Radiator Vent Line

Hi pat, Sorry for the delay in answering your question. The top vent in the radiator and the steam vent from the top of the intake manifold both eliminate air pockets the coolant system. The “Steam” is dumped into the top of the expansion tank and ulitimately vents to the coolant recovery tank. Fluid Make up back into the engine from the expansion tank or the coolant recovery tank is only liquid with air seperated out. In reality on my CAV, the expansion tank, the intake vent, and the radiator all connect via a tee coupling. I understand this to be a standard air bleed method. Hope this is helpful.
 
Hi pat, Sorry for the delay in answering your question. The top vent in the radiator and the steam vent from the top of the intake manifold both eliminate air pockets the coolant system. The “Steam” is dumped into the top of the expansion tank and ulitimately vents to the coolant recovery tank. Fluid Make up back into the engine from the expansion tank or the coolant recovery tank is only liquid with air seperated out. In reality on my CAV, the expansion tank, the intake vent, and the radiator all connect via a tee coupling. I understand this to be a standard air bleed method. Hope this is helpful.
Do you know if there is any other way to bleed a system if the radiator doesn’t have a bleed port?

Can I use the steam port at the top of the manifold only to bleed the system?
 

Ian Anderson

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Do you know if there is any other way to bleed a system if the radiator doesn’t have a bleed port?

Can I use the steam port at the top of the manifold only to bleed the system?
Turn your car upside down so the highest point in the radiator is the inlet and outlet pipes, and keep the rear of the car higher then the front so the fluid will flow to the front and the air escape to the back.

Really not practical.

Just drill a hole and tap the fitting to mount a manual air release system or bleed line back to the header tank.


Ian
 
Steve, look at the radiator, unless you have a steam/bleed port above the intake and return hoses, you can't bleed air as the trapped air floats above the coolant hoses. As Ian posted, you'll never be able to fill it unless you can remove the air first. Otherwise, you'll never displace it to allow in the coolant.
Perhaps you can vacuum fill the system by sucking out all the air with a vacuum refill kit but I'd think you'd need to apply so much suction to reach all that you may damage something. Again, check with the manufacturer and others that own your kit.

vacuum fill coolant - Bing video

Bob,
I had assumed the tee fitting on the CAV was to purge/bleed air FROM the manifold to the expansion tank as well as take the steam/air feed from the top of the radiator to the same tank. The single feed works that way and that's why the second "steam" one from the radiator was confusing me. It seems redundant.

Note diagram:
 

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Thanks Pat. Very frustrating. I bought a brand new radiator supposedly for a gt40 and there is no bleed port.

I guess I’ll have to take it to a welder and have one tig welded in. Any suggestion what size hose I should use? I want to make sure I weld in the right sized fitting.

Thanks
 
Steve, when i get home tonight i will post some pictures of manual operation weld in vents i added to the very top of my radiator. I also have a welded in line that connects to the expansion tank. Pat, I agree that having both radiator and intake vents are some what redundant but working together they throughly clear air from the system within minutes of a coolant refill with no need to worry about the degree of tip or rake of the car.
 
Steve, when i get home tonight i will post some pictures of manual operation weld in vents i added to the very top of my radiator. I also have a welded in line that connects to the expansion tank. Pat, I agree that having both radiator and intake vents are some what redundant but working together they throughly clear air from the system within minutes of a coolant refill with no need to worry about the degree of tip or rake of the car.
Thanks Bob
 
Steve, I'm sure Bob's pics will be what you need. As for the fitting size, I'd go with whatever may be on the header tank available from Active Power. You may want to ask Chris about the setup he used in the other customer cars. I think I have a -4 fitting.

Also, I'm near Orlando, if find yourself in the area, bringing the kids to Disney etc. you're always welcome to come by and take a look at my '40 or take a ride. PM me for contact info.
 
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Have a look at this picture
http://www.gt40s.com/forum/attachment.php?attachmentid=30801&d=1215116428

My radiator and in the same location a bleed hole, fitted with a Allan he’d grub screw.

Loosen the Allan head and release air, pinch up tight.radiator now full of water.

Repeat process a couple f times a year till you stop getting any air

Ian
I wonder if it’s safe to drill a hole in that mounting thread. Wouldn’t want to get metal shavings in the coolant system, but it is a good idea.
 
Steve, I'm sure Bob's pics will be what you need. As for the fitting size, I'd go with whatever may be on the header tank available from Active Power. You may want to ask Chris about the setup he used in the other customer cars. I think I have a -4 fitting.

Also, I'm near Orlando, if find yourself in the area, bringing the kids to Disney etc. you're always welcome to come by and take a look at my '40 or take a ride. PM me for contact info.
That’s awful nice of you Pat. Thank you!
 
Have a look at this picture
http://www.gt40s.com/forum/attachment.php?attachmentid=30801&d=1215116428

My radiator and in the same location a bleed hole, fitted with a Allan he’d grub screw.

Loosen the Allan head and release air, pinch up tight.radiator now full of water.

Repeat process a couple f times a year till you stop getting any air

Ian
Ian,

You may be a genius.

I can drill a small hole in the radiator where the acc mount is, blow it out with forced air to get the metal shavings out and put in a bolt.

It will be a small bleed hole, maybe 3/16, but it would be big enough to allow air to escape.

Do you think this will work???

It’s all tig welded.
 

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A screw might seal if you put a locknut with a sealing washer. I'd think brass would be a good option for the screw. But I'd want to over engineer the solution so you don't have to worry about it later.

That said, it may need a pipe thread fitting to get a good seal when the system is under pressure. A machine shop should be able to drill and tap a 1/8NPT for you pretty easily or even thread the nipple for an AN fitting that allows you to run a vent to the header tank.

The thing is that at this stage of your build, getting the radiator in and out is far easier than once you get the car all together and fluid filled.
 

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I just heard from Chris at Active Power.

He has the same radiator and he drills out the hole and puts in a screw with a crush washer and Teflon tape after the system bleeds all the air out.

And Pat, that radiator is harder to remove than you think. I sort of “overbuilt” the cabinet that it goes in and you need to stretch open the sides to sneak it out.

I’m going with Chris!

PROBLEM SOLVED!

I love this forum, you learn so much!!!
 
Glad it worked out Steve. I think you'll find it useful maintaining your build log on the forum. Others will find it interesting and may provide a suggestion or experience they had that's applicable to your situation.
 
Hey Steve, Looks like you have all you need now.

The radiator air bleed valves are available in brass at most race supply houses. Some are spring loaded push button and other screw on caps. The screw on versions are probably more secure long term.

A -4 size AN hose is also added to the top of the radiator and connects back to the top of the expansion tank for a continuous air bleed.

This website has always been the number one place for info. Good luck with your car.
 

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Glad it worked out Steve. I think you'll find it useful maintaining your build log on the forum. Others will find it interesting and may provide a suggestion or experience they had that's applicable to your situation.
Thanks Pat. I think I will start a build log, it will probably just take me longer than most.
 
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