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MG Midget and Sprite Technical - Coolant Confusion & Slight Radiator Fitting Leak

Hi All,

It is getting cold, so I decided today was time to flush out my car's cooling system and make sure there is some fresh antifreeze in it!
I drained as specified in the handbook, but didn't bother with the block drain plug (seems like it is fiddly to reach and read they are generally blocked anyway).
Drained a fair bit of fluid, flushed, backflushed.
When it came to refilling, the system only accepted about 3l (rather then the expected 4.25l).
I ran the engine for a while to clear any air out, but it seems it really is full, and after a drive the level is the same.
Is this just because I didn't actually manage to drain out all the coolant?

Additionally I noticed that the expansion tank output on the radiator seems to leak a bit when I wiggle it.
Need I worry about this, is there anything I can do (the radiator is in otherwise great condition, no other leaks, and never noticed it losing coolant.

I popped a video online to illustrate the problem, note that when I wiggle the fitting/barb a bit of fluid leaks out of the base (where it connects to the radiator).

-- Josh
J Levine

If you don't fix it now you will lose it when you can't afford it and you will be stuck far away from home.

There is a certain amount of coolant trapped within the block below the water pump hose casting so that may contribute as does the coolant trapped within the heater rad.

Oh yes and however many rad fins that have cloggage after years of indeterminate coolant use.

I wouldn't be happy with a hose connection that leaks like yours :(

You may be able to fix the leak using something like QuikSteel (halfords about a fiver) to reseal the fixture if you scrupulously clean all around the target area

I would rather have it repaired properly with solder, do you have a a local radiator guy who could do the job? If the rest of it is safely soldered it would be a shame to risk beggaring up the soldered joints elsewhere with uncertain amateur soldering, it will certainly need a gas soldering or an immensely hot large iron to do it proper like.

I need to use the car next weekend, so I intend on making an epoxy-putty based repair in the short term, and have it soldered thereafter.

-- Josh
J Levine

good idea to deal with the coolant system

the reason you needed to use so little coolant to refill tells you how much of the system you didn't do the not bothering >>with the block drain plug (seems like it is fiddly to reach and read they are generally blocked anyway)<<

you've left the most important bit, the whole cooling system is to cool the engine

you can unblock the drain plugs with bent bits of wire

if you thoroughly clean the whole system this time then for a very long time you just need to keep up with regular coolant changes

sometimes you have to unhook old hoses

it's best to use rounded-edge clips and not to overtigten them, you can always nip them up later if required

I think it's best to premix the correct coolant mixture then add as required

when you take the rad out for repair you can do the job properly and consider a full overall of what's required

full works here for consideration at least:-
before starting consider if the water pump (good ones are only £14) and heater fan motor need replacing and (if not already fitted) whether to install an electric fan as this would dovetail in with the work below

also you may want to check or change:
∑ filler pressure cap
∑ fan belt
∑ thermostat
∑ hoses - as recent new rubber cooling hoses tend to be poor quality you may also want to change your existing rubber hoses set to silicone - - with round-edged clips
∑ heater tap

a) clean the whole system with something like Bars Flush Cooling System Cleaner

b) drain the whole system - engine block, heater matrix and radiator

c) get the radiator and heater matrix out of the car to give them a good shake at the same time as flushing and back flushing

∑ flush clean water through each of the three until water runs out thoroughly clean

∑ reverse flush each of the three until water runs out thoroughly clean

∑ final flush through each of the three until water runs out thoroughly clean

d) gently brush clean both sides of the radiator fins

e) gently brush clean the heater matrix and renew the seals and foam around the heater matrix and heater box case base

f) refill with the correct coolant mixture but bear in mind tap water isnít always the best water to use, distilled would be better

g) follow the refill instructions from the owners Handbook to avoid getting air locks or Ďhotspotsí that could cause overheating of the engine
Nigel Atkins


Do the job properly...

That radiator neck needs soldering and not an attempted glue with epoxy..

The block drain tap may well be blocked... that tells you that there will be sediment in the lower part of the block thus potential overheating in the future.

There are no compromises when it comes to reliability.. do the job properly and don't risk a break down...

If you NEED to use the car either fix it or park it and use something else..

M T Boldry

Thank you for the useful advice Mark and Nigel.
I intend on doing it properly, but wanted to be sure there was some good antifreeze in the system before it gets cold out here.
In the meantime it has never had any cooling problems (always sits at medium or less on the temp gauge, whatever that means), so I assume it isn't too terrible.

-- Josh
J Levine

a little bit of extra work now means less later and vastly reduces the thepossibility of problems, breakdowns and repairs from this later

be one of the ones that doesn't work about being stuck in crawling traffic on a very hot day or driving on a very cold windy day

or giving the car a few beans on some very steep up and down roads

reliability equals greater potential for extended fun with the car

also remember the other engine cooling system - oil - so keep on top of regular serving with that too

and a thorough cleaning if required

as I tell my wife gauges are called gauges not very-accurates, although the midget fuel gauges id more accurate than her modern car as was the mileometer
Nigel Atkins

This thread was discussed between 11/12/2011 and 13/12/2011

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