Problem burping coolant!

[Lt.Jim]

I recently replaced my water pump, thermostat and radiator. While doing this I also added a mechanical temp guage. I am getting the infamous temp guage dance. I also have the air thump sound after shutting the engine off. I can hear the coolant gurgling in the heater core when I get the thump sound. I am not loosing any coolant and the system is holding pressure. I have tried everything I know to do to get the air out of the system, squeez top hose, park on an incline, but still have air in there. Anyone know a trick to get the air out?

 

[Turdle]

Have you removed the cap while it is still a bit warm, to allow the bubble to come out? I do this while front is raised as high as I can get it.
Remove the cap very slowly, mine bubbles into the reservoir tank when it finally does burp out--
Then I top off the coolant directly into radiator--not into the overflow bottle

 

[410Fortune]

heat up water in a pot, remove the upper radiator hose from the radiator, pour the hot water down the hose, to the back side of the thermostat, it will open and the air will escape.

Did your new thermostat have a weep hole? Is it facing up?

Every once in a while I will run into an OHV that will not burp, just like you describe. My buddy dave used 2 coffee pots of water on his like this and it works 100%

 

[Lt.Jim]

no weep hole on the new thermostat. I tried opening the rad when it was still warm and no bubbles. I'll have to try the hot water in the top hose trick.

Thanks guys

 

[gijoecam]

Hot tap water won't be hot enough... Hot water heaters usually top out about 150... The t-stat opens at about 190-195.

Your thermostat should have had a bleeder on the flange that gets placed at the 12:00 position to allow the engine to burp itself.

-Joe

 

[Lt.Jim]

I boiled the water on the stove. No joy. I guess I'll have to pull the tstat and drill a hole in it.

 

[snoborder42]

How long has this been going on. When I changed my t-stat it took over a week before the gauge stopped dancing.

 

[Lt.Jim]

Not quite a week.

 

[Lt.Jim]

Okay I think I got all the air out. No more thumping when I shut it off. The temp guage still jumps up and down when the engine is up to temp. The engine is getting hot. It starts pinging like it is overheating but I'm not getting any overflow. I think my new tstat is not opening up at the proper temp.

Any thoughts?

 

[Lt.Jim]

Grrrrr!

Okay here's where I'm at now. I changed the t-stat to one with a weep hole(in the 12o'clock position) The gurgling sound is still there. The dancing temp guage is still there. I found out this morning that the temp guage only bounces when I'm running the heat. When I don't use the heat the guage never passes 190 and I don't get the gurgle. I'm no mechanic but my guess is the air is trapped in the heater core.

Am I right?
If so, how do I get the air out?

 

[gijoecam]

I don't see how the air could be trapped in the core... the inlet and outlet hoses are mounted right at the top of the core, so unless they're sagging under the hood allowing the core to become a high spot, I'd be surprised if that was the issue.

Have you pressure-tested the system? AutoZone should have a kit for rent to pressure test the cap and the system. I almost wonder if the cap is not holding the system pressure?

Also, you mentioned that if you don't run the heat, it doesn't make the noise... are you sure it's not the AC system gurgling? The AC system will run the compressor even with the heat in the wintertime to help dehumidify the air. Could the gurgling be the system pressure bleeding down through the evaporator?

When the temperature fluctuates, what temperatures does it move between, and how quickly? Where is the direct-read gauge connected to the cooling system?

-Joe

 

[wolfnutts]

i noticed u didnt say any thing about ur top an bottom hoses when u replaced parts are they ok ?? if one or the other is soft an close up while ur trk is running it could make ur gauge go dancing up an down along with running hot

 

[Lt.Jim]

gijoecam, I did pressure test the system and it held fine. When the temp fluctuates it will slowly climb to 190 then jump up to 220 and drop back down to 175/180. The climb and drop happens in seconds never hangs up high for more then 3 or 4 seconds. The sensor for the new guage is mounted in the same spot the stock guage sensor was. I also replaced the cap.

wolfnutts, the hoses are in great shape.

 

[gijoecam]

I thought I remembered you replacing the cap back in round 1...

Hmmm.... somethin's fishy, that's for sure..... It almost sounds like it's getting a surge of coolant when the thermostat opens... then the hot water that's built up in the head flows past the sensor, to be quickly replaced by the cooler water coming up from the radiator.

I've gotta ask a dumb question: Is the thermostat facing the right direction? I don't think it'll go into the housing backwards, but you never know.... IIRC, the bulb needs to be inside the engine, but don't quote me on that...

It shouldn't matter for this case, but you're running a 50/50 mix, correct?

 

[Lt.Jim]

t-stat in the right way and new 50/50 mix.

 

[Lt.Jim]

Hmmm.... somethin's fishy, that's for sure..... It almost sounds like it's getting a surge of coolant when the thermostat opens... then the hot water that's built up in the head flows past the sensor, to be quickly replaced by the cooler water coming up from the radiator.

Why would this not happen regardless of heat on or off?

 

[rmcknight]

drain the fluid - check its ok! then flush & reverse flush the radiator & engine with the garden hose on full with no thermostat.
leave the thermostat out and run it like that for a while and see what the temp guage does, then put the real fluid back in and run it like that for a few days.
tell us what happend.

 

[gijoecam]

Why would this not happen regardless of heat on or off?

That's a good question. I dunno. This whole thing's got me stumped.

The only other way I can think of to purge the air out of the heater core would be to tee into one of the two hoses, connect a garden hose, and positively force the water out the other hose.

As for the temp swings, if the thermostat is slow to react both opening and closing, that could cause it too... What kind of thermostat did it have before?

I suppose it's possible that it's normal, but it's acting as though the thermostat is not opening and closing smoothly. I wonder if you got a bad t-stat right out of the box? no, wait... that wouldn't explain why it does it only when the heat is on.... hmmm.... {scratching head} I think I'm fresh out of idears.

-Joe

 

[Turdle]

Could it possibly be a voltage issue? Low voltage with blower switched on?
Just reaching here--or bad wiring to the sensor-

 

[Lt.Jim]

gijoecam, the first replacement tstat was a stant superstat without a weep hole. Thinking that may have been the cause I replaced that one with a napa tstat with a weep hole.

jtsmith, the new guage is mechanical not electric.