The Stovebolt Site Forums The Shop Area Engine Shop What is "TOO HOT"??

I read this board constantly but haven’t had a question for sometime. The 1951 3100 with 1958 235, two 2bbls, Fenton Headers, 3:55 rearend and SM-420 has been storming like a true champion.

I have a question now that it is Summer. I intend to tow a 1957, 17’ Shasta travel trailer with it. The trailer, loaded, weighs approximately 1900 lbs. I need to know what is “overheating”. I have seen “overheat”, “too hot”, “excessive heat” but never a number. Everything is in excellent shape but I’m sure it’ll heat up somewhat when I’m on a hill. At approximately what temperature on the gauge is “too hot” so that I should pull over and let it cool down? I don’t think I’ll ever have to but one never knows.

Thanks for any input and comments.

Thruwurkin

Is this trailer yours or one you will rent? If it is yours why don't you hook it up and take it for a test run? Then if it overheats you can get a fan shroud, and a puller installed before the big adventure.

The trailer is mine and has the entire front off. I'm in a restoration process and it will be a bit before I can pull it.
I have a 16" electric "pusher" fan on the front of the radiator.

Thanks for the comeback

Thruwurkin

I think that it is common to see these motors run at 180 or less. I have a 180 thermostat in mine so it stays there all the time. The old style rads provide a lot of cooling capacity.

I could tell you specifically if the engine was newer, however my guess would be start to get concerned at 200F, and pull over as you get near 210. Straight water boils at 212 at sea level, however a 50/50 mix is 234F. add a few PSI for the pressure cap and the boiling point is higher.

Just to be on the safe side, I would add a fan shroud which will make a world of good by simply making sure the air is being pulled thru the radiator vs 50% of it swirling around the fan.

Scott

Scott's right on the fan shroud. Somewhere I saw figures on what the avg. temp it would bring down. Whatever it was it was remarkable.
I still say hook up and tow around close to home to test it before you get to "Bugbash Idaho" and need help.

With a 50-50 solution of a freeze & a 7 lb. pressure cap running around 200-225 degrees won't hurt. What damages engines is when the coolant gets down below the cyl head.

As long as the coolant stays liquid, and inside the system, you're probably OK to 220 or so. A minimum of a 7-lb. cap should work, and 12 lbs. or more will give an extra safety margin IF you've got a tubular radiator. The old honeycomb design core won't stand that kind of pressure. If you fit a shroud, be sure it stops halfway over the fan blades- - - - -don't totally enclose the blade, or you'll end up moving less air, not more.
Jerry

Thank you all for your input. It is as I expected and makes me feel better to know that. As I said earlier, I have a 16" pusher fan on the front side of the radiator. I don't have an attached mechanical fan (not enough clearance). The old style radiator is new and the engine only has about 5000 miles on it.

Thank you all again and again for easing my mind.

Thruwurkin

most electric fans do not move enough air for towing.

This may be your problem. The best 16" electric fan on the market is sourced to NASCAR and pushes 3200CFM at 0" of restriction. At the typical 1.4" of restriction you find in a radiator core, it is down to 2200 - 2300CFM. The best commercially available fans (Spal or Tri-Pac) flow 2900CFM at 0" and drop to about 2000CFM at 1.4"

If you have a hayden or other 16" fan from your local FLAPS, you are pushing about 1500CFM thru the radiator which is about half of the airflow you need.

Scott

I'm not having an overheating problem. I was just very curious about what the MAX temp is. I don't even use the fan in city driving unless at a LONG traffic light. The temp stays at 180 degrees with the occasional spike.

Thanks again for all the input.

Thruwurkin

I have my doubts about temps of over 200. We used GMC's in the 50's and 60's as work trucks and ran 50/50 anti freeze. We never used Chevs because my uncle sold GMC's. We had lots of heads to crack into the exhaust valve seats. We built fan shrouds out of a 14 gauge sheets, cut a hole a little larger than the fan and bent a hoop out of 1" flat and bent it into a hoop. It kept trucks with a 180 thermostat from going over 190 and put an end to the head cracking. I did the same in the GMC's I hot rodded. I really don't think the inliners were built to run over 200. Boiling which puts air bubbles in the coolant passages creates hot spots, but our experience with over 200 was not good. In addition to cracking heads, engines that ran over 200 used oil prematurely. If you intend to pull a trailer, I would really recommend a shroud. Especially because you are pulling a lot more HP out of it than the factory designed into it.

Maybe someone here could add more info here as to the spark plug range that you could try. I have heard that changing the induction system and changing the exhaust system also changes the requirments of the spark plug heat range.
The way I understand it is adding more carbs and better exhaust flow will cool the engine somewhat and require a cooler than stock spark plug to be used. Maybe you could be running spark plugs that are to hot for your engine causing your engine to run hot.

He's not having an overheating problem, he just wanted to know what temp was too hot so he could pull over and let it cool off IF IT DOES overheat.

I would first buy a Taylor cooking thermometer, 100 to 400 deg. range & when the motor is up to operating temp & while still running, CARFULLY remove the rad. cap & drop the thermometer in to 'calibrate' the reading on the truck temp. gauge. Using that as a starting point, I would try to not go much past 200 deg. with it due to possible hot (steam) spots in the motor.
Doug