I have a 96 bonne with about 215,000 miles on it. Runs pretty good, tuned it up, changed all the vital sensors.
My question is. I changed the thermostat and toppped off the coolant level, both in the coolant tank, and in the radiator. When the heat gauge in on the dash gets to like almost 200, I turn on the hater and have some heat.
I know that when you open the system, you need to "burp" it to get the air out of it.
Well 2 things come to my attention when I go to do this. One is the upper radiator hose isnt hot, and 2 when I open the screw that is on top of the thermostat housing, shouldnt you get some air and then all coolant to come out when you open the screw?
I dont get any at all, weather I crack it when the car is running or when it is shut off.
I guess one other thing, and this may be the main culprit of all of this is, the radiator cap is still cool, and I can take it off and not have any pressure on it at all.
Does the radiator cap make the pressure? If so, then I will start with the cap....
So to review>>>>>
The top hose doesnt get hot when at full temp,
No spray out of the thermostat housing when screw is cracked open
Cap is cool and can be opened up and has no pressure behind it.
Thanks for your expertise in this.
Ray.......

What temperature t-stat did you install? If its a 195, your gonna have to wait longer than what your seeing 200. Seems like the t-stat is not getting hot enough to open up. Could be due to the current cold temps.
And those dash temp gauges are not always accurate.

Drive it around the block to get everything warmed up, park it and leave the engine running, and conduct the tests again.

You should be getting some heat off of the engine well before the thermostat opens. There are 2 hoses that run to your heater core. One is supply one is return..but coolant runs to the heater core the minute you start the car. Do You have the original Orange colored Dex-Cool in the system? very problematic...likes to build up gunk.

Here is what I suspect. Plugged heater core. Here'e what I would do. Back Flush it.

How: Disconnect both hoses to the heater core. Hook up 4-5 foot sections of heater hose or garden hose to the heater core and back & forward flush the system with water from your home or shop water supply.

When I did my daughters' 97 Blazer, I went and bought 6 ft or so of both sizes of heater hose, bought cheap plastic garden hose repair fittings. I used 2 male fittings, I attached a female quick connect to the end of each hose and a male quick connect to the garden hose (so I could easily move the garden hose that I was using for flushing from one hose to another.) I used a couple of stainless steel band clamps to attach these hoses to the heater core fittings. I ran the output hose to a bucket...turned on the water...and a bunch of crap flew out into the bucket...Reversed the garden hose...hooked it up to the hose that was in the bucket. (this is when the quick connects come in handy) put the other hose into the bucket. flushed it that way a bit. reveresed it again... 3- 4 times in each direction..

This may sound complicated but it'* really simple. You may lose a little coolant from your heater hoses when you disconnect 'em.. you can try to plug or clamp 'em either way refill and recheck the radiator for proper level. Hang your hoses up in the garage and you'll have'em the next time you ned 'em. I recently re-did this for my son-in-laws Jeep Cherokee when he had no heat worked like a charm..

Radiator pressure is 14 PSI, Water pressure most homes is 40-65 PSI running the higher pressure backwards will blow out all kinds of crap that otherwise just blocks the flow and the water pump doesn't have the umph to move it out.

Good Luck Let us know how it works.

Spit

Wow! Ill have to try that on my 96 LSS that the heat is tempermental! Thanks!