FJ62 ran hot, now engine is misbehaving

[TheElegantFox]

Just had my temp sender replaced and the coolant swapped on my 3FE in the FJ62. I was sitting in traffic and noticed the temp gauge going up, I had driven the truck a few times around town without issue. Sitting in gridlock I noticed that the needle was moving into the upper third range of the temp zones and I decided to shut it off an open the hood to cool it all off.

I didn't jettison the coolant and the overflow tank was full.

After I let it cool, it was hard to start the truck, but it eventually turned over and the temp gauge was normal again. However, the truck started to choke under throttle every other attempt. I was able to get it off the highway and I left it again for an hour.

After all that the truck is still hard to start and chokes under throttle. What's super odd is that the idle can sometimes be 1k or even 2k though it goes back and forth from the normal 800 RPM idle.

I'm gonna have the truck towed to the shop so they can give the cooling system a once over to see if they busted anything.


Could this be a head gasket going? Could this be a sign of more serious engine damage or is it a simple coolant related fix like air in the lines?

 

[cruisermatt]

EFI relay

 

[TheElegantFox]

EFI relay

That would be a good place to check. I’ll make sure the shops tests the part.

Is choking under throttle a symptom of EFI failure?

 

[TheElegantFox]

Got it back from the shop and they couldn't reproduce the over heating, told me to keep an eye on it and see if it reproduces. They also mentioned there's a suspicion of the fan clutch getting tired and hot therefore failing to spin the fan at a higher RPM.

Any thoughts? Leaning towards air in the coolant lines that might've been freed after a few cycles.

 

[CRZR45]

Same happened to me.. drained and filled coolant.. started to run hot.. then finally burped itself by driving up something to get the front end higher. Now runs cool. There are threads on proper “burping of air “ from system but above worked for me.

 

[rrv333]

When your temperature gauge went into the upper third did you happen to notice if the fuel gauge was maxing out as well? 62's share the same ground for the temperature and fuel gauges. The grounds get corroded and it causes the gauges to periodically max out. Happened to me when I was new to my 62 and I was driving down the Interstate. Scared the S#%* out of me. There's write ups in Mud explaining how to correct the issue.

 

[TheElegantFox]

When your temperature gauge went into the upper third did you happen to notice if the fuel gauge was maxing out as well? 62's share the same ground for the temperature and fuel gauges. The grounds get corroded and it causes the gauges to max out, periodically. Happened to me when I was new to my 62 and I was driving down the Interstate. Scared the S#%* out of me. There's write ups in Mud explaining how to correct the issue.

The fuel gauge didn't rise in tandem, although that's a helpful bit of info. I could tell the truck was running way hot just from the heat off the transmission tunnel.

 

[Gretsch]

Just had my temp sender replaced and the coolant swapped on my 3FE in the FJ62.

There are threads on proper “burping of air “ from system

Where did the temp get to on the gauge? Mines an '84 but anytime I even look at the cooling system on it, it takes weeks to get the air out no matter how much burping is done. Burp the system again while running the heater. Eventually bubbles will work themselves out without you doing anything but driving it. But get a funnel for the radiator and try burping it again to get ahead of it. Like this:

Amazon product ASIN B00A6AS6LY

When's the last time the fan clutch has been replaced? Did you hear the fan kick in while stuck in traffic? Nothing helped my cooling system like a working fan clutch. HTH

 

[TheElegantFox]

I only let it get to the last tick mark before the end of the top of the gauge before shutting it off. As far as I can tell, the fan was running pretty high, I've also never replaced it under my ownership. The shop said it appeared to be in ok working order, but to see if it stopped working correctly this week.