gto_70

Can anyone tell me if the cyclinder head air bleeds are really necessary and can they be blocked off? I have a 2002 6.0 liter (using as a conversion in a 1967 Chevy truck) and in the back of the engine the holes have block off's so i purchased 2 more of them and they fit in the front, which cleans up the look, but will the engine burp it self without them hooked up, elimination also gets rid of the coolant passing thru the throttle body, might be bad for cold weather but not intended for cold weather driving. i did do a search but didn't see much on this.
Please help shed some light on this subject.
Thanks,
Steve

Scooter70

iTrader: (1)

I thought that I had heard that someone ran their car for a while with the front crossover pipe blocked off, but I don't remember who it was.

TTT!

crainholio

iTrader: (2)

Possibly you could bleed the air thru them manually, then block them off. You'd make a mess doing it, but you'd have the air out. Any time you open the cooling system, though, you'd risk introducing air into the system...and the heads are the highest point so the air would accumulate there and create hot spots.

I wouldn't do it. You can bypass the throttle body and just return the air bleed to the rad.

-Kevin

Brains

iTrader: (7)

With the motor set at an angle, you can safely block the rear ports -- the LS6-intake equipped cars do this from the factory. The front ports are best returned to the radiator to avoid air bubbles and hot spots.

Scooter70

iTrader: (1)

Thanks guys. Does it matter where it's returned to the rad? Could it just go to the overflow bottle or should I put some type of port in the top of an end tank?

crainholio

iTrader: (2)

If you're running one of the newer-design pressurized overflow bottles, OK to return it there. If you have an older vented overflow bottle, don't...the cyl head air bleed flows coolant continuously. In that case, you need to find or create a place to connect it on the rad or Tee it into one of the hoses.

I used to think this connection had to be at or above level with the cyl heads, but evidently not...my '02 Silverado has the air bleed return about 1/2 way down the passenger side radiator tank, way below level with the heads.

Whistler

iTrader: (46)

My 67 would slowly overheat until I hooked the small line up to the radiator.

gto_70

My Radiator is the stock radiator for the truck and the radiator cap is above the cylinder heads (at a higher point), so with the 15lb pressure cap wouldn't the system bleed itself off like the older small block and big blocks did forever???

crainholio

iTrader: (2)

No. Unlike a regular smallblock Chevy, where the thermostat and it's output hose are the highest point on the engine, an LS1 has the in/out hoses much lower than the heads...making the heads the highest point on the engine.

Air trapped in the heads has no way to migrate down to the radiator hose, so you have to let it out via the bleed holes.

defiftyae

excellent post, important info everybody should know. just a question how many people have the vent holes on the back of their 5.3L with factory plugs?

Stu Cool

iTrader: (13)

Does anyone have a part number for the coolant tube kit to use with the LS6 manifold? I will be swapping the LS6 manifold onto a 2000 motor, I found a manifold, now I need the front tube and rear plugs.

thanks

Pat

TJ

iTrader: (10)

ive got an 02 6.0L.... it has front and rear coolant lines.
i also have a 04 6.0L.... the back is blocked like your 5.3L.
if i have an old school chevy radiator, where can i vent the line too? tap and put a barb in the radiator im guessing. up high or down low?
very good topic for conversions.......

MrDude_1

iTrader: (4)

theres a how-to about it here:
http://www.ls1howto.com/index.php?article=5

- 1x 2001+ front coolant pipe - #12568478
- 2x 2001+ rear coolant plugs - #12562788

MrDude_1

iTrader: (4)

anywhere on the drivers side tank is fine... the airbubbles will be pushed into the endtank, once in the tank, they can rise to the top, where they get "burped" out by the radiator cap.

TJ

iTrader: (10)

thanks for the info.
i think i might go ahead and swap in a LS1 radiator while im at it, so i can use stock hoses.
ill prolly get the fans too, seeing how they clip on so nice and neat.
does the factory LS1 radiator have a tune already on it for the bleed hole?
thanks for the info and the link.

Stu Cool

iTrader: (13)

Thanks!!