Overheats and pops the cap on the coolant overflow

snorztnt · Feb 9, 2018

truck parked on a 10 degree down angle with the front being lower than the back. Did a radiator flush and ever since then have had overheating problems and gurgling sounds in the radiator when I park. Also it keeps popping the cap on the coolant overflow resavour...resivore... the coolant holder. Evidence of splashed cooler outside of it. Checked level at work (level parking garage) and found it at least a quart low, (guessing by how much i had left in the gallon jug container). has started getting hot while on my 45 min commute home, but a quick gun of the engine brings it back down. Welcome any comments, thoughts, suggestions.
99 Ford Ranger XLT
145k
3.0 v6

ericbphoto · Feb 9, 2018

My first guess is you have an air bubble in the system. I believe I have read several places around here that the heater hoses are a high point ok n the system that like to trap air. By having the truck pointed downhill when you filled it, you made that problem even worse.

A while back, I installed a flush tee in the hose going to my heater core. The tee comes in the flush kit from Prestone. Now, when I refill my coolant system after it has been drained, I fill the radiator to the top. Remove the cap from the tee. Then I start the engine so the water pump is pushing coolant to the heater. Some coolant comes out of the tee. But I put the cap back on the tee while the coolant is coming out. That way, I know I don't have an air bubble there. Then I keep topping off the radiator while the engine is running. (Keep the radiator cap off so you don't build pressure. Eventually, the thermostat opens and the air in the upper radiator hose burps out. Then I can finish filling the radiator.

This method makes a mess and wastes a bit of coolant. But I haven't had any air bubble problems. Others may share better techniques.

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cbxer55 · Feb 9, 2018

Probably kills a lot of them stray neighborhood cats too. You know, the ones that piss on your tires and leave them nice yellow stains that need to be cleaned. :annoyed:

ericbphoto · Feb 10, 2018

I have no desire to kill the stray cats. But I hate all those lousy dirty paw prints on top of the truck. Uncle Randy's dog comes over and pees on my tires. I watch him like a hawk because I'm afraid that one of these days, he'll come over while i'm working on the truck and pee on my tools when I'm not looking. That would make me very, very unhappy. :annoyed:

I keep my dogs in the fence or on a leash.

Rearanger · Feb 11, 2018

snorztnt said:
Also it keeps popping the cap on the coolant overflow resavour...resivore... the coolant holder.

The reservoirs (spell check) have air vents in them, should not be overflowing unless you have super heated the coolant from a bad head gasket.

has started getting hot while on my 45 min commute home, but a quick gun of the engine brings it back down.

Either a bad water pump and/or bad clutch fan. How old is the WP?

I've never had a air lock problem on my ranger when refilling coolant. I will check level after refill and road run, then have to add maybe a quart.

snorztnt · Feb 13, 2018

Rapid temp changes.

Looking like the water pump, but have a question. .. radiator doesn't suck fluid BACK from the coolant resIvor and the temp swings from normal temp to high are fairly rapid, and slowing down usually makes it drop back to normal. Thoughts? Much appreciated.

Rearanger · Feb 14, 2018

snorztnt said:
.. radiator doesn't suck fluid BACK from the coolant resIvor

If the coolant expands violently with boiling/bubbling then siphoning is broken and coolant will not be sucked back on cooling.

and the temp swings from normal temp to high are fairly rapid, and slowing down usually makes it drop back to normal. Thoughts?

Only thing I can think of is the engine heats more under load/speed and the WP flow cannot handle the extra heat load. Slowing down reduces the heat load so the WP can keep up.

How old is the rad?

snorztnt · Feb 16, 2018

Changed out the thermostat with a factory recommended temp replacement. And so far the level of fluid in the resivour has stayed steady, and no more temp swings. Still hear a gurgling sound but is at least 50 percent less noticeable than before.

Overheats and pops the cap on the coolant overflow

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