Upper Radiator Hose --- Swells then Pops Off

[Evan]

My upper radiator hose swells and pops off.

This started happening after I replaced intake, pcv, water pump, and associated seals and gaskets.

Coolant temp stays fine but the upper hose just swells and pops off every time I think I have the system bled properly.

The heat works fine... the lower hose and lower radiator get hot.. there is no coolant in the oil.

What could be causing this buildup?

[Rus]

Check the cap on the coolant reservoir. If it isn't letting hot coolant escape into the reservoir, you could be building up way too much pressure in the system.

[Evan]

thanks... i've been checking and rechecking everything... especially the thin line to the expansion tank.

i'm mystified

[632 Regal]

get a new hose dude

[Boone.Msi]

get a new hose dude

+1

Hows your radiator looking, mine kept doing that due to the plastic connector chipping/breaking off.

[Evan]

the radiator is in good shape and water flows freely from top to bottom. i replaced the expansion tank hoses including the long plastic one that runs along the driver's side of the engine compartment.

the restriction causing this buildup seems to be in that area.. the area between the radiator and the expansion tank when i loosen the clamp on the tiny radiator outlet all the pressure is relieved.

jeff, i have new hoses but i don't think they'll help.. lend me your 850 for a month or two while i sort this out

[MBXB]

Did you check the small hole in the expansion tank where the hose runs to?
Make sure it wasn't obstructed? Use a hobby hand drill to clear the opening up. Forgot what the bit size was.

[Evan]

I got around to checking this again today and this is what I found:

the hoses from the radiator to the expansion tank are unobstructed

when the expansion tank cap is on it doesn't allow pressure to escape.. I'm at my wit's end on this one... I feel as if I've isolated the problem but I may be on the completelyt wrong track!

[Dave M]

I got around to checking this again today and this is what I found:

the hoses from the radiator to the expansion tank are unobstructed

when the expansion tank cap is on it doesn't allow pressure to escape.. I'm at my wit's end on this one... I feel as if I've isolated the problem but I may be on the completelyt wrong track!

See Rus's post above. Time for a new cap??

[Evan]

I should have mentioned I just picked up the cap at the dealer...

so the lines are all unobstructed.. the cap is new... but pressure is building up...

i must have missed something?