The Stovebolt Site Forums The Shop Area Engine Shop Overheating Problem

I searched the forum and found a few comments, but here's my situation. '53 Chev 3/4 ton with a 235. I bought the short-shaft water pump from Carters a few years back. With the radiator clearance, I was told to get a four-blade flat back 216 fan which I did. There isn't sufficient clearance for the old original 235 fan. I bought a radiator off of E-Bay which was a piece of junk (bad leaks), so just bought and installed a new radiator from Classic Parts. Started it up today. Ran idling in the garage for about 15 minutes and it boiled the water right out of the radiator. Temp pegged and I first noticed it when I started hearing a whining noise and immediately killed the engine. The upper and lower radiator hoses were both warm to hot. The heater was putting out good heat. So the only thing I can think of is that the small flat back fan isn't sufficient to cool the radiator. I had about 12 quarts of antifreeze and water in the system at the time, so I know it wasn't just in the radiator and not circulating. Also, if I understand cooling systems well enough, the heat comes from the water passing through the block and back to the radiator (right?) I noticed that the fan sits way low between the engine and the radiator because of the style of the shortshaft pump. There is about 1/4" of clearance between the fan and the lower radiator frame. Surely others have run into this problem, so I'm curious about solutions. I've read some about electric fans and maybe that is the solution. If so, if anyone has photos of this set-up and some advise on installation, I'd sure appreciate some responses. By the way, I had the truck running outside awhile back before I put in the new radiator and it didn't overheat this bad. It just leaked because of the condition of the old radiator. This time it was inside the garage with the bay door open. Maybe not as much air circulation, but it still shouldn't overheat in less than 15 minutes I wouldn't think. Any replies would be appreciated. Thanks.

Rick,

When you installed the new radiator, did you install a new thermostat and then fill the cooling system?

Sitting in the garage idling doesn't allow good air flow through the radiator, but it shouldn't make the truck blow its top. My guess is that every thing is actually OK, but that the system might have needed burping. After the thermostat did open, because the truck wasn't moving through nice cool air, it just couldn't cool down fast enough.

I would fill everything back up and head down the road. Take a jug of water, but I'll bet things will settle down and be fine.

Stuart

Stuart I didn't put in a new thermostat after installing the radiator. Since I didn't I should be able to take the thermostat out now and install a new one. Right? Sounds like I may need to drain the system though first, or is that necessary? If I just drain the radiator and not the block, is that sufficient?

Rick just drain the radiator enough to install the new thermostat, you won't have to drain it completely. What you could do also when refilling it is have the top heater hose off at the firewall. This will help remove air from the system...Joe

Sounds good. Thanks Joe.

Rick ,
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Tim

What is the history of your truck? Did the truck motor cool OK before this or is this the first run up after installing the 235? There are two things not mentioned here that can affect the cooling. One is that the fan is not centered on the rad and therefore is not pulling air across enough of the rad. That is one of the reasons for using an old style water pump and an adapter plate. The other is the pulley size on the water pump. If there is not enough flow through the pump at idle it can be a factor. With some of these sixes, running at idle can be more of a cooling challenge than running down the road. From your description of the rad hoses, I doubt that your thermostat was the problem. However a new one could prevent a disaster sometime in the future.

Having traveled down the same path you've taken with the short waterpump, trying to use the stock fan w/new radiator, getting only 3/4 of the cooling system capacity into the engine I would offer these suggestions:

1. The cooling system capacity is 16 quarts....give or take a little. Without a thermostat you should have been able to completely fill the system. With a thermostat in place you often have to"burp" the system to get it full. Without the thermostat you should have been able to fill it completely. No thermostat will allow the pump to circulate the water too quickly to effeciently cool the engine.

2. The short shaft pump pulley may not give you the correct pump speed which adds to the above problem. Overspeed of the pump can cause cavitation and result in overheating. Add to that a stock fan which is located low on the radiator and I could see where you could have problems.

3. The solution to ALL of my engine temperature control problems was relatively simple:

A. Using the ADAPTOR Plate and the early 216-235 water pump you achieve the correct pump speed and more importantly locate the pump in the center of the radiator.

B. Replace the stock fan with a 15" 5 blade fan such as the Flex-a-lite FLX-1615P (Summit@$24.95). You will need to open up the center hole to 1" to fit the 1" snout of the "early" style 216-235 pump. This can easily/carefully be done with a circle template, scribe, and a rat-tail file. In addition this eliminates all clearance issues with the harmonic balancer, A/C compressor, Alternator/generator, and power steering pulleys.

C. After you've added the adaptor plate/early pump setup, fill your engine block from the thermostat housing before you add the thermostat. This gives you a full block of coolant. I also drill a 1/8" hole in the thermostat rim to allow full refilling to "burp" the engine.

D. Make sure that your engine timing is fairly close, you'll want a 50/50 antifreeze mix, add a 4-7 psi cap, a 180 degree thermostat and your temperature issues will be a thing of the past.

E. Hang the "short-shaft" water pump up in your shop and enjoy driving your truck with NO CONCERN about OVERHEATING issues. In addition, you can purchase a replacement pump should you ever need it from your local auto parts supplier.

BTW....54 my truck is a daily driver, has A/C and never goes over the 180 thermostat temperature during normal driving. I've added pictures and documentation to my webshots albums of the ADAPTOR PLATE install. Click on the "Full Size" feature to read the instruction sheet on the adaptor plate. Do youself (and your truck) a favor and make the conversion and be able to enjoy driving.

Dave

Also drill 2 tiny holes on the flat lip of your thermostat, this will let the air pass through it...Joe

All great suggestions and thanks for the replies. To answer the question about the history of the truck, this is a rebuilt 235. When I first put it all back together and started it up, it didn't overheat but it leaked bad from the radiator I bought on E-Bay. The only things I've done since then is remove the radiator and replace it with the new one and then refilled the system and also I rebuilt the temp control valve for the heater replacing the seal since it was leaking into the cab the first time I started it up with the old radiator. Dave, I looked at one of those adaptor plates in the catalog, but I saw a post somewhere that mentioned it would be a problem getting it to work with an early 60's car engine and mine is from a '61 Biscayne, so I opted for the short-shaft water pump instead. It does sit low down on the radiator the way it is installed and I had to use the flat back fan. Even at that, I only have about 1/4" of clearance, so I don't know if the larger fan you mentioned would fit or not. Also, the system didn't take the full 15-16 quarts when I filled it. I was able to get in about 12 quarts, although it might have gone down a little on the level before I had a chance to fill it on up. Once it started overheating, I shut it off and found that about a gallon (maybe a little more) had come out the overflow into a pan under the truck. Guess I'll try the burping first and see if that fixes the problem. If it doesn't I'm not sure where to go next. I would be interested in hearing why the adaptor plate won't work on the car motors.

The adaptor plate will work on any 235 from 55-62, whether it be a car or truck motor. I tried the so-called "short pump" and it failed to give me adequate pump snout/radiator clearance to run anything but the puny stock fan, kept the fan down low so that I had interference problems with the fan/harmonic balancer.

As I mentioned before, the adaptor plate/early pump/5 blade fan has proven to be the cure for all of the cooling problems we experience with the later model 235 engines in the AD trucks.

If nothing more, fill your engine through the thermostat housing, install a 180 thermostat to slow the flow of coolant through the radiator, fill the radiator and give it a shot. If you have overheating immediately you need to run a radiator pressure test to see if you don't have a leaking head gasket that is pressurizing your cooling system and belching out your coolant. You can sometimes get an idea by topping off the radiator, pinch the overflow hose to you can fill it all the way up to the top of the neck....run the engine at fast idle and watch for big soapy looking bubbles that smell of gasoline. A bad head gasket between the cylinder and the water jacket is not that uncommon of a problem, especially in an engine that has run hot.

Hopefully, filling the system completely and adding the thermostat will bring your overheating problem under control. I've outlined the best fix to insure you'll solve ALL your cooling problems. The choice is yours....

Dave

Okay, I'll give it a shot and see if the burping does the trick. If it doesn't, then looks like I'll be looking at the adaptor plate. I'm a little nervous about drilling holes in the block, but sounds like the directions that come with the plate are forthright enough. I'm hoping I don't have to go that route though. Thanks Dave.

I had the impression that the radiator cap should be left off when burping the cooling system. Is this wrong?
My 235 doesn't overheat now but the radiator leaks at the top and after getting it fixed I'll be going thru the same process of filling and burping.

The saga continues. I pulled a heater hose to allow the system to burb. Didn't hear any air, but the coolant flowed at the hose when I removed it. This was with the radiator cap off. Now here is what happened next. I paid a little closer attention to what was going on this time. I watched the gauge. No coolant coming out the overflow. The upper tank stayed cold to the touch until the gauge hit about 180 - 200 degrees. When the thermostat opened, the upper hose was hot and the tank got hot, but as soon as the coolant hit the radiator through the upper hose, it went right out through the overflow. I don't know if this means the thermostat is defective and not opening early enough, if the thermostat is too high of a temp unit for the truck, if there is still air in the system or what. It wouldn't seem like the fan is the culprit, but I don't know much about cooling systems. The fan is putting out really good air, but it all seems backwards to me. The flat surface of the fan faces the radiator, but the way it is designed, it can't be turned the other way. Seems like all of the air flow would be going back toward the engine and not toward the radiator to cool it. Anyway, hopefully this additional information will shed some light on the fix for it. Thanks guys. Jim, I think you are right about the cap needing to be off to burp the system.

I forgot to ask something. Dave, you mentioned using the adaptor plate along with the original water pump. But I replaced the original with the short shaft pump because the original wouldn't allow the fan to clear the radiator. I was under the impression that the adaptor plate raises the fan to the center of the radiator, but it seems this would also reduce the distance between the block and the radiator by 1/8th to 1/4". If that is the case, how can you use the original pump which lacked the clearance needed? What am I missing?

Disregard what I said about the flat fan. I went back and looked and it has more of a canted surface than I thought and isn't flat.

Rick,
The fan is designed to pull air through the radiator, not blow on it. It sounds like your not getting circulation of the coolant. When the t-stat opened and let hot water through to the radiator, cool water should enter the engine at the same time maintaining a balance, not just dump out the overflow. Wrong rotation water pump maybe?

Here's an update. I pulled the thermostat and replaced it with a 160. Before installing, I drilled two 1/8" holes in the flat area and then filled with coolant through the thermostat opening as Dave recommended. On startup, I immediately noticed the top hose and the top of the radiator warming up. I confirmed circulation inside the radiator and then let it run for about 10 minutes or a little more. The bottom radiator hose was warm as water went back into the engine and hot coming out the top. The temp gauge went to about 140 or so, but seemed to hover in that area and no water coming out the overflow. So it appears, at least, that the problem was resolved with the new thermostat and drilling the holes. Probably had air in there somewhere to boot. I didn't run it longer, but don't think I'll need to at this point because the coolant circulation appears to be doing what it is supposed to do. Thanks one and all for the posts and helping me through this.

Glad to hear you've got it under control. However, a 160 thermostat is not going to get your engine temperature up to it's optimum operating temperature. It may seem like a good idea to run a "cooler" thermostat but in the long run, it will be reflected in excessive cylinder wall wear, oil dilution with fuel and oil contamination with condensation.

Now that you've got your overheating problem sorted out move up to the 180 thermostat and your engine will run more efficiently.

Rick....to clarify...the adaptor plate is used in conjunction with an "early" 41-53 216-235 waterpump. Using this combination even with a 5 blade fan will give you adequate clearance and an engine that runs efficiently.

Dave

Thanks for the advise, Dave. I wasn't aware that a 160 thermostat would make that muich of a difference, but it stands to reason. I had a Dodge a few years ago that wouldn't heat to optimum temp and condensation build-up trashed the engine over time. I will change it out to a 180 now that I know the problem is solved. Thanks again.