Cooling

[D35 Torpedo]

So I've been avoiding the elephant in the room. But with warmer weather coming, I can't avoid it much longer. I'm finding that the engine temp goes up and down as it pleases. When left to idle long enough, it really starts to creep up there. If I turn on the heater blower, it will pull the temp down. I suspect, by the way it acts, that there is no thermostat installed. But, why would it overheat? I've heard the argument that a stat slows the flow down to give the rad a chance to cool it. Not sure if that idea holds any water! It seems the rad needs a fan shroud or maybe I need to send it out to get cleaned. Thoughts?

[Sam Buchanan]

Looks like something is restricting water flow, maybe the radiator or water distribution tube? Or a bad water pump?

[Los_Control]

I will add that my engine had a overheating problem .... went straight to overheat.

I will add that my water distribution tube was plugged with hard water deposits.

Once I cleared it & flushed out the block, it would not warm up with no T-stat.

With a 180 T-stat installed, it would warm up & maintain steady temps for long periods of time.

 

I also pulled all the soft plugs & replaced them while working on it .... flushing the block at same time.

[D35 Torpedo]

36 minutes ago, Sam Buchanan said:

Looks like something is restricting water flow, maybe the radiator or water distribution tube? Or a bad water pump?

I'm want to assume the tube is good. The engine was rebuilt and only has 160 miles on it. Ill pop the cap off and see if i have good flow. I would think so because the heater core works well. 

 

31 minutes ago, Los_Control said:

I will add that my engine had a overheating problem .... went straight to overheat.

I will add that my water distribution tube was plugged with hard water deposits.

Once I cleared it & flushed out the block, it would not warm up with no T-stat.

With a 180 T-stat installed, it would warm up & maintain steady temps for long periods of time.

 

I also pulled all the soft plugs & replaced them while working on it .... flushing the block at same time.

 

I didnt think it would overheat without a stat. I think i will need to pull my rad and have it cleaned. While its out i will pull the water pump and take a look around.

[D35 Torpedo]

Ok guys I'm working on this issue today. From what I can tell, everything is normal. Help, insight, recommendations??? Someone has been in this pump as everything is rtv'd together. I can't get the distribution tube out. It's just tearing the metal. But it all seems really clean. I stuck a rod down it and there is no crud or blockage. I find it odd that the round hole in the head only has a small passage into the pump, and half of it is covered. Has anyone enlarged it? Also, there was no T-stat.

Edited March 26, 2023 by D35 Torpedo

[D35 Torpedo]

[kencombs]

IMHO, heat rising at idle is more indicative of reduced airflow coolant issues.  Our flathead idle really slow compare to most(all?) more modern engines.  Not much air happening there.

 

Quick check, assuming you have a fairly large fan in your home, sit it directly in front of the radiator, as close as possible and repeat the test.

[Sniper]

The small hole is the bypass, do not enlarge it.  No thermostat, RTV, etc tells me someone had a cooling issue before you.

 

Have the radiator flow tested, you can use the FSM method if need be.  Bet it's plugged up.  My 51 can idle all day long in 100+ degree heat and not have an issue.  Even before the electric fan conversion.

Edited March 26, 2023 by Sniper

[Los_Control]

The hole size is normal .... I have never heard of anyone modifying the hole in the years I have been here.

 

If the tube is clear, then that is not the problem.

 

Check the petcock on the block, down by the distributor or oil fill tube .... if you open it does coolant come out?

If not it is likely you have casting sand in the block ... the petcock is the lowest point and where all the sand settles.

This takes up space that normally would be filled with coolant. ..... Cleaning it would be equivalent to installing a larger radiator.

If the petcock drains, it is not clogged with sand.

 

You have the water pump apart, you can physically check it is working.

 

The only thing left is the radiator. .... Or T-stat

IMHO, if you disconnect the lower hose, you should be able to put a garden hose in top & turn it on at a fair pace.  It should not backup & overflow out the top.

 

.A clear radiator should flow a lot of water freely. ..... Also pay attention to how much crud & color of the water coming out of the radiator.

Probably can turn the hose on high enough to overflow .... then adjust it down slowly a step at a time til it does not overflow.

Then look at the flow from the hose, will give you a good visual of how much water your radiator can move.

 

Personally I would skip that test & just pull the radiator.

Turn the radiator upside down & insert the hose in the lower hose outlet, reverse the flow .... be surprised how much crud you can loosen and back flush it.

Spend a few hours with it just flipping the radiator from top to bottom til you get clear water running from it .... you should get a improved flow also.

 

When you put the radiator back in, then use a flush when you fill it. I filled mine with cleaning vinegar from the grocery store .... A gallon for $2 & has a higher acidity then cooking vinegar. Take it out for a drive, leave it in there for a week .... a very mild acid to clean the radiator as it sits, same time heat helps it along.

 

CLR is another option some have had good results with .... Then there is Cascade soap for your dishwasher. Gets the tough stuff without harming your brass or stainless steel pots.

 

You can take it to a radiator shop if you can find one. I have not been to a radiator shop in 30 years .... All our modern chemicals for cooling systems are for aluminum materials .... possibly not best choice for a 75 year old brass radiator. .... I dunno, is why I chose vinegar to clean mine ..... still too many leaks and had to replace it anyways.

[Sniper]

45 minutes ago, Los_Control said:

Turn the radiator upside down & insert the hose in the lower hose outlet, reverse the flow .... be surprised how much crud you can loosen and back flush it.

Spend a few hours with it just flipping the radiator from top to bottom til you get clear water running from it .... you should get a improved flow also.

 

This also works well for a weak heater core. 

[Los_Control]

Just now, Sniper said:

 

This also works well for a weak heater core. 

You know me, I'm too long winded anyways .....

I was thinking about the heater core .... I just was not going to bring it up.

I figured if the heater core is clogged, wont get any heat but will not cause the car to overheat.

 

My truck a heater was a option, I have a valve to turn off the flow to it in summer time.

Part of the cooling system, but would not cause a overheating issue.

[D35 Torpedo]

I had the heater core recored a couple months ago because it was leaking. Radiator flows good. Not a lot of crud coming out when I back feed it. I did it once already, about six months ago when I first put the car together. It looks like there is some white crud inside the core. Been throwing everything under the sink at it. First lye, now vinegar. Vinegar seems to be doing something. It's turning white. 

[Los_Control]

Is it a original radiator, or a modern replacement aluminum?

Only thinking that sometimes we do not buy a big enough replacement radiator. Today we have 2 core ... 3 core ... height width.

The originals were pretty bulky.

 

You mentioned there was no T-stat .... With all this trouble, I would try one of them a long time ago.

While most do not need one. Your engine is rebuilt, if the cylinders are bored the walls are thin .... you might need a Thermostat .... then still run warmer then normal.

 

If the head was shaved, you raised compression .... again it could run hotter then normal.

 

On 3/16/2023 at 9:34 PM, D35 Torpedo said:

I'm finding that the engine temp goes up and down as it pleases. When left to idle long enough, it really starts to creep up there. If I turn on the heater blower, it will pull the temp down. I suspect, by the way it acts, that there is no thermostat installed. But, why would it overheat?

  So I just read your post again ..... everything on your car checks out ..... But temps rise & fall as it pleases .... Your T-stat is not doing it's job.

Sticking open or sticking closed ..... then swaps again .... at some point in failure it will simply stay open or stay closed. .... not bounce around.

 

Always nice to know your complete cooling system is in good condition while you change the faulty T-stat  ???

 

Sometimes we go overboard checking for problems. For me a good cooling system in West Texas is a major concern .... I want to know everything is as it should be.

I have seen T-stats before fail in this manner.

[LazyK]

Just a thought

How do we know the accuracy on the gauge. 70 years on the gauge and sending unit. I think sometime we look for problems when the problem is ????.  My 51 seem to run hotter than I remember. After setting 35 years and a complete rebuild on the motor and new radiator. Before I panic I'm going to get a thermometer and stick it in the radiator, then I should know if it is my memory or something else.

[D35 Torpedo]

3 hours ago, Los_Control said:

Is it a original radiator, or a modern replacement aluminum?

Only thinking that sometimes we do not buy a big enough replacement radiator. Today we have 2 core ... 3 core ... height width.

The originals were pretty bulky.

 

You mentioned there was no T-stat .... With all this trouble, I would try one of them a long time ago.

While most do not need one. Your engine is rebuilt, if the cylinders are bored the walls are thin .... you might need a Thermostat .... then still run warmer then normal.

 

If the head was shaved, you raised compression .... again it could run hotter then normal.

 

  So I just read your post again ..... everything on your car checks out ..... But temps rise & fall as it pleases .... Your T-stat is not doing it's job.

Sticking open or sticking closed ..... then swaps again .... at some point in failure it will simply stay open or stay closed. .... not bounce around.

 

Always nice to know your complete cooling system is in good condition while you change the faulty T-stat  ???

 

Sometimes we go overboard checking for problems. For me a good cooling system in West Texas is a major concern .... I want to know everything is as it should be.

I have seen T-stats before fail in this manner.

I didn't build the engine. The way it was acting, I figured it didn't have a T-stat at all. Today my suspicions were proven correct. So I put an original stat in, the bellows type. I stove tested it first ofcourse. Well! I should've done that a while ago. The heater works better, It's holding operating temp, and fluctuating much less. I really think that was the problem. We will see on a hot day. An old timer friend of mine said a t-stat will keep the engine cooler. Because it slows down the coolant flow in the rad, allowing it more time to cool off. I've heard that before, but didn't have the experience to verify its validity. I'm glad I pulled it all apart. I got to replace all the rtv with gaskets, fix a belt alignment issue and verify the condition of the distribution tube. 

[D35 Torpedo]

2 hours ago, LazyK said:

Just a thought

How do we know the accuracy on the gauge. 70 years on the gauge and sending unit. I think sometime we look for problems when the problem is ????.  My 51 seem to run hotter than I remember. After setting 35 years and a complete rebuild on the motor and new radiator. Before I panic I'm going to get a thermometer and stick it in the radiator, then I should know if it is my memory or something else.

It's a mechanical gauge. They work forever. They can be adjusted. But since there aren't any numbers anyways, it doesn't really matter

[Sniper]

12 hours ago, LazyK said:

Before I panic I'm going to get a thermometer and stick it in the radiator, then I should know if it is my memory or something else.

 

I have a meat thermometer I bought just for this.

[Sniper]

10 hours ago, D35 Torpedo said:

Because it slows down the coolant flow in the rad, allowing it more time to cool off. I've heard that before, but didn't have the experience to verify its validity.

 

Lots of people think this.  Lots of people don't understand thermodynamics.  Group A is always part of Group B.

 

https://www.enginebasics.com/Engine Basics Root Folder/Engine Cooling.html

[D35 Torpedo]

3 hours ago, Sniper said:

 

Lots of people think this.  Lots of people don't understand thermodynamics.  Group A is always part of Group B.

 

https://www.enginebasics.com/Engine Basics Root Folder/Engine Cooling.html

That's an interesting article. The major question is the time component. With no T-stat, does the flow rate exceed the goldilocks zone? My thought is yes. I get that lowering the flow throught the rad, increases the cooling, but then slower coolant through the engine, increases heating. But if it is to fast, the cooling portion is to short, and the heat transfer portion is equally as short. Slow it down and the engine can transfer sufficient heat to the coolant. The rad can then get rid of it. It was engineered with a T-stat. The engineers flow tested it for optimum cooling. 

[kencombs]

1 hour ago, D35 Torpedo said:

That's an interesting article. The major question is the time component. With no T-stat, does the flow rate exceed the goldilocks zone? My thought is yes. I get that lowering the flow throught the rad, increases the cooling, but then slower coolant through the engine, increases heating. But if it is to fast, the cooling portion is to short, and the heat transfer portion is equally as short. Slow it down and the engine can transfer sufficient heat to the coolant. The rad can then get rid of it. It was engineered with a T-stat. The engineers flow tested it for optimum cooling. 

The red part is interesting.   first part results in a cooler flow into the block so that mostly offset the increased heating.   Net is probably a wash. 

 

Still think it's airflow, not water flow.

[Kilgore47]

One of the cooling problems with the P15 was the honey combs in the radiator were plugged with dirt dobber nests. There were lots of them. Pulled the radiator - cleaned out the dirt with a wire. Made a big difference. Doesn't over heat at idle now.

[D35 Torpedo]

3 hours ago, kencombs said:

The red part is interesting.   first part results in a cooler flow into the block so that mostly offset the increased heating.   Net is probably a wash. 

 

Still think it's airflow, not water flow.

 

1 hour ago, Kilgore47 said:

One of the cooling problems with the P15 was the honey combs in the radiator were plugged with dirt dobber nests. There were lots of them. Pulled the radiator - cleaned out the dirt with a wire. Made a big difference. Doesn't over heat at idle now.

The rad is spotless on the outside. You can see right through it. It is not honey combed, just straight tube and fin. All I did was straighten some bent fins and painted it. Everything is factory as far as sheet metal and grill goes. The front is designed like a giant air funnel. I had it out today and the heat stayed fairly consistant. 

[kencombs]

1 hour ago, D35 Torpedo said:

 

The rad is spotless on the outside. You can see right through it. It is not honey combed, just straight tube and fin. All I did was straighten some bent fins and painted it. Everything is factory as far as sheet metal and grill goes. The front is designed like a giant air funnel. I had it out today and the heat stayed fairly consistant. 

So, not the original radiator.  Got any idea how it compares to the original in capacity?

[D35 Torpedo]

4 hours ago, kencombs said:

So, not the original radiator.  Got any idea how it compares to the original in capacity?

It has the DPCD logo and part number on the top tank. Maybe recored?

[FarmerJon]

If I recall correctly,  the "HOT" on the factory gauge is only 212, due to the factory coolant not having a much higher boil point than plain water, and the radiator not being pressurized. Studies have shown that hotter (within reason) engine temps yield less sludge build up, less ring wear, and better efficiency (turning gas to HP).

Obviously, running a 210* stat might be a bridge to far, but a 180-190* with 40-50% mix would give you a safe margin with a good condition, stock system. However it might mean that your stock gauge reads closer to the "HOT" than without a thermostat.