radiator not hot to touch

[drjconley]

I put in new head gaskets on the multifuel in my m62a2, and when I drive it the temp gauge will go to the upper portion of hot. I pulled the thermostat hopeing that was the problem. With the thermostat the radiator wasn't hot at all, without the thermostat the radiator is warm to the touch, but it is definately not hot. That was after driving it 15 miles pulling a trailer with a tractor on it. When I pull the radiator cap off I dont see any obvious coolant flow even with the thermostat out. Should I order a water pump or should I get a hand held infrared thermometer and get some temps off of different areas of the engine.
Thanks for any help,
Jim Conley

 

[armytruck63]

I'm not super familiar with these 5-tons, but are the radiator hoses extra squishy? Many vehicles have a spring inside the lower suction radiator hose to prevent collapse at higher RPM's. I have heard of this happening on gasser 5-tons. The water pumps on 5-tons can produce plenty of flow, so perhaps your spring has corroded away and the hose is collapsing.

Just a thought...

 

[Jake0147]

This is a multi fuel, right? Make sure the lower hose is not full of sediment and restricting coolant flow. Also, with the thermostat removed there is nothing to block the bypass circuit, so if there's any restriction to flow through the radiator the coolant will take the easiest path back to the water pump inlet, which will not be through the radiator.

 

[998Junkie]

If I read your post right, it sounds like the thermostat is bad.

Thermostat in = Cold radiator (no flow)
Thermostat out = Warm radiator (continuous circulation)

That is where my knowledge stops…I don’t know how a 5 ton thermostat looks but there must be a spring?

If so drop the unit in a pot and bring it to boiling…I would think you should see some movement around the seal as it should open.

 

[drjconley]

998, yes I would state that the thermostat was bad. It is just that I would assume I would see some sort of movement of coolant with the themostat out and the radiator cap off. Also, should I trust my temp gauge? When it says it is getting hot I haven't had any coolant excape from the radiator cap. If I could get my hands on a temp gun what kind of temps would I expect to get off of the block?
Jim

 

[998Junkie]

998, yes I would state that the thermostat was bad. It is just that I would assume I would see some sort of movement of coolant with the themostat out and the radiator cap off. Also, should I trust my temp gauge? When it says it is getting hot I haven't had any coolant excape from the radiator cap. If I could get my hands on a temp gun what kind of temps would I expect to get off of the block?
Jim

I don't know the layout of the engine but a service manual (probably in the resource library) should tell you a few things. I'm guessing the temperature sensor is attached to the engine block and not the radiator, I would think 180-190 would be a good operating temp.

I don't know how much movement of coolant you would see moving. The flow would be top to bottom? I would think the engine vibration would make it hard to see any movement. You could try an oven mitt or by hand when cold and try to obstruct the flow going to the radiator, which might let you see or feel some movement within the hose?

Of course I'm sometimes a contestant in the Darwin awards...

 

[drjconley]

I too have been in the running for the Darwin awards, I have the scars to prove it.
Thanks for your help.
jim