The Stovebolt Site Forums The Shop Area Engine Shop What is the normal operating temperature?

Hey folks. New member, and new to fixing and driving 235's.

I have a 1962 Grumman Olson Kurbside step van built on a Chevy P30 platform from the factory.

It's got a 235 in it. I'm wondering what normal operating temperature should be? I have no idea.

Also, I put a 180 degree thermostat in it which, I believe, was the standard thermostat for it. I live in NM where we have very hot summers, and relatively mild winters. Does that sound about right?

Please let me know if I need to provide any more information.

Thanks!

The temperature should remain between 180° and 200°, but 180° is where these engines should stay under normal circumstances..

Thank you, Otto.

I'm typically running between 190-200. Every so often when climbing a hill it may go up to 205.

I just ordered a straight blade electric fan to replace my curve bladed fan, having read that may pull more cfm.

Any other suggestions?

A friend suggested looking into Hawk/Evans coolant. Do you, or anyone else, have experience with this coolant?

To be clear, my vehicle was missing a radiator when I bought it. I got the largest 3 core aluminum radiator that would fit, but it's still about 2-3 inches shorter than what I assume the original size was.

Evans coolant is used by lots of collector car owners. By collector cars, I mean 100 year old vehicles and brass era cars. A collector here in Atlanta uses it in certain vehicles with unusual cooling systems or cars with various types of metal parts in the system to prevent corrosion. Jay Leno swears by it for certain cars in his collection. It's expensive but it works.

I don't think a Chevy inline 6 would necessarily have to use it but it isn't going to hurt anything. It's hot as Hades here in Atlanta and my vehicles use regular Ethylene Glycol without overheating.

To use Evans, you must prepare the system properly. There can be NO WATER or COOLANT remaining in the system at all. Every drop must be removed. That pretty much means an engine tear down.

Gotcha! Thank you for the detailed information.

I'm going to install my new fan and see what that does. I also have some other things to try before going the Evans route.

I have a 160 degree thermostat in my '60 235. This past summer the engine temp ran around 180. Now that the weather is cooling down, the temp has been running a little below 180.

So, it seems I'm running a bit hot then?

Even a short excursion to 205 degrees isn't a reason to freak out. Maybe try a different thermostat, but once it's open it's on the radiator to keep things cool. In other words, putting a lower temperature thermostat won't make it run cooler if the radiator isn't up to snuff, it won't run at that lower temperature. A higher capacity fan (such as the one that bolts onto the water pump) should help. Most electric fans are too weak, no matter what the claims are.

And Evans coolant (100% propylene glycol) can't work as well as 50% ethylene glycol. 100% water is even more efficient at transferring heat, but has freeze issues. It's a heat capacity thing. Boiling points are higher with 50% EG and Evans, but that isn't usually an issue.

A thermostat sets the minimum operating temperature of a cooling system. Max temp is determined by the capacity of the radiator, load on the engine, and airflow across the radiator core. Either get the radiator cleaned thoroughly, add a fan shroud and/or a fan that moves mor air, or increase the heat load capacity of the radiator. Also check for the possibility of combustion gases leaking past a head gasket by using a "block check kit" that has a liquid that changes color in the presence of combustion gases in the radiator. NAPA stores sell a very good quality of block test fluid- - - -better than the stuff sold by O'Reilly's or Advance Auto Parts.
Jerry

Over years of use, or just siting around, these old 6 cylinders engine accumulate a lot of sediment in the bottom of the water jackets in the block. If the different fan doesn't seem help, try flushing the block out. Keep in mind that some of it gets like concrete.

Also, verify the accuracy of the gauge. 190 to 205 is not that hot, if it's not boiling fluid out on the ground and it cools off once moving, just keep an eye on it. If it cools off a lot once moving at a decent speed, you have a air flow issue at slow to idle speeds. You could also have a water pump rpm issue, any chance you can find a smaller water pump pulley? A solid steel mechanic fan will double you air flow over an electric if you have room for one.

Fan and rad placement sounds looking into. Curved blade should be fine. Centered on the rad and an inch or so from...
you should be able to feel the air pulling from the front. If it`ll hold up a sheet of paper at idle. thats good.

Thanks to all for the input and responses. I figure I'd comment once to all of them.

Thanks for the clarification regarding thermostat temperature ranges. I was trying to verify that 180 was stock (I'm pretty sure it is). I'll keep it there at this point.

My radiator was a new, 3 core, aluminum unit when Installed it four years ago. I had done a quick flush to clear out the water journals in the motor but I was in a rush because I needed the vehicle the next day, so another multiple flush is likely a good idea.

The radiator is as wide, and more cores than the original (as far as I can tell), but about 2-3 inches shorter. I assumed the extra depth would make up for that.

I can't use as mechanical fan. Not enough room with the new radiator.

I am currently using a curved blades fan with a shroud, centered on the back of the radiator, definitely wired to pull air. I verified with a paper towel being held onto the radiator when I first installed it.

I did some reading and video watching and it seems straight bladed fan pulls a bit more cfm, so I bought one. I believe it's a bit more cfm than what I currently have installed. I don't see it doing any harm in installing it, so I'm curious now, for the sake of experimentation, as to if I see any difference in temps.

When sitting at idle, the temp stays steady at 180-185 according to my temp gauge. I haven't tested the gauge for accuracy, but it does stay steady at those readings. When the temp does go up to 205, I haven't noticed any boil over or loss of fluid, but I'll check again to be certain.

I live up in the hills, so the temp going up to 195 tends to happen when I'm climbing those hills, no load in the back, in not so hot weather, which is why I got concerned. In the dead of summer, it's gone up to 210, maybe slightly higher when going up the steep hills, but then goes back down when I'm back on level ground.

Once I get the fan installed, I'll see if that changes anything.

I want to add, I have no room up front to install a push fan as an additional method of cooling.

When I reinstall the heater core I figure that - a) I will have more fluid in the system which may help with cooling and b) I'll first do a thorough flush of the system before reinstalling any of the hoses. Is my thinking correct there in that the heater core adding more fluid may help with heat dissipation?

If, after all that, there is no change, I have two aces up my sleeve.

One is, on the front of the vehicle under the headlights, there were two spots for driving lights. I didn't have any so I added some black louvered fixtures because I like the look (see attached pic). I can add hoses to the back and direct them to the radiator for extra air to be pushed onto the radiator.

The second ace is that there is an old timer in my town that builds radiators. If I absolutely have to, I can have him build me one that is larger and will fit in the frame.

I can't thank you all enough for your taking interest and helping. It's been a while since Ive been on a forum that is active, and with helpful, friendly people wanting to send a hand.

I'll keep you posted.

A related question.
What would be a good reason to use a 160 degree thermostat?
The only thing I can come up with is that the thermostat opening sooner would warm up my ole lady's shoes quicker.

That's pretty much the only thing it does. It draws heat away from the engine before it's at full operating temperature.

Living in the desert probably means the quick heater warm-up is less important than a quick engine warm-up

160 degree thermostats went out of style back when alcohol-based antifreeze quit being manufactured. A 180 would make the alcohol boil away. The trick to dealing with 200+ degree coolant temps is a pressure cap. Every pound of pressure on a cooling system raises the boiling point 3 degrees, so a 7# cap will keep the coolant from boiling up to 233 degrees. A 14# cap takes the boiling point up to 254- - - - -way above anything a good condition stovebolt engine with a good radiator should ever see. Be sure the heater core you install is rated for pressures equal to or above the cap pressure. A new aluminum radiator should be able to handle 20 PSI or a little more.
Jerry

Excellent information. Thank you!

Quick update.

I've needed to adjust the fuel/air idle mixture and idle RPM's since finishing replacing my blown out exhaust manifold gaskets.

Ends up, I was running a bit lean at idle, and my idle RPM's were too high (700rpm's). Looking at my plugs, they all looked equal, but slightly lean being tan colored, rather than chocolaty brown.

I hooked up my vacuum gauge, fattened things up at idle, and lowered the idle rpm's and now it's running really well. Best it's every run since I've owned it, actually. The last four years of work finally paid off today!

I took it for a drive and, wouldn't you know it, my engine temp stayed steady at 180-182 degrees the whole time, even driving up the hill that previously had me temporarily warm up to 205. I'm wondering if my
fuel adjustment at the carb helped it run cooler? Given that the adjustment is at idle, I'm not sure that that would have made a huge difference in running a bit cooler.

Todays temps were 64F. When I drove it last week at the same time, it was 69F. I don't think that 5 degrees of ambient temps would make much difference in regards to it having run warmer last week.

Anyway, that's where I'm at.

How does the air enter the radiator on the Grumman? Are there shrouds or anything to direct all of the air that passes through the grill bars through the radiator?

Is air able to get around the sides, top or bottom of the radiator? If so, perhaps you can fashion something(s) to funnel all of the air through the radiator itself. Any sort of rubber seals on the top or sides of the radiator?

Earlier I mentioned the louvers installed where I could attach hoses to direct more air to the radiator if necessary, and that I'd attach pics. I forgot, so here you go.

At the front, there are no shrouds or anything. Air goes through the front grille and hits the front of the radiator.

On the back, there is a pull fan that is attached to a shroud made for the radiator.

Are does get around the sides, top, and bottom.

If need be, I can try and fabricate some sort of air funnel.

I also had mentioned earlier that I have louvered fitting I mounted on the front of the Grumman. I just added pics as you were sharing your response.
I can likely attach hoses to the back side of the louvers and direct them to point at the radiator.

That being said, I also just happened to post that after enrichening the fuel/air mix at idle, and lowering my idle speed then taking a drive, the temp stayed at 180-182 the whole time, even climbing the dreaded hill.

Right, but what is the stock configuration for airflow through the radiator. The truck didn't overheat or run hot when it was new. Is there anything to prevent air from escaping around the radiator before it goes through it after passing through the grill?

Id be inclined to rig up one or both of those vents to snorkels to direct fresh cold air to the carburetor.

I understand, and I honestly have no idea, as I have never seen one in person that was stock.

That being said, I don't believe they had a shroud that directed airflow on the front, but I'm not sure.

Also, it originally had a mechanical fan. I'm not sure if there was a shroud on the back side of the radiator.

And, I believe the original radiator was as wide as my current one, but about 2-inches taller.

I'm guessing my 3-row radiator is thicker/deeper than the original was.

Yeah, I think the snorkels, if necessary, will be a clever solution.

That being said, I don't know if you read my above post but after adjusting my carb today, and topping off my radiator reservoir a tad, I ran at 180-182, so my issue may have been rectified.

Good to hear it's running cooler, the added fuel could have been just enough to help it, even though it's an idle adjustment. You can also help a hot motor with a timing adjustment, so double check that when you get time.

I was going to suggest adding a couple small heater cores behind your front openings to add extra capacity to the system, you could gain a gallon or two of coolant and extra cooling with not much work.

Thank you so much! Yeah, seems the little bit of fuel may have helped, even though it was just at idle. I think I forgot to mention that I also added a bit of coolant to my overflow bottle. That may have also helped a bit.

I love that idea about adding a heater core for cooling. I'm a big fan of practical solutions to things
I'm hoping when I add my heater core back to the circuit it will help.

My new fan is arriving today so that won't hurt either, when I get around to installing it.

Thanks for mentioning timing. I am planning to give it a look as it was last timed when things were running poorly (faulty coil, massive leak at the exhaust manifold), so it definitely wouldn't hurt to check.

The only way to make a spark plug turn "chocolate brown" these days would be to get in the "Back to the Future" time machine and buy sone leaded gasoline! The old "white/gray/ chocolate brown/black" method of diagnosing fuel mixture also stopped being accurate, somewhere in the 1970s when leaded gas went away. The lead additives were what made the plugs change color.
Jerry

Well, I do run ethanol free fuel and tend to put lead additive in it because I don't know if I have hardened valve seats. Not sure if the additive does the same as the actual lead.

That being said, I disagree that you can't examine a plugs color to diagnose running conditions.

There's no reason to waste money on lead additives. Your engine will run fine on regular unleaded without damaging the exhaust valves (as is the popular myth). Unleaded fuel has been available in the USA as premium unleaded for over 100 years.

I've never owned a modern car and all of my vehicles operate on unleaded fuel without additives, exclusively.

Thanks Otto! Good to know! It's something I've been concerned about. Now, I won't worry.

Never say never, if you operate the engine hard for a long period of time, you can damage seats pretty fast without lead added to the fuel. Just driving around, sure, no problem, but hook up a trailer and head over the mountain a few times, you might be looking for a new head.

If the engine was driven with leaded fuel early on, the seats should have enough lead embedded in them to last a life time if they haven't been cut down too much. Thats how most survive now, along with not working the engine to death.

Running a lead additive solved this heating problem, it colored the plugs, so I would say thats a win. It sure won't hurt adding a can every so often to keep the seats coated, considering the type of truck it is and the amount of wind it's going to be pushing, this engine will work harder than a pickup will.

I agree that it's possible to ruin a valve, but unless someone is beating a 70 year old engine to death auto-crossing it or some other foolishness, you're never going to damage the exhaust valves. High rev racing engines or engines operating at the redline all the time are in danger of burning valves.

Driving antique vehicles under normal circumstances at normal speeds and normal loads won't hurt them.

I've put a couple hundred thousand miles on The Bismarck over the last 25 years. That included highway trips of over 500 miles at 75+ mph as well as local stop and go driving. It has only ever had unleaded fuel in that time and the heads are stock.

The same is true with the other vehicles. Drive like a normal human being and you'll be fine.

Really good points. I hadn't realized that if it had been run previously with leaded fuel that there would be lead embedded in the seats which could help it out. Thank you for explaining that.

I do load the rear up from time to time, and I do live up in the hills, so then I will continue to add lead additive from time to time.

Thanks so much for that information.

Also good to know. Thanks for your experience and input.

Although I don't completely flog the heck out of the Grumman, I also do just tend to drive all my vehicles, even my 1970's motorcycles I've rebuilt and ride regularly, like they were built in 2026 and just ride the heck out of them.
That being said, those engines were designed for unleaded fuel.

I guess it won't hurt anything to add some lead additive from time to time, but I also won't worry about having to do it every single time I fill up with fuel.

This begs the question, is there some way to find out if I have hardened valve seats without pulling the head?

I appreciate all of the input from everyone. Being new to working on these 4 wheeled vehicles, I'm learning a lot of important details the more we chat.