Can't get air out of cooling system

My wife has a 97 cherokee 4.0L. It wasn't getting hot so I put a 195 thermostat in it. I didn't bother draining the system and just pulled the housing off to let it dump. I put a new thermostat in it, buttoned it up and can't seem to get it to take very much coolant at all compared to how much came out. I have the radiator and heater core/hoses full but don't think the motor, especially the head is full at all of coolant. Since this is the case I am paranoid to get it too hot since if the ECT sensor is only exposed to air it may not read rationally and I will overheat it. The upper radiator hose isn't getting hot but I may not be letting it run long enough cause I am paranoid. One thing I noticed is the old thermostat had a bleed hole but the new one doesn't, how big of a deal is that? Can anyone give me any pointers? I am mechanically inclined but always get hung up on retarded things. If I run it with the radiator cap off it slowly overflows. If I rev it it will suck the coolant down a bit but when returned to idle will overflow.

Jack the front end up. With the radiator cap off, run the engine. The bubbles should come out.

Even if the thermostat isn't opened and the air is trapped in the head?

Cold (or reasonably so) park it on a steep incline, at an angle so that the radiator cap is at the highest point.

Remove the radiator cap--that is why it should be cold or nearly so.

Start the engine and let it warm up until the thermostat opens, then rev the engine a bit to get all the air out. Now top off the radiator and cap it, then make sure the recovery tank is filled to the HOT mark, as the engine cools and the coolant contracts it will pull coolant back into the radiator.

Park with nose up and pull the temperature sensor out of the housing. There is a bypass next to the thermostat that directs coolant to the heater core so air will get out even if the thermostat is closed.

X2 what Joe said. then do Not open radiator cap again, add(or remove) from recovery tank. If radiator cap is opened start over.
The system works on a syphon- rad to tank. Heats up, expands coolant and any air, out thru R Tank then cools and pulls coolant only back from R. Tank. A few hot-cool cycles clears air out. Opening the R.cap breaks syphon. Level in R. tank varies around 1/2-1 inch cool to hot engine normally. Check level in R. Tank first few cycles till it settles in.
(note: the R. Tank is lower than the R. Cap so syphon is needed)

Good Luck,
Orange

I park it level, remove the cap, start the engine, top off the filler neck so you can see the coolant, once the tstat opens it will look like fizzy soda. Keep it topped off till all the fizzys are gone then blip the throttle body with your thumb, coolant gets sucked down, quick top off and quickly put the cap on. That last step keeps you kind of busy

I jacked the front up a good foot off the ground and ran it with the radiator cap off until it was up around 200 degrees. Some bubbles came up but it pretty much continually would slowly overflow out of the radiator filler unless the RPM was increased. I loosened the ECT sensor until coolant spewed out and didn't get much air out of it but at least I know it is reading rationally and submerged in coolant. I capped it and filled the overflow tank but it still won't seem to take coolant anywhere near as much as came out.

were you running the heater full blast at the same time?

ehall said:

were you running the heater full blast at the same time?

Click to expand...

Are the 97s post-coolant control valve?

And people wonder why I drill thermostats as a rule. It's not just helpful to RENIX - it can make pretty much any system self-purging.

I agree with 5-90: does your thermostat have a hole in it to let air pass thru? I always drill one or two 1/8" holes in the flange of the thermostat to let it burp the system easier. Put the holes at 12:00 and 6:00.