Mssingkid

iTrader: (7)

I tried to search but couldn't find what i was looking for. Anyone have an issue with a new thermo popping for the first time. Started up the new motor and it quickly overheated. Seemed like the Thermostat didn't want to open. I know the system has tons of air in it, i'm having a hard time getting air out of the system without it opening.

Mssingkid

iTrader: (7)

Bump!

No one's had this issue?? Guess Speed Inc is getting their malfunctioning thermostat back.

SweetS10V8

iTrader: (4)

Throw it in a pot of boiling water first. That will tell you if its working or not.

WS6Power

With an LS1 you have to hold the RPMs at 3K until the new stat will open for the first time.

1BADTALS1

iTrader: (4)

don't you have to have the fans set also? so they go on sooner or what not?

2000Hawk

iTrader: (5)

I just tossed in the 160* t-stat when I changed out my water pump. If yours is faulty then get a new one rather than risk ruining your motor. I got the air out of the system by following the t-stat swap instructions on installuniversity.com.
-Joel

Mssingkid

iTrader: (7)

Well since i have a 98, i was able to read the true temp.. or well close to it. I turned over the new motor.. she idled then i held it @ 2K to get her warm... and well the temps started to creep past 210 so i shut it down.. no sense damaging a new motor. It was taking very little fluid from the radiator..

I'm going to try the install univ's method, and try to get as much air out first.. hope that helps. thanks for the input folks.

Frost

iTrader: (45)

Are you being serious?

LS6427

iTrader: (2)

Thats some funny ****.

Mine was installed and I let it idle with the radiator cap off until it opened and the coolant started to flow. Guess I got a good dud.

LS6427

iTrader: (2)

Top off the radiator, leave the cap off, as its warming up squeeze the upper and lower radiator hoses fast. Squeeze them like 20-30 times each as its warming up. It works every time. If you top it all the way off as you squeeze the hoses it will splash up and out, just squeeze them so you don't make a mess. When it opens up and the level goes down, top it off and your done.

Y2KblueZ-28

I had the same issue i let my car cool down and started it up again i held it at 3,000 rpms and still kept heating up so i let it cool down again. started it let it idle for a min and rapped the **** out of it a few times and it stopped oeverheating. make sure your radiator is full first .

WS6Power

Yep, I`m serious. If you don`t believe me just give GM a call. When you change the fluid or stat on an LS1 you have to hold the RPMs at 3K in order to get all of the air pockets out of the block. Air wont open the stat and you take a chance at really damaging the engine. Once it opens top it off and lower your fan temps.

up2nuthingud

iTrader: (18)

you need to get the air out of the motor, try disconnecting the coolant crossover tube where it connects to the rubber hose until the coolant comes out.

LS1-450

iTrader: (33)

As correctly stated many times in this thread, the problem is air. Start car, heater on high, run for 3 or 4 minutes tops. Open radiator cap (make sure not hot to touch), add fluid. replace cap. Start car, heater on high, run for 5or 6 minutes; let cool. Remove cap, fill raditor & overflow container. Start car, heater on high & run for 10 minutes. Let cool down. Open radiator & overflow container; fill as required. Go for a short drive. Let car cool. Check radiator & add fluid as needed. Check fluid levels after driving during the next few drives, just to be sure. The problem is air, not the thermostat.

EDIT:
BTW, when I called GM, they said to hold gas pedal to the floor until engine blows, then replace engine w/ a crate engine & then to repeat the process until one learns the proper way to fill & bleed the coolant passages.....whala, overheating problem solved.

davered00ss

iTrader: (4)

When I did my heads it took quite a while to work the air out of the system.

Did an engine swap with an electric water pump and was able to work out the air before we started the car.

Mssingkid

iTrader: (7)

Thx everyone. I did put the thermo in boiling water, and sure enough it opened...

This it seems was my biggest problem. I ended up filling the motor from the top of the water pump with the coolant crossover unpluged. Sure enough once the motor got warm the thermostat opened up. I'm guessing that the motor had so much air in the system, there wasn't enough warm coolant getting to the thermo to make it open. She has to be bled a bit more but the new motor isn't getting hot anymore..