Diagnosing high temperature issue (1 Viewer)

[Gretsch]

I have found when I do anything with the cooling system on mine requiring draining the coolant, it takes forever for the bubbles to get out of the system. I literally have spent hours sitting there burping the system over and over again. After the burping along with several weeks of daily driving she finally settles in to 'normal' temps, which for me is usually just below middle on the stock gauge. I can burp the system, appear to have all the bubbles out, drive her a few days and wait for it to go through the same hot cycles you are experiencing, then burp again and see all sorts of bubbles as if I had never burped it to begin with. After this and refilling the coolant a couple of times, she finally settles in.

One thing I did last time this happened was pressure test the system. Found several decent sized leaks which could contribute to hot temps. I don't recall what cooling system work the OP did but maybe checking the system is holding pressure would be warranted here? I think the boiling point of the coolant changes if the system does not hold pressure properly. I know you were after just getting the coolant flow figured out with this thread but I thought I would mention my experience with troubleshooting cooling system things anyway. I know lots of folks bag on the inaccurate readings of the cooling system gauges here. I am not sure about accuracy of them in terms of actual temp readings, but I can tell you that mine is fairly consistent which allows me to at least generally trust what it shows me.

Somewhere deep on my list of things to get to is fixing my temp gauge that only reads slightly past low after running a while.

When I first got my truck my gauge read this way too. These will read that way if the top thermostat gasket is not in place on the thermostat inside the housing. I replaced my T-stat last winter and sure enough no gasket was there. Replaced it and now the gauge reads correctly. Dunno if that's your issue but thought I would mention it.

 

[g-man]

I think I'm in the same boat as the OP. Temps rising toward the red line after getting off the interstate. Even had some coolant push out of the overfill bottle. I'm guessing my radiator is shot. It has the greenish white stains running down the coils. My coolant is new, my radiator cap is new and holding pressure. No leaks. Water pump is working. But now after the overheating my temp gauge is reading low around 1/4 and is taking longer to warm up. I think that when it overheated the coolant steamed and pushed the t-stat seal out of position. So now I have to wait til I can afford a radiator before I replace the the thermostat, seal, and gasket.

 

[FJ Noob]

I have found when I do anything with the cooling system on mine requiring draining the coolant, it takes forever for the bubbles to get out of the system.

Thanks for the experience input. After the first long session or so I would have gotten pretty frustrated....sounds like I need to be prepared for multiple sessions.

I ended up flushing the radiator last night because I've been wanting to do it anyway, it just got bumped up in priority. I've got the front PS elevated higher than everything else and rigged a tall funnel with tape to fit the radiator filler hole. I put some coolant in the funnel and ran the truck with heaters on to get to temp and make sure the t-stat opened. I didn't get any bubbles voluntarily come out on their own. The only bubbles I got was when I squeeze the upper radiator hose. Even then it's not a ton of air. As the coolant heated and expanded, it just started to fill the funnel more....I'm assuming because normally the cap would keep it pressurized. All that to say...am I missing something or doing something wrong?

For the first 1K miles I was driving the truck, the gauge read higher than what I considered normal, but like you said was consistent. I haven't technically overheated in the sense of boil over, but moved past the previous reading and basically peg out at the top white hash mark. From what I've seen, that's still technically within operating temp but too narrow of a margin or me.

I'm going to keep messing with it, but I think I'll be taking some of my Christmas time off and stealing @HemiAlex 's idea for the digital temp gauge install.

 

[FJ Noob]

Just to hopefully close this one out...

I think I might be ok with my high temp issue. I finished flushing the radiator last night and refilled with coolant. I got off work early so I came home and burped the air out today. I didn't really get much air out, but I'll keep trying over the weekend just in case. After burping it we ran down the street to pick up a Christmas tree. It was reading hotter than I would have liked, but not pegged out like before. We came home to put the tree up and I screwed around for a bit, then decided to go fill the gas tank. The engine was cool again and the gas station isn't far enough away to really warm it up so I jumped out on the highway and ran it hard (65-70ish) for 20 min or so with no heat on in the cab. It stayed just a bit below half. Not surprising because of all the cooler forced air. I got off in town and did a few minutes of stop lights and normal street traffic like where I seeing the needle start shooting up the gauge. Nothing happened...it moved up to maybe just a hair past the half-way point. Drove back home and even sat in the garage idling for a few minutes and no real change. I'll see what happens tomorrow, but I hope this is it solved.

Thinking about it while I was driving, the only thing that changed from driving it after the burping was filling the gas tank. I'm wondering now if my issues really do have something to do with the temp gauge/fuel gauge relationship that's been mentioned previously? I put that lower on the list of probable causes and things to do because I haven't seen any of the other fuel gauge spiking symptoms described by others.

 

[John McVicker]

Until you get either a different gauge or different sending that will allow you to trust your gauge reading, I would be using your IR gun as your bible. If the IR gun shows that you are within safe perimeters, then you are good...simple as that.

As you said tho, you will want to get some sort of accurate working gauge. What @HemiAlex did is a great option.

Another thought: consider going to an auto parts store and getting a real, purpose made, ‘burping‘ gizmo. Before I bought one I tried the funnel and duct tape...I was never able to do as good of a burping job with it. It really made a big difference. ‘The right tool for the right job’.

 

[FJ Noob]

Another thought: consider going to an auto parts store and getting a real, purpose made, ‘burping‘ gizmo. Before I bought one I tried the funnel and duct tape...I was never able to do as good of a burping job with it. It really made a big difference. ‘The right tool for the right job’.

I've hit all the stores here in town and have yet to find a purpose built "funnel". I tried looking for the Lisle one that comes up in the MUD threads and that doesn't come up either. I guess Amazon to the rescue...

 

[John McVicker]

Yep. Amazon for sure.

 

[Gretsch]

consider going to an auto parts store and getting a real, purpose made, ‘burping‘ gizmo.

I tried looking for the Lisle one that comes up in the MUD threads and that doesn't come up either.

The thing with the Lisle is because its sort of opaque, it makes like a little window at the base where you can see bubbles coming up into the funnel. If looking down into the funnel while not squeezing the hose, I never really see bubbles just coming up on their own. I sit by the driver side of the truck with engine up to temp and idling and squeeze on the upper radiator hose pretty hard repeatedly. You can see it sort of force coolant up into the funnel (sometimes splashing over). The Lisle is tall enough where you can usually keep the splashing down to a minimum. The squeezing is just to help the bubbles get moving and out. The Lisle just makes it super easy to see the bubbles, and thus easy to tell when you got them all. You can also tell when the coolant level drops in the funnel to be able to tell when air is being replaced by coolant. I know folks do the funnel with tape trick, but to me the Lisle kit is one of those tools that is just the only way to get the job done. So silly and relatively expensive IMO, but worth every penny. I got mine local at O-Reily's.

https://www.oreillyauto.com/detail/b/lisle-4148/tools---equipment-16488/oil---lube-tools-16607/funnels-17328/9227a0a2bf37/lisle-clear-plastic-funnel/24970/5763327?q=lisle&pos=46&manufacturer=true

Looks like its a ship to store thing now so Amazon would prolly be just as easy. They used to carry it in store when I got mine years ago.

I would agree here you would want to just make sure the engine bits are where they need to be temp wise with the gun since you have it. I just have found the stocker gauge to just be consistent enough for me as to allow me to trust what its saying. When mine creeps up, I trust its actually something going on and not an incorrect reading. But it doesn't let you know the actual temp. An aftermarket gauge (the @HemiAlex solution is great) or using the gun to confirm is still warranted.

I replaced my radiator several months ago. I had the same issue as you with the truck heating up after coming off the highway. Seemed generally to happen when coming to any sort of stop after speed (traffic, highway off ramp stop light, etc.)After several burp sessions, pressure test to find/fix leaks, and adding coolant to the overflow, everything seems to have worked itself out. Seems these trucks struggle to evacuate air out of the cooling system with engine running at idle. Almost need to run them at higher RPM to really get the coolant flowing and the bubbles moving out. HTH.

 

[ff347]

Amazon product ASIN B07CNJ4JSQ
Get the temp monkey off your back! Get the mechanical gauge of your choice and be done worrying.

 

[4runner2FJ60]

I've hit all the stores here in town and have yet to find a purpose built "funnel". I tried looking for the Lisle one that comes up in the MUD threads and that doesn't come up either. I guess Amazon to the rescue...

I just got one 2 days ago from my local Napa in stock.

 

[HemiAlex]

I fought all these issues. I never believed the factory gauge until I installed the Koso gauge.

Took 10 mins to install and put my mind at ease.

Builds - The 60 known as Mamabear: a tale of rust and good times.

Your list resembles mine....every night is another check box. Keep it up!

forum.ih8mud.com

My only regret is putting the temp sender in that cylinder head line. I need to move it to the upper coolant hose. I’ll use this 38mm kit from them.

Koso BG038B01 Water Hose Adapter (38 mm Sensor Not Included), Pack Amazon product ASIN B01ISPDQ4K

 

[aviafx]

I’ll throw my suggestion into the ring, I’ve used this funnel kit from EPauto on both a CSF and Champion radiator in my 60 as well as an OEM XJ radiator. Not super expensive and well worth it.

 

[OSS]

Usual suspects:

1. If pulling off the freeway, the engine starts getting hotter & hotter while idling at a stop light - that's a air flow and RPM issue. Fan clutch likely is faulty and idle RPMs should be kept higher while waiting to keep coolant flowing faster. Keep revs up near 1000. The engine isn't actually getting hotter as the needle climbs higher & higher while waiting at a stop light, it's the coolant that's getting hotter. The engine is actually cooling down (the second you took your foot off the gas).
2. If after replacing coolant the gauge reads higher than normal - that's "normal" annoying behavior from the 2F. Happens every time. Burping helps, but the engine will evennnnnntualy purge out all the air after a few weeks. In my experience, it usually took about 2 weeks of daily driving until the gauge returned to normal.
3. When the coolant truly overheats and begins to boil, the thermostat often can be permanently damaged. The failure fortunately is always a stuck open thermostat, so subsequent drives after an overheat will often show the engine running too cool. So it's best to replace the thermostat after a coolant boil (true overheat).

 

[Gretsch]

In my experience, it usually took about 2 weeks of daily driving until the gauge returned to normal.

This has been exactly my experience as well.

 

[FJ Noob]

Well, I'm back to this annoying issue. I installed an OEM 190* t-stat. I burped, burped, and burped the system until it seemed like it wouldn't take anymore coolant. I kept to driving it fairly close to the house in case I needed to limp back home. The gauge was showing hotter than I preferred (about 1/4 inch from red), but I was being patient as many of you suggested.

This morning I ran it into work but had to go back to the house for something (only about 25 min and 12-14 miles round trip; 2/3 hwy 1/3 street traffic). Outside temp was 33* and it took a while for the gauge to come up on the hwy. While doing about 60mph, the cool forced air kept the gauge just over half. On the street, after a few minutes it got back to its new "normal" at the 1/4 inch from red. I've been patient because it's been stopping at the same spot on the gauge.

When I got home and back in the garage, it started overflowing coolant a min or so after I shut it down. Total overflow was about a cup and a half of coolant before it stopped. I gave it a min or two and started it back up to shoot it with the IR gun.

Temp in front of the upper rad hose was 206*. Temp on the block was 216* at couple points (not sure if that might be off because of heat being soaked up after shutdown). Even with a 206* temp on front of the upper hose, the hose didn't feel the least bit pressurized. It was warm, but not hot enough to make me want to let go any time soon.

I've got no signs of an exterior coolant leak. I replaced the rad cap with an OEM cap. I used a block test kit and came up negative on any emissions gas in the coolant. No burning coolant smell at the exhaust. No signs of water in the oil. Previously, the coolant in the reservoir would return right back to the exact same level after cooling down. The fan will not free spin if I spin it by hand. The water pump isn't leaking out the weep hole. The belt seems to be tight enough to run the WP without slipping. I adjusted my idle RPM up a little as suggested by @OSS .

I'm at a loss at this point. Could it have been an air bubble working its way out? That doesn't explain the rad hose to me though. Unless somebody else has some ideas, I'm ready to just replace the whole rad, WP, and fan clutch. Not sure what to do if that doesn't help...I'll probably lose my mind and my kids will learn a few new words!

 

[OSS]

The cooling system is losing pressure somehow.
Also, it's pretty much impossible for a normal 2F to overheat when driving in 30° ambient air temperature. Something is definitely out of whack.

An unpressurized cooling system will keep the engine at the proper temp while driving in normal circumstances but once the engine is shut off and allowed to sit for a bit, the latent heat from the engine will continue heating up the coolant (heat soak) and will boil unless its pressurized. I'm very familiar with it because I ran my cruiser with an unpressurized cooling system for quite a while.
Boiling at engine shutdown is easy to prevent (if the system is unpressurized) just by idling at about 1000 RPMs for about a minute after stopping and before turning off the engine to allow stuff to cool down.

When you checked the upper radiator hose for pressure after the boil over- it was too late. Once the coolant starts boiling, air is getting generated inside the head and the system loses pressure.

I'd definitely replace the radiator. It's the obvious thing left to do.
There was a thread in the 40's section I read of a guy who had endless overheating problems and had replaced everything (except the water pump). Out of desperation and a last ditch effort, he decided to replace the water pump and discovered that it was almost completely clogged up with a jellified clay muck- coolant could barely flow through it. After he replaced the pump - all was well.

So although that might not be the problem in your engine's case ... it's something to consider.

Also if at any time in the engine's history, Orange Dexcool coolant was added to the cooling system, it's pretty much guaranteed that the small cooling holes in the head gasket are now gummed up and restricting coolant flow.

 

[FJ Noob]

@OSS Makes sense. Forgot to mention I also ran a heavy duty flush through the system before installing the t-stat. Hopefully that helped any clogs that might have been in there. Is there a way I can check flow through the block easily? Pull t-stat, disconnect upper & lower hoses, flush water through and look at output?

I’m just going to go ahead and replace all 3 major parts. I have a fan clutch, WP, and new hoses on hand. I’ll just pick up a radiator.

Thanks

 

[Spike Strip]

And new OE or OEM 13 lb cap. Aftermarket OEM are around and half the price of Toyota.

 

[FJ Noob]

And new OE or OEM 13 lb cap. Aftermarket OEM are around and half the price of Toyota.

OEM from FJ Parts...not listed as aftermarket like the other item they have available. PN 16401-54750

 

[Spike Strip]

If you get a new radiator, it takes a small cap, not a large one like the stock radiator. I don't remember if the 1-1/8" is the correct size or not, but sounds like it. Verify.

FJparts sells quality parts, but on the other end of the Country from you.