Stovebolt.com Forums The Shop Area The Engine Shop 261 Operating Temperature

Also if you are running straight coolant try 50/50 water mix and see if that makes a difference. Best of luck

I have used a surfactant called "Water Wetter" on my rig. It is supposed to improve heat transfer from the metal to the coolant and vise versa. It helped some, maybe 10deg.

Also, I have run across situations where the crank pulley was slipping on the rubber it was supposed to be bonded to. So the water pump/fan did not turn as fast as expected. This problem took me much too long to figure out.

I have run Chevrolet 235s for many years and 200+ water doesn't seem to bother them. Running continuously above 2800RPM does heat the oil to 250 and up. I don't think that's good. Do you have an oil temperature gauge? On a 261 with an external oil filter you could install an oil cooler if you find high oil temperature.

Thanks for the replies, folks.

Coolant is 50/50, currently, or real close.

I have heard of the Water Wetter, but have not tried it, yet.

We are not monitoring oil temperature. We do not have oil filtration on this engine.

Take Care,

Joshua L. Coder

I’m currently running a 261 in Texas (100 degree days already). I have an aluminum radiator, 7 lbs radiator cap, pusher fan, 160 degree thermostat, and 848 heads (with steam holes). Have not had an issue getting above 190 degrees yet.

Do you have the correct steam holes in your head or have a gasket blocking a hole?

Just a thought. You’ve gotten pretty good advice in this thread!

Chris

Chris,

Thank you for your post. I have only just recently become aware of the steam holes 'issue'. I have not the first idea if the holes are present and/or a gasket may be blocking said holes.

If other remedies do not resolve the high operating temperature (high by my estimation) we may have to pull the head and have a look. That is not something I have ever done but suspect we could figure it out.

Take Care,

Joshua L. Coder

"Steam hole" is a misnomer. The holes in the head are there to provide coolant flow alongside the three pairs of cylinders that are "siamesed" together without a gap between them to allow for the big pistons. An 848 casting number head can be drilled to work with the 261 engine by using the 261 head gasket as a drilling template. The small block 400 V8 used the same system to avoid hot spots when the cylinders were siamese-cast to allow for a 4 1/8" bore size on that engine.
Jerry

fix261 Did you drill the steam holes in that 235 head ?? Also the 261 gasket with those holes in it??

I used waterwetter in my race bikes which were only rode when warm out and kept inside. Although it’s good for heat (racing), I’m not sure if I’d use it in the great white north. It changes the freezing temp of your radiator fluid mixture which will cause issues next fall when the tundra freezes.

SKOL!

Chris

The only reason we ran water wetter in the race engines at Nashville was a $500.00 fine by the track management for getting caught with antifreeze in the engines. Even a tiny coolant leak while running antifreeze left the track as slippery as snot!
Jerry

Jerry,

Is that Midwest snot in January or Texas snot in august?

That’s why I used it as well!

Chris