Another overheating thread

[mindcrash]

I apologize as I know this has been covered ad-nauseum, but posting here is my last resort before taking it to a shop. I've consumed every overheating thread I can find and none of the solutions have helped. I'm still running too hot when climbing or when driving for extended time when it's hot outside. When driving from Denver to Ft. Collins she would get up to 220 on the highway, turn off the AC, and cool back down to 216 and the AC would turn back on, and the cycle would repeat. When climbing from Denver on I70 she was at 230 when I pulled off the highway at the Lookout Mountain exit (this is basically the first exit in the mountains, still in the foothills really).

I've owned this 1997 FZJ80 since January. 196k currently on the odometer. Since my ownership I've had the engine completely resealed (including head gasket), had a new radiator installed, new water pump, new thermostat, new hoses, new drive belts - all are OEM. I've installed a modified blue hub fan clutch from Landtank, foam gasket around the fan shroud, flushed the system until the water ran clear 2x, and made sure she was burped after refilling with 50/50 Toyota Red. Belts appear to be tensioned correctly by feel but I have no way to verify for certain (they give about 1/4" when I tug on them). I have an ARB front bumper and winch installed, but nothing is mounted in front of the grille to restrict airflow. 3" lift on 33's running stock gearing.

I'm planning on checking the timing tomorrow, but assuming that was done correctly at the shop, what else can I do here? I don't think an upgraded radiator should be necessary and am trying to avoid that.

Any tips would be greatly appreciated. We have a trip planned to go wheel in Palo Duro Canyon in 3 weeks and want to make sure she'll make it there and back.

 

[lumbee1]

Which fan hub do you have?
Does the fan spin easily by hand with engine off?
Does the fan pull a huge rush of air at startup?
Is there foam around the radiator?
Which coolant, red or green?
What does the coolant look like?
Did the overheating start after the headgasket?
Has the system been burped?

 

[jonheld]

With the radiator, water pump, thermostat, hoses and fan setup already addressed, I’d verify the things that can still make a healthy 3FE run hot before buying a bigger radiator.

He's got a 97 FZJ80.

 

[mindcrash]

Which fan hub do you have?
Does the fan spin easily by hand with engine off?
Does the fan pull a huge rush of air at startup?
Is there foam around the radiator?
Which coolant, red or green?
What does the coolant look like?
Did the overheating start after the headgasket?
Has the system been burped?

OEM Blue Hub modified by Landtank
It spins by hand but does not spin freely - as in when I remove my hand it stops spinning.
Yes, there's a whoosh.
I installed foam around the sides and bottom of the fan shroud.
Red coolant, brand new.
Unknown - I bought it in January, drove it from Tulsa to Denver with no issues regarding the temperature (but no scanguage for that drive). I took it for the headgasket and other work within 2 weeks of bringing it home. The original headgasket was leaking.
Yes, the system has been burped.

 

[lumbee1]

OEM Blue Hub modified by Landtank
It spins by hand but does not spin freely - as in when I remove my hand it stops spinning.
Yes, there's a whoosh.
I installed foam around the sides and bottom of the fan shroud.
Red coolant, brand new.
Unknown - I bought it in January, drove it from Tulsa to Denver with no issues regarding the temperature (but no scanguage for that drive). I took it for the headgasket and other work within 2 weeks of bringing it home. The original headgasket was leaking.
Yes, the system has been burped.

If you continue spinning the fan, does it ever get easy? Somehow my OE fan hub modified with 15K lost some of its fluid. It provided resistance to spinning but if I continued, the fan would all of a sudden free spin.

 

[landtank]

Remove the front O2 sensor and go for a drive. The exhaust will be loud but if it says cool temperature wise it could be a clogged CAT

 

[Marvelicious]

Remove the front O2 sensor and go for a drive. The exhaust will be loud but if it says cool temperature wise it could be a clogged CAT

I'd never heard of that one, but it makes perfect sense. Good trick.

 

[mindcrash]

If you continue spinning the fan, does it ever get easy? Somehow my OE fan hub modified with 15K lost some of its fluid. It provided resistance to spinning but if I continued, the fan would all of a sudden free spin.

No, I tried and it kept having the same amount of resistance.

 

[mindcrash]

Remove the front O2 sensor and go for a drive. The exhaust will be loud but if it says cool temperature wise it could be a clogged CAT

Will try that in the next few days and report back.

 

[Gascan]

Sounds like your engine and its cooling components are in good shape at this point but the overheating during prolonged high RPM still happens, I second that this is a partially clogged cat (likely the forward cat). I had an overheating issue that shares some parallels to your... the cat was the culprit.

 

[thedoughboy]

You might want to bump your fan oil up to 30K. I forget what Landtank's are modified too, but that was the magic number for my rig. I tried everything, then did this, and it's been good for ~15 years.

 

[Kernal]

Tstat properly installed?

Rare that a new OEM Tstat would be defective but you can test it by placing it into a pan of water on a stove with a meat thermometer to check the water temps, watch to see if it opens fully as the water heats up (should open ~10+mm @ 95C/203F)

New OEM Tstat on left, Old OEM Tstat on right. Note the gap is wider on the new Tstat @ ~203'F

The old Tstat in the photo did open but not as much and not as quickly as the new one

 

[mindcrash]

Remove the front O2 sensor and go for a drive. The exhaust will be loud but if it says cool temperature wise it could be a clogged CAT

Tried and failed tonight. I pulled the sensor and did the same test drive and still got up to 222. This was also in the evening and it was only 60 degrees out so I’m going to say the cats are fine (the forward is brand new).

 

[mindcrash]

You might want to bump your fan oil up to 30K. I forget what Landtank's are modified too, but that was the magic number for my rig. I tried everything, then did this, and it's been good for ~15 years.

I was hoping to avoid this but will give it a shot. The 30k oil should be here tomorrow.

 

[mindcrash]

Tstat properly installed?

Rare that a new OEM Tstat would be defective but you can test it by placing it into a pan of water on a stove with a meat thermometer to check the water temps, watch to see if it opens fully as the water heats up (should open ~10+mm @ 95C/203F)

New OEM Tstat on left, Old OEM Tstat on right. Note the gap is wider on the new Tstat @ ~203'F

The old Tstat in the photo did open but not as much and not as quickly as the new one

View attachment 4214039

I’ll pull it and check!

 

[Mark W]

You mention much more precise temperature numbers than the OEM gauge can provide. How are you determining these numbers? You do not mention any aftermarket gauge (Or I just missed it) but you do mention (seemingly) reading the temp while you are moving down the road, not just after you stop and pop the hood.

Mark...

 

[mindcrash]

You mention much more precise temperature numbers than the OEM gauge can provide. How are you determining these numbers? You do not mention any aftermarket gauge (Or I just missed it) but you do mention (seemingly) reading the temp while you are moving down the road, not just after you stop and pop the hood.

Mark...

I have a scanguage 2 installed on the steering column, sorry if that wasn’t clear.

 

[Mark W]

I have a scanguage 2 installed on the steering column, sorry if that wasn’t clear.

I assumed it might have been something like that, which is why I verified before heading off down a rabbit hole. I think we can trust those numbers and. Which rules out a couple of easy answers.

Mark...

 

[Kernal]

@mindcrash : You could leave the Tstat out and go for a drive to check where the temps go ie: the engine should run too cool (less than ~190F) without the Tstat.

IMO/IME there's any question about the Tstat (function) might as well replace it.

 

[mindcrash]

Update: So I did the 30k oil in the Landtank modified fan clutch and sure enough I still hit 220 on my test drive in the mountains. I'm surprised because it's definitely much harder to spin now by hand. I'm wondering if I added too much or too little oil. I was shooting for 50ml but wasn't able to put in that amount as the clutch was full. I probably got 40ml in (pure guesstimate).

Also, when I got home I put a thermometer on the metal pipe that connects to the upper radiator hose on a whim. It read 166, whereas the Scangauge indicated 191 at that time. I thought the reading would be closer, even considering it's a cheap digital meat thermometer. Is there a better place to check this? Could this be an indication the water temp sensor is bad? I suspect it's the original sensor.