The top of my radiator blew off, The neck that holds rad cap popped right off! I replaced waterpump then top popped off, I replaced thermostat, and the hoses feel like they have alot of pressure on them. So I removed thermostat so I can look for water flow in the top of radiator, and there is no flow whatsoever! I recall reving up engine and seeing coolant flow faster as revs went up(with old water pump). I have a new rad, new water pump(napa), new thermostat, new hoses and no flow! Any ideas what I can check?
Its an 82 cj7, 258 6cyl, 4 core rad from ebay(175$). Shouldnt I see flow? Thanks for any help.

that only leaves:

blocked water jackets!

I took the blower and blew thru the hoses and they seem clear. Every hose I blew thru had water exiting whatever opening in the system that I had left open, it dont seem clogged. My cheapo temp guage reads 160 to 165. In fact my computer scanner(hooked to Howel EFI port) also says 160 degrees. Im going to buy another temp guage tommoro and install it lower in the block. The present guage is taking temp readings from intake manifold, I think getting a reading from another section of the engine will help me feel better while letting it run. I also put a tefba coolant filter on. Its on the upper hose. In put is coming from thermostat housing rad hose, output is facing radiator. This engine has about 3000 miles on it since new in 2000.

What I am worried about is blowing up this radiator. It happened to my old one and it wasnt in to bad a shape. Theres no warranty on overpressurized radiators. What two hoses would you take a blower to, to check for a clog? The rad hoses get rock hard and Im affraid to let engine get up to temp. Any other suggestions? Edit to ask again, Shouldnt I see water flow thru rad cap neck? I put a drop of food coloring in rad and it moves very slow towards passenger side.

Did this start befor or after the coolant filter install?

Started before. I had to buy a new rad ,cause I blew top off of old. Figured Id buy a filter to keep new Rad clean. Any body have any ideas?

When I run jeep with radiator cap off, the coolant gets hot pretty quick. It gets hot at the neck area anyhow. Could it be flowing and I dont see it? Anybody else? EDIT:
Did a few hrs searching, I can only hope its not a head gasket. Never ran this jeep hot even when RAD top blew off. I keep my eye on guage at all times. Maybe I can get these three questions answered.
1. Is threr a way to check for coolant flow?(other than my finger getting hot when its in rad neck with jeep running)
2. Should coolant shoot out of top rad hose if I start jeep with hose disconected at top of rad?(I tried it avd there is no flow)
3. Where can I put the blower to clear the area that migdht be cloigged.
Thanks again in advance.

Don't know much about the 4.2L but on the 2.5L and 4.0L there are two different water pumps depending on the type of belt system. The serp belt water pump spins the opposite direction than the v-belt system. The look the same unless you take a close look at the impeller. I have seen 4 different rigs where people bought a replacement pump and the parts house gave them the wrong one. The remanufacturer boxed them wrong.

They don't pump worth jack when switched and cause overheating just as you describe. I'm thinking since the motors are so close in other respects that the water pumps might be interchangable and you may have gotten shafted.

Guess Im gonna pull this water pump off and check it. My spare pump has a R stamped on the back were the fan bolts to it. I didnt check the one I installed from napa. Hopefully some one else will have some input.

Napa Sold Me The Wrong Water Pump!!! Impeller Was Wrong!!!