throttle body coolant line on swapped vehicles

[brharris27317]

I am swapping a LQ4 into a 94 Chevy truck and wanted to know what you guys do with that little 3/8" coolant line that goes from the driverside head to the throttle body and then to who knows where since I don't have donor vehicle. I know on my LT1 swap that I made a 1.5" pipe with 3/8 barbed fitting coming out of the side and cut my upper radiator hose and put that piece in as the 3/8" line was important to bleed the air out of the LT1 heads heads. Is this also true of the LS series engines and I need to do something similar for that line or do you all just plug it. I thought it might not be important since I don't see anything on the passenger side head to bleed the air out. LT1's have a pipe going between each head in the back and that line goes to 1 line down the intake and tied into the upper radiator line on LT1s but I don't know where this 3/8 LQ4 line is suppose to go and how important it is.

Brian

[RedHeartbeat]

Its the same thing. There is an air bleed hole in all 4 corners of the cylinder heads. what you did with the LT1 will work. It is important to leave the small hose off while filling the radiator the first time and when you see a steady stream of coolant coming out of the line you can put the hose back on. BTW, we normally just bypass the line that goes the the throttle body.

[brharris27317]

THanks,

[josh@truckbuildermag]

I have heard of people filling the front two steam holes and then capping them with the solid plugs like on the rear. Is that correct?

[NITROUS]

Yes, you can plug the holes. The LT1 heads were reverse flow so you needed the bleeder. The LS1 isn't so you can do like Greg and plumb it into the water pump or plug it off like I do on all my swaps. The only reason for that line is to heat the throttle body. I plugged Patriot, GM and AFR heads with no temperature issues. You want to make sure and finish filling the radiator through the upper hose and then break the bolts loose on the plugs to remove any air before startup. You can purchase the rear plugs for an LS6 and they will fit the front holes on the head.

[DBRODS]

I just went through this with my LS2, I ran the crossover tube down and tapped the thermostat housing to tee it in. When I topped the radiator off it was getting hot fast until I loosened the crossover bolt on the pass side head and all the air came out. I let it purge for a while then tighened it back down. No problems after bleeding it from the tube....

[brharris27317]

THanks guys.