coolent cap mod

[brent777]

On my nissan pickup It was leaking coolent
So I did the old trick when you take the coolent cap half way off
So pressure does not build up and that helps it not leak.
But when I did this I was looking at
The scan gauge and it seemed that I got better mpg but I want to
Ask if any one has done this?

Most cooling systems are 13 to 16 psi so maybe if your not makeing it build up pressure it will lighten the load on the motor? Or so I think

[brucepick]

Re. looking like mpg is up -
As long as there's enough coolant in the system, the thermostat etc. would keep the same temperature regardless of whether the system is sealed or not. So efficiency would stay the same.

But if coolant level was dropping, the ECT sensor would pick up different readings if the sensor is not covered as it should be. Would likely read hotter as it's picking up temperature from the (now drier) head it's screwed into. Might influence the computer to adjust operating parameters - more rich, more lean, who knows?, compared to regular operation when the sensor is flooded.

Losing coolant = there's a leak somewhere; you'll have to solve that or at least keep the system topped up.

Sealed system = it creates pressure, which means the water will boil at a higher temperature than without pressure. My guess is that without pressure it won't spray out as violently, but it will boil at a lower temperature. You won't see puddles etc. because it's boiling/steaming off, not spraying. I think you'll lose it more slowly with cap off due to when its under pressure, the pressure probably blows out a bigger quantity of water.

[brent777]

I have the leak fixed now btw and I did add and keep as much coolent in it as I could
And your right about the coolent steeming off. But I have a idea there is a spring in the
Coolent cap I could remove and keep a little bit less coolent in the system and keep the
pressure from building up with out it steeming off

[mcrews]

check to see if there is dirt/road dust built up in the radiator. I was clueless and checked EVERYTHING....including replacing the water pump(unneeded).
Turned out that road dust from driving on ranch roads 4 times a yr clogged up my radiator vanes.

And I'm a guy who spray cleaned his engine bay at least once a month.

[oil pan 4]

The radiator cap pressureizes the cooling system.
Pressureized coolant prevents nucleic boiling which causes hot spots to form on cylinder heads, hot spots cause cracks.
Pressure also it keep the coolant pump from cavitating.
It doesn't seem like a good idea to me.

[brent777]

Originally Posted by oil pan 4

The radiator cap pressureizes the cooling system.
Pressureized coolant prevents nucleic boiling which causes hot spots to form on cylinder heads, hot spots cause cracks.
Pressure also it keep the coolant pump from cavitating.
It doesn't seem like a good idea to me.

After reading that ya it is a bad idea

[nbleak21]

Originally Posted by oil pan 4

The radiator cap pressureizes the cooling system.
Pressureized coolant prevents nucleic boiling which causes hot spots to form on cylinder heads, hot spots cause cracks.
Pressure also it keep the coolant pump from cavitating.
It doesn't seem like a good idea to me.

Awe, you beat me to it!!!

I'm with Oil Pan on this one, Brent. But your observations make me wonder whether there may be a slight difference between using EGW & PGW in our engines.

[nbleak21]

Originally Posted by nbleak21

But your observations make me wonder whether there may be a slight difference between using EGW & PGW in our engines.

As quoted from Wiki: Antifreeze - Wikipedia, the free encyclopedia

"Ethylene glycol has desirable thermal properties, including a high boiling point, low freezing point, stability over a wide range of temperatures, and high specific heat and thermal conductivity. It also has a low viscosity and, therefore reduced pumping requirements."


And there we have it! guess I'll be sticking to the green stuff for now. shucks, thought I might have been onto something with the PGW (As I would like to be more environmentally friendly) :/

[oil pan 4]

Prestone lowtox was Propylene glycol based but they discontinued it due to low sales.

[Christ]

If you remove the spring from your rad cap, you're effectively leaving the overflow circuit open. That's all.