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MG Midget and Sprite Technical - Filling the heater on a 1500

Guy wrote some stuff in a thread some time ago about filling the system from the highest point (the heater). Good advice no doubt however:

Before I get it appart and then mutter a lot about the world and my inability to cope with the cooling system and get all wound up as I am so near to being on the road. (just the wash bottle to prime and a wire to put back on the hazard switch appart from the carpets - doing now tonight - a wash down and some water in the heater system to drive it to an MOT).

I wondered:
Which pipe should I fill the heater and therefore cooling system through?
Is this what the average garage back in the day did when the AF needed changing or did they do something else?
And more importantly what permanent changes can I make that someone has tried that I can add to make filling with coolant simpler in the future?

We are looking at an unknown beasty here so I will probably have lots of things to do to the engine over the next 12 months. I already have the carburetter gasket kit cos I had the tops off the float chambers on first start and the gaskets just fell appart. Its going to be the car for me to use as an on off day car so its a rolling restoration from now on and I need to think of minimising down time as stuff fails as its bound to until its been run enough.

All ideas welcome appart from throwing the triumph unit away :-)

Thanks in advance, Dave
Dave Squire - Notts

Dave, no need to throw the 1500 away, how I do it is, first to drill a small hole in the thermostat, unless you have the old type with the hole already in it, this helps to speed up the filling process. Next i disconnect the hose from the expansion tank and keep it up high, so that air can escape from the radiator, and then proceed to fill the system through the opening in the thermostat cover. I used to remove the top hose from the heater and squeeze the top radiator hose until water came out, but then i fitted one of these instead:

Make sure the expansion tank is only 1/2 full when you reconnect the hose. Before you do this replace the plug in the thermostat cover, otherwise the expansion tank may start to fill up. I have found that it takes 2 or 3 heating up/cooling down cycles for the system to stabilize, so keep a checking the level for the first few time you use it.


A Pritchett

Hi Alan, I see what you mean and how you do it. So the bleed valve goes into the top hose of the heater and then its easy to bleed air out and therefore fill with water anytime through the normal filler cap on top of the thermostat housing.

The site you pointed me at has other good stuff I would like as well.

Thanks a lot, Dave
Dave Squire - Notts

What your doing is fighting bubbles because there are alot of plCes for air pockets to hide when you do a full re.-fill up of the coolant system

The way i do this is to fill the system up and leave the radiator cap off and run the engine for about 1/2 hour then put the cap on and drive the car around the block a few times and watch the temp gauge... Then turn off for about an hour and restart watch the temp guage agian for about 10 minutes and then go for a drive if after 15 minutes the temp stays good... Then im good to go pat myself on the back

After 100 to 200 hundred miles with new hoses ...retighten them, for some reason in the past several years new hoses seem to leak after about 100 to 200 miles... Not sure why that is

Prop and the Blackhole Midget

Hi Prop,

Thanks for that, I remember doing such things in my youth with my Moggie and the old mans Victors each year now you mention it.
Now at the risk of all hell breaking loose from everyone by asking you this:
What are your thoughts on anti-freeze? I can't remember if you joined the last debate in some thread titled something else that got a heated exchange going about the stuff. I know it gets hot in the summer where you are. Doesn't it get a mite cold as well in the winter? And do you therefore use the stuff in the midget or do you keep it indoors in the garage and empty in the winter so no worries?

Just askin:-)
Dave Squire - Notts

In winter i use the green glycol 70 anti / 30 distilled water. I keep my car in a storage locker so no heat. As long as the fluid is topped up you should be good to around 50 below zero degrees, not sure about celcious

Id make sure your rubber hoses are in good shape

If you have access to electric they make engine heaters that can be spliced into the radiator hose that keeps the car nice and toasty warm

Prop and the Blackhole Midget

as usual the Driver's Handbook is your friend here and gives you the details you need

to be sure not to be mixing different types of coolant/antifreeze you need to have fully drained, cleaned and flushed the engine block, radiator and heater matrix

add pre-mixed coolant/antifreeze that way you can pre-measure the quantity required (from DH) and know it's at the correct ratio

if you make up the pre-mixed yourself bear in mind not all tap water is best for this and from this BBS I learnt distilled isn't either

I believe in doing a thorough clean of the cooling components and then you know the engine will keep cool, not freeze and the heater get hot

with standard anti-freeze the ant-freeze element will last longer than the condition element so if tested it's it can pass and still be not fully doing its job which is why its replaced at intervals

for the 1275 I've just followed the instructions in the DH and not had any problems

if you want my simple thorough cleaning method just email me
Nigel Atkins

>>for the 1275 I've just followed the instructions in the DH and not had any problems<<

this should be -

for refilling my 12754 I've just followed the instructions in the DH and not had any problems
Nigel Atkins

Hey nigel

Whats wrong with distilled not aware

How does the driver hand book say to fill the coolent system...haynes just says dump it in and go if memory serves correctly...but that always creates a huge steam and coolent volcano when pop the cap because the engine temp sky rockets....

got to love those air pockets

And so true you cant cross anti mix glyco to glyco and the pink stuff to pink....i think glyco is still the best for our cars


Prop and the Blackhole Midget

Hi Prop,

distilled water - don't you remember FRM explaining this in a previous thread

I don't know how the Driver's Handbook describes the refill as I've never read it, that why I held back commenting before as the 1500 is a different engine and often catches me out with the differences

70% anti-freeze mix would be well over the top here
Nigel Atkins

Sorry nigel

I must have missed that topic on distilled water

I use 50/50 for summer time as its rare for an engine to freaze in august

But 70/30 is the standard here in usa
Prop and the Blackhole Midget

50/50 would be a heavy mix here, perhaps your stuff is different over there

for distilled water Iíll quote FRM
>>Go to MGA board, (archive now) "coolant temperature".
You decide.

(biting tongue)

Nigel Atkins

This thread was discussed between 03/12/2012 and 04/12/2012

MG Midget and Sprite Technical index

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