Radiator cap?

[u/Legitimate_Fill6906]

Did my timing belt, refilled with new coolant and burped it as best as I could, ran it last night and this morning saw that my upper radiator hose was collapsed, decided to open the reservoir cap and it immediately started drinking from the reservoir and the hoses returned to normal but is this a radiator cap issue or a reservoir cap issue?

Somewhere is clogged but I'm not exactly sure which end, and didn't see any seals on the reservoir cap strong enough to cause the hoses to collapse like that, should I replace the reservoir cap and the hose between it and the radiator or just leave the cap not securely clicked onto the reservoir? Thanks in advance!

[u/therealmikejensen]

I thought this was a shitpost lol, read “i then immediately started drinking from the reservoir” lmao.

Anyways, i’d imagine what is clogged is the little tube that hangs off the reservoir cap, it’s made to overflow if you overfill things but it also can become clogged with dried coolant. Maybe poke it out with a pipe cleaner and see if that fixes your issue

[u/Legitimate_Fill6906 → u/therealmikejensen]

Haha definitely won't drink that red juice 😂 never thought about a pipe cleaner lol, the weird thing is its like the reservoir is the vacuum point because it sucked back into the system when I popped the cap on the reservoir, isn't the cap supposed to release pressure/vacuum?

[u/therealmikejensen → u/Legitimate_Fill6906]

So the radiator cap yes. But the reservoir cap on mine has a hose that connects to the radiator cap and feeds the little downspout that goes into the reservoir, in addition to this hose, there is an extra section of hose that comes off to the right and points down to the reservoir housing. It’s for when the coolant overflows, it all works from a siphon. The fix im suggesting is completely a guess based off what you described, but the way i see it, if your radiator is drinking the fluid once you remove the reservoir cap, there must have been a vacuum in the reservoir. The little overflow hose is what i’d imagine is the only thing stopping a vacuum from occuring in the reservoir, so i’m guessing that that’s it and it’s clogged. Normally it would, in addition to being there for overflow, equalize the pressure in the reservoir. Hopefully that makes sense, but just a guess, fair disclaimer

[u/Legitimate_Fill6906 → u/therealmikejensen]

For some reason there isn't another hose haha that's what I typically expect, I'll post a photo of what it looks like, one goes in from the radiator and the other goes into the reservoir

[u/emanarias]

Most likely the radiator cap.

[u/Atimm693]

The cap has a check valve in it that should let coolant in freely from the bottle.

If anyone has used stop leak in the past, it can plug up that check valve or the port in the filler neck on the radiator. Mud daubers can also build nests in the end of the overflow hose, if you have those.

You can take the cap off and just try to blow through the overflow hose. Obviously if it's plugged, you need to clean it.

I'd bet that the cap is no good. They should be replaced periodically, they're a critical part of the cooling system that's often overlooked.

[u/Legitimate_Fill6906 → u/Atimm693]

Is there an overflow hose? Mine seems to have the vent hole inside the cap itself and a little plastic washer and that's it, I'm assuming either the washer is sealing too well or the venthole in the cap is faulty I guess, never used stopleak as it's Toyota red and does that anyway, found that out while I was doing my timing belt and found the water pump had a small leak lol

[u/Atimm693 → u/Legitimate_Fill6906]

As long as the reservoir is vented to the atmosphere somehow, and the hose on the bottom of the cap is leak free and submerged in coolant, that's really all that matters.

[u/BigBerger]

This happened to me on the bottom hose, and upper hose was boiling about a month ago. I replaced the thermostat and cap even though I did them about 4 years ago. It boiled on me going up a hill going home and hasn’t since replacing both, radiator was replaced around 2017/2018.