Engine running too cool?

[D2Cat]

We most often hear issues of engines running too warm. Here's a statement about engines running too cool and how it was remedied. Simple solution.

Caterpillar had a heating problem with the D330 and D333 engines. The coolant circulates too fast and was not cool enough going back to the engine from the radiator. The way they solved it was weld a washer in the thermostat neck. The later 3304 and 3306 engines the neck opening was smaller to solve the heating problem. I don't remember what size washer they used. Somewhere I have a D3306 thermostat neck. If I can find it I can measure the opening.

Early model Cats had an oil pressure gauge that got owners concerned about pressure being too low. Many engines were rebuild and the problem still seemed unchanged. The solution was Cat changed the display on the gauge. They simply used colors to indicate proper operating range, and no numbers. The engines were fitted with a low pressure/ high volume pump and those low numbers were a concern to the owners.

 

[Henro]

We most often hear issues of engines running too warm. Here's a statement about engines running too cool and how it was remedied. Simple solution.

Caterpillar had a heating problem with the D330 and D333 engines. The coolant circulates too fast and was not cool enough going back to the engine from the radiator. The way they solved it was weld a washer in the thermostat neck. The later 3304 and 3306 engines the neck opening was smaller to solve the heating problem. I don't remember what size washer they used. Somewhere I have a D3306 thermostat neck. If I can find it I can measure the opening.

Early model Cats had an oil pressure gauge that got owners concerned about pressure being too low. Many engines were rebuild and the problem still seemed unchanged. The solution was Cat changed the display on the gauge. They simply used colors to indicate proper operating range, and no numbers. The engines were fitted with a low pressure/ high volume pump and those low numbers were a concern to the owners.

To me the above description doesn’t make sense. I think the blue text should be replaced with something like was too cool going back to the engine.

 

[6869704x4]

To me the above description doesn’t make sense. I think the blue text should be replaced with something like was too cool going back to the engine.

There is some validity to that. If the fluid goes through the radiator too fast it doesn't have time to cool off.

 

[Henro]

There is some validity to that. If the fluid goes through the radiator too fast it doesn't have time to cool off.

Yes, but in that case the engine would run hot, rather than too cold.

 

[Henro]

Yes, but in that case the engine would run hot, rather than too cold.

I’m trying to make some sense of this. I found it very interesting. Seems like the solution would’ve been to change the thermostat to one that opens at higher temperatures…

Sounds like the water pump was so powerful that the ability for a thermostat to control the temperature of the engine was not sufficient. Installing a restriction in the Flow path may have been needed to bring things into balance where the thermostat could do its job properly.

 

[6869704x4]

I’m trying to make some sense of this. I found it very interesting. Seems like the solution would’ve been to change the thermostat to one that opens at higher temperatures…

Sounds like the water pump was so powerful that the ability for a thermostat to control the temperature of the engine was not sufficient. Installing a restriction in the Flow path may have been needed to bring things into balance where the thermostat could do its job properly.

Yes, there is a balance, the pocket protector engineers should be able to figure that out. This works for air also. I won a bet with a friend. After replacing compressor and dryer in a Ford truck we had it blowing pretty cold with the fan on max. Pressures in specs. The bet was if we turned the fan to low it would blow colder. I won, it was ten degrees colder. The air coming through slower had more time to cool off.

 

[whitetiger]

The coolant circulates too fast and was not cool enough going back to the engine from the radiator.

The old Ford flathead V-8 engine was the same as the old Ford, which had two water pumps and no thermostats. Their cure was to insert a washer into the radiator hose and put a hose clamp on the hose to secure it.

 

[Lil Foot]

I had a '69 Mach 1 with a 390 HO that needed a new radiator & water pump.
I replaced the 2 core stock radiator with a new 4 core radiator, new water pump, hoses, coolant, and thermostat.
It immediately began running hot & sometimes overheating.
I could not figure it out until a guy from the local Shelby owners club asked me where I got the thermostat.
When I told him I bought it at a local auto parts store, and he laughed his A$$ off.
When I asked him what was so funny, he told me to go to the Ford dealer and buy a thermostat for my specific engine, model, and year.
I did, and found the factory thermostat had a restrictor bell on it to slow the coolant circulation down.
The coolant was circulating too fast to cool off.
The new thermostat solved the problem completely.
It was a new one on me.

 

[TheOldHokie]

There is some validity to that. If the fluid goes through the radiator too fast it doesn't have time to cool off.

In general the mass unit rate of heat exchange has nothing to do with rate of coolant flow.

In general, if the coolant flows faster the total volume (mass) of coolant moving through the system increases and more heat is exchanged per unit time.

There are a lot of other competing factors that play into both the rate and magnitude of heat exchanged in an automotive cooling system so changing things can sometimes produce unexpected results.

Dan

 

[6869704x4]

I knew somebody smarter than me would come along

 

[lugbolt]

After replacing compressor and dryer in a Ford truck we had it blowing pretty cold with the fan on max. Pressures in specs. The bet was if we turned the fan to low it would blow colder. I won, it was ten degrees colder. The air coming through slower had more time to cool off.

There's more to it, but that is part of it