Rampant speculation about 2H cooling issues... (1 Viewer)

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Joined
Aug 23, 2013
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Location
Germany and Namibia
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www.domvonstoeser.de
OK so I'm about 8500km north of my Uri (Namibian-built 2H / H55F / 4.11 full floaters etc.), which has been taken by a friend to a mechanic whom i trust to address an electrical gremlin (which turned out to be the alternator) and a mysterious overheating problem.

I reiterate, I am nowhere near this truck right now, so I turn to you, listers / ih8mud'ers, for speculation.

The mechanic told my friend that the radiator had been hooked up wrong, and that it had somehow been bypassed.

I have no idea how to hook up a radiator wrong, so my guess is that there's some kind of bypass circuit which never let coolant through the radiator? Assume standard Cruiser engine, standard Cruiser radiator.

Additional guesses welcome!
 
The 2H rad has one inlet and one outlet, there is no way to hook it up wrong.
Maybe the mechanic was talking about the thermostat. If that is in wrong or does not open, you never get good flow through the radiator. But even there, I am not sure if it is even possible to fit it upside down.
J
 
The 2H rad has one inlet and one outlet, there is no way to hook it up wrong.
Maybe the mechanic was talking about the thermostat. If that is in wrong or does not open, you never get good flow through the radiator. But even there, I am not sure if it is even possible to fit it upside down.
J

That's what I thought. I do see that there is some sort of bypass hose. I can speculate that this has been hooked up in some weird way, but I don't have close-up photographs to be sure.
 
That is the bypass hose for the thermostat from the water pump, I think. It is of pretty small diameter.
Best, Good Luck,
Jan
 
Do you know that it is actually overheating or are you just going off the gauge? I'd check that first if it hasn't been done already.

Also a heater tap that doesn't seal closed creates a loop in the cooling system that can cause over heating.

Goodluck.
 
Also a heater tap that doesn't seal closed creates a loop in the cooling system that can cause over heating.

There is no heater installed in this vehicle at all. Perhaps there is some weird plumbing there... I'll do some more research there. The engine came out of an HJ60, if that's any help.

Toyota's temp. gauges leave a lot to be desired and can often read high if the gauge has a grounding issue.

The temp gauge is aftermarket (VDO), but I don't know about the feeler...
 
Out of interest: in which factory manual is the heating system's plumbing actually described? I don't see it in the 2H's manual, nor in the applicable body manual (which I'm guessing would be the 1984 Chassis and Body manual for heavy duty Land Cruisers).
 
The engine manual should cover the cooling system (pages 228-240 in nov 1985 print of 2h, 12h-t engine repair manual)
 
The engine manual should cover the cooling system (pages 228-240 in nov 1985 print of 2h, 12h-t engine repair manual)

Yes, I found that. But I found nothing to cover how engine waste heat is transferred to the cabin heater of a stock Land Cruiser. And since the vehicle I'm dealing with is only sort of like a stock Land Cruiser, and there are not even the vestiges of a heating system for the cabin, I'm at a loss.
 
What are the symptoms of this mysterious overheating problem? Does it get hot idling in traffic or when you reach hwy speeds. Or does it just start getting hot from the moment the engine starts and gets worse.
These types of situations can often be pointers as to what the problem is.
Most overheating is from blocked cores,radiator caps that no longer hold pressure,leaking hoses,worn out fan clutches /or a combo of all those things.
Of course there are cracked heads and blown head gaskets also.
There is also over fuelling from incorrectly set fuel pumps.

Eliminating these things can help us give you ideas.


Im assuming this a very basic model that was never fitted with heating/aircon?
 
What are the symptoms of this mysterious overheating problem? Does it get hot idling in traffic or when you reach hwy speeds. Or does it just start getting hot from the moment the engine starts and gets worse.
These types of situations can often be pointers as to what the problem is.
Most overheating is from blocked cores,radiator caps that no longer hold pressure,leaking hoses,worn out fan clutches /or a combo of all those things.
Of course there are cracked heads and blown head gaskets also.
There is also over fuelling from incorrectly set fuel pumps.

Eliminating these things can help us give you ideas.


Im assuming this a very basic model that was never fitted with heating/aircon?

The vehicle is an Uri – a Namibian-built off road utility vehicle. Engine and drivetrain, along with other mechanical bits and pieces, derive from an assortment of Cruisers, in this case mostly an HJ60. Ergo no heating, air con, nothing.

There is no EDIC; it's been replaced with a sort of pushrod in the cabin: pull for enriched fuel to start, push to shut off engine. It's bulletproof, but fuelling is not very precisely adjustable. There's definitely room for improvement there.

Symptoms are basically that the vehicle gets very hot under load and at high ambient temperatures. For example climbing a mountain pass during the summer will result in stops every couple hundred metres. The same drive after dark (= usually much colder in the desert): no worries. Weirdly, opening the bonnet a crack doesn't make much difference, so I'm wondering what impact ambient temperatures under the bonnet can even have.

The rad has been re-cored, and a shroud added. The fan clutch has been replaced with a fixed fan. Anything between the front of the truck and the radiator has been cut off to allow better airflow to the radiator. I've moved the air intake to a sort of proto-snorkel on the outside of the vehicle with a big honking cyclonic air cleaner poking out the side of the truck. There are also two electric fans to force air through the rad at lower speeds.

I should add that the smoke is not white or blue, so I don't see much water or oil being burned. Likewise both the coolant and the oil don't appear cross-contaminated.

The cooling system has now been flushed and pressure-tested, and (again, I'm 8500km north of this vehicle right now, hence the speculation) any leaks have been seen to. The mechanic did find that there was something wrong with the plumbing; in his approximate words: "The radiator was connected wrong, it could never have worked correctly, hot coolant never went through the radiator itself." I have no idea what he could mean by that, so I thought I'd ask what peoples' theories might be.

Cheers -

d
 
Yes, I found that. But I found nothing to cover how engine waste heat is transferred to the cabin heater of a stock Land Cruiser. And since the vehicle I'm dealing with is only sort of like a stock Land Cruiser, and there are not even the vestiges of a heating system for the cabin, I'm at a loss.

Some of that is covered under body electrical in the body manual, under heater section..
 
Some of that is covered under body electrical in the body manual, under heater section..

Featured word: some.

How does the coolant get to the heater core? Can someone point me to a photograph of the plumbing? To my shame I never paid attention to a part of my 79 that just always sort of worked, and simply isn't present on the Uri...
 
I can take a picture of my hj61 insides if you want, you can see the plumbing for heater core fairly easily under the hood...
 
My thermostat stuck closed and I ended up blowing the Bypass hose. This bugger is hard to put on when mad, covered in coolant, and its getting dark.

I too could post up pics if needed. GOod luck!
 
Out of interest: in which factory manual is the heating system's plumbing actually described? I don't see it in the 2H's manual, nor in the applicable body manual (which I'm guessing would be the 1984 Chassis and Body manual for heavy duty Land Cruisers).

Featured word: some.

How does the coolant get to the heater core? Can someone point me to a photograph of the plumbing? To my shame I never paid attention to a part of my 79 that just always sort of worked, and simply isn't present on the Uri...

I did a bit of research/study with my BJ40 and here's what I came up with... (I'd expect the 2H to be similar):

CoolantFlow.JPG
Thermostat1.jpg

thermostat2.jpg

ThermostatClosed.jpg

ThermostHot.jpg


:beer:
 
The vehicle is an Uri – a Namibian-built off road utility vehicle. Engine and drivetrain, along with other mechanical bits and pieces, derive from an assortment of Cruisers, in this case mostly an HJ60. Ergo no heating, air con, nothing.

There is no EDIC; it's been replaced with a sort of pushrod in the cabin: pull for enriched fuel to start, push to shut off engine. It's bulletproof, but fuelling is not very precisely adjustable. There's definitely room for improvement there.

Symptoms are basically that the vehicle gets very hot under load and at high ambient temperatures. For example climbing a mountain pass during the summer will result in stops every couple hundred metres. The same drive after dark (= usually much colder in the desert): no worries. Weirdly, opening the bonnet a crack doesn't make much difference, so I'm wondering what impact ambient temperatures under the bonnet can even have.

The rad has been re-cored, and a shroud added. The fan clutch has been replaced with a fixed fan. Anything between the front of the truck and the radiator has been cut off to allow better airflow to the radiator. I've moved the air intake to a sort of proto-snorkel on the outside of the vehicle with a big honking cyclonic air cleaner poking out the side of the truck. There are also two electric fans to force air through the rad at lower speeds.

I should add that the smoke is not white or blue, so I don't see much water or oil being burned. Likewise both the coolant and the oil don't appear cross-contaminated.

The cooling system has now been flushed and pressure-tested, and (again, I'm 8500km north of this vehicle right now, hence the speculation) any leaks have been seen to. The mechanic did find that there was something wrong with the plumbing; in his approximate words: "The radiator was connected wrong, it could never have worked correctly, hot coolant never went through the radiator itself." I have no idea what he could mean by that, so I thought I'd ask what peoples' theories might be.

Cheers -

d

Thanks for the detailed reply. Do you know if the coolant system is building pressure? This is why I asked about the radiator cap.For me ,when I have a coolant problem I replace the cap as a starting point so I know its working. If they can maintain pressure ,the boiling temperature is raised which in turn keeps them cooler.
I guess you cant give us a pic of how the coolant system is rigged up now but I dont see how it anyone could get it wrong.
Maybe the gauge ir sensor is wrong
 
Here's some pics (not the best ones i'm afraid)...

Piping for heater core and rear heater
2014-05-13%2006.35.35.jpg


Radiator piping
2014-05-13%2006.35.47.jpg
 
Thanks for all the great details, everyone. Much appreciated.

I won't be near the truck until late June, so it's all still rather speculative. I can only imagine that whoever hooked up the engine sort of kludged a loop for the non-existent heater or something.
 

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