Upper radiator hose collapsed?

[pushpole]

I just had my injectors replaced. So the coolant was replaced at the same time and a new upper radiator hose installed (old one had a wear spot from an accessory). The hose is collapsed, there is plenty of coolant in the overflow tank. Temps were normal during the 4 hour trip home yesterday.

[pushpole]

I opened the coolant reservoir and there was a vacuum in the system. The venting resulted in drawing coolant into the system and the hose expanded. The new hose does not have any internal support to maintain its shape. I'm used to these hoses being pretty ridgid.

[JohnC]

Your pressure cap should vent to prevent any significant vacuum in the system. Might be plugged...

[DmaxMaverick]

In addition......

The collapsed hose is likely due to the coolant not being completely bled of air. This is not too uncommon, as even most techs don't know how, or just don't bother to bleed the system properly. Any air in the system will immediately show up as excessive system vacuum after a shutdown, but can cause long term issues if not eliminated.

A 4 hour drive won't bleed the system, in itself. The procedure is specific, and all the conditions aren't normally encountered during regular driving, and certainly not if you are a conservative driver.

[pushpole]

I just finished the service manual bleeding process. It took about 30 minutes....I do not routinely run my engine to 3000 rpm! We'll see the results in the morning.

[pushpole]

Hose collapsed this morning. I followed the service manual venting technique to the letter. If somebody has a chance. Would you squeeze your drivers side upper hose and let me know how easy it is to collapse. My is brand new and really easy to collapse.

[JohnC]

The hoses are quite flexible, as long as there is no pressure in the system. If yours is getting sucked down then the cap is not venting vacuum properly. You can prove this by loosening the cap and seeing if the hose "un-collapses".

(Oh, I see you already tried that...)

[DmaxMaverick]

I agree with John. Once properly bled, it should not collapse, significantly. If you replaced the hose, you may have a more "soft" hose now, allowing the condition.

I suggest replacing the cap, as John said. If it continues, bleed again and repeat.

[ross1147]

Is the hose collapsed when the truck is running? My hose is always collapsed in the morning, but when I start the truck up it hose opens back up in a minute or so. Then it stays open. I just thought it had too do something with the coolant contracting as it cooled down causing the hose to collapse. I figured if it opened back up when the engine was running it wasn't a problem. Maybe I need to bleed my system?

[JohnC]

I just thought it had too do something with the coolant contracting as it cooled down causing the hose to collapse.

As the coolant contracts, first the pressure in the system maintains the volume and keeps the hose from collapsing. Once the pressure is dissipated, if the coolant continues to contract, a vacuum is formed in the system. Any significant vacuum *should* be vented by the cap. If the hose is collapsed, and opening the cap causes it to return to normal, then there is a vacuum being held in the system. Either the cap is not venting correctly or the hose is *very* soft.

[ross1147]

John,

I went out and took the cap off when it was cold. Sure enough, there was a vacuum and once the cap was off the hose went back to normal. Guess I need a new cap. Thanks.

[jjcsnlynn]

I did a flush and fill with dexcool last weekend (had green fluid in it). Afterwards the hose would collapse. I changed the cap and it got better.

I did not do the proper bleed (I guess). Where can I find the proceedures for doing a proper bleeding?

[More Power]

I did a flush and fill with dexcool last weekend (had green fluid in it). Afterwards the hose would collapse. I changed the cap and it got better.

I did not do the proper bleed (I guess). Where can I find the proceedures for doing a proper bleeding?

There is a vent screw located on the thermostat housing. Open this screw a couple turns till coolant begins to flowing out - while filling the surge tank to the cold fill line. Tighten the screw. There may still be some amount of air in the system, but it should work itself out over a few days of driving. Check the cold coolant level in the radiator surge tank every morning for a few mornings till you see that the level is remaining constant. You may need to add a little. This would be normal soon after a drain/fill.

Jim