Radiator cap blew off/coolant loss

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Some background: 96 fzj80 that’s been staying cool during 90-95 degree weather. There was one time a couple months ago where I noticed my temp gauge rose to the 3/4th mark, when I was going up a steep hill with the ac on in the heat. Never happened after that.

Just now I started a 7 hour road trip and about an hour in, noticed some coolant running up my hood. As im pulling over, that small stream turns into coolant spraying everywhere, and then eventually a lot of steam. After the steam/smoke went away I noticed my radiator cap had come off and was sitting in my engine bay.

The entire time this was happening before I shut it off, the temp gauge was still in the center. There is coolant and what appears to be sediment all over and underneath the 80. Which leads me to believe it might be due to a clogged radiator?

Any insight is appreciated!
 
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Don't know if I can help with specifics, but on the factory temp gauge, if you didn’t already know, unfortunately it stays dead center until you are already starting to overheat. Something like 160-230F?

Sounds like some related combo of overheating and over-pressurizing?

Time to inspect and/or replace radiator, thermostat, water pump, radiator cap, fan clutch, etc

Good luck to you, and regardless of what the issue & fix is, highly recommend getting a scangauge or equivalent to monitor actual temps.
 
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i think it’s smart to do a full cooling system overhaul. I’m at 200k miles and think everything is original. I didn’t know the temp gauge works like that, good to know for sure!
 
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If it’s all original, I’m not surprised this happened, unfortunate as it is. All new parts as listed above, including hoses, heater control valve, etc. Check rear heater lines too - they can be a crusty time bomb. Bypass or fix them. You can service the fan & check water pump & replace as needed, but I’d just replace the rest, including the tricky hoses. Given the high heat, probably a good idea to do a few tests too.. head gasket (combustion gas in coolant), compression, leak down, etc

There’s an electrical mod for the gauge that makes it more active/accurate, but it’s really nice having something like a scangauge. Before I had one, I used a cheap OBD2 wifi adapter for my phone, which I’d run a few times a month just to make sure things were normal. With all that real-time info at your disposal, it’s easy to become obsessive, but I’d rather that than not know something is wrong.
 
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LandLocked93

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Time to sell.
Give you $3k for it.
 

Devils Paw 80

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Some background: 96 fzj80 that’s been staying cool during 90-95 degree weather. There was one time a couple months ago where I noticed my temp gauge rose to the 3/4th mark, when I was going up a steep hill with the ac on in the heat. Never happened after that...
So, gauge went to 3/4 without incident, or so it seemed. Did you check your coolant levels in radiator and overflow tank after this trip?

Low coolant level or bad radiator cap would be the best case scenarios. Maybe refill with coolant and run it up to temp at home to see what happens.
 
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1st step: drain it, flush and fill with DI water. Replace thermostat and radiator cap. Check belt tensions.

Doing this should give you a bit of time while you prepare for step #2: Gather up all the other new cooling system parts and get the system overhauled.

Another member was kind of enough to post this master list with every cooling system oem part #.

Post in thread 'What Did You Do with Your 80 This Weekend?' What Did You Do with Your 80 This Weekend? - https://forum.ih8mud.com/threads/what-did-you-do-with-your-80-this-weekend.586191/post-14534508
 
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Just a sidenote; radiator caps don't just pop off. Either it wasn't twisted into proper engagement and it blew out, or the radiator cap is damaged, or the radiator neck fitting is damaged. If any of these are the case, I wouldn't trust that radiator cap ever again; just order a new OEM cap (*or two), and start again.

Your description of coolant running up the hood sounds like the radiator cap neck may have cracked from age, allowing a spray to go toward the front, but there's a rubber dam there to control airflow. It would take a LOT of coolant spray to make it out the front. There are a TON of overheating threads here on Mud if you do some reading. Several of us have had old or original radiators explode at the top tank, which sounds and feels like piston trying to pop through the hood.

Take a close look at your radiator. If the plastic top tank has a brownish tinge to it, it's time for replacement. If the radiator has that coloring, check your heater distribution valve at the firewall, too.
 
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So, gauge went to 3/4 without incident, or so it seemed. Did you check your coolant levels in radiator and overflow tank after this trip?

Low coolant level or bad radiator cap would be the best case scenarios. Maybe refill with coolant and run it up to temp at home to see what happens.
Coolant was still full, and the overflow was empty after that incident.

Just a sidenote; radiator caps don't just pop off. Either it wasn't twisted into proper engagement and it blew out, or the radiator cap is damaged, or the radiator neck fitting is damaged. If any of these are the case, I wouldn't trust that radiator cap ever again; just order a new OEM cap (*or two), and start again.

Your description of coolant running up the hood sounds like the radiator cap neck may have cracked from age, allowing a spray to go toward the front, but there's a rubber dam there to control airflow. It would take a LOT of coolant spray to make it out the front. There are a TON of overheating threads here on Mud if you do some reading. Several of us have had old or original radiators explode at the top tank, which sounds and feels like piston trying to pop through the hood.

Take a close look at your radiator. If the plastic top tank has a brownish tinge to it, it's time for replacement. If the radiator has that coloring, check your heater distribution valve at the firewall, too.

Before this latest incident I did a pre-trip check and double checked the radiator cap was on, so I'm leaning towards it being damaged. I'm in the process of saving up/ordering a new rad, water pump, t-stat, and hoses. Will keep everyone updated, I appreciate all the help!
 

lumbee1

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I love my Scangauge.

Previously when my fan hub was going bad there was no indications on the dash gauge there was an issue. Scangauge gives me real time temperature of the water and helped identify the bad hub. New blue hub sits at 182* driving and 207* in extreme circumstances.
 

ToyotaMatt

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Some background: 96 fzj80 that’s been staying cool during 90-95 degree weather. There was one time a couple months ago where I noticed my temp gauge rose to the 3/4th mark, when I was going up a steep hill with the ac on in the heat. Never happened after that.

Just now I started a 7 hour road trip and about an hour in, noticed some coolant running up my hood. As im pulling over, that small stream turns into coolant spraying everywhere, and then eventually a lot of steam. After the steam/smoke went away I noticed my radiator cap had come off and was sitting in my engine bay.

The entire time this was happening before I shut it off, the temp gauge was still in the center. There is coolant and what appears to be sediment all over and underneath the 80. Which leads me to believe it might be due to a clogged radiator?

Any insight is appreciated!


perhaps simply installing a correct genuine NipponDenso made in Japan SAUDI. Spec. high heat disipoation non usa cap like this may correct you issue ,


especially if a original cap or a aftermarket cap too ?






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