2005 Powerwagon, 5.7 Hemi

Ok, I have a problem that I can't figure out. I have a sporadic (every 300-400 miles) pressure problem. The truck will blow out anifreeze and then get hot, if I don't catch it.
I have had the coolant system checked out: checked 3 times for combustion gasses in coolant sytem, radiator flushed, new cap, 2 new thermostats, and replaced the water pump after it started leaking. Nothing can be found.
I should also state that the bottom rad hose has blown off too.

There is no reason for it to act up when it does. I mean that it can happen on a cool day, hot day, loaded or empty. It has always happend while driving not just sitting. When it does happen, I can add more antifreeze and be good for several hundred miles.

I took it to a well respected radiator place and was not charged a dime and told to let them know what it was when I find it.

I am at a loss. Anybody have any ideas??? Thanks.

 

Im betting you have a bad head gasket or warped head and it is allowing you to suck in air and built pressure to the point where it needs to relieve and something gives.

 

If that were the case, wouldn't I get combustion gasses in the radiator?

 

Your cap should relieve all the pressure so it sounds like there's pressure being built up very fast. Too fast for the cap to do it's job properly. Have you had a pressure check done?
Make sure your fan is spinning properly. it should rotate faster once the t-stat opens. Only other thing I can think of is your radiator might be partially clogged.

 

Not necessarily. I only made the comment I did because my mom had a van that did the exact same thing

 

Check your oil fill cap and dip stick for a milky residue. That can be the sign of a bad head gasket or cracked head or block.

 

Thanks everybody for the suggestions. I didn't mention everything as I think my fingers would tire before I was done!!! I have replaced the cap and had a pressure check. I also had the rad flushed and the rad tech said it was spotless.
I do have a question for the van that acted the same. Did it overheat/overpressure sporadically? I can drive down the road and have the truck blow up (anitfreeze). I can remove the rad cap carefully and add 1.5 to 2 gallons of antifreeze and then drive for several hundred miles before it happens again. And, it doesn't matter if it is cool or hot outside or if I am empty or loaded. I am really confused. Thanks again for the help.

 

Oh and I replaced the fan clutch too.

 

Pull your spark plugs see if one set is cleaner than the rest. That will show what cylinder has the problem.