Coolant expansion tank boiling

[Emanuel]

I have a 01 Corolla with almost 290k miles, it´s thermostat have been removed I know that I should buy and put one again but I can´t afford it and I will stick with the consequences, I live in Venezuela and hyperinflation is crazier than you will ever be able to imagine so please focus on the rest of the post: - The car doesn´t have any problems on under 60 minutes drives. - It doesn´t overheats in heavy traffic in the middle of day when the ambient temp and solar radiation are crazy. - After long journeys the coolant in the expansion tank is boiling and I can feel bubbles in the upper radiator hose. - In long journeys the coolant temp is very low because there is no thermostat. - The car has good torque and I have tested opening the radiator cap to see if there are combustion gases in the cooling system and everything looks fine, it doesn´t have a blown headgasket. Is my car overheating? Can a car overheat even when the coolant temp is very very low? Are bubbles in the upper radiator hose normal? Thanks

 

[tig1]

Blown head gasket?

 

[KneeGrinder]

Do you have an overflow bottle with a small hose line feeding it from the radiator just below the radiator cap? Do you, or have you added any coolant or water to the radiator? or overflow bottle? Bubbles are not ok. They are not normal.

 

[Emanuel]

Originally Posted By: KneeGrinder

Do you have an overflow bottle with a small hose line feeding it from the radiator just below the radiator cap? Do you, or have you added any coolant or water to the radiator? or overflow bottle? Bubbles are not ok. They are not normal.

I was confused when I said coolant expansion tank, it has a overflow tank. When the radiator cap reaches certain pressure the coolant goes into this overflow tank.

 

[Emanuel]

I think that the engine needs the thermostat because it creates a restriction so bubbles can form in the cooling jackets

 

[mk378]

Before each trip, when completely cold, open the radiator cap and confirm the radiator is full to the top. The expansion tank should be about 1/3 full, or to the "FULL COLD" line if it has one. If it stays cool on the highway, the radiator fan may not be working. That causes overheating when sitting still or in slow traffic.

 

[KneeGrinder]

Your goal will be to evacuate all air out of the coolant system. Like post above says, start with filling radiator upon every cold start. "No air bubbles around and cooling jacket or anywhere else"

 

[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.

 

[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...

 

[Ducked]

Originally Posted By: Emanuel

- The car has good torque and I have tested opening the radiator cap to see if there are combustion gases in the cooling system and everything looks fine, it doesn´t have a blown headgasket.

How do you know this? I have some evidence of bubbling into the expansion tank, and I suspect I have a blown head gasket, but its slight, intermittant and so far doesnt seem to be getting ant worse. Yesterday I tried working a plastic bag full of coolant into the overflow tank and everting it. The idea is that if its blowing combustion gases through the tank the bag will trap some of the bubbles. If its blowing steam, it won't, because the steam will re-condense. Tricky to get the bag to evert neatly so I dunno if it'll work. Yesterday it didn't seem to catch anything. 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.

 

[Ducked]

Venezuela Apologies; that was sloppy.

 

[Silk]

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...

This - if your thermostat has a poppet valve, it also controls the bypass circuit...coolant will be doing a loop in the bypass (often the heater) and not going through the radiator.

 

[Chris142]

Replace the radiator cap.

 

[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.

 

[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.

 

[SwampSurvivor]

Why was the thermostat removed?

 

[Tman220]

Originally Posted By: OneEyeJack

The thermostat slows the coolant down so that it spends enough time in the radiator to cool down.

^^^But doesn't this mean the coolant would spend more time in the engine and heat up more? This is often repeated, worn out, wives tale, that defies the laws of thermodynamics. The OE thermostat does indeed have a poppet that closes off the bypass when it opens. The problem is your thermostat doesn't just regulate when hot coolant leaves the engine to go to the radiator, it also regulates HOW coolant flows through your engine to effectively cool it. Without proper flow hot spots can develop inside the engine where localized boiling can occur. But if you are boiling into the overflow tank something else could be going on. You never said why the thermostat got removed in the first place?

 

[Emanuel]

Originally Posted By: mk378

Before each trip, when completely cold, open the radiator cap and confirm the radiator is full to the top. The expansion tank should be about 1/3 full, or to the "FULL COLD" line if it has one.

This could be the problem, the radiator doesn´t stays full all the time. I think I need a new radiator cap

Originally Posted By: mk378

If it stays cool on the highway, the radiator fan may not be working. That causes overheating when sitting still or in slow traffic.

It isn´t overheating sitting still, only after long highway driving

 

[vwmaniaman]

Is the electric fan running>

 

[Emanuel]

Originally Posted By: eljefino

It could be the radiator cap is no good. This keeps pressure on, and prevents boiling.

I had a faulty radiator cap before, I replaced it and know I can feel that the upper radiator hose has more pressure

Originally Posted By: eljefino

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

Premixed coolant

Originally Posted By: eljefino

Maybe the water pump is no good?

I would think that if the water pump is bad the car would overheat standing still, not in long highway driving.

Originally Posted By: eljefino

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.

That´s the weird thing about my case, the coolant gauge never shows a overheat condition, nor the radiator fan switch