86 BIG BLOCK C10 upper radiator hose collapsing. Why?? Video inside.

[Nasty-LSX]

I have seen the lower hose do this (not on this truck) I have never seen the upper hose do this. I was going to pull the thermostat out and see if it was sticking, but wanted to wait till I got a response from this great forum.
has this happen to anyone else. I have 180 thermostat in it. Pay close attention to the upper hose. Thats CRAZY
crazy!

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[MarineOne]

Most likely a bad radiator cap

 

[Nasty-LSX]

here is a update.
took rad cap off and the hose will not collapse, but water shoots out like a fountain at only 195F look close and you really dont see water coming out of the radiator cores. Thermostat is next to be removed. My guess will be the thermostat for the fact there is very little water flow through the core's. I did put a new cap and test the reservoir(not clogged) and the upper hose still collapse.

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[Rustisbest]

With a serpentine belt I'm guessing someone may have installed the wrong rotation water pump. The hose shouldn't be that soft either

 

[squaredeal91]

Yes very well could have wrong water pump. Easy to make the mistake if parts guy looks up wrong thing and 86 is right around lots of changes.

 

[Nasty-LSX]

Thanks guys. Its a 1999 vortec with a reverse water pump. This was running perfect 1 month ago.
All of a sudden this issue just started.

 

[squaredeal91]

You mentioned it seems like flow is the issue. How old is the Radiator? Might be time to have it rodded out

 

[shanegtr]

I'd pull the thermostat and check that its opening correctly. No really normal to get a low pressure area there so I'd say either a stuffed thermostat or maybe your upper hose has just gone soft and is collapsing under the slightest hint of low pressure

 

[JohnRod]

dont buy a motorrad made in Israel. almost no good when new! pretty sure I got it at autozone. always ran hot. bought a cheap Rock Auto and the temp runs right on 180.
Rod in hot AZ

 

[Rusty Nail]

Cavitation.

The water pump is pumping air. (water vapor)The cooling system is probably full of water which equals STEAM and water VAPOR raising to that place- the highest point in the cooling system.
We/I were just talking about this exact issue in a different thread. Great video.
That noise is steam bubbles popping.

I bet it stops if you fill the system with a 50/50 mix of green or yellow antifreeze using (distilled water) and properly bleed the air out.

You/he/she/me/we should always fill the radiator with the engine running and not replace the cap until no more bubbles appear in the fill neck. Replace cap AND THEN fill the overflow to the proper level. It is marked with a line.

Hope this helps!