2005 LS V8 running hot but not.

[erkinatl]

I have tried the search feature and the sticky and looked there before I posted this.

2005 LS V8 124k. Some background, in 8/2011 the t-stat housing broke at the nipple inside the house that the t-stat uses to push against to open up. replace the housing and t-stat with one from O'Rielys. Car ran fine through the rest of the summer here in GA even took a trip to NYC in September over Labor Day weekend and it ran great. In the past two weeks I have noticed after driving the car for about 20 minutes and coming to a stop i will here the engine cooling fan coming on high and the heat "hotness" will decline. Start to move again and the cooling fan seems to turn off and the heat returns to normal. The temp gauge on the dash will barely raise above the 9 o'clock position when driving. Hooked a scan tool up to it and when the cooling fan is running the coolant temp is 238F if you get the engine speed up to about 2,000 rpm the temp comes down to 224F and the fan shut off. If you touch the upper radiator hose when the engine is warmed up it is extremely hot, when you touch the t-stat housing it will be cool to the touch.

I am thinking that the radiator is clogged. If I understand the cooling system flow the t-stat controls the return flow from the radiator which is the exact opposite of how other engines operate. I have tried to bleed the cooling system multiple times and it seems to bleed out correctly, now having said that it seems to need coolant added to it before each time it's being bled. The other thing i noticed tonight is that the upper hose seems to be very "hard" to press when the engine is running like something is either pressurizing it or it's flow is restricted.

I am beginning to wonder if the degas bottle is leaking after reading the threads on this but i don't think that covers my whole problem.

Any ideas would be appreciated as to where I should look to sole this problem as it will only get worse when spring gets here.

Thanks

 

[brack86svo]

Sounds like you have air in the cooling system. I would try bleeding the system before anything else.

 

[joegr]

...If I understand the cooling system flow the t-stat controls the return flow from the radiator which is the exact opposite of how other engines operate. ...

You do not understand the cooling system. The LS thermostat controls how much hot engine coolant enters the radiator, just like most other cars.

... it seems to need coolant added to it before each time it's being bled. ...I am beginning to wonder if the degas bottle is leaking after reading the threads on this but i don't think that covers my whole problem.

...

Almost certainly, your degas bottle is leaking. You need to also check all the other plastic cooling system parts, including the radiator hoses. It's around $500 in parts to replace the parts that are most likely to be cracked or about to crack.

...The other thing i noticed tonight is that the upper hose seems to be very "hard" to press when the engine is running like something is either pressurizing it or it's flow is restricted.

That's because the cooling system is a pressurized system (like most other cars). If the hoses didn't get very hard to impossible to compress after the engine warmed up, it would indicate a fairly big leak somewhere. Since you can compress it some, then you probably do have one or more small leaks.

It's not from restricted flow.

 

[erkinatl]

I will order the bottle in the next week and repace it and post my results!!! Thanks for the help!!!

 

[erkinatl]

Turns out the Radiator is leaking from the right side tank. The car has been parked in my garage from the time I posted this and looked at it this weekend and there was a puddle under the car on the right side removed the under cover and saw the right side tank was wet at the bottom. Dried it off and in about 5 minutes with the car not running it was wet again.

This seems to expalin what was happening to the coolant and then the air.

As for the degas bottle I did look at that as well and short of getting the hose off the bottom of it, it was inspected and found not leaking. there were no tell tale signs of coolant on the bottle or the fire wall or any of the sheet metal in the area of the bottle.

I almost wish it was the bottle though as it would be an easier and much less expensive repair.

Evan