2F ran hot for 1,100 miles--Help deciding what to do next

[KS-Ryan]

Some background info--

83 FJ60 with stock 2F/H42. Engine is not the original, but was an 80k mile, resealed block from an FJ40. This was installed about 7 months ago after the original engine spun a bearing after I bought it. The 60 has 33x9.50-15's and I'm pretty sure it has 4.11's. I pulled a 1/4 ton Bantam military trailer that maybe weighs 1,000 llbs. all in.

Took the 60 on a 2 week family vacation from Kansas City to Glacier National Park in Montana and Yellowstone National Park in Wyoming. On the trip back home, the 60 started to run hot. The temp gauge would sit just below the red mark. It was hot, 95-100 degrees on the drive home, but even driving in the early morning or after the sun when down, it would still run hot. At points, I could only go 30-40 miles between cool downs before it would get hot again. This happened if the a/c was on, off and even if we ran the heater on max.

Things I tried during the drive home--

1. Changed the thermostat. It had a 192º one in it and I put a new 160º one from Napa.
2. Pulled the gasket off the top of the thermostat. I read that can make the engine run cool.
3. Dumped the coolant after the truck ran hot for a whole day and put fresh coolant in.
4. Tried to gently clean all the bugs and junk stuck on the radiator
5. Burped the temp sensor multiple times
6. Drove slower (around 50 mph) sometimes with the heater on

Sometime early on on the trip, it sounded like I developed an exhaust leak. There is a welded spot on the manifold. I don't know if it cracked or what, but the truck sounds like a lawn mower when I get on the gas. Don't know if there's any connection there.

The whole drive home, the engine seemed to be running okay. I added a little bit of coolant to the overflow bottle every couple of days during the 2 weeks. When we would stop to let the engine cool down, I would check the radiator temp with a temp gun. The radiator would be around 210-215. The upper radiator hose would be 175-190. Right before we got home, the engine started to have a slight miss at idle. There was no engine miss when accelerating.

A few weeks before the trip, the engine got hot on a 100 mile drive when it was hot outside and I had the a/c on max. I let it cool down. The next day I did a cooling system flush. The radiator had a bunk of nasty coolant in it. I ordered a new radiator but didn't get it in time to swap it out. I have a new 3 row aluminum radiator from Cruiser Corps and also a new fan clutch to install.

So, now I need to figure a game plan to see what damage, if any, I've done to the engine. I'm looking for some help to start that process. It was suggested to me that I should do a compression test. I suppose I should do a test to see if the head gasket is leaking/blown? I was planning on replacing the water pump while I replace the other cooling system parts. I was also going to order a new temp sensor. Any other suggestions?

 

[John Smith]

I would start with not putting a ton of trust in a 41 year old stock gauge. I will go so far as to say I doubt you did any damage whatsoever, and your truck may not have been running "hot" at all. If your truck was really running hot, you would know it, it would have boiled the radiator or blew the headgasket, or had some other failure due to overheating. I would first install an aftermarket gauge in one of the spare ports on the head so you have an idea of how hot you are actually running. I certainly would not start throwing parts at it other than a temp gauge to start with. Autometer makes a nice cheap 3 gauge mechanical set with water, oil, and volts. I've used in many trucks over the years.

 

[OSS]

As @John Smith so succinctly put it — there’s no way to determine if the engine is actually running too hot by looking at the notoriously unreliable stock temperature gauge.
It’s very possible it wasn’t running too hot at all. Hot? sure. 240°F? Unlikely.

It’s also possible of course that your engine was running too hot, but the odds are higher that it actually wasn’t.

Consuming coolant isn’t a symptom of a too hot running engine. It’s either a symptom of a small external leak somewhere or a little leak somewhere along the headgasket.
As a data point, my 2F engine never consumed coolant. A year could go by with daily driving without me having to add any.

That NAPA 160° thermostat isn’t doing your engine any favors. The original 190° Toyota thermostat with top gasket is a much better choice even on a 120° day climbing a mountain.

Your next plan of action should be:
Install an aftermarket temperature gauge and sender. Autometer has good ones.

Then …. see if the engine actually is running too hot (>235°)

Why do you think there’s 4:11 gears in the differential? The stock gears were 3:73.
3:73 gears + 33” tires + pulling a 1000 lbs trailer = no good.

 

[Skreddy]

Do you burn or leak coolant? Mine had a small leak and I could always tell when it needed more because the gauge would read hot (I’d also hear a rush of water in the dash when I turned the heater to hot). My theory is that the sending unit isn’t submerged in the coolant but instead just steam or splashes, making it read warmer than the coolant temp.

Edit to add I agree with the other posts about the gauge. I use the gauge as a guide something may be wrong. I have an infrared temp gun and even when my gauge is almost to the red and it will take 1/2 gallon of coolant, still temp readings are acceptable: 190-210 depending where I point it.

 

[toy_tek]

Right before we got home, the engine started to have a slight miss at idle.

Agree w everything above. Timing is the other factor not yet mentioned that can affect engine temp (not to mention rough idle).

 

[KS-Ryan]

Why do you think there’s 4:11 gears in the differential? The stock gears were 3:73.
3:73 gears + 33” tires + pulling a 1000 lbs trailer = no good.

Playing with the gearing calculator, I find that the speed I should be running at 2500 is 60 mph with 4.11's and that is what I'm doing (using a GPS speedo). It seems weird that someone would have installed them since it had 31's when I bought it.

 

[KS-Ryan]

Do you burn or leak coolant? Mine had a small leak and I could always tell when it needed more because the gauge would read hot (I’d also hear a rush of water in the dash when I turned the heater to hot). My theory is that the sending unit isn’t submerged in the coolant but instead just steam or splashes, making it read warmer than the coolant temp.

Edit to add I agree with the other posts about the gauge. I use the gauge as a guide something may be wrong. I have an infrared temp gun and even when my gauge is almost to the red and it will take 1/2 gallon of coolant, still temp readings are acceptable: 190-210 depending where I point it.

I don't see any evidence of it using coolant other than that I had to a some to the overflow bottle every few days. The radiator was always at a good level.

 

[KS-Ryan]

Agree w everything above. Timing is the other factor not yet mentioned that can affect engine temp (not to mention rough idle).

I think the timing must be advanced a bit too much. It pings like crazy with 87 octane gas but runs great on 91 octane.

 

[Skreddy]

I don't see any evidence of it using coolant other than that I had to a some to the overflow bottle every few days. The radiator was always at a good level.

Mine using coolant was doing the same thing. I had replaced all of the hoses except the couple going to the heater valve and I could see them wet around the hose ends after driving but no puddles or anything.

 

[KS-Ryan]

Bringing back my old thread for a bit of an update.

I thought I had everything set for this year's vacation with the family. Replaced the radiator with an aluminum one from Cruiser Corps. Did a short 200 mile drive in 90 degree temps with the A/C on full. Everything seemed good. Loaded the family up, hooked up the little trailer and we set out from Kansas City heading to Idaho. Well, fast forward, the Cruiser is in Boise, ID with a cracked head (SN Land Cruisers looked at it for me). I expect this engine is toast. I have to still drive this thing back home and pray it makes it. One of the guys at the shop gave me 50/50 odds on making it.

Am I asking too much of a 2F engine? I'm doing 60-65 on the highway-- the truck is loaded down with camping gear plus our 1/4 ton trailer. These summer trips without A/C are getting old. I don't mind the truck being slow, I just need it to be able to handle these long trips without having cooling issues.

 

[Themcfarland]

A cracked head isnt a thing id put trust in myself , if you must gst home before fixing it id make alternative plans for the family if you get stranded and they can go on without you in a rental van with your belongings and you stay with truck or even perhaps Uhaul and dolly it back

 

[Spike Strip]

I hate the stuff as it can cause other issues, but I'd at least put a bottle of Bar's Leaks or equivalent Head Gasket sealer in before the trip, if your only option is to try and drive home. There are different ones, not sure what is the best as I only recommend in an emergency. I suppose this qualifies as one.

Go as slow as is safe. Keep an eye on the temp gauge. Bring as much extra coolant as you can carry. Stop and let the engine cool if it gets hot. Then replenish the coolant. ... This is going to be a long drive for you.

And check the oil before you go to make sure it's not a milky milkshake color. If it is, change it after you put in the Head Gasket sealer.

Not something I'd personally attempt with a family, but I'm not in your shoes.

Good luck.

 

[Skreddy]

My 60 had a cracked head this winter. I went from adding a quart of coolant every month or so to burning a gallon in the 10 miles home from work.

I would not chance driving it because when it does decide to go full death, you’ll likely be in the middle of nowhere, in the heat, with no cell service or nearby towns.

 

[OSS]

A cracked head is only an issue IF the cooling system is pressurized. And guess what? The 2F can run just fine on the freeway - or anywhere else - in the summer too -- without a pressurized cooling system.
How do I know this? I did it for 5 years

If the cooling system isn't pressurized, coolant won't be forced into a combustion chamber - so you won't burn coolant.
If a cylinder is blowing a little gas into the coolant (another option), that won't hurt anything.

Its easy as pie to run the engine without a pressurized cooling system : just mangle the radiator cap with some vice grips so that the pressure valve doesn't work anymore - then screw the cap back on the radiator.
Coolant will still expand into the expansion tank normally when the engine heats up - and get sucked back into the radiator when the engine cools down - normally.

The only time that running an unpressurized cooling system is an issue is when bombing up a mountain hill in the summer then immediately turning off the engine without letting it cool down at fast idle for a minute or two.
Coolant will boil inside the engine after shutdown if there's no idling to cool down.
Easy to prevent. Let the engine cool down a bit before shutting it down.

Diluting ethylene glycol with 50/50 water, the unpressurized boiling point is 225° F

 

[BurntToast]

U-Haul rental and pull it behind you maybe

 

[KS-Ryan]

My wife and youngest son will be flying home. My oldest son who is 14 wants to come with me.

I do plan to add a head gasket sealer and will buy extra coolant. The engine does not seem to be consuming much coolant but I will be checking it often.

My plan is to avoid the heat of the day and drive in the evening and early morning, so we don’t die in the heat. My fridge will have cold water and food and I can set up my ezup if needed.

I do have someone who can come get us should the worst happen.

 

[mattressking]

Your dummy gauge is likely doing EXACTLY what it should, telling you the engine is running warm. Hot (red area) means at or beyond boiling point and usually it is clear due to steam starting to exit radiator vent or via fluid/exhaust gas leak in coolant system (internal/external). The fact you had a rough idle points to the fact that the engine now has an issue performing efficient combustion.

If heater does NOT initially reduce or modulate temperature (usually the first few minutes you can see a drop), coolant is too warm reduce engine temp after circulating through the rear heater.

Next steps: IR gun when its hot to all points of cooling system to determine temperature like @OSS mentioned, I'd skip the gauge, never saw a need for granular detail on these simple motors., dummy gauge tells you exactly what you need to know. THEN compression check hot and cold leading to combustion check on radiator for exhaust gases hitting coolant.

Skip headgasket sealer, you're adding junk to cooling chambers, you just spent a bunch on a rebuilt motor, don't throw crap into it.

 

[OSS]

I expect this engine is toast.

Absolutely not. A cracked 2F cylinder head can be repaired for not much cost and the engine will be good to go (for another 200,000 miles) afterwards.

 

[KS-Ryan]

There is exhaust gas in the coolant. The test showed that. The shop said it was pretty significant. They did a compression check and numbers were good (I don’t have them with me).

 

[Skreddy]

Just know that head gasket in a can stuff is going to be running through your front and rear heater cores, as well as radiator. Will it clog them shut, probably not, but it’s likely going to reduce their efficiency. As said, a uhaul and trailer or dolly may be a lot cheaper option than all the other parts that could end up toasted by chancing driving it.