Coolant bleed pipe question
 

Im finishing up my 4.8 swap and ran into an issue with these pipes. Under the throttle body are 2 small nipples for the coolant. One has a rubber hose going to the drivers side head and the other had a long hose going to I assume the radiator. The problem is I am using my stock SBC radiator and I don't know what to do with this other side. Can I simple put a rubber cap and clamp it shut? Anyone else run into this problem?

Thanks
Jeff

Re: Coolant bleed pipe question
 

It's like a preheater I think....I didn't hook it up...just stuck a vacuum cap on each side just to plug the holes..

Re: Coolant bleed pipe question
 

You just made life a bit easier! Wasn't sure what to do. Thanks!

Got another problem with the drive belt being extremely hard to get on but I will try again this weekend and probably end up posting for help...

Re: Coolant bleed pipe question
 

It is a steam port, it should be hooked to somewhere with constant flow in the cooling system. It helps with hot spots in the head by allowing any air or steam that accumulates under the increased heat of the heads a place to escape. It also allows the system to purge on the initial fill of coolant

I drilled and tapped a port into the back of my water pump that lines up with the upper radiator hose. This at least allows constant flow, and any air build up a path to the radiator where it can be burped off.

Re: Coolant bleed pipe question
 

I think He's talking about capping the fittings on the throttle itself....not the engine steam ports...
Steams ports are important...I also plumbed mine into the water pump.....

Belt shouldn't be a issue...make sure you have it routed correctly...a socket or wrench on the tensioner should do the trick...

Re: Coolant bleed pipe question
 

I agree, those specifically on the throttle body arent needed.

Re: Coolant bleed pipe question
 

I read it as looking what to do with the long hose on the pass side tb long hose . Being the radiator was mentioned I would suspect it needs to be hooked up to the cooling system .

So yes , it needs to be hooked somewhere in the system as for reasons stated above . You can by pass the tb if you like and hook it directly to the drivers head to the cooling system .

Re: Coolant bleed pipe question
 

That picture is exactly what I'm talking about. The one on the drivers side is connected to the head and the pass side is open. If that is not needed I plan to just cap that off.

Re: Coolant bleed pipe question
 

Mongo I will take pics of the belt problem when I get in this evening to show you what the problem is.

Re: Coolant bleed pipe question
 

As was stated here you can cap the 2 ports on the throttle body. If you do this, you should NOT cap the line coming from the heads. So you still have to plumb that line back into your cooling system.

The line that feeds coolant into the throttle body comes from the steam ports in the heads. It should NOT be capped off.

Re: Coolant bleed pipe question
 

Ok I got you. Thanks Curt. Do you guys have any pics of your set up so I can get a better idea of how I should plumb mine?

Thanks

Re: Coolant bleed pipe question
 

TB coolant bypass is one of the earliest LS1 "free mods." Supposedly it's to warm the incoming air and keep the throttle body from icing up in cold conditions who knows. Easiest way to bypass is get a double barbed coupler and plug the hose together.

Re: Coolant bleed pipe question
 

I am facing the same thing and pics would be great.

Re: Coolant bleed pipe question
 

i have mine plumbed like the yellow lines show...it goes under the tb and into the water pump in the raised boss of the pump....I had to later change water pumps and the new pump didn't have this boss area so I drilled and tapped npt in the same spot....pump housings are thin so be careful if you do it this way...there is also a heater hose fitting that can be used in your top radiator hose..

Re: Coolant bleed pipe question
 

Would one of those radiator hose T connectors do the same thing? I read a thread on LS1tech and somebody said they did that.

Re: Coolant bleed pipe question
 

Aren't the two lines running to the TB the steam lines? The driver's side going to nipple on front of D side head and the other can go to the in-line radiator hose fitting pictured above or to water pump or any other option out there. Some run 4 corner vents, some just to front of heads, and there's also spacer kits with steam barb to run fbody/car water pump.

Re: Coolant bleed pipe question
 

yes...hose t connector will do the same as tapping into waterpump...

Re: Coolant bleed pipe question
 

Ok. Should I tap into the upper or lower radiator hose?

Re: Coolant bleed pipe question
 

upper

Re: Coolant bleed pipe question
 

ok thanks again

Re: Coolant bleed pipe question
 

mongocanfly

Where to purchase steam vent fitting?

Re: Coolant bleed pipe question
 

Jags that Run has them. https://jagsthatrun.com/collections/co

Re: Coolant bleed pipe question
 

Ls1 nova ...I couldn't get your link to work...
Flexlite...................https://www.flex-a-lite.com/1-1-2-in...e-adapter.html
And summit...................https://www.summitracing.com/parts/f...kaAiEeEALw_wcB
JTR........https://shell7.tdl.com/~jags/Pages/P...g_LSI-tee.html

Just google...(ls steam vent radiator hose)

Re: Coolant bleed pipe question
 

There are a few variables on water pump and steam port pipe routing. I cut the factory hose nipple off of my steam port piping, drilled it out to 11/32 to the right depth, and threaded it for 1/8 npt. From there I used an 1/8 npt to 1/4 barb 90.

This thread has some good pictures as well, one of my favorite engine builds. http://67-72chevytrucks.com/vboard/s...d.php?t=668385

Re: Coolant bleed pipe question
 

I couldn't find any specifics online to be exact but I measured the upper hose OD at 1 1/2 and I know LS are metric and that puts it at 38mm. Can anyone confirm or correct me on this? (Reason being I am going to plumb the bleed pipes into the upper hose)

Thanks