Bleeding Cooling System?

[nobbyv]

Replaced my leaking T-stat yesterday on my '95 4.0L. Drained all of the coolant and replaced with new. Now, the engine is overheating and the heat is blowing cold. I assume there's some air in the lines, but I can't find a bleed valve or anything. What's the best way to bleed the air? Thanks!

 

[srteach]

There is no bleed valve.

The air bubble is (probably) in the cab heater lines.
Raise the front of the truck if possible. Remove the (cold engine) radiator cap. Start engine and run it till warm. Pay attention to coolant level and keep it topped off as you run it. After the system is burped, fill the radiator, and the coolant bottle to the proper level. Keep a close watch on the overflow bottle coolant level for a few days. Over time it will stabilize.

 

[cr_the_machinist]

Make sure you turn the heater on as well when you are burping the air out of the system. I just did my t-stat about a month ago. Watch the coolant level for a good 10~15 minutes while the bubbles surface out of the rad.

 

[Big Jim M]

Very few vehicles have the coolant stop like Rangers do anymore. There is a device in the heater hose under the hood that opens and closes the flow of coolant into the heater. If you do NOT turn the heat to HOT while filling the radiator there WILL BE an air bubble in the system.
Nearly all vehicles today have constant flow of coolant into the heater. The temperature is controlled by gates (doors) that open to allow air to flow thru the heater core.. Our beloved rangers don't do heating thataway..
Big JIm

 

[ranger712]

Very few vehicles have the coolant stop like Rangers do anymore. There is a device in the heater hose under the hood that opens and closes the flow of coolant into the heater. If you do NOT turn the heat to HOT while filling the radiator there WILL BE an air bubble in the system.
Nearly all vehicles today have constant flow of coolant into the heater. The temperature is controlled by gates (doors) that open to allow air to flow thru the heater core.. Our beloved rangers don't do heating thataway..
Big JIm

I think you will be able to fix this problem . .

* the system cannot be bleeded successfully . . which means, that when it is bleed within a day or two air gets back into the system and so much so that you can hear it knocking under the hood as it passes through the hoses . the air leak increases . . tnad pushs the reserve tank to the limit at the top . . .

* it will not pull the coolant back into the engine, rad . where it should be . . it just stays in the reserve tank until I take it out with siphon . .

* MORE . . . for some time oil was leaking into the coolant but just oil into the coolant . . not water into the oil . . . never . . . .

* I think the T stat is locked open . . the rad temp gauge runs cool . . . even in this summer heat . . .

* the most disturbing part is the air . . leaks back into the engine somehow and starts knocking loudly in hoses . .then pushes the coolant back into the reserve tank . .


* only a few times has the reserve tank stabzlised properly . . .for a day or two after I bleed the system for a hour or so . . drained all the coolant severy times . ran cleaner ect . . .

* E test was fine . . it passed . . 422K mileage . . . . compression is good . .gas mileage is as good as it can be I will guess . . .

What do I do to fix this mess . .this has been ongoing for 2 years or so . .

* it is worse in winter . . .during warm months it seems to be a bit more moderate . .

Brian