Thanks disco. I would think a pressure test was done when it held pressure for 18hrs. I'm not talking a little. It was trying to shoot the coolant out as I opened the cap. I had to close it quickly it was coming out so fast. I basically have no thermostat so the entire system is under pressure. It never white smokes on startup and I did a block test with the blue dye last night and it didnt change colors at all. It wouldn't overheat when the cap was off and I put the cap on after I shut the truck off and it started to build pressure quick. I tested the temps on the radiator and the driver top was super hot and the passenger top was ice cold after the truck was up to operating temps. Could there be an air pocket? I have not been filling it the proper way since this issue started again. I have been just filling up the overflow and trying to limp it home. Thanks for any info. Kevin. Oh and I'm gonna try to flush the radiator tonight and see if it's gunked up. Any special ways you would suggest doing it. Thanks

 

Rather than air pocket, it is possible that radiator is clogged. Take hoses off and try to flush in reverse direction with garden hose and rag stuffed in bottom outlet.

 

Is the feed into the rad at the top of the driver side? Is there a petcock to let the coolant out on the passenger lower? It has a bunch of plastic stuff in the way and I can't see anything? The whole hot on one side and freezing on the other side has me wondering for sure. Thanks for the info

 

Could the cap be bad? It won't overheat at all when the cap is off?

 

Purpose of cap is to hold pressure, up to say 20 PSI, then vent before hoses pop. With no cap and just water will boil at 212. With 50:50 coolant mix, that rises to 234. With cap, maybe 265. Here's the plumbing layout, no drain petcock, have to take hose loose.

Be very careful around part 13, or you'll crack the stub and need a new radiator. Bad radiators get full of gunk from dexcool and failure to always use distilled water. Worst water is country well water, lots of lime. Usually blocks lower tubes first, so bottom feels way cooler than top.

 

Not seeing the steps. Got pix of a cruddy radiator though. Thanks.

 

Well I reverse flushed the rad and it flowed out the top an bottom within seconds and was clean. I flushed thru the waterpump also and it was fine. The thermostat looked like it was blocked off a little by the other part of the stat. Not the part I opened up which is the main part in the main body. I think I'm gonna get a replacement stat and refill it and see what it does.

 

Any more help would be appreciated. My main question is since the water flowed freely thru the radiator why would the driver top of the RAd feel super hot an the top passenger be cold. Cold as in not warm even a little. Does this indicate a rad issue. Just because it had flow when I reverse flushed it doesn't mean it's working properly I wouldn't think. I'm also not thinking the electric fan is working. What kicks the fan on? Thanks for any info. Kevin

 

The ECU is supposed to turn fan on at 212F. Earlier if AC is working. Fan has separate fuse, sometimes more burns out. Water flow freely means one thing to us, might appear different to indy rad shop. My shop guy says good condition radiator would be about 10F difference to to bottom. Water pump has a spec flow rate of 2.6 gallons per minute at 1000 rpm at 10 PSI. So if you can fill a five gallon pail in two minutes that is good. If it is a slow steam, not so good. Rad is like $200 up.

 

Well I put a new stat in it and burped the system properly. Wouldn't overheat at idle. Drove it and it started to overheat. Pulled over and the radiator looked weird. Like it was 2 different colors. I touched the top drivers side and it was scolding hot. Top left was freezing like the water I just put in it. The bottom left hose was freezing cold. Not warm at all. I think the waterpump is working because the fluid in the system is hot. The hot radiator stopped about 10in from the top hose then went freezing. Surely this is a radiator issue. Lmk what u think. Thanks kevin