1968 M35a2 over heating

[coreyphillips123]

Hello what's up guys my name is Corey, every time I'm on here you guys offer amazing help. My problem is that I'm getting over heating 3/4 of the way up. I've made sure my belts are tight. I did a radiator flush. As well as to make sure i have a "50 /50" mix of green coolant . My water pump is good to my knowledge. I use straight 30 weight oil. I do run WMO , roughly 30-40% and diesel #2 to thin it out. I make frequent trips (30 miles or so) and I run on the hot side. I tow a 16 ft flatbed with a toyota on it twice a week. I have the 395s on the truck , which I know affects gear ratios (more engine load). Roughly 2200-2400 rpms in 5th gear, And down to 4th when i need to....... I'm a youngster to you guys. (30)
Looking for some old dudes to give me some tips. Don't worry I can take the criticism. Is my waste oil playing a part in this? Or is this a typical thing with the good ol' deuce? I won't get mad. Give me the yelling.

 

[18operator]

Have you checked and or replaced the thermostat? In doing the radiator flush, did you also flush out the engine block? Do you have a fan clutch on the cooling fan? If so, is the clutch in working order? What is the engine temp after making the 30 mile trip?

 

[Karl kostman]

The gauges on these trucks can be pretty inaccurate at times, remember how old things are. I would invest in a electronic thermometer where you just point the red laser at what you want to know the temp and pull the trigger and you get a digital readout they will work good for you to verify the actual temp of your engine and also good for checking hub temps on your truck also. Based on what you said first get the actual temp with the gun and if in fact its running warm then I would pull the thermostat and test that in a pan of hot water and see at what temp its opening or if its opening at all. There is a good chance this will cure your "maybe" problem.

 

[gimpyrobb]

First thought would be to verify coolant temp. If you are in fact running hot, I'd look for a radiator place that can rod the core. That means the tubes might be clogged and they will run a rod through to clear any stopped up tubes.

 

[rustystud]

I would just add this. Don't thin out your "waste oil" with Diesel fuel. Use "Gasoline" instead. You want the end product to be the viscosity of "Diesel" fuel. What you have now is just a very thick Diesel fuel.

 

[silverstate55]

The gauges on these trucks can be pretty inaccurate at times, remember how old things are. I would invest in a electronic thermometer where you just point the red laser at what you want to know the temp and pull the trigger and you get a digital readout they will work good for you to verify the actual temp of your engine and also good for checking hub temps on your truck also. Based on what you said first get the actual temp with the gun and if in fact its running warm then I would pull the thermostat and test that in a pan of hot water and see at what temp its opening or if its opening at all. There is a good chance this will cure your "maybe" problem.

Harbor Freight carries one that is relatively inexpensive and works good…I use it quite a bit.

 

[silverstate55]

Hello what's up guys my name is Corey, every time I'm on here you guys offer amazing help. My problem is that I'm getting over heating 3/4 of the way up. I've made sure my belts are tight. I did a radiator flush. As well as to make sure i have a "50 /50" mix of green coolant . My water pump is good to my knowledge. I use straight 30 weight oil. I do run WMO , roughly 30-40% and diesel #2 to thin it out. I make frequent trips (30 miles or so) and I run on the hot side. I tow a 16 ft flatbed with a toyota on it twice a week. I have the 395s on the truck , which I know affects gear ratios (more engine load). Roughly 2200-2400 rpms in 5th gear, And down to 4th when i need to....... I'm a youngster to you guys. (30)
Looking for some old dudes to give me some tips. Don't worry I can take the criticism. Is my waste oil playing a part in this? Or is this a typical thing with the good ol' deuce? I won't get mad. Give me the yelling.

Don’t think any yelling is called for here; nice to hear of a younger member with such an involvement with a Deuce, especially working one like they were made for.

What did you flush your radiator with? Just water? Might try it again with a 50/50 mixture of distilled water & white vinegar….run it til engine is warm, then let it sit for a few hours to see what breaks loose. Then thoroughly flush the radiator & block to remove all traces of the vinegar. It’s worked for me in the past, but sometimes too well as once it cleaned the crud out of the radiator, a leak was exposed that led to me removing the radiator for repairing anyway….

 

[18operator]

Harbor Freight carries one that is relatively inexpensive and works good…I use it quite a bit.

Yes, it works well, I've had mine for a couple of years.

 

[ToddJK]

I think everybody had a good idea as what to check and what to do. As Rusty said, you want to use gas to thin your wmo. Add a little bit of diesel, which helps it blend in, but mostly gas.

I would replace the thermostat or at least another one anyways, they do go bad after a while and it's nice to have one on hand, kinda like having extra belts.

Get the temp gun from HF or local shop and verify actual temps, you can hit the engine block, radiator, hoses, basically everywhere and you'll have a good idea how hot it is.

If you did a flush, was it a radiator flush or engine block flush or both? You can use vinegar or buy radiator flush cleaners off the shelf, but make sure you thoroughly flush your system after using any additives as to not cause future issues.

Another anomaly I've seen with vehicles and it can vary from deuce to deuce, but have you tried a higher or lower concentrate of antifreeze? I've always had to add more water in all my Mopar vehicles as they run hotter with just 50/50 antifreeze, ford's we're the opposite. I don't know why but it was just that way.

Another question, is there blowby from the slobber tube? Does it leak or lose coolant over time? If so, may be an early sign of head gasket failure, if no blowby and no coolant loss, than disregard.

Lastly, have you physically checked the front of your radiator? If there is a lot of debris such as mud, bugs, dust, stuck into the radiator, this makes the heat transfer less efficient and cause things to run warmer. It doesn't take much to start affecting this cycle as I have found out just from some mud getting stuck on the lower half of the radiator,cause my engine to run 15-20 degrees hotter than normal.