My 160,000 mile 2001 2.3l ranger was leaking coolant slowly (never found leak) and showing bubbles or boiling in coolant tank. Then it blew and I had water pump and radiator ( due to melting) replaced.
Now runs great but...still bubbles or boiling in coolant tank.
Dash heat gauge shows normal.

Worried boiling in coolant tank will eventually ruin something.

Thinking it may not be boiling but due to head gasket?
Help.
Dan

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2001 ford ranger, 2.3l manual transmission.
Color black.
150,000 miles

if your rad fluid has proper amount of antifreeze good to 260 degrees then you have a possible head gasket issue. check plugs and do compression check to start.

Thank you. I'll do it tomorrow and post esults. Appreciate the help.
Dan

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2001 ford ranger, 2.3l manual transmission.
Color black.
150,000 miles

Bad radiator cap not holding any pressure? Without pressure to keep the heated coolant in a liquid state, the coolant will "bubble"- the bubbles are coolant that went above 212 degrees when in contact with a hot surface in the block.

Go to advance auto and rent a coolant system pressure tester. The kit I rented was $200, but you get it back when you return it. Use the kit to test the cap- it should vent any pressure above ~16psi. If its less than 15, the cap needs to be replaced.

Also pressurize the cooling system at the degas bottle (the overflow looking tank that the radiator cap screws onto). You want to put 16psi of pressure on it, then wait- you shouldnt lose more than 1-2 psi overnight (~8 hours). Also consider that about ~1psi will be lost as the hoses settle/expand, so dont be alarmed when 30 minutes later its 15 instead of 16psi.

If you lose more than that, see if you can tell where the coolant is leaking. Common places include: 1) water pump shaft seal 2) heater control valve 3) plastic tee under intake manifold drivers side (if cracked) 4) radiator plastic tanks 5) upper/lower radiator hose. You do NOT have to worry about coolant leaking at the intake manifold gaskets, egr valve, or timing cover.

Start there and report back with what you find.

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

Did compression test and all were within a couple of pounds of each other. 206, 202, 204, and 208. I put new plugs and wires on.
So,..no head gasket I presume. Is thermostat a,possibility or is it air bleeding?

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2001 ford ranger, 2.3l manual transmission.
Color black.
150,000 miles

Prolly a leak or a bad radiator cap. Out of curiosity, was the engine cold or hot/warm when you did the compression check?

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

Just keep in mind that for air to get in, coolant has to go out. Fixed volume, and if the head gasket is ok, the coolant has to go somewhere.

It dawned on me as well- we never asked specifically WHEN the bubbles show up. Is it right away on a cold start and all through the run cycle, or only when the engine gets warmed up?

If its the latter, I really want to stress that you should test the radiator cap. Something so small and stupid, but it can cause you to throw all types of money and parts at the cooling system for no reason.

If it does it right from cold start, than it has to be getting the air from somewhere- thats likely to be a head gasket.

With your compression readings Im willing to bet it only does it when warmed up, and id bet money its a weak spring in the radiator cap.

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

This is a relatively common issue with the Duratec cooling system. Here's what you need to do: take the cap off of the degas bottle (thing the coolant goes into) and carefully examine the threads and everything in that area. More likely than not, there are hairline cracks down there. When the system is under pressure, they'll expand just enough to start relieving pressure. This will lower the boiling point of the water, which is the bubbling you're seeing.

I actually had the exact same issue with mine. Hypothetically, you should be able to coat those hairline cracks with some JB weld to seal them up. I tried that, but it didn't work for me. Then again, it was a really crappy application on my part, so you might have better luck. In my case, I just gave up and bought a new one. It's $50, which is really annoying. But hey, what can you do? I found the best deal on Parts Geek. Best of luck!

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2003 Ford Ranger XLT
2.3L I4 Duratec DOHC, 5R44E 5-speed auto, RWD, 7.5" Open w/ 4.10 Ratio, Gibson split-rear catback
Sonic Blue Pearl with dark gray trim

Yeah, sadly I think im going to have to replace my degas bottle before too long. For now, it holds pressure and has no cracks at the threads/cap area. However, it looks like someone took it loose and jammed it up against the fender lip because it has a gouge out of it there. Carefully examined and am virtually certain the trucks never had a front end collision, but I suppose its possible it did and the gouge happened then (frame is straight and alignment is good though).

Ive been meaning to get to a junkyard, but considering the issues these bottles have, I prolly should just drop the 50 to get a new one. All hail the duratec- a super reliable 4 cylinder engine with a shitty-everything-else-under-the-hood design.

Any updates OP?

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

Any update? Mine is doing the same thing. Lower radiator hose isn't getting circulation I think. It stays cold. Could bad radiator cap keep coolant from making it to lower radiator hose?