aluminum coolant bottle

I ordered a ‘standard aluminum’ radiator coolant bottle from macsradiator.com, for my 1989 closed cooling system, and when it arrived, much to my surprise, the filler neck had a nipple on it. I never noticed it on their web picture. When I downloaded their picture and blew it up on my screen, the necks between ‘standard aluminum’ and ‘diamond plate’ are different. See pics below. Their web site does not mention the difference.

So, it seems that I have two options; 1) cap the nipple and use it as a closed system, or, 2) use the nipple, route it to an overfill bottle and convert to open system. Does the second option make sense? Do you think the neck nipple is there for the conversion option?

From all my readings on debate over closed versus open cooling system, the general consensus seems to be that the closed system provides better cooling when the entire cooling system is working properly. I have had little trouble with my closed system, and when I did, it had to do with a marginal radiator, H2O pump, leak somewhere, or a bad cap.

So I am leaning towards staying with the closed system, by capping off the nipple. Would any rubber cap work, or would it have to be of some special material to withstand the heat/pressure? Of course I’ll use a clamp on it.

Any other ideas?

Since the closed system runs a pressure cap at the bottle, would you not just leave the nipple and run a hose down the bottom ? all systems have some type of outlet in case of excessive pressure?

Well first off, im glad you found that out! I have been thinking about getting one, and its nice to know what exactly they provide you with. Does the two spots for the coolant hoses look right? Does the cap go on it correctly?

The guys in the sheet metal shop here at work say they can probably make one for me though, would you be willing to provide 360 degree pictures, and full dimensions?? I would really appreciate that.

Anyway, i would not "try" to convert to the open system. Im one of the rare people who prefer the closed. You couldnt use just that nipple to convert over however. You would need a radiator etc.

It looks like that nipple is threaded into the filler neck... I think it would be best to go to a local hardware store and find a cap with the same thread pitch and diameter and screw it in. This would be able to withstand the pressure better then any cap on the nipple could in my opinion.

Hope that helps.

Mine came the same way. From what I can tell, its a pressure relief nozzle. The tank is designed to take a standard radiator cap. If/When the engine overheats, pressure builds up, it pushes the cap up a bit and vents some of the pressure out of the nozzle. Without it, the tank would explode if the engine overheats.

I've been running it for over a year now with nothing attached to the nozzle. My coolant system is in good shape and I've had no overheating issues. So far, nothing has come out of the nozzle with the cap on and tight. I'd say it'll be fine with just the cap on it.

Yeah I just bought the non diamond plate one as well and it also has the nipple on the filler neck. I am going to put a hose on mine and run it down by the frame so if it overheats or the pressure becomes to great the anifreeze will run out the line onto the ground instead of all over the engine bay.

Maz said:

I ordered a ‘standard aluminum’ radiator coolant bottle from macsradiator.com, for my 1989 closed cooling system, and when it arrived, much to my surprise, the filler neck had a nipple on it. I never noticed it on their web picture. When I downloaded their picture and blew it up on my screen, the necks between ‘standard aluminum’ and ‘diamond plate’ are different. See pics below.

Click to expand...

They look the same to me. Look closer, the hole is there on the diamond plate one, just there is no bung threaded in.

FordGuy said:

Since the closed system runs a pressure cap at the bottle, would you not just leave the nipple and run a hose down the bottom ? all systems have some type of outlet in case of excessive pressure?

Click to expand...

No. Thats the whole point of the closed system, it does not have some type of outlet.

It is designed to run higher pressures, and when working correctly, cools better.

I converted my 87 to open, and I'm going to convert it back to closed.

The closed system does have a point of exit if it overheats, it sprays out from under the plastic cap all over everything under the hood! That nipple in the new aluminum bottle will not let anything out unless the pressure becomes to high. Hook a hose to it so you don't coat everything under your hood in antifreeze if you ever over heat.

That's an "overflow" nipple, just like anywhere else. It only comes in to play if you're overheating (and you'll have bigger problems anyhow.)

If you don't want to run the thing, just remove it and put in a pipe plug - it looks like a standard NPT-hose barb nipple (probably 1/4" NPT.)

5-90 said:

That's an "overflow" nipple, just like anywhere else. It only comes in to play if you're overheating (and you'll have bigger problems anyhow.)

If you don't want to run the thing, just remove it and put in a pipe plug - it looks like a standard NPT-hose barb nipple (probably 1/4" NPT.)

Click to expand...

If he plugs that hole where is the excesive pressure going to vent if it overheats?

jeepboy381 said:

If he plugs that hole where is the excesive pressure going to vent if it overheats?

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I don't think you are understanding.

Its a *CLOSED* system. It doesnt have a place to vent. Its closed.

cal said:

No. Thats the whole point of the closed system, it does not have some type of outlet.

It is designed to run higher pressures, and when working correctly, cools better.

I converted my 87 to open, and I'm going to convert it back to closed.

Click to expand...

If it does not have a way to escape what do you think will happen when your t-stat sticks? It will blow a hose or your Radiator!

I bought the diamond plate one, and used a 20 pound cap. It iwll release if the pressure is too great, but as others note if it doesn't vent out of the radiator cap, it will blow the weakest link... much easier to fix the cap or let it cool off, than have a blown hose, freeze plug, or radiator. Any auto parts house will have the caps, so just find the highest pressure you can. 20# is not uncommon... got mine a kragen in the SF bay area!! A truly closed system with no outlet would eventually self distruct in heavy duty application.:sunshine: :sunshine:

FordGuy said:

If it does not have a way to escape what do you think will happen when your t-stat sticks? It will blow a hose or your Radiator!

Click to expand...

Usually the cap on the pressure bottle blows, or the bottle itself blows.

I didnt design the system.

Looks to me like the bottle takes a rad cap if it does the nipple will be blocked by the cap. Only way it will open then is the pressure is to high.

I never said it was a good idea to block it off - I just mentioned it as a possibility. I'd run it to a catch can, meself.

The radiator cap still has the ability to vent - but you're right. If you put a plug in that nipple, where's the pressure going to go? Something tells me that the one without a nipple is probably already drilled and tapped for it - they just didn't put it in the pic.

Muad'Dib said:

.....Does the cap go on it correctly?

....would you be willing to provide 360 degree pictures, and full dimensions?? I would really appreciate that.

Click to expand...

I'll post up how the bottle and cap fit, when I get around installing it, unless someone who has used one wants to chime in.

For measurements, see the pics below. The tape measure is to the edges, but it does not show in the pictures because of the camera angle. Hope that helps

Jes said:

They look the same to me. Look closer, the hole is there on the diamond plate one, just there is no bung threaded in.

Click to expand...

Ah, I think you are right. My eyes aren't what they used to be.

Thanks for the dimensions... do you have it installed yet?

The guys in the shop here would like better dimensions like how you did with the second to last picture. That would really help them. They are pretty sure they can make it.

The only problem is that check valve thingy... is it just open to the inside of the bottle? Or does it actually have a valve in it?

Does it use a standard radiator cap now? If so what poundage did they recommend, or did it come with?

Thanks for your time and effort.