Featured Projects Overheating problem 33 chevy

My radiator doesn't have the bottom reservior for the automatic transmission fluid, so I install a transmission oil cooler in front of the radiator with about a 1" spacing between the cooler and the radiator. I also have a fan shroud with a 14" fan. I first ran the V8 in the frame, but the trans wasn't hooked to the ring gear so no trans fluid was going thru the cooler and the engine temp was 185-195.

Once trans and engine was hooked up togerther the engine temp will get up to 220. The engine didn't seem hot, I was a little concerned that the cooler might be the reason for my high engine temp. The V8 wasn't in perfect tune at this high temp reading. Everything is in tune right now but haven't run the engine long enough to see any high temps.

My question is has anyone had high engine temps running an trans oil cooler in front of their radiator?

 

Idling is the hardest time to cool the engine as forward movement is not pushing air through the radiator. Air only moves by the fan.
I'd say the trans cooler is blocking enough of the radiator to cause less cooling than needed at idle.

I'd suggest moving the trans cooler under the car, even if it is mounted horizontally. Convection (hot air rises) should carry adequate heat away from the cooler.

 

Or mount it under the car at an angle with a scoop to grab some air when you are moving.

 

It never made any difference on my 32 3w. I also run a window screen behind my insert and I don't have a shroud.

 

Depending on the thermostat you are running, and the outside temp. 220b is not over heating. If you have tuned the motor since, you may not see those 220 temps again.

Its hard to tell in the picture, but it appears that your fan is completely inside of the fan shroud, it should be 1/2 of the fan blade pitch inside of the shroud, and 1/2 of the fan pitch outside of the fan shroud. That probably doesn't make much difference at an idle, but it could cause a problem at higher speeds when the car is moving through the air.

It also appears to be one of those flex blade fans, I don't like them much, seen way too many flatten out way to easily, way too fast. It it flattens out too fast, it can't pull the air through the radiator like it should.

I find it hard to believe that small car is generating that much transmission fluid heat into the trans cooler to cause a 25 - 35 degree temp rise in the water temp.

 

I run my cooler up front too with an Eelco tank blocking the air and no fan shroud. It only gets hot (210) if it's at 170-180 driving around then get caught in sitting still traffic for 10-15 minutes.
As soon as I get moving again the temp drops pretty fast, I definitely need to make a shroud for it.

 

Your trans cooler looks way too large. The one in my 33 Chevy is about 1/3 that size and is mounted under the fender. I also have an A/C condenser in the front. No overheating.

.bjb

 

Auto trans torque converters are huge heat pumps, especially when sitting still and your foot is on the brake. I used to have a deuce highboy with a SBF/C4 in it and an electric cooling fan on a manual switch, no aux trans cooler. If I stopped with my foot on the brake for more than a couple of minutes I had to use the fan, if I popped the trans into neutral after stopping I could sit through a complete red light cycle without the fan, even in hot weather.

 

That trans cooler looks bigger than the one on my 5.7L Tundra with the trailer towing package.
Coolant temp will always be dependant on ambient, so without knowing your ambient temp, difficult to say if there is a “problem”.
I would say at anything below 80F ambient, at engine idle, your coolant temp should be less than 200F. If you have a thermostat, what is it set to open at?

 

At idle, how much air is the fan moving? Can you feel it out front? With hood open, can you feel the air around the engine? Your shroud is blocking the air from getting out away from the blades since its so deep. Pull the spacer off or remove the shroud, and look for a better fan. I have a 17" fan in my '37 Chevrolet, it's the same width as the core. Go as big as possible even if it hangs over the core in places.

 

Every car I build with an automatic gets a separate trans cooler, and always mounted horizontally under the radiator area. Cooler mounted so air can flow through the fins, and perpendicular to air flow. Never have any engine cooling issues, and transmissions last forever this way also.

 

Don't know if it would help but I always installed the transmission cooler under the car. HRP

 

That's a big cooler. Might try unbolting it from in front of the radiator, run the engine. If all good, you'll know if the cooler is blocking air.

 

Your car is looking real nice, great fabrication work!

I agree with @gene-koning about the fan inside the shroud. I had a similar problem on an off-topic car where the fan was too far inside the shroud.
I'm not saying that it's the root of your problem, but it something that's easily corrected.

Pictures can be deceiving, but from the looks of it if you eliminated the spacer behind the fan, it'd be right about where you want it to be. As it is it's too far inside the shroud to be effective.

 

Fan spacing inside the shroud looks ok, but with another look notice the fan looks rather wimpy for pulling much air. It may be that a fan with larger blades, could be the ticket to getting sufficient air through the rad. with the cooler in front. Good luck!

 

Thanks everyone for the great advise from all of you.
I did have a 1/2" fan spacer during the first start up and changed it to a 1" spacer that you see in the pictures. I did this after reading that the fan should be half the thickness inside the shroud, but haven't run it yet. Another common thing is everyone that had posted picutres shows that your coolers aren't in the center of your radiator. This gives me an option to move my cooler down to the lowest point on the radiator. That should free up more clean air to go thru the radiator. There is another idea of installing a larger diameter fan. I did check the air flow and the fan is pulling air and it's a real had breeze. I wish my shroud had more depth, but the fan mounted without a spacer to the water pump, the baldes hit the harmonic blancer, more depth would give greater draw across the radiator.

I know I'll get this issue worked out with y'alls ideas, and will post my solution when the temp is correct.

Also, keep the ideas coming.....
Thanks again everyone,

 

A fan test on Engine Masters

 

Look at Vintage Air fans, I had similar issues with spacing on my truck. The Vintage Air fans are center mount, meaning the blades are mounted with equal parts towards front and back. Your fan has all the blade behind the mounting flange. I had a pile of fans from swap meets, most were 1/4 - 3/4 with 3/4 of the blade to the rear The center mount worked perfect for what I needed.

 

Just noticed that your shroud has no “collar” around the opening. Without some sort of collar surrounding the blades, I’m guessing based on my experience, that shroud is almost useless. Blade tip clearance between blade and “collar”, and blade depth into the “collar” are important parameters in fan efficiency.

 

I had just looked at that today, with real close clearance issues I could put the 1/2" spacer back on and maybe put a 3/4" thick collar on at best. That would be at least something.

 

This is absolutely correct. The concept of having the blades half in and half out theoretically cancels the centrifugal effect of the air on a propeller fan blowing out radially. With the tips of the blade inside the shroud as it appears to be your your recirculating a fairly large percentage of the air right back into the inside of the shroud. As pointed out, the collar cancels out that centrifugal loss of flow. He would probably be better off if the fan was slightly outside of the shroud. Take the spacers at and check it again.

 

Only thing is to try and see. You can buy inexpensive vane anemometers on Amazon to measure air velocity. Set up a grid system with some string/fishing line in front of the rad, and measure air speed at each grid point before and after any mods. It will tell you if you are going in the right direction.



https://www.amazon.ca/dp/B0DFGDB9WZ/?tag=atomicindus04-20

 

A lot of good advice here. Fans pull very little air in their center. Most of their draw is from about 1/3 of the blade out to the tip. One other thing, it seems counter-intuiative but your cooler should be mounted as close to the rad as possible. Any gap between them causes airflow buffeting. The larger the gap the worse it gets. A long time ago I read up on early speed record cars and the use of aircraft physics to make them more streamlined and still cool those gigantic early engines, very cool stuff. Anyway, more stuff to ponder...

 

I got to say you all have given me a ton of good information, and the last few days I have researched all of the suggested solutions. I'm going to try them one at a time and see if any change is good or bad and give feedback on each one.
1) Add a collor to the opening of the fan shroud (done just need to install) and set the depth of fan in shroud collar.
2) Shorten the gap between the cooler and the radiator from 1" to 3/8" (done)
3) Lower the trans cooler to the lowest point on the radiator.
4) Go to a larger diameter radiator fan and new fan shroud.

One thing that I'm puzzled on is, I looked up the specs on a 68-327 radiator cap and it is rated for 16psi. The first year of the 327 in 62 is rated for 13psi. Does anyone know what is the different in the cooling system from these years, because I've owned these year cars and don't remember what could have changed to use different psi radiator caps. I do know that the radiator I have in the 33 is a whole lot smaller, and presently using a 16psi cap.

I hate to be a rookie on this built but in all my builds, I've never had a heating problem. I guess all my other builds were restorations and had all the parts. This build was missing 50% or more of parts and had to use my witts and ask a ton of questions.

Thanks, again

 

I got the shroud modified with the collar and installed.
It's only a 3/4" wide, which is about all I could do with a 1/2" fan spacer.


Before


After


A little bit closer view of the fan blades in the shroud collar...not to clear of a pic. The gap between the outer blade and the collor is about a finger width.


Another thing I forgot to add to all of this. On the first start up, my digital fuel gauge was reading 11+ psi, which in turn over powered my float seats. So I install a fuel pressure regulator and on the next start. I cranked it to get more pressure and all I could get was just under 4 psi. Then I installed a manual gauge to the outside of the regulator and it read the same as the digital gauge, so I cranked the regulator further in and eventually got right at 6 psi. This is what the carb specs call for.

The point I'm trying to make is I ran the engine for quite some time with extremely low fuel pressure, (1.5psi) and I did some research and low fuel pressure could cause engine over heating due to having a lean fuel mixture. I now believe I've had more than one problem causing my cooling overheating.

Still waiting to finish a few more items to the 33 before I do the next start up. When I do I'll let everyone know what happened.

 

I believe you are on the right track. Your testing would have been more refined if you could have made a test run after each modification, then you would know which modification was the most helpful, but that requires a lot more time and effort. As is, at least you are documenting the difference a few modifications done together have accomplished.

I found the engine master's video concerning how much HP was lost with each fan design change interesting. I can say I was not too surprised at the outcome, but I do wish they would have measures how much the air movement through the radiator changed with each fan change.
If you are just chasing just the HP change that video worked well, but if you have an over heating issue that could be caused by the air flow through the radiator, the video is pretty worthless.

 

I agree with you on the video, you're right I tried to focuse on the easiest soluation that made since. Of the three changes I made, if that still doesn't solve the problem the cooler closer to the radiator and the fuel pressure will still be the same with the new change of going with a larger diameter fan. I still have the opiton of moving the cooler away from the radiator, I'm hoping this is not needed. I'm still puzzled on the dfifferent 13 and 16psi radiator cap pressure from 62 to 68 engines.

It seems I'm not going to run out of soluations to look at for awhile.

 

I would put a smaller water pump pulley on it. looks like it is the same size as the crank pulley. a smaller pulley will spin both the fan and water pump faster.

 

I suspect the rise in the cooling system pressure is because of the more modern vehicles operating at higher temps. Here is a kind of a quick overview, though other factors were also involved with the increase of the cooling system.

In 62, most guys were running their cars at 160 degrees water temp. Most guys were concerned that because the boiling point of water is 212, any operating temps close to that was going to be a problem, even though a 13 lbs cooling system pressure raised the boiling point of the water up much higher since it was under pressure. Those lower temps (often because of a 160 or no thermostat) reduces the efficiency of the motor operation and produced more cylinder wear, but it operated at well below the 212 degrees temps that water not under pressure boils at. Back then, a motor that lived more then 80,000 miles without being rebuilt was unusual.

By the emission era (1968), the auto manufacturers had to increase the efficiency of the motors to meet the new Fed Emission Standards. The early adjustments were pretty simple, add a PCV system, and increase the operating temp of the motors. They could raise the operating temps to 180 and bump the pressure up a pound, and over heating was still not an issue. Another strange thing occurred, the life expectancy of the motors increased to just above 100K miles before a rebuild was needed.

Tighter emissions (mid 1970s) required more motor efficiency, so the operating temps increased along with another increase of another pound or so in the cooling system pressure. Other things were required to meet the emission standards. There was also a bump up in the life expectancy of the motors.

By the mid 1990s, the car companies were facing longer motor life requirements in order to sell their cars, many car companies offered a 100,000 mile warranty. Past experience taught them that increasing the operating temps and raising the cooling system pressure increased the life expectancy of the motors. the change from 13 lbs to 16 lbs was a slow one pound at a time, spread over several years. Some of the current systems are experimenting with 19 lbs of cooling system pressure.
There are charts on line that can tell you how much each additional pound of pressure increases the boiling point of the coolant.

 

Ain’t hot unless it’s puking coolant