I searched through some threads and couldn't find an exact answer so figured I would ask!
Decided to flush my coolant today and replace all the old stuff with HOAT and distilled water, along with a good cleaning, and thermostat replacement.
-Replaced thermostat
-Drained radiator at plug on a cold truck
-Filled back up with tap water and ran until to about 200, shut down and drained.
-Filled back up with tap water and Zytrex (descaler, cleaner) and looked her back up. Open up heat wide open and took off. Temp began to rise, got to 200 and kept going, at 240 pulled over and shut her down. I felt the top radiator hose and it felt as if it was pressureized, it was very hard and hot. I cracked open the radiator cap and the pressure was released. I suppose it was a vapor lock or something of that sort.
-Got home drained system again, refilled with tap water, ran to about 195 with heater wide open, wouldn't get any hotter, until thermostat opened, drained again. Water was hot.
-One more flush, refilled with tap water, this time the truck ran at about 210. And heater never got hot in the cab. Drained the water again and it was cold, I am assuming that I had air in the system again?

I plan on doing one more flush in the AM and then refilling with the HOAT coolant and distilled water at the appropriate levels, is there something I am missing or do I just need to make sure that the system is purged of all air? I know that is says not to remove the radiator cap while truck is running but it seemed to alleviate the problem the first time, or would removing the thermostat, upper radiator hose before starting be a better choice.
This is a 2003 3500 with a Cummins! Thanks in advance for any help and glad to be on a forum with so much knowledge floating around.

 

you had a air pocket or something, i just did a flush also and had the same thing. at first i was worried when my temps got high, but then i would take a infrared temp from the bottom of the radiator (where the drain is) to make sure it wasnt getting that hot.

Just a FYI, you shouldnt use tap water. I know the instructions say to, but depending on the quality of tap water in your area, it could have too many minerals in it and will cause you system to corrode over time. I went to walmart and bought 24 gallons of distilled water @ .76/ea. less then $20 for all of them. and used distilled for my flush.

 

Sevir, Thanks for the advice, much appreciated! My tap water is pretty bad so I may get some more distilled water tomorrow and do a couple of more flushes, and try to correct the mistakes I already made! I assume anyway I can get the air out is the best way!

 

To get the air out of the system, remove the heater hose from the short pipe back on the left side of the motor. With the hose removed you can now fill the system and when you see coolant coming out of the pipe your system is air free and full. Hope this helps.

Jim

 

Sure does! Thanks!

 

Seems to be running fine! Heading over to check cows then to the coast, hopefully all is well! Thanks guys for all the help!