Coolant issue

[Brock]

I'm having a brain fart here... on my 08 Cat c15 when it's running, the coolant level goes down.

When your coolant gets hot, doesn't the level usually rise a bit in the expansion tank? Mine goes down 2.5" like it's being pressured from the top. When I shut it off and relieve the pressure, I can hear a crap load of bubbling from ansmall hose that runs from the top of my resevoir to the thermostat housing.

I did just have a coolant pressuring issue where it was over spilling to the other side of the expansion tank but that was a bad compressor and there's no compression gasses now and it's not over filling.

Im thinking something stupid like a air bubble. Could a bad thermostat have anything to do with this or do you have any other ideas?

I changed the pressure cap with a new one. Maybe there's a internal check valve that's bad in the tank?

Thanks guys.

[Brock]

Well I thought I would update this. My issue was just air pockets, a shop recently ran heater hose from my bunk to wrap around my product pump and load valves on my tanker to keep them from freezing, it got massive amounts of air in the system. I noticed the coolant hoses around my engine were hot but the ones running to my bunk were freezing cold and no valves were shut.

Bled it out by taking the cap off and letting It run at high rpm, made a hell of a mess but got the job done.

[Rawze]

Tell them to invest in a vacuum fill system before they destroy someones engine next time eh?

[Brock]

Tell them to invest in some common sense!