2500 mile road trip, seeking advice

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So I drove from so-cal to WA state and back and everything seemed fine the whole time.

The next day or two I drove around for about an hour and parked and noticed the coolant in the expansion tank was boiling. At no point did the stock gauge deviate from the middle. Next thing I did was try to make sure air wasn't in the system and put in a different radiator cap. I let my girlfriend drive it for a while and she said it boiled a little bit once but otherwise behaved normally. Next I installed an inline coolant temperature sensor in the top radiator hose. I also replaced the clutch fan with a new AISIN unit. Today I drove to the store and the temperature on the new gauge reached about 220 and stabilized there. To me that seems too high since it's not even hot outside right now (~60f).

Backstory the rest of the cooling system had been replaced a year or two ago, it has an aluminum radiator with an OEM thermostat and all of the hoses replaced. I guess it's possible the new gauge is reading wrong, and I haven't driven it for long enough or in hot enough weather to see if it boils again.

The only thing I can think of that could have caused the issue was that I've put some of the radiator stop leak tablets in the system. The radiator had a pinhole leak at one point (possibly a mfg defect) and I've put a tablet in a few times to try to stop the leak (which it did). Now I'm wondering if it's blocked a passage in the block or in the radiator somehow. This may have been stupid in retrospect lol. I'm not really sure if there's a way to pinpoint whether or not that's the issue. They are the barr's tablets and they supposedly won't clog things up...

I'm considering throwing the radiator in the trash and putting in a new one, but I'm interested in hearing advice before I try it.
 

NeilC

 
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The coolant in the overflow probably wasnt "boiling". It was probably combustion gases working there way out of the radiator. This is usually a sign of a blown head gasket. Dont ask me how I know...
 
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The coolant in the overflow probably wasnt "boiling". It was probably combustion gases working there way out of the radiator. This is usually a sign of a blown head gasket. Dont ask me how I know...
I've considered this but I'm not sure if this is the case, wouldn't it be doing it all the time then? Also my temperature is clearly too high, would the blown head gasket CAUSE the temperature to increase? I'm not sure. I'm not saying you're wrong...
 
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I guess I should have asked how much coolant is actually in the radiator first?
Full or nearly full, with the level in the expansion tank on the cool line more or less. When it was boiling the coolant was past the hot line and nearly about to come out of the tank though.

I guess maybe I need to do a leak down test?
 
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Another thing I'm wondering about. It doesn't have the OEM overflow tank. The one I have is sitting lower than the OEM one did and has more volume, however, again, until the day I boiled, it didn't seem to be an issue and again the stock temp gauge never went above middle even when it boiled.
 

ceylonfj40nut

Waiting for Barn Time
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Get an oil sample analyzed. It will tell you whether you have a headgasket issue.
 

-Spike-

 
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You added crap to your rad and now it doesn't work. First step is get the crap out, in this case I'd say replace the rad.
 
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The coolant in the overflow probably wasnt "boiling". It was probably combustion gases working there way out of the radiator. This is usually a sign of a blown head gasket. Dont ask me how I know...
Considering it is a 3fe I doubt he has a blown head gasket. I would replace the thermostat and o ring with oem and flush the radiator and see if that helps. Also check your fuel trim to make sure your air fuel mixture hasn't become too lean.
 

AverageTanner

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I had a similar issue with my 1FZ last year - it would only rise above the half way point on the gauge on drives of 45+ minutes. My 20 minute commute to work was just fine and it never went passed half way on the gauge. I was paranoid about my head gasket but decided to try replacing every part of my cooling system anyways. The last thing I tried, the radiator, is what ended up being the fixing item. I have not had any issues since.

If you want to know if combustion gasses mixing with your coolant, buy the test kit:

Amazon product
 
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Thanks for all the replies. I’m going to just replace the radiator since it had a pinhole leak anyway and I had been planning on either welding it or replacing it anyway. I’m going to also do a thorough flush of the block and see how that goes. I kinda don’t think the head gasket is blown but if the radiator and flush doesn’t fix everything then I’ll begin exploring that issue. The thermostat and o ring it has are both aisin but I’ll replace those anyway while I’m flushing the system and changing the radiator.

I’ll also double check the timing and try to make sure it’s not running lean, as well as doing another valve adjustment.
 
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new aftermarket gauge installed at the location you described is correct, do you have a picture to show us where the gauge is tapped on the upper hose? 220F is during driving or at stop and go traffic? There is a difference in how you read the readings....the stock gauge is a dummy gauge and it sits in the middle between 155F - 230F. @ about 235F or so, the stock gauge will creep to about 3/4 and you at the point, you rig is overheating and should already have coolant boiling over the overflow. which aftermarket radiator did the PO run? FYI, i have gone thru the entire cooling system and troubleshoot mine over the course of 2 yrs and 220F is definitely on the verge of overheating.... I can run my rig up steep grade say the Grapewine with AC on full blast and full load @ 4k rpm for the entire duration of the climb and my temp barely go over 195F.....187-190F on highway.
 
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new aftermarket gauge installed at the location you described is correct, do you have a picture to show us where the gauge is tapped on the upper hose? 220F is during driving or at stop and go traffic? There is a difference in how you read the readings....the stock gauge is a dummy gauge and it sits in the middle between 155F - 230F. @ about 235F or so, the stock gauge will creep to about 3/4 and you at the point, you rig is overheating and should already have coolant boiling over the overflow. which aftermarket radiator did the PO run? FYI, i have gone thru the entire cooling system and troubleshoot mine over the course of 2 yrs and 220F is definitely on the verge of overheating.... I can run my rig up steep grade say the Grapewine with AC on full blast and full load @ 4k rpm for the entire duration of the climb and my temp barely go over 195F.....187-190F on highway.
I have a huge aluminum (60mm) radiator for a diesel land cruiser, I think it's just clogged. My stock gauge never left the middle so it probably approached 230 and boiled because it lost pressure somehow from the cap or expansion tank being vented to atmosphere, or at least that's my guess now.

The aftermarket gauge is about in the middle of the upper hose.

I have a new radiator here so we'll see.

 
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I have a huge aluminum (60mm) radiator for a diesel land cruiser, I think it's just clogged. My stock gauge never left the middle so it probably approached 230 and boiled because it lost pressure somehow from the cap or expansion tank being vented to atmosphere, or at least that's my guess now.

The aftermarket gauge is about in the middle of the upper hose.

I have a new radiator here so we'll see.

This radiator do not have a build in tranny cooler for the 3FE., probably for a 5 sp. I thought about bypassing the tranny cooler, but decided against it...
 
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