need help with cooling system
need help with cooling system i recently built an ls1 iron block from an 08 5.3 block and fired it up today for the first test drive well filled the radiator and started it and before i got out of the driveway it got to almost 220. i opened the radiator cap and it and that water was still cool, could it be air trapped in the engine ? or a bad thermostat?
I had a similar problem and had to crack open both bolts on the crossover tube then slowly added fluid to the radiator until air stopped bubbling out of the holes. I did this until I got a steady flow of coolant from both holes and after that, all was good. Its seems like that wouldnt be a big problem but it really is! Mind you this takes a little times and be sure all air is out. That coolant system traps alot of air and venting the crossover tube is a necessity. If that doesnt work, remove your thermostat and boil it to see if it opens.
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Following a coolant change I usually just use the crossover tube connection to the radiator return tube to "burp" the system. Following a head swap however, I like to loosen all four crossover tube connection points (my LS6 actually only has one front crossover with plugs on the rear of both heads) to make sure I have no air pockets at either end of either head.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Place a length of clear tube on the crossover tube (where you removed the rubber hose), then you can watch the air coming out, eventually you will see coolant only.
The clear tube keeps you from spraying coolant on the pulleys/belt.
If the front of the car is jacked up, then trapped air will migrate to the front of the heads.
The crossover flows sufficiently, you shouldn't have to loosen the crossover bolts, if you do then that indicates a blockage.
The clear tube keeps you from spraying coolant on the pulleys/belt.
If the front of the car is jacked up, then trapped air will migrate to the front of the heads.
The crossover flows sufficiently, you shouldn't have to loosen the crossover bolts, if you do then that indicates a blockage.
you would think so but it didnt lol. i didnt even run it i just unbolted the cross over tube on the front after the car had warmed up and as soon as i unbolted it the level dropped and i began putting water into the radiator until water came out the holes.then bolted it back up topped off the radiator and ran it for a while. let it cool down and topped it back off now im good to go
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
you would think so but it didnt lol. i didnt even run it i just unbolted the cross over tube on the front after the car had warmed up and as soon as i unbolted it the level dropped and i began putting water into the radiator until water came out the holes.then bolted it back up topped off the radiator and ran it for a while. let it cool down and topped it back off now im good to go
