FZJ80 Overheating Again (1 Viewer)

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Von Hayek

Von Hayek

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Well, Rhea's truck just likes to run hot.

Had this happen last year https://forum.ih8mud.com/va-dc-md-capital-land-cruiser-club/436182-big-problems-florida.html, so I know my radiator is good. Yesterday it started overheating like a mother when driving. Haven't tried while idling. So I'm guessing thermostat (which I did not replace last year) or water pump.

Interesting side note is that when I ran the heater to try and cool it off a little bit, it was not remotely warm. So either there was no coolant left to heat up the core or there was no circulation. I'm getting very tired of coolant.
 
Von Hayek said:
Well, Rhea's truck just likes to run hot.

Had this happen last year https://forum.ih8mud.com/va-dc-md-capital-land-cruiser-club/436182-big-problems-florida.html, so I know my radiator is good. Yesterday it started overheating like a mother when driving. Haven't tried while idling. So I'm guessing thermostat (which I did not replace last year) or water pump.

Interesting side note is that when I ran the heater to try and cool it off a little bit, it was not remotely warm. So either there was no coolant left to heat up the core or there was no circulation. I'm getting very tired of coolant.
Click to expand...

Just sell it to me, its not worth the hassle.
 
Bart, you can always check the tstat by tossing it in a pan of boiling water to see at what temp it opens or that it even opens at all. My understanding of the toyota tstats is that when they fail, they fail in the closed position.

If you haven't had the radiator checked for flow, you may want to drop it off at a rad repair shop to check, if there's flow impediment, they may choose to use muriatic acid to clean it. There have been a number of threads on how to do this yourself, I know that Mark Whatley had posted some.

Waterpump: if you're seeing fluid at the weep hole, it's a good bet that the bearing's gone/going. You also may want to test the fan clutch to see that it's locking properly - check threads for how to.

Only other thing it could be would be blocked passages in the block. Tim Minnner of BBRC rebuilt his head on his '80 a coupla years back and may have some pointers for you. You could also check his thread on the rebuild. HTH
 
OK, replaced the thermostat and that ain't it. The only thing left is the water pump. Don't see any coolant from the weep hole, but see if this makes sense. After I replaced the thermostat and filled the system with coolant, I waited with the radiator cap off for the system to burp itself but the coolant never moved an inch. Isn't that indicative that there is no flow? Shouldn't there be quite noticeable flow visible through the neck of the radiator once the thermostat opens up? Also, there is no heat at all even though the engine is overheating indicating no flow as well. Thoughts?
 
water pump

Did you listen to the water pump ? Bad bearings make noise , i would think you could hear it. Maybe ? maybe not, i know nothing. :hillbilly:
 
Here’s something you can try. It’s a long shot but it’s easy to do and it won’t cost you anything.

You can often fix an air blockage by removing the heat gauge sender to relieve the pressure. Somtimes you can actually hear the air escape.

Good luck
 
TRFCSUX said:
Did you listen to the water pump ? Bad bearings make noise , i would think you could hear it. Maybe ? maybe not, i know nothing. :hillbilly:
Click to expand...

A very long screwdriver or pry bar up against the pump and your ear on the handle will let you hear bearings. Not sure where the water pump is on an 80 or if you can safely get it there but thats how Ive always done it. Good suggestion. I would think you should see water movement. Couple other suggestions, put the front end up on ramps and run it with the cap off. Sometimes the angle helps with air bubbles. Another thing, and we used to do this with MGBs all the time at the shop but it requires equipment, is to pressurize the system by sucking all of the coolant out using shop air and then it literally sucks the new coolant back in not really giving an air bubble a chance to form. Again, might require going to a shop though. New radiator? Was it completely flushed and have you mixed coolants? Ive seen some different types of coolants actually turn to gel and block up rads when they mix. Nasty stuff.
 
jcj_78FJ40 said:
Here’s something you can try. It’s a long shot but it’s easy to do and it won’t cost you anything.

You can often fix an air blockage by removing the heat gauge sender to relieve the pressure. Somtimes you can actually hear the air escape.

Good luck
Click to expand...

I don't know a thing about air blockages, but wouldn't I have eliminated any bubble problems when I drained the system to replace the thermostat?

derelict said:
A very long screwdriver or pry bar up against the pump and your ear on the handle will let you hear bearings. Not sure where the water pump is on an 80 or if you can safely get it there but thats how Ive always done it. Good suggestion. I would think you should see water movement. Couple other suggestions, put the front end up on ramps and run it with the cap off. Sometimes the angle helps with air bubbles. Another thing, and we used to do this with MGBs all the time at the shop but it requires equipment, is to pressurize the system by sucking all of the coolant out using shop air and then it literally sucks the new coolant back in not really giving an air bubble a chance to form. Again, might require going to a shop though. New radiator? Was it completely flushed and have you mixed coolants? Ive seen some different types of coolants actually turn to gel and block up rads when they mix. Nasty stuff.
Click to expand...

System was not flushed, but coolant was not mixed. It had red when I drained it and I replaced it with red. Water pump is very accessible, but I certainly do not hear any noise coming from it now.
 
I’m not familiar with your engine but usually the thermostat is in the front of the engine with a direct feed from the radiator. If there is an air blockage in the block you want to try and relieve the pressure from the rear of the engine.
Try removing and reinstalling the heat gauge sender. I used to have a 91 4.0 J##P and I had to do this every time I messed with the coolant. If nothing else, it will cost you 15 min.
Also, check for bubbles in the coolant reservoir. I believe this is a popular check for a leaky head gasket for that engine.
 
X2 on the air blockage or low coolant but with low coolant the heater will blow warm then cool then warm. In intervals as the coolant circulates. I think you have an air bubble. Witch draining it may have made it worse.

I had to install a T for flushing the coolant with a hose on my heater hose to easily bleed air on a POS bronco 2 I had.

Chris

Sent from my iPhone using IH8MUD
 
what works very well for a system with the thermostat in the lower hose circuit, is pulling the upper hose off the radiator and filling the engine through the hose until full. then reconnect the hose to the radiator and fill like normal.

making sure the truck is level makes a difference as well.
 
Any luck on solving the overheating?
 
Thornton said:
Any luck on solving the overheating?
Click to expand...

Nope. Just went out and drained both the radiator and the block. Flushed it. Filled the radiator and the block through the top radiator hose per Vince's suggestion and it still overheated. I do believe I am looking at blown head gasket #2.

After it cools down, I'm going to yank the water pump just for fun, but it didn't wobble or make a hint of noise when I turned it. I seriously doubt that is the problem now, but I may as well check it before I start ordering head gasket kits, etc.
 
:(. Ugh
 
Cruiser Dan inflicted the coup de grace and diagnosed a blown head gasket. Steve has kindly offered me his garage and I'll probably be jumping on this Sunday after the trail ride.
 
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