[30 Closed Cab PU]

Some of this you perhaps already know. Try running water/Arm and Hammer Baking soda or Dawn for a few miles.


Then thoroughly Backflush and Flush. Could have a build up of grease.


Perhaps over greasing the Water Pump? Only use a partial pump of grease, especially on the block side of the Water Pump.

Have you always used the same type of antifreeze, can not mix types. Typically the green stuff is recommended. Mixing antifreeze types can cause a reaction that clogs things up. If you have been mixing types do the Baking Soda/ water or Dawn and then a through backflush/flush. Repeat a couple of times.


Are you using distilled water or tap? - use distilled.


Also what post 3 says, may have to do treatments of Rust 911, thermocure, etc if you have rust buildup in radiator/block - is fairly common when using water instead of 50/50 antifreeze.


Use a filter, many use the Gano Filter in the upper radiator hose.