MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Heater Pipe Connections

I am not sure it makes any difference, but should the output from the heater tap on the block on a MK 3 midget go to the bottom or top inlet pipe on the heater?
C Martin

Pretty sure its the top one.
J Lodge

Mine's on the bottom...


Dave O'Neill 2

Just been looking at a sales brochure for the 1275.

As Daves - heater tap hose to bottom heater connection.

Richard.
richard boobier

HHHHmmmmm, I always thought it was on top...wouldnt it be easier for water to flow down rather then up thur the heater core.

prop
Prop

Prop, it's at the bottom so any bubbles can work their way out of the system. Since in theory there's no air and it's being pumped, it doesn't make any differernce to the water flow.
Clive Reddin 76 Midget

Would seem to make sense if the flow was bottom to top, so the air bubbles could escape into the rest of the system - say into the rad to be 'blown out' as expansion gas.

Air bubbles collecting in the heater will reduce its efficiency.

A
Anthony

So which way does the water flow through the heater tap? - towards the head or away from the head?

I think that the water pump pushes heated water away from the head and through the large hose to the bottom of the main radiator. The small hose to the heater feeds off this larger hose, (going via a Titan inlet manifold in my case) before arriving at the bottom of the two heater core connections. The top connection goes back to the heater tap.
Both connections are pretty well at the top of the heater core because it is angled downwards, helping to dispel air upwards. When refilling a system I always pull that top connection off to allow any air to escape. I keep thinking I should add one of those little bleed valves that look like a tyre valve, that many "moderns" have.
Guy Weller

take the easy way out, put on a nice header on, that will increase cabin temp by 572 degrees(great for highway BBQing), that way you can scrape the heater and have a great place for something else....thats what I did, no air bubbles for me...

prop
Prop

I believe that water flows through the head and 'out' the tap.

I believe this to be the case because during my car's "lets see which cooling components can blow on this journey" season, the tap stripped its threads and blew skyhigh against the bonnet. Niiice.
Rich Amos (1330cc Blaze Red '72)

Guy the pump is on the block not the head (but you knew that) and I think the pump pushes cool water into the block, where it heats up, rises through the head gasket holes into the head, thence either round the heater circuit (where it cools) and back to the inlet hose to the pump, or via the thermostat housing - when it opens - into the top of the rad, where it cools and falls to the bottom, back to the inlet hose again.
David Smith(davidDOTsmithATstonesDOTcom

Richard,
I would suggest that your heater tap "blowing skyhigh against the bonnet" was nothing to do with which direction the water was circulating, but due to the pressure in the system.

David, of course I meant that the pump was bolted to the block, not the head. My mistake! I agree you are also right about the direction of the circulation. Must be, else the thermostat would not control rate of release of hot water to the radiator.
Guy Weller

Thanks for the input, it seems like output from the tap goes to the bottom of the heater is the most popular.
Colin
C Martin

Colin,
I make that 5:2 in favour of Tap to Top as the connection. I think...

Guy
Guy Weller

I was really going with the sales brochure.........I guess those guys should know as they probably used cars from the factory. At the end of the day I gather it really wont make a lot of difference as those with it on the "wrong" way dont seem unduly affected.
Colin
C Martin

Ah, but you don't know how efficiently their heaters are working ;o)
Dave O'Neill 2

Check out Horler - original sprite and midget pages 100 and 102.

Bristows - pages 18 and 19.

Moss page 98.

All 3 show heater tap to bottom.

Thats 5 all !

Take your pick

Richard.


richard boobier

from a heat transfer efficiency angle I think it should be tap to top (like the rad) but tap to bottom will be better at purging air locks so probably that takes precedence.
David Smith(davidDOTsmithATstonesDOTcom

just do not do what i did. I had the heater bypassing the thermostat routing water unrestricted through my suzuki radiator untill the temp gauge droped off into colder and the motor would not run right. lessons learned right?
Stefan

Every Spridget of whatever variety I looked at at Stoneleigh today had "tap - to - bottom", regardless of which heater was fitted. Square box or later posh type.

Any help?
Bill

Outlet tap to bottom of heater it is then !!!!!!!!!!!
Colin
C Martin

This thread was discussed between 17/02/2008 and 25/02/2008

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.