Johnous John Montgomery (22 posts) Registered: 01/11/2010 01:29PM Main British Car: 1978 MGB Roadster 3.5L British Leyland V8 |
Coolant Overflow Tank Return
Hello all! I am getting closer and closer to starting my long-term MGB project. Finally found some time to get working again, and I have a plumbing question for you learned folk.
I am planning on using the old MGB coolant overflow tank, albeit somewhat polished up. I wanted to ask about where I can route the bottom line that returns coolant to the system. I understand that these are (typically?) connected with a T fitting in the lower radiator hose, but my mustang radiator came with some nifty bungs that I wanted to utilize (see photo). I have gone ahead and plugged the left bung, and was planning on using a brass 90 degree fitting to run the coolant return from the bottom of the overflow tank. Does anyone know if this would be problematic? I am assuming that enough suction from the water pump will circulate coolant through the line via the bottom radiator tank. However, I want to make sure that nothing bad will happen from having the overflow tank directly plumbed to the radiator. As always, many thanks for everyone's expertise! This is my first custom car project, and I will never cease to be amazed at the complexity of this process. |
pspeaks Paul Speaks Dallas, Texas (698 posts) Registered: 07/20/2009 06:40PM Main British Car: 1972 MGB-GT 1979 Ford 302 |
Re: Coolant Overflow Tank Return
Hey John, unless I'm mistaken, those nifty little ports on the bottom of your radiator are for cooling automatic transmission fluid and don't go into the water tank, or at least they're not designed to.
Paul |
Johnous John Montgomery (22 posts) Registered: 01/11/2010 01:29PM Main British Car: 1978 MGB Roadster 3.5L British Leyland V8 |
Re: Coolant Overflow Tank Return
Paul,
Thanks for the info. So it is likely they are a closed loop between the two ports? That certainly wouldn't be good for my application. |
pspeaks Paul Speaks Dallas, Texas (698 posts) Registered: 07/20/2009 06:40PM Main British Car: 1972 MGB-GT 1979 Ford 302 |
Re: Coolant Overflow Tank Return
I suppose maybe I should reconsider it, but I have an aluminum cross-flow radiator and don't have an expansion tank.
Paul |
britcars Phil Ossinger New Brunswick, Canada (346 posts) Registered: 02/02/2009 07:58PM Main British Car: 1977 MGB Roadster, Rover 3.5 ADVENTURE BEFORE DEMENTIA! |
Re: Coolant Overflow Tank Return
John, I use an early Mustang radiator along with the stock overflow tank in the stock location. I plugged the tube in the neck of the tank, ran a hose from the other tube in the overflow tank to the tube in the neck of the radiator. I removed the rubber seal in the filler cap on the oveflow tank. Works great for me.
Photo attached............ Edited 1 time(s). Last edit at 05/11/2014 08:23AM by britcars. |
|
hirot Ian Hart Ashbourne UK (88 posts) Registered: 06/01/2011 05:15AM Main British Car: 1971 MGB GT (conversion) Rover 3947 R380 gearbox |
Re: Coolant Overflow Tank Return
John, don't know if it helps but I used the old 1800 header tank and put as high as I could near the firewall. The hose runs from a fitting at the top of a standard MGBV8 radiator by the filler to the tank. Which is I guess is the same as Phils. I keep the tank about 1/3 full and bleed all the air out the system via a bleed screw in a copper pipe fitting on the heater pipe and it seems to work well.
|
pspeaks Paul Speaks Dallas, Texas (698 posts) Registered: 07/20/2009 06:40PM Main British Car: 1972 MGB-GT 1979 Ford 302 |
Re: Coolant Overflow Tank Return
I did a heater delete as well (Gen II Mini system) and plan to move my odyssey battery there. As there's room for an over-flow tank as well, I'm seriously considering that addition, thanks Rick, hadn't thought of that. BTW, I just installed my RV8 bonnet and the new struts, I love it, and can now close my hood with the carb installed. Thanks again Rick, I love the way it looks.
Paul |
Addicted Mike Hagadorn Warren PA (132 posts) Registered: 09/27/2013 03:46PM Main British Car: 1976 TR7 Victory Edition Ford 302 |
Re: Coolant Overflow Tank Return
How many ports are on the coolant tank? If there is a third one that I can't see in your pic, the hose tee would be a good choice. With three ports, one should be connected somewhere in the lower radiator hose/water pump inlet. Another is connected to the very top of your cold side radiator tank. The slight pressure drop in your lower radiator hose creates a delta-p in your top tank. This creates a little flow and actively pulls air from the top of the radiator. This works extremely well. Probably not the best description, but I can sketch it if you want.
If you only have one hose (plus the burp hose in the neck) I'd say it can go anywhere on the "cold" tank of the radiator. Edited 3 time(s). Last edit at 05/11/2014 09:03PM by Addicted. |
mowog1 Rick Ingram Central Illinois (1523 posts) Registered: 10/17/2007 09:36PM Main British Car: 1974.5 MGB/GT 3.9l Rover |
Re: Coolant Overflow Tank Return
The stock MGB tank only has two ports.
One on the neck (see clear/white tubing on my picture) and one at about 4 o'clock as looking directly at the tank (see black hose). |
Johnous John Montgomery (22 posts) Registered: 01/11/2010 01:29PM Main British Car: 1978 MGB Roadster 3.5L British Leyland V8 |
Re: Coolant Overflow Tank Return
Hey yall, thanks so much for the fantastic insights. My understanding of the system is that the surge tank is part of the active circulation of coolant - as it expands and contracts beyond the radiator's holding capacity, coolant should flow through the surge tank (what Mike is describing methinks).
Running only one line to the tank would make it merely an overflow tank, which may be the least complicated option for me at this point (like Phil's application). Would I then need to run the other line, near the cap on the surge tank, to an open air hose for overflow drainage? Sounds like there are many ways to do this.... Sometimes I wonder if "custom" car really means "arbitrary" car? Edited 2 time(s). Last edit at 05/12/2014 09:14AM by Johnous. |
hirot Ian Hart Ashbourne UK (88 posts) Registered: 06/01/2011 05:15AM Main British Car: 1971 MGB GT (conversion) Rover 3947 R380 gearbox |
Re: Coolant Overflow Tank Return
John, it is an expansion tank as the pipe at the tank goes to the bottom of the tank which is why you only keep it part full. The cap on the radiator is a blank and the rad cap is put on the expansion tank. So as the water expands it blows into the expansion tank and then gets sucked back as it cools.
Depending which year tank you have the inlet pipe fits near the top and then has an internal pipe to the bottom of the tank, or earlier ones had the pipe go to the bottom of the tank. They do work. Regards Ian |