DIC displaying engine overheating AC off what do you do

[Happy Hummer]

Hey guys completely confused

Hummer 2006 h3 about 85,000 miles it's my girlfriend's truck...lol again!

Went ahead drained out about 5 quarts of transmission fluid from the bottom hose closest to the battery box (sm. metal line) because we suspected a leak in this line.
We placed the H3 on wheel ramps, blocked the tires and dropped the front armour.

The nut that holds both lines were loose and I tightened the one closest to water pump and removed the one closest to battery box. Drained approx. 5qrts. as stated & cleaned all surfaces. Replaced fluid and top of rad over flow jug. Took it off ramps started engine and within a min. it pegged all the way to red/high.
Im at a lose.
I noticed during the transmission draining that the over flow kept gurgling and siphoning off so we added new dexcool. We used dex VI trans fluid.
I tried burping the system. Also reset computer.
Nada. dic still (eng over heat) (ac off).
Ugh! wtf...lol...
Chris
She purchased it about 2 and a half months ago and they replaced rad then.

Bottom hose cool to luke warm.
Top hose hot to touch.

 

[06PullUouT]

Thermostat not opening? I replace my thermostats every 25,000 miles whether they need it or not. Got stranded one time in my M3 because of a thermostat! Probably a little over cautious but I hate walking or calling tow trucks!! :shame:

 

[rsc]

Thermostat not opening? I replace my thermostats every 25,000 miles whether they need it or not. Got stranded one time in my M3 because of a thermostat! Probably a little over cautious but I hate walking or calling tow trucks!! :shame:

If the thermostat was stuck, the bottom hose would be hot as well as the hot radiator fluid has to make it to the thermostat on the lower, left corner of the engine block first. I'm betting the radiator is plugged somewhere before it exits back to the thermostat. Take off lower hose and see how fast the fluid drains out of the radiator?

 

[f5moab]

Coolant enters the top of the engine, circulates then exists via the thermostat and the outlet house at the bottom of the engine. If the thermostat is blocked shut, coolant in the engine/cylinder head (where the temp sensor is located) will be hot since it CANNOT circulate out of the engine, through the radiator.

 

[06PullUouT]

Coolant enters the top of the engine, circulates then exists via the thermostat and the outlet house at the bottom of the engine. If the thermostat is blocked shut, coolant in the engine/cylinder head (where the temp sensor is located) will be hot since it CANNOT circulate out of the engine, through the radiator.

Agree!

 

[Happy Hummer]

my question is should the hose then be cool on the bottom or should it be hot.
f5 for instance if it's pumping through the top will the bottom then be warm.
If there was an air pocket inside the radiator could that stop flow?
Thank you
Chris

 

[Happy Hummer]

thank you everyone for all your help so far...

 

[f5moab]

If there is no flow of coolant through the thermostat, the bottom hose will be cooler than the top hose.

An air pocket could cause the engine to run warm. In fact, GM highly recommends using a pressurized filling system for the cooling system.

Also, the thermostat in the H3 is pretty reliable, but with an overheat condition, and a cool lower hose, and 85K, I would say it is the stat. It could be the pump not circulating the fluid but the bottom hose would still have hot fluid in it when the thermostat opened.

 

[Happy Hummer]

We let it cool down for several hours (WI.) and it ran for 10 min. without heating past 3/4 mark and then rose quickly and there is ZERO heat coming out of the vents just cold air..Lol! not good in winter.


Chris

 

[4speedfunk]

You're air-bound. This happens because there is a loop of air trapped in the top of the cooling system. It basically cavitates the pump, and you will not get flow to the heater core. In most cases you will only get heat when you take off quickly from a stop. This happens because the g-force of the start will slosh a big gulp of coolant into the pump and for a second or two...and hot coolant will make it to the heater core. Then after you're done accelerating and level off your speed...the air bubble will return to its original position and heat will disappear...it will blow ice-cold again. Almost all late-model cars have this problem because the heater core is usually higher than the radiator cap. This is why dealers use a pressure-fill system. You can purge the air out yourself using several other techniques....

Try parking nose-up on the steepest hill you can find (you'll have to be nearly vertical...not a problem for the H3). Then pop the radiator cap and squeeze the hoses with your hand to work out the air. Fill the system while on the hill. Let the truck idle until the stat opens and keep filling the system and squeezing hoses, until it won't take anymore. Replace the cap, and let the truck sit until its completely cold. As the truck cools, it will pull coolant from the overflow tank to replace the air that was trapped. Hours later...drive it around, and re-check the coolant level. Another way to do it, is to pull a heater hose off the firewall while you are filling it. This will break the vaccum and purge the air bubble out. You can also fill the system from a heater hose, (plug a garden hose into it). This works but, its very messy.

In the future, to prevent this from happening...drain your radiator only when the truck is totally cold. The stat will be closed and this will seal the upper half of the cooling system. While its true you won't be draining the ENTIRE system...its also true you won't have this air bubble problem. Given the small amount of old coolant you're leaving in the block & heater loop...its probably a non-issue. Some people are so anal they insist on draining & filling the entire system, and this is the proper way to do it. But, keep in mind you'll have to deal with the air bubble issue.

 

[ArtHummer]

Exactly what 4speed says... Jack the nose up, tip of the overflow canister, open the radiator cap, top of the radiator (squeeze the top hose to push the air out) and LEAVE THE CAP OPEN, start the engine and let it run. When the coolant will get warm up, you will see the level will go up a bit and when it will get hot and thermostat will open the level will go down quickly. WHEN THAT HAPPENS you have to give it more coolant to keep it fool at all time.(maybe be not a good time to drink beer, hold the coolant and be ready to fill it up quickly as soon as the level will go down) Do that for about 3-5 times, then top it off and close the radiator cap. Let it run for about 10-15min to check if the temperature will not go up.

 

[Happy Hummer]

OK

Now I'm really lost. We did not replace the rad or fluid, we were working soely with the trans lines and put 5 qrts. of Dex VI in and topped of rad fluid because the overflow was low when we put her truck back on the ground after (being nose UP on wheel ramps).
So, question is would 4speedfunk's posting still apply?
Is it possible that air is caught in side the closed system because the car lot she bought it from did not fill the rad system properly 2 + mons. ago?
Or is this something else?
Also does the the Tstat have a bleeder hole in it so as to get air pockets out from behind it? They usually have a very tiny one...

Chris

 

[4speedfunk]

would 4speedfunk's posting still apply?

Regardless of whats going on...fill the over-flow tank, then go find a steep ditch and try the "hill-fill" method.

Is it possible that air is caught in side the closed system because the car lot she bought it from did not fill the rad system properly 2 + mons. ago?

Yes...no question...you got air in there. How it got there could be any number of reasons...not necessarily the fault of the car lot. This is a very common problem.

Or is this something else?

There could be something else but, the first thing is to purge the air and get the system properly filled. After that you can monitor coolant level and go about finding a leak, if that's the case.

HOW IT WORKS...
The system is designed so that as it heats from ambient to 220F...the fluid expands and spills into the over-flow tank. This also vents MOST of the air out of the system into the tank as well. (The fact that you heard "gurgling" is proof that there was air in the system...a properly purged coolant system will not "gurgle".) Then as the system cools from 220 to ambient...it pulls coolant FROM THE BOTTOM of the overflow tank back into the main system. Pulling from the bottom ensures that only COOLANT goes back into the system and over several cycles...it essentially self-purges itself of all air. The only problem is...you must keep the overflow tank full. If the tank runs dry it will actually pull AIR back into the system, instead of coolant.

Stay calm. Put your wallet away. Get the air purged out. Fill it up. Keep an eye on the tank level. Its totally normal for tank level to drop over the next 4 or 5 heat cycles. Keep it topped-off up to the fill line, and leave the radiator cap on and shut. If you open the radiator cap...you'll disrupt the vacuum and pressure that makes the system purge itself. In a couple days it will have completed its self-purge and the tank level will find its equilibrium. It should drop to the cold line and rise to the hot line accordingly.

 

[06PullUouT]

Just for reference Happy Hummer, here is a diagram of the cooling components on the I5

 

[Happy Hummer]

Wow,
Thank You everyone for all your help!
This forum (and ones like it) are indispensable.

I took your guidance into consideration 4speedfunk and did as you recommended. It took the better part of hours lol but it finally made the weirdest sound like a baby crying/sighing and back farted up the over flow and the girl is running again.

I was also able to detect where the Trans fluid is dripping from but uncertain if it is worth replacing like or just leaving drip and check monthly?
It is the hard line closest to the pullies where it is crimped to the rubber.

Chris

 

[alrock]

Good stuff, didn't know about this type of issue.