Cummins 8,3 ISC Coolant System Bleeding

[Jim Byrd]

I had a slight drip of coolant from the bottom hose connection on the recovery tank.  I tried tightening the hose clamp with no success,  I proceeded by siphoning the fluid (5 gallons) from the recover tank to allow me to remove the hose to inspect the nipple on the nylon tank and the hose. The nipple look good, hose was deformed from over tightening of the clamp.  The hose was long enough to allow me to cut the hose just below the area where the clamp was.  Hose was reconnected and I proceed to slowly refill the coolant with a small pump however I could only get 4 gallon in and I was at the MAX level line on the recovery tank..

I assumed that I had air in the system and I started the engine ran it with the pressure cap removes until the the thermostat opened. I observer this by watching my Scan Gauge get up to 165 degrees then decreasing to 161 degrees.  I left the pressure cap off and let it cold down for several hours with no change of the level in the recovery tank, still at the MAX level.

I then place the pressure cap pressure tank and took the RV for a 20 mile drive, temperature were normal 165-170 and heater output was normal.  Checked level and still at MAX line,

Appears to have air trapped some where in the system.

Anyone have any idea on how to the system.

I plan on replacing the nylon tank and hoses as soon as I can get a replacement tank. 

Does anyone know were the 2 small hoses (1/4") on the top of the recovery tanks go? 

Thanks for your help.

Jim

 

 

[Rikadoo]

Hey mornin Jim, yes it sounds like air, when i replaced my radiator i used a system that pulls all the air out of the cooling system then you attach a hose and feed the new coolent in thru the same device. As for the two small hoses, 1 goes to top of radiator, the other goes next to thermostat housing, the intension is that they burp any air traped within the system. Remember the heater also is a source of coolant, so while driving be sure to turn the heat control open to “high” to allow it to eventually purge any trapped air in it.

[Jim Byrd]

1 hour ago, Rikadoo said:

Hey mornin Jim, yes it sounds like air, when i replaced my radiator i used a system that pulls all the air out of the cooling system then you attach a hose and feed the new coolent in thru the same device. As for the two small hoses, 1 goes to top of radiator, the other goes next to thermostat housing, the intension is that they burp any air traped within the system. Remember the heater also is a source of coolant, so while driving be sure to turn the heat control open to “high” to allow it to eventually purge any trapped air in it.

Thanks for the response. I removed the coolant by using a vacuum canister thru the recovery tank.  I only drew the fluid about 2 inches below the bottom of the recovery tank which is about the same elevation as the top of the radiator.  I did run the heater on high when running the engine with the pressure cap off.  I felt the heater hose at the temperature control valve and they were warm.  I expect that the trapped air is in the heater core because it's the highest point in the system.

I refilled the coolant with a low volume battery operated pump thru the recovery tank.

Did your device just pull a vacuum from the system when connected to the recovery tank?

I'm going to try and run the engine at hi idle with the pressure cap off and the heater on HI and see if it does any good.

Jim