The Stovebolt Site Forums The Shop Area Engine Shop Running hot, what's too hot?

I've got a freshly rebuilt '54 235 that's running hot, and I'm looking for some help.

I did a 20 minute 2000 RPM break-in on first startup, no problems.

When driving the truck (1/2 ton) around, the temp will get as high as 220. New radiator. Everything on engine stock. 180 thermostat. No fan shroud. I have a fancy IR temp sensor I can use to pin-point different spots on the engine. Here's the recording I see after driving around for some time, and then measuring at idle:

bottom of radiator: 190
top of radiator: 210
top of thermostat housing: 215
left side of head, near temp sensor: 230
right side of head: 210

When I shut engine off, I'll loose fluid out the radiator overflow.

I don't have heater installed, so I've made a 3 ft. loop with the heater line.

It's a '56 head with a '54 block.

Motor doesn't have tons of power, so maybe I'm off on timing. I timed it with timing light and I have the BB right at the pointer. Sometime when stopping motor, it'll backfire thru carb and or turn backwards.

Any ideas what might be going wrong? I'm assuming these temps are too high.

I'd suspect the radiator or fan. I think the bottom should be cooler than that.

yes, a 20* drop thru the rad is really minimal, are you sure the fan is close enough to the rad? 1/2-3/4", and pretty centered on the rad .... also yes, likely timing could use tweaking. although the backfire on shut down could also be the heat causing detonation

Bill

how long does it take to get high temp when it is just at idle..
you for sure have a problem with the engine, backfire, etc
and that might be why it is running a tad hot

usually one would think a radiator might be stopped up but
you have a new one.. what about the water pump, new or old...
I am thinking when you get it tuned right you may no longer have a high temp problem.

Adjust the carburetor mixture and the timing to maximum vacuum reading (at idle) using a vacuum gauge.

What procedure did you use to adjust your valve lash?

I don't know the extent of the rebuild but sometimes the old rust and crap in the water jacket can plug up a new rad. Then it has to be cleaned.

Lot of good stuff questions, thanks guys.

Answers:

valve lash: set per shop manual...let oil get up to operating temp then set per shop manual specs.

vacuum gauge: i have a good vacuum gauge, so i'll try adjusting timing using it.

Rebuild: block/head were hot tanked and cleaned really well. I'm not seeing any discoloration in the fluid i'm loosing out the overflow when I shut engine off. Looks real clean.

Carburetor mixture: haven't adjusted that yet.

fan: it's 1/2" from radiator, stock fan, install in the right direction.

how long to get to high temp? It will not get to high temp without load (driving). If I start it cold and let it warm up, gauge reads 180. Then if I go for a drive, it'll go past 180.

water pump: it's old, about the only thing I did not replace on engine. It seemed functional when I had it out and turbine moved freely. How do these fail, and how do I know if it's failed?

I'm going to pull the thermostat out completely and see if there is an issue there.

I've run tide laundry detergent through many radiators when I wash tech. It cleans all sorts of crap from the cooling system. Sounds lame but it works wonders. Your carb and timing should be addressed as well. Just a thought. Dose it diesel when you shut it off?

It will diesel for a short bit after shut off after running hot. Not all the time, 50% of the time. Does it for about 1 second.

One question that was raised privately, and also above by red58: is fan centered on radiator? Yes, left-to-right. No, top-to-bottom. Top of fan is 2-1/2" below top-most fin on radiator. And bottom of fan is 1/2" or 1" below bottom-most fin on radiator. Looks like I could lower radiator to center it top-to-bottom. I'm not sure how I ended up with fan not centered. In any case, seems off-centered fan wouldn't be an issue at speed, but I see no temp drop at speed.

Will try timing suggestions tomorrow...

You have a 1954 engine with a 1955st or earlier water pump (and truck fan)? That pump/fan should be orientated properly to the 47-55st truck radiator.

It's a '54 (truck) block with a '56 head. Water pump is low-profile one that fits '54 block. Truck fan, as far as I know. Was in truck before rebuild.

Longer answer: it's a '54 1-ton cab/front clip sitting on '54 1/2 ton frame. Front clip has 1-ton radiator surround. Engine block is original to '54 1-ton truck, but now sitting in 1/2-ton frame. So all '54 1-ton parts, except '54 1/2 ton frame, new after market radiator (for 1-ton, 4 core), and '56 848 head. (My '45 head was cracked). Fan and water pump are from same engine that was in 1-ton.

Can someone get me a measurement from top of fan blade to top-most fin on radiator? I looked at pics of another 1-ton I had and my 2-1/2 inch measurement doesn't seem that far off.

Maybe the thermostat is not working correct. Not open at 180. What is ambient air temp when this check was done?

Personally I think your temperatures are high and you risk doing damage. I would pull the thermostat until this gets solved.

Pulling the thermostat is not a fix. In fact that action could cause overheating in a functioning cooling system by allowing the coolant to flow too fast to be cooled efficiently.

Actually I would go by what the real water temp gauge says. You may be reading radiation temps thru metal with the IR. A common problem when radiators overflow is owners filling radiator to full. It needs room for expansion after shut off. If you have a recovery tank, that's a different story. Need to read another vehicle with your IR at the same places. As others have said, if it is really overheating, it will be the water pump, the thermostat, timing, air flow, fan slip or not shrouded properly. I would be darn sure your sender and gauge are correct. Make sure no water in oil and oil press OK. I second what Cletis said about removing thermostat. As far as water pump fail, all the ones I have had will start to seep out the seep hole, but sometimes the water gets evaporated by engine before it hits the driveway. But watch for that. Check belt. You can remove belt and check pump play, but if they are cheap and easy, put on a new one for sure. New engine with old water pump makes no sense. I assume you didn't use an old thermostat. Detonation, as said, and Dieseling is caused by heat caused by timing OR exhaust manifold leaks, especially with headers OR idle too high.

my 1959 261 with the 180 degree thermostat runs 180 degrees at the gauge. You are running too hot. Good idea to find out that is causing it. I too have an IR gun, and I don't get numbers that high. The first thing that comes to mind is sediment inside the block (from looking at your numbers).

I wouldn't ignore this.. its too hot.

Did you miss what he said?
"Rebuild: block/head were hot tanked and cleaned really well. I'm not seeing any discoloration in the fluid i'm loosing out the overflow when I shut engine off. Looks real clean."

Does the coolant flow when your idling and the cap is removed? Can you see it move?

your statement,
how long to get to high temp? It will not get to high temp without load (driving). If I start it cold and let it warm up, gauge reads 180. Then if I go for a drive, it'll go past 180.



you can't get it to run hot at idle?
that is strange, at least to me it is.

how far under load do you have to drive to get it hot..

I'm with joker, if it only 'overheats' under load, not at idle, I'd suspect it's a timing issue - might also have a loose fan belt, so the water pump isn't turning full speed .... in fact, are you sure you have the right size pulleys on the pump and crank?

Bill

Don't forget one of the procedures too cool a hot engine is to pull over and run at high idle.

roger that bartamos, might check to see if the grill has any trash on it...you know, like the nascar cars get all those wrappers on them. all of mine have gotten hot by.. stopped up radiator or
one that leaks, closed shut thermostat, water pump usually as
Bartamos stated, a slow one leak, busted hose,broken fan belt, being in a mountain area, or behind a flat bed chevy truck with granny gears in a very long parade, and was begging for air to get around it..

being a fool and putting in new antifreeze and then not
closing the radiator peacock tight, losing the fluid
early one morning and not seeing the temp gauge getting hot and ruining a good 232 engine in my 70 International pick up..

those would be the issues I had, others may vary.. but, seems like that folks do have problems with running hot after a rebuild.. I have never had that experience so...

last my not least, is it possible to have to much antifreeze in one?

Yeah I believe so. Usually it's a 50/50 mix they recommend. Never actually read the warnings. I'm thinking its the timing more and more. Maybe leaning it out and causing it to run hot. Is the 54 block comparable with the 56 head? Do all the holes in both mating surfaces line up? Is the gasket possibly blocking a channel?

1953-62 heads will all interchange, that will not cause a cooling problem.
Advance the timing at least 5 degrees over stock with today's fuels.
Have you tried running it without the thermostat?

I was just curious because Ive gooned a carb with the gasket from throttle plate to carb housing. Blocked a fuel hole. Sounds idiotic but it happens when you're excited. And I had to do two of them..

How does it run at speeds?

If you let it idle after a drive, will if overflow the radiator?

If you catch what comes out, How much coolant is it?

If you don't refill it, will it overflow the next time?

How tight is the engine? can you turn it over fairly easy or does it struggle?

How many miles on it?

Newly rebuilt engine should run a bit hotter till broke in completely, rings are tight causing heat build up.

You sure you have all the air out of the block? Don't remove thermostat, it will just run hotter, most of the time. Try putting a aspirin in the thermostat to hold it open. Once the coolant fills the block and head, the aspirin will melt out and close the t-stat.

Highway driving, (over heating) is a air flow problem. How does does it cool at slow speed driving? You sure you have all the baffles and air dams around the radiator? Air will always go around something if its easier then going through it.


joe

Almost never will removing the thermostat cause overheating.
Please read my blog on the Thermostat myth,

how does "most of the time" relate to "almost never"?

removing the thermostat may not causing an overheating of the coolant, but it is likely to cause an overheating of internal components, the coolant flow [size of hoses, pump, passageways, and thermostat opening] are engineered

Bill

I know I will never dispel the myth Bill but you are incorrect that the internals will over heat.
You may not be able to cool a hot piece of metal by applying water to it(the water will turn to steam), but you will never get a piece of metal very worm it it is in contact with cool water first.
Could you tell me how the early cars and trucks managed to operate before thermostats were used?
I would also question you on why they sell high volume water pumps for high performance engines?
I don't want to come across as argumentative but this myth drives me crazy.

you're right about not being able to dispel the "myth", but that probably has to do with thermodynamics, maybe you have a degree in physics? .... early IC engines cooled by thermo-syphon and convection, or air cooling, and don't bear much resemblance to more modern machines, which have systems based on a lot of engineering to overcome the drawbacks of early ICE's

while it may be that removing the thermostat will "almost never cause overheating", I'll stand by saying removing the thermostat will never cure overheating, except possibly if the thermostat is defective, and there's easy ways to diagnose that without risking overheating internal areas of the engine

Bill

Cadillac's and Packards were using thermostat's as far back as 1919. The cars back then had hugh radiators with plenty of coolant capacity, plus they never ran very hard, but a lot of them still over heated due to poor design. My uncles 1921 Cole has two thermostats, one for each bank of 4 cylinders (V8).

In all my years of racing cars and being around cars, they always cool better with a thermostat or restrictor plate. I can't argue with what I have seen and done, and I tried a lot of stuff drag racing for 15 years.

As my 1920 Automotive Engineering Text books says, " all liquid cooled engines are in fact, air cooled" . It all comes back to how well the radiator can get rid of the waisted engine heat.

As far as high volume pumps for race engines, they move a lot of water to a radiator designed to handle it. Dad's 478 ci Pontiac block is half filled with concrete, it doesn't overheat due to properly sizes cooling system and well tuned engine. It uses half the water of a stock system, and yes it has a 180 thermostat and a aluminum 2 core radiator. It can set in traffic and idle for hours or be driven on the road for hours, we have done both.

Joe

You can not prove if something is a myth by theory or writing a blog. The Tstat is a simple bypass valve. Here is some opposite theory blog stuff from the webernet. Controlling engine temp with a thermostat to maintain constant operating temps, reduces engine wear, deposits and emissions. If the thermostat fails to close, which can happen if the sensing element binds up, the return spring breaks or a piece of rust or debris jams it open, the constant flow of coolant through the thermostat will prevent the engine from reaching normal operating temperature. This can cause poor driveability in cold weather, a sharp increase in fuel consumption, little or no heater output, and accelerated blowby and ring and cylinder wear.
In this case, it would be a band aid, if it helped. What would it really do to identify the problem? just put in a new Tstat. You can not compare older or newer engine designs. Newer race engines have improved water jackets, are made of highly thermal conductive aluminum.... bigger, better, aluminum high flow radiators with modern air flow features and electric, "thermostatically" controlled, fans. Apples and oranges. In a modern vehicle, it would totally screw up the computer. 90% of the old, old cars were in the FLAT, cold, east/mid west. When they were used in Arizona or in the mountains, they ALWAYS overheated. Anybody remember the canvas water bags? As a kid I remember going to California from PHX. They had specific water stations along the way. I still can't believe we had to stay overnight in a motel half way! It's 375 mi! But of course back then it was much farther....no freeway. 45-50 mph. Sorry, had a childhood flashback.

Depending on the reason for the overheating (a bad/closed thermostat, for example), removing the thermostat might or might not solve the over-heating problem. Obviously, if the thermostat is stuck in a closed position, removing the thermostat will solve the problem. If this is the only reason for over-heating, removing the thermostat will "solve" the problem - the engine will no longer over heat, but it will warm up much more slowing and most likely run inefficiently during that time.

Here is a little Auto Education on your vehicle's cooling system.

"Thermostat: The thermostat controls the flow of coolant through the engine. When your engine is cold, it actually operates with less efficiency. So until the engine warms up to it's ideal temperature, the thermostat keeps coolant from flowing. Your thermostat can fail in either an open or closed condition. When it fails in the open position, your engine may actually run too cold and you will have bad gas mileage. If the thermostat fails in the closed position, your engine will overheat since no coolant will be flowing through the engine."

If I run my 235 (1954) and 261 (1960) engines without a thermostat (I have only done this at up to 75 degree days), they would never reach the ~180 degree temperature at which my 160 degree thermostats would regulate the temperature. After I cleaned the interiors of my engine, I had to put in a thermostat to assure myself that my temperature gauge was working OK (I was eventually going to put one in anyway).

My dad is a retired chemistry and physics teacher and he is the one that educated me on this subject, along with many years experience working on cars, and all sizes of trucks, and machinery.
I definitely agree with you on the fact that removing a good thermostat will not cure overheating, it is just that it will not cause it.
If he happens to have a bad thermostat or trapped air in the system removing it for testing is a good start.

^ yes, ^ yes, and ^ yes .... still, removing the thermostat will not cure overheating - and might help with diagnosis only by indicating the thermostat is or is not the problem [and yes Bart, having started life trying to keep flathead Fords cool in the AZ desert I remember those bags well ]

note that "overheating" is referring to the coolant temperature - in a running engine there is a tremendous amount of heat being generated by massive contained explosions of fossil fuels along with the resultant friction [particularly if the lubricating oil is cold or too hot], that heat is what's being transferred to the coolant and then to the atmosphere by the radiator .... if the coolant is not getting to design temperature [measured by the probe in the engine], where is all that generated heat going? is it being whisked away through the 3 steps of heat transfer so fast it can't be measured? is it magically not heating the engine metal? is it being "air cooled" away?

maybe someone should experiment: with a system that's cooling properly, bring it up to operating temp and check various points on the engine with a good laser thermometer, including the top and bottom of the rad - remove the stat and repeat, checking for any differences in temperatures in the same locations

Bill

Hey Im with this guy what is normal I have a 54 235 with 160 thermostat no backfire no issues when shut down no boil over but it runs 180 to 190 going down road long idle times (drive Thru) it has come up to 220 but comes down when driving down road. 90 degree day. Have done all the flushing and all that stuff.

I say two aspirins, one for the thermostat and one for me!
"Mommy? what was life like before Infrared Thermometers?"

My old 216 engine used to creep up to 210 + degrees on extremely hot days but to my knowledge, never boiled. I do NOT have a Science /Physics degree but it appeared to me that it took an entire Bunch more of energy to make it boil. I am running the new to me 235 engine with a 180 therm. Same radiator and it runs at a very steady 180 degrees unless I drive it extremly hard, it may go up to 185 degrees! I know this 235 block is clean, I think old 216 block had some crud.
Jerry

You can pull the t-stat and test it..

The original post was how hot os to hot? If it boils over every time you shut it off, its too hot. If it only boils over the first time, you had the system to full, do not refill after the first boil over and see what happens. 180 to 200 is not hot, 210 - 220 is getting there, 230 or more I would worry.

Its still a new engine, drive it a little more to break-in the cylinder walls. Do not keep adding coolant, let it seek its own level.

Did you get out on the freeway? or was this drive just around the block? Hood on or off? makes a difference in air flow.

Joe