Coolant expansion tank boiling

[Emanuel]

Originally Posted By: PeterPolyol
Having no thermostat is bad news. It not only regulates flow to the rad but when it opens, it closes the bypass circuit. No thermostat means the bypass is fully open along with the radiator and so coolant flow is unpredictable. Find a tstat asap, even a used one if you have to...

I will look for a tstat, but I had to remove the heater core recently, I put a hose between the heater core ports in the engine, shouldn´t this eliminate any problems with the bypass flow?

 

[Emanuel]

Originally Posted By: Ducked
The usual "First World" advice is to get a chemical test for combustion gases. Dunno if that's available here (in Taiwan) or in Venesuala, or how I would ask for it here, or how much it'd be likely to cost.

There isn´t a coolant chemical test avaible, but the coolant looks as clear as the day I put it. I would think that the combustion gases would turn the coolant dark.

 

[zeng]

Faulty cap not holding up pressure, OP has no overheating as yet.

 

[Emanuel]

Originally Posted By: Miller88
Why was the thermostat removed?

Venezuelan mechanics are crazy, they think that because we live in a hot climate cars don´t need a tstat. The original tstat lasted 12-14 years and then we put a aftermarket one that failed 1 year later, we decided to not use tstat anymore but know I have learned that the car does need it even here in the tropic

 

[Emanuel]

Originally Posted By: vwmaniaman
Is the electric fan running>
Yes, intermently when the car is standing still

 

[Emanuel]

Originally Posted By: zeng
Faulty cap not holding up pressure, OP has no overheating as yet.

So do you think that only putting a new radiator cap and continuing without a tstat my weird overheating will stop?

 

[HoosierJeeper]

I think it would be a step in the right direction. Probably one of the less expensive options.

 

[mightymousetech]

Originally Posted By: OneEyeJack
The thermostat slows the coolant down so that it spends enough time in the radiator to cool down.

Many also control a bypass circuit as suggested above.

Can you use the Internet to get one from Florida? Working out getting one will be cheaper in the long run than paying for the damage in the short run.


It does not slow down the coolant, it increases the pressure in the block, raising the local boiling point. Without a thermostat, the coolant will boil in the block and the head.

OP, you NEED a thermostat. Doing anything else will not fix the problem.

I feel we have already discussed this?

 

[mightymousetech]

Originally Posted By: Emanuel
Originally Posted By: zeng
Faulty cap not holding up pressure, OP has no overheating as yet.

So do you think that only putting a new radiator cap and continuing without a tstat my weird overheating will stop?


No.

 

[meep]

It will not boil if the system is holding pressure and you have decent antifreeze in there. If it's boiling, there is a slow leak that is allowing the cooling system pressures to drop. Once enough has dropped during the drive, the coolant can begin to boil. once the car sits, coolant is pulled back in from the bottle, allowing your next drive cycle to be normal until enough pressure bleeds off and it repeats.

you have a leak in your system. could be a water pump, could be a faulty rad cap, could be the beginning of a head gasket problem.

-m

 

[zeng]

Originally Posted By: mightymousetech
Originally Posted By: OneEyeJack
The thermostat slows the coolant down so that it spends enough time in the radiator to cool down.

Many also control a bypass circuit as suggested above.

Can you use the Internet to get one from Florida? Working out getting one will be cheaper in the long run than paying for the damage in the short run.


It does not slow down the coolant, it increases the pressure in the block, raising the local boiling point. Without a thermostat, the coolant will boil in the block and the head.

OP, you NEED a thermostat. Doing anything else will not fix the problem.

I feel we have already discussed this?

Diverting coolant flow pathways either through the radiator or bypass radiator all together is the job of a thermostat, not radiator cap.
Increases coolant system pressure, hence raising system coolant boiling point, is the job of a radiator cap, not that of a thermostat.

 

[cjcride]

Originally Posted By: mightymousetech
Originally Posted By: OneEyeJack
The thermostat slows the coolant down so that it spends enough time in the radiator to cool down.

Many also control a bypass circuit as suggested above.

Can you use the Internet to get one from Florida? Working out getting one will be cheaper in the long run than paying for the damage in the short run.


It does not slow down the coolant, it increases the pressure in the block, raising the local boiling point. Without a thermostat, the coolant will boil in the block and the head.

OP, you NEED a thermostat. Doing anything else will not fix the problem.

I feel we have already discussed this?
We have a Winner!

 

[zeng]

Originally Posted By: mightymousetech
Originally Posted By: Emanuel
Originally Posted By: zeng
Faulty cap not holding up pressure, OP has no overheating as yet.

So do you think that only putting a new radiator cap and continuing without a tstat my weird overheating will stop?


No.

Yes, replace the faulty radiator cap (that's unable to hold pressure) with a new one will raise the system pressure, hence boiling temperature of the coolant system as intended.
A thermostat's function is to promote quick heating up of circulating coolant while cold for increased combustion efficiency, among others.

 

[OneEyeJack]

Originally Posted By: Ducked
Originally Posted By: OneEyeJack
The tjavascript: void(0)hermostat slows the coolant down so that it spends enough time in the radiator to cool down.



This seems very unlikely.

I'd think the radiator will remove heat at a rate determined by the air flow from the fan plus forward movement and the temperature differential between the coolant and the air.

If the coolant goes around faster, the temperature differential will be maintained at a higher level, so more heat will be removed.


No matter what the airflow might be it takes time for the coolant to reject the heat. If the coolant is flowing too fast a hurricane of airflow won't help.

It's just that simple. Most thermostats even when completely open restrict the flow just a bit. In some cases, it helps to keep air pockets from forming upstream. Mess with the design and you probably won't improve things at all.

 

[Ducked]

Originally Posted By: OneEyeJack
Originally Posted By: Ducked
Originally Posted By: OneEyeJack
The tjavascript: void(0)hermostat slows the coolant down so that it spends enough time in the radiator to cool down.



This seems very unlikely.

I'd think the radiator will remove heat at a rate determined by the air flow from the fan plus forward movement and the temperature differential between the coolant and the air.

If the coolant goes around faster, the temperature differential will be maintained at a higher level, so more heat will be removed.


No matter what the airflow might be it takes time for the coolant to reject the heat. If the coolant is flowing too fast a hurricane of airflow won't help.

It's just that simple.


IMO, it's just that simply wrong. I say this because it simply doesn't make any sense.

The other stuff (design change, bubbles, bypass) you might be right, dunno.

(Well, probably not the bubbles)

 

[mk378]

Even with no thermostat, the dash gauge should be going up some off of cold with the car sitting still. The system will heat up until the fan thermostat starts the fan. If the gauge never moves it may be broken or disconnected, and you don't know the actual engine temperature.

 

[mightymousetech]

Originally Posted By: OneEyeJack
[

No matter what the airflow might be it takes time for the coolant to reject the heat. If the coolant is flowing too fast a hurricane of airflow won't help.

It's just that simple. Most thermostats even when completely open restrict the flow just a bit. In some cases, it helps to keep air pockets from forming upstream. Mess with the design and you probably won't improve things at all.


The higher the flow rate of the coolant, the greater the heat transfer. Period.

 

[The motor guy]

Originally Posted By: eljefino
It could be the radiator cap is no good. This keeps pressure on, and prevents boiling.

Are you running 50/50 coolant or is there more water in there?

I'd say, yeah, you're overheating.

Maybe the water pump is no good?

If you have bubbles in the upper hose, your radiator fan should be running, and you should feel the car throwing off a lot of heat if you stand by the driver's door. If it isn't, you aren't getting water flow to or through the radiator, the fan is weak, etc. Similarly, turn on the heat inside and run the fan high, it should roast you out of there.


This is correct, an increase of pressure increases the boiling point and a vacuum also decreases the boiling point.

 

[Emanuel]

Originally Posted By: mk378
Even with no thermostat, the dash gauge should be going up some off of cold with the car sitting still. The system will heat up until the fan thermostat starts the fan. If the gauge never moves it may be broken or disconnected, and you don't know the actual engine temperature.

My coolant gauge IS working, it goes to operating temp when I´m driving in the city traffic but goes to a very low angle when I´m on the highway

 

[Emanuel]

Originally Posted By: zeng
Faulty cap not holding up pressure, OP has no overheating as yet.

I don´t think this is the problem, I have a new radiator cap