Coolant question

[MalibuRacing]

Today was the first day I drove the Father/Son Malibu under it's own power. Man, this little 4.8 has some scoot, especially with the 2.41 gears in the rear! I plan on changing those, but to my question....

I noticed the temp gauge (autometer Phantom electric) was showing over 210 degrees, but the thermostat did not seem be opening. The sending unit is in the passenger side head. There was no coolant flow, and both the upper and lower hoses were cool to touch. Do I have a stuck thermostat or is there something special I need to do with an LSx engine to get the coolant flowing? Since the thermostat was not opening, the electric fan was not turning on, since the thermostat is in the radiator. I has been sitting a while, so I guess a stuck thermostat is possible....

Any suggestions or ideas?

 

[blubaldmontess]

Don't quote me, but did you bleed the system, I can't remember if we had to bleed the truck system or not, but hey its worth a shot. If not, check the tune on you're computer, mine was not tuned right, which sucked and overheated the engine one time....good luck

 

[MalibuRacing]

I did not bleed the cooling system.

This may be a stupid question, but how did you bleed the system?

 

[blubaldmontess]

On a LS1 there is a coolant crossover tube that runs at the end of the cylinder heads and crosses over to the head on the other side. It should have a line that comes off that so you can run it up to the high point of the cooling system (you can tee it in the return tube at the top of the radiator). If your motor only has little blocks held on by a bolt on both ends of each cyl head, you can loosen each one and bleed the air out of the cooling system . I would do each one to ensure you bled everything completely. Some engine builders use the crossover tube and some do not. It comes with it on the stock engine.

Thats how...and theres also the question, where do yourun you'r coolant bypass tubes off the front end of teh block, they are supposed to run from the drivers side front of the head, through the throttle body and I believe into the passenger side head. Mine are blocked off, on the passenger side, but on the drivers side, I ran a rubber tube into the radiator, it allows steam to not build up in the heads, this way the computer isn't making the car retard timing, if you want pics, pm me and I'll get them in the morning

Otis

 

[Cain]

had the same problem. I filled the block up by pulling the upper hose off filling through the water neck. then topped off the rad.

 

[HP JUNKEY]

My guess is that it sounds like an air lock, gotta bleed it out.

 

[MalibuRacing]

had the same problem. I filled the block up by pulling the upper hose off filling through the water neck. then topped off the rad.

That's what I was thinking, but wasn't sure. It makes sense that if there isn't any coolant in the block, the thermostat is not going to work. I'll give that a shot.

 

[83LSWagon]

If its a stock thermostat, wont the car run at around 220-230? I thought this was OT for LS motors(not running mine that hot though )

 

[blubaldmontess]

I am not sure but I believe the normal op temperature is 205-210...but then you can recalibrate teh fans (mine come on as a single at 195, double at 200)so they come on earlier...

The only reason I say that is because teh thermostats I've seen aftermarkte are anywhere from 168 degrees to 185 degrees.

 

[MalibuRacing]

The engine is out of a 2004 Tahoe. My wife drives a 2007 Yukon, which runs at 210, so I'm guessing that's what it should run. The Malibu was running higher than that before I shut it down. Plus, I wasn't getting coolant flow.