Head Gasket? (1 Viewer)

[Perioman]

Hey folks! I have an issue with some overheating I think - yet I can't figure out if it's the head gasket or not.

Facts: Truck runs a but rough on startup for a minute, some moisture out the tailpipe (a few drips really is all) but there is a lot of condensation here - everything is wet in the morning. Truck runs great - no smoke, no oil contamination, no coolant loss - I think (still measuring) I might be - but it may simply be the air purging after replacing all the cooling system components and getting so much air. When I got it, Temp gauge would go highest about 1/4. Usually 1/2 is where it sits from history with a different FJ60, so I knew something was off. Truck has been desmogged.

Since then : replaced: New Toyota thermostat (wrong thermostat and no gasket was in there) New Aisin Fan clutch (it was bad), flushed coolant, new coolant, air bubbles out, new sending gauge (From China though), new Radiator hoses, new Toyota radiator cap.

So... after all that, the gauge sits at 3/4 now and close (3mm from the end of the white when hot) but laser still reads OK. Laser temp gauge reads 190-200 at the thermostat housing and I can read it opening - goes from 80 (ambient air temp on warmup to 210 - then back down to 190) with lower temps in the radiator and block. No radiator hot spots - pretty even all over. Both radiator hoses - send and return hot when warmed up.

I've got a factory temp sender gauge on order but the chinese one came from a reputable cruiser place that has sold hundreds apparently without issue. I'm thinking the needle position may be the new normal - never had a desmogged truck.

I took a 2 hour ride in the heat Saturday and I'm pretty sure I lost about an inch of coolant level in the expansion tank (I had it overfilled a bit to let it get sucked back in overnight so it could have boiled off)

Thoughts?

 

[gregnash]

Water pump may be going out. If you had a HG issue you would probably know it and see other signs like smoking, coolant loss, oil loss, etc.
I had a similar issue at the beginning of the year. Check my build thread, WP was going out slowly so the temps would climb to just under the red line, couple mills like you say, but never actually get into the red. Definitely sounds like time for a new WP.

 

[roadstr6]

What is the condition of the radiator? Check real close for pinhole leaks. Also, the thermostat takes two gaskets, an upper and lower. Make sure you got both. Check the lines to the rear heater as well. They tend to get pinholes too. I would consider putting the OE temp sender back in if it didn't get destroyed during removal...or replace with a Toyota sender. If it all checks out, drive it a while and keep a close eye on the expansion tank. The system does take a while to purge all the air. Mine took several weeks of adding an inch or so to the bottle before it quit dropping. It seems fine now.

 

[Perioman]

What is the condition of the radiator? Check real close for pinhole leaks. Also, the thermostat takes two gaskets, an upper and lower. Make sure you got both. Check the lines to the rear heater as well. They tend to get pinholes too. I would consider putting the OE temp sender back in if it didn't get destroyed during removal...or replace with a Toyota sender. If it all checks out, drive it a while and keep a close eye on the expansion tank. The system does take a while to purge all the air. Mine took several weeks of adding an inch or so to the bottle before it quit dropping. It seems fine now.

The radiator seems new. Its clean at least. 128k miles on truck. Im going to check for exhaust gas in the coolant tomorrow.

Could be water pump agreed. It took a few heat up cool down cycles for the pressure to build in the top radiator hose. I dont see any coolant leaks though anywhere.

I did notice the gauge will stay a bit lower if i start and drive right away, but if i let it warm up, then drive, the gauge sits higher. Once the guage establishes itself it seems to stay put. Never gone past the white.

 

[gregnash]

Yup my gut tells me WP! Go with OEM from @beno (Onur) and do it right the first time.

 

[Jesper]

I think with regards to mysterious maladies that commonly drive a normal person crazy, running a little hot is second only to a carb running a little rough...so many potential reasons why. Especially on a truck that's been modified, desmogged, etc.

If I'm understanding you correctly, your IR temp gun is confirming proper operation of the thermostat and showing normal temps, but the dash gauge is reading higher than normal. The prudent thing to do, as gregnash and roadstr6 mentioned, may be to replace the water pump and any other legacy cooling components - just because. They are all relatively cheap, especially for the peace of mind you get in return. I know you have an OEM sender on the way, the other piece of that puzzle is the actual dash gauge itself. I don't know that they were ever designed for accuracy per se, and 30 years of dirt, heat, cold and moisture certainly won't help. I've chased similar ghosts with mine. I pulled the radiator and had it cleaned out and tested, replaced the water pump, thermostat, all hoses, fan clutch and temp sender as well. The only thing I haven't replaced is the original dash gauge. It occasionally reads a touch high. I keep an IR temp scanner in my console and have pulled over countless times to check it and find all temps normal. I installed an aftermarket water temp gauge to cross check. I no longer obsess over it the way I used to.

 

[Perioman]

Thank you for the feedback. I just ordered a new WP - Toyot

I think with regards to mysterious maladies that commonly drive a normal person crazy, running a little hot is second only to a carb running a little rough...so many potential reasons why. Especially on a truck that's been modified, desmogged, etc.

If I'm understanding you correctly, your IR temp gun is confirming proper operation of the thermostat and showing normal temps, but the dash gauge is reading higher than normal. The prudent thing to do, as gregnash and roadstr6 mentioned, may be to replace the water pump and any other legacy cooling components - just because. They are all relatively cheap, especially for the peace of mind you get in return. I know you have an OEM sender on the way, the other piece of that puzzle is the actual dash gauge itself. I don't know that they were ever designed for accuracy per se, and 30 years of dirt, heat, cold and moisture certainly won't help. I've chased similar ghosts with mine. I pulled the radiator and had it cleaned out and tested, replaced the water pump, thermostat, all hoses, fan clutch and temp sender as well. The only thing I haven't replaced is the original dash gauge. It occasionally reads a touch high. I keep an IR temp scanner in my console and have pulled over countless times to check it and find all temps normal. I installed an aftermarket water temp gauge to cross check. I no longer obsess over it the way I used to.

Jesper,
Yes you are correct. The gun is showing proper temps - interestingly though, yesterday, I detected spiking temps at the temp sending sensor when I put the laser gauge directly ON the sensor - 220 to 240 degrees, while normal everywhere else - normal near the sensor on the block, normal at the thermostat housing, normal in the radiator coils - actually quite cool there. Then when I checked it again after checking everywhere else and going inside to check the gauge. this is yesterday after driving to Lowe's and back - about 30 minutes - air temp 75. this is a bit lower than it's been hovering.

I understand the obsessing - that's why I like it here lol.

 

[Perioman]

I did turn down the fuel regulator that was installed after the desmogging a couple of clicks. do you think that can affect temp? Seems like it would with too much fuel.

 

[roadstr6]

Fuel cools the combustion process. Leaner is generally hotter. That said, I doubt if that is your issue. Keep troubleshooting your cooling system and don't worry about fuel.

 

[gregnash]

Yup that is almost exactly where mine was, drove it like that for close to a month due to the fact that it never really got into the red. Final straw for diagnosis was the Exhaust Gas test in the coolant coming back positive.

 

[Perioman]

Well this is good news. This is the 2nd test. Tested once, ran it a few minutes, tested again. A shop guy told me to let it sit overnight so i will.

Looking like water pump and/or sensor.

 

[Spike Strip]

Maybe put a real gauge in before ripping other stuff apart.

Mechanical Water Temp Gauge Install Write-Up

 

[gregnash]

Maybe put a real gauge in before ripping other stuff apart.

Mechanical Water Temp Gauge Install Write-Up

Definitely agree with @Spike Strip.... Wish I had done mine when I had everything apart but something to add down the road.
Here is what mine looked like when I tested...
Untitled by Greg Fisicaro, on Flickr

 

[Spike Strip]

FWIW, many of the "High Temp" issues can be the result of the wonky gauge, if you can't find other obvious issues.


Temp Sending Unit?

 

[Perioman]

FWIW, many of the "High Temp" issues can be the result of the wonky gauge, if you can't find other obvious issues.


Temp Sending Unit?

Thanks!! None of the photos are up in the thread though. there is a red x over a generic picture icon for all of them. Can it be fixed? I want to do a mechanical gauge for sure.

 

[Spike Strip]

Those pix in the first few posts aren't really very pertinent now, they were just of the Autometer he used and the adapters. I think I listed them elsewhere. But you really should put a mechanical gauge in as it's pretty easy and way more accurate. The thread also shows a fix for the crappy "VR" that makes the temp gauge inaccurate. FWIW, some local Land Cruiser specialists near me "fix" it by putting a 15 ohm resistor in the line to the stock temp sensor.

This pic was from a FJ60 I bought and the PO had it done. Really high-quality installation.

 

[Perioman]

So - after being told by the local repair guy that I definitely have a blown head gasket....NOT. No more riding anxious.

Thanks everyone - since I have a desmogged truck - I used the lower thermostat housing port - and the adapter that came with the gauge fit. It's actually screwed in there quite a few turns even though some threads stick out.

Actually - just after it hits 200 the thermostat opens and the needle drops like a rock to 180 or so.