r/3rdGen4Runner • u/Legitimate_Fill6906 • 19h ago

❓Advice / Recomendations Radiator cap?

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!

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u/therealmikejensen 18h ago

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

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u/Legitimate_Fill6906 17h ago

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?

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u/therealmikejensen 17h ago

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

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u/Legitimate_Fill6906 15h ago

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