Cooling Problem

[Bnewton530]

okay everyone, I am experiencing a cooling issue on my 2004 LS8. It will drive fine and the hvac will work fine. Then intermittently it will pin the temp gauge and blow ice cold. I am somewhat confused. It has full coolant and zero leaks anywhere. I know these systems are temperamental. ant ideas I what's wrong? 80% of the time the cooling system works as it should.

 

[joegr]

Pin the gauge at hot or cold?
Everybody says "zero leaks," but they are almost never right about that. Just because you aren't seeing liquid coolant on the ground and not having to add coolant often, does not mean that you don't have a leak. Do you see powder white or orange stains anywhere on any of the cooling plastic? Do you know if the system is pressurizing?
Your symptoms suggest the possibility that you have micro-cracks, and air is being sucked into the system. You get enough air in there, and it blocks coolant flow, at least temporarily.
When was the last time all the plastic parts were replaced? Did you use all OEM?
GenII LS8 Cooling System Overhaul

 

[Bnewton530]

I recently bought the car. The cooling parts in question would be the thermostat housing which would also replace the thermostat. And the degas bottle correct? I just have trouble believing that the degas bottle would cause air bubbles in the engine. I didn't think that the bottle was actually in circulation. Also when the car overheated I was hearing a clicking sound near the degas bottle

 

[joegr]

I recently bought the car. The cooling parts in question would be the thermostat housing which would also replace the thermostat. And the degas bottle correct? I just have trouble believing that the degas bottle would cause air bubbles in the engine. I didn't think that the bottle was actually in circulation. Also when the car overheated I was hearing a clicking sound near the degas bottle

No, look at my link. There are way more parts than that to replace.
The degas bottle does have some circulation.
The clicking sound is air/steam bubbling into the the bottle.

You don't have to believe the experiences of hundreds of people on here if you don't want to. Did you at least read some of them?

 

[Wabel]

In those instances when the car did overheat do you recall hearing the cooling fan?

The cooling fan will kick into a high speed at about 226 degrees and max in the 230's. The sound the fan makes is very noticeable.

 

[Bnewton530]

I believe it. I guess it's time to pressure test. And yes the fans are at full speed.

 

[Bnewton530]

I re bled the coolant and I have a steady stream of coolant. The car had just overheated and the coolant coming out wasn't even warm

 

[joegr]

Cold heater / coolant pretty well rules the fan out as the problem, and for the record there is only one fan, not fans.

Note that you are bleeding the heater circuit, more than the engine. A bad degas bottle will keep the engine circuit from bleeding.

Your best course of action is to replace all the plastic parts. Specifically, probably you either have air being sucked in or the plastic ears holding the thermostat have snapped. More may break when you go to remove the thermostat housing to look at it. If you want to do it a part at a time, then you'll be working on it over and over again. Do it all, and you may not have any more cooling problems for as long as you keep the car. To add to the link, also check the front side of the passenger tank of the radiator. If you see a crack there or residue, then add the radiator to the list.

 

[Bnewton530]

Thank you for the help. I will begin collecting plastic parts for this car. You guys really make it possible for anyone to own an LS. They aren't too bad to work on but they do act up and when they do there is a bunch of guessing involved and for the month that I have owned this car I have lived on this forum. It's almost sorted out now.

 

[Wabel]

I agree with Joegr. However, based on what I have learned dealing with my car(2004 V8) and your symptoms it sounds like a bad thermostat and/or thermostat housing to me.

You can't go wrong with correctly replacing it all but If you want to try to get away with the minimum then I suggest the following:

1. Verify absolutely no signs of cracked or leaking coolant parts.
upper radiator hose
lower radiator hose
t-stat housing
coolant outlet pipe
coolant inlet tube/pipe
degas battle
radiator

2. Replace OEM only! It really does matter there are differences.

T-stat - MOTORCRAFT RT1163 {#2W938575AB, 2W9Z8575AB}
T-stat Housing - MOTORCRAFT RH134 {#2C3T14B060BM, 3W438594AB, 3W4Z8592AA}
Gasket - MOTORCRAFT RTS1079 {#2W9Z8590AB}

 

[cammerfe]

Having read all the 'cooling problem' threads that have cropped-up here over the years, I notice a common error in the narrative that's offered.

It's often said that small cracks let air into the system, thus causing the problems we encounter. But please consider these facts:

The cooling system is pressurized. This means that there is pressure on the inside of the system pushing out. The system starts essentially full; the warming-up of the engine causes the coolant to expand and thus pressure is created.

Coolant is forced OUT of the tiny cracks that have developed in the plastic parts over the years. The coolant residue left by evaporation of this coolant is what is left to offer a guide as to where the leaks are.

As the engine subsequently cools, the coolant contracts and air is AT THAT TIME 'sucked-in'. Now there is less coolant in the system and therefore a greater opportunity for further overheating.

To keep it simple, coolant leaks OUT first and air is introduced LATER

 

[joegr]

I don't really disagree, but it actually is possible for air to be sucked in without coolant being forced out. When the engine warms up and the coolant warms up, pressure builds. When the pressure goes above 15/16 PSI (and it does this each time), excess air is vented by the degas bottle cap, from the degas bottle. When the engine cools back down, pressure in the cooling system goes to a slight vacuum because there is no longer as much air at the top of the degas since some of it was vented before. The degas cap does not let air back in. (In the old days, the radiator caps did have a vacuum relief valve. It allowed coolant from the overflow bottle to be sucked back into the radiator.) Anyway, this slight vacuum can cause air to be drawn in through the very tiny cracks in the plastic. What's the problem? After all, it had the same amount of air before. The problem is with where the air is. It's now in parts of the cooling system that should be liquid only, not at the top of the degas tank where the air is supposed to be.

All that said, most of the time people say that there are no leaks, a small amount of coolant really is leaking out.

 

[04_Sport_LS]

Then intermittently it will pin the temp gauge and blow ice cold. I am somewhat confused. It has full coolant and zero leaks anywhere.

This points to the fact that you are getting an "air pocket" in the cooling system,,, that ends up in the heater cores, ( the most remote and hardest to bleed part/point in the cooling system).

So... whether it seems likely or not,,, you are still "sucking air" into the cooling system... which means you have a leak somwhere. Fix it quickly,,, because if the air pocket ends up in/around one of the heads... you could possibly torch a head if you continue to drive it in that condition.

I forget the "head temp" OBD2 code. Joe would know that.

 

[Bnewton530]

Thanks for the info you guys. As an engineer I came here for perspective and got it! I rebled again and when I went to fill the engine I just kept pouring and pouring. The degas bottle was at level and everything. There must have been a massive bubble in there that caused the car to boil off coolant. Wow. I believe there may be a crack somewhere now. The strange thing is that it doesn't leak at all

 

[04_Sport_LS]

Yeah... the LS cooling system won't let you be a rebel. It will win every time if it is not happy.

Cooling systems of years past are more tolerant. My 95 F150 has had an external head gasket leak for roughly 35k-40k miles. I just add coolant as needed,,, and it doesn't overheat. With the LS cooling system design,,, you WON'T get away with that.

Part of this is the required heat of the cooling system... to be able to pass emissions. Those regulations weren't as stringent in 1995.