Collapsed rad hoses

[DaveMarcotte]

Dealing with a few small things post engine rebuild. One of which is after engine is completely cooled the upper rad hoses are all sucked in. Opening the fill cap I installed at the heater hose to flush and fill, the air goes in, the hoses come back and I add about a 1/4 cup of coolant. Ive done this about 4 times now. No external leak or white smoke. Heat good. Am I still working on air in the system? THOUGHTS. thanks

[zachmac]

First problem is your radiator cap. They are not supposed to lift to vent to the overflow jug until a certain pressure but it should be allowing it to pull water from them reservoir back into the system as it cools. Clearly your system is venting to the overflow canister as it heats and expands but isn't allowing flow back as it cools.

[DaveMarcotte]

First problem is your radiator cap. They are not supposed to lift to vent to the overflow jug until a certain pressure but it should be allowing it to pull water from them reservoir back into the system as it cools. Clearly your system is venting to the overflow canister as it heats and expands but isn't allowing flow back as it cools.

That makes perfect sense. Thanks. The rad and cap are new but I'll try the old cap. Thanks!

[RRoller123]

+1. Replace cap could do it. Cap pressure should be 11 psi per my manual. Flow seems to be going out but not back. It could also be that the coolant level is too low in the overflow tank, (maybe due to a slow leak somewhere in the system?) The overflow tank level has to be above the nipple top that is suspended about halfway up in the chamber. If lower, thermal expansion of the coolant would force coolant out, it would flow out the nipple and down into the bottom of the tank, but air would then be pulled back in when things cool. My best guess anyway.

[klweimer]

Did you get the cap from one of our regular vendors? I had the same problem and got a new cap from AR. No more problem. I did a search on the internet to see how radiator caps works. Very instructive. What I found was that some radiator caps need a minimum amount vacuum to open up and pull coolant back into the system. The new cap I got has no minimum vacuum to open it back up.
Kirk

[DaveMarcotte]

Did you get the cap from one of our regular vendors? I had the same problem and got a new cap from AR. No more problem. I did a search on the internet to see how radiator caps works. Very instructive. What I found was that some radiator caps need a minimum amount vacuum to open up and pull coolant back into the system. The new cap I got has no minimum vacuum to open it back up.
Kirk

Well I got the rad and cap as one from Vicks. I haven't been impressed with their products or customer service. AR on the other hand have been stellar!!

[DieselSpider]

Also check the cap and vent on the overflow tank. If the vent on the overflow tank is plugged then the upper hose can collapse. Some cut a slit in the center of the overflow tank caps rubber gasket just in case to prevent this.