uneven cylinder head temp

[just me]

Make sure the 1/32 hole has been drilled in the T-STAT. Might solve your issue.

[rickf]

The gauge on the dash is just an indicator, and if it is the original military one it is a pretty inaccurate indicator at that. You may have a gauge that is out of range, a sender that is out of range or something as simple as a bad connection that has just the tiniest bit of resistance and that will change the gauge reading. A colder thermostat may or may not help. If the water flows through the radiator too fast it will not have a chance to transfer the heat to the air before going back into the engine. This is a problem I used to see at the race track all the time. Guys would remove the thermostat thinking the engine would run cold and it immediately overheated because the water did not stay in the radiator long enough to cool off. It sounds counterproductive but most times a hotter thermostat will run as cool or cooler than a cold one. very seldom will the thermostat be the cause of overheating short of a failed thermostat. And even then they are designed to fail open, it is rare that they fail shut. The temps you are seeing with the gun are fine, they are nowhere near red flag territory. And I would guess that when you are buzzing down the road they are a lot more even across the head, you just can't check it then. By the time you get out and check the engine has heat soaked and the back half is hotter.

[RMS]

you say you dont have a heater but do you have a heater hose running from the back of the block to the port on the lower rad hose ?
the heater hose helps move heat from the back of the block.

culprit two could be the water distribution tube. when inserted the tube should fit tight at the front of the block. if big gaps are present at the front of the tube the cool coolant will not make it to the back of the block.

[NAM VET]

I know from years of reading this forum, that many of you are a lot more experienced than I with these vehicles. So for now, I won't mess with anything, as I don't really have sufficient tools here to make any real changes anyway. When I get back home, I will put in a new temp sender, and likely a new gage. Plus see what the flow direction is from the NPT (now plugged) on the back of the head, to some other place in the cooling system, see about running a hose from the rear to some other place in the system where it will increase flow from the rear of the head. And I did peen the new water tube to fit the opening run the block. I have been looking over the TM's and the internet trying to find out what the coolant flow directions are, but no luck, and if any one has such a diagram I would appreciate your posting it here. Appreciate all the thoughts.

hal Copple

[RMS]

the canadian manual has the flow diagram for the 251s

[NAM VET]

Let my truck idle to warm it up, while I put in a nice Cup Holder on the dash. When my cab temp gage settled at around 210 degrees, used my infra red temp gun all over my engine's head and block, and other engine parts. The temps are all over the place, hotter over the side of head, especially near the exhaust valves, but most reassuring my temps all over the rear of the head and block, near the water temp sender, is fine at around 180 degrees, my T Stat's temp. So my sender must be bad, or perhaps the gage. I feel a lot about this, and thanks to all of your opinions and thoughts. I don't know why I got a hotter temp previously.

NV

[ashyers]

Hal,
Didn't take the truck to Costco, but we're participating in a parade tomorrow. I'll put the IR gun in the front seat and check the head temps when we pull of the freeway on the way to the parade. It's a 30 mile run so it will be up to temp.

Andy

[ashyers]

Hal,
My readings are similar to yours. The T-stat housing is ~170F and towards the rear of the head I'm about 20F higher. I'll take an image of it and post it when I get the opportunity.

We've been busy with parade stuff lately. Yesterday I rounded up 9 MV's to transport members of the American Legion post in a local parade. It was fun and we met some great people. We had a nice showing: 3 GPW's, 1 WC53, 1 M37, 1 M151, 1M35, 2 5 ton's. I can't get over the size of the 5 ton's. I was told the wheel and tire assy. is nearly 400lbs!!!!!!! Last time I complain about Budd wheels . Hope you had a good 4th.

Andy