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MG Midget and Sprite Technical - Stupid Question # 23...

Hi all,
1275 MkIII RWA
yet another daft question from me.
I have replaced the heater valve from the PO's mini style valve to the correct midget one. It doesn't appear to be leaking when running.
IF I've norsed it up, would it have leaked by now?

I need to do a two mile Journey to get to a classic friendly garage to have one of the heater valve studs replaced as the thread is a bit crap( I can't shift it ). Is it likely to get me there?

(& Yes, I DO know I'm a pillock ! )

Cheers colin
colin frowen

It'll be fine; just chuck a gallon of water in the boot as insurance.
David Smith

From experience Colin (MINE!) it would get to a garage two miles away with an empty radiator and no damage done

But taking reasonable care you will be fine

watch the gauge
Bill sdgpM

May I ask what the first 22 questions were? ;).
Lawrence Slater

After being advised to chuck a gallon of water in the boot question #24 must surely be how to get rid of the water that is sloshing around in the boot and how to dry out everything contained therein.
Alan Anstead

Alan, it will run to the back under acceleration and then drain out of the rust holes along the seam between floor and back panel ;-)
David Smith

Ah David, you mean you have a seam still


I see where Lawrence is coming from too, if a question helps you with anything how can it be stupid?

Colin we'm here because

Bill sdgpM

Hi Guys,
Just that my ( all) questions seem so dopey compared to typical questions posed here.
I'm definitely a tryer - not an achiever!
Glad you are here though!!!!
Cheers all
colin frowen

No no. I won't have that colin, you can't just claim the 'dopey' prize, without corroborating evidence.

According to Pete Moreland-Moore, all my questions are drivel. I claim it :).
Lawrence Slater


You are very welcome.

There are no stupid questions, and very seldom any stupid answers!

What makes this forum great is people happily asking for advice and it freely being given,with good ideas sharing. And regular traffic. There is often more to learn and share about technical problems, how to identify them and often a range of ways and tips on solving them.

As I have rebuilt my car I found my questions move with the new technical and parts supply challenges I face, just like for many people before as they learn more about fixing these deceptively elegantly designed and fun cars, and themselves.

Please also share your ideas in response to other folks questions.


M Wood


Before you leave, warm up to operating temp with the cap loose, top up the water with it still running and then put the cap on ,just to the first click
This way you won't have the water trying to expand and there won't be any pressure build up

William Revit

'put the cap on, just to the first click'

Yes, that can work if the leak is 'pressure' driven.

I was about 10 miles into a 90 mile drive home and the temperature started to go higher than normal, which 'never' happens. Stopped at the side of the road, and sure enough the water level was low and drips coming out of the water pump spindle.

Did as Willy suggests, 'put the cap on, just to the first click', and made it to the next garage and filled up the water and bought a 5 litre can and filled that too.

Drove gently to the M27 and pulled off at the first services to check the water, all OK, so on to the M3 and then A34, again temperature and level all OK at the next services, so picked up a bit of speed and drove the rest of the way home, and all still OK!

Obviously replaced the water pump quickly afterwards.

Richard Wale

If topping up coolant in these circumstances, I was always told to be cautious about adding cold water in case of cracking the block. I have no idea if it actually happens, or if it was ever a real issue. Maybe just an old mechanic's sucking teeth tale! But having that in my mind I always add cold water slowly, and have the engine running at the time so the water is quickly circulated and mixed with the hot.

The other thing to watch for is that in some circumstances, the temperature gauge can actually DROP on an overheating engine. At least that is what happened on a couple of occasions on my 1500. Counter-intuitive, but I think what was happening was that the low coolant level left the sensor "high and dry" so it wasn't responding properly.
Guy W

78 1500.

My temperature reads less when the coolant is low.

If its only 2 miles I would make sure my oil is up to the mark and set off cold with some water available for top up. You should make the two miles easily if you live in the sticks like me without traffic controls and junctions or if not you may have to stop to cool down if in traffic. During my 'sort it out to run well enough' time I had several times when something went wrong with the coolant from a burst hose through crud blocks to stuck thermostat.
I could drive for two miles even when the engine was already warm anyway.
I watched for the temperature to drop then stopped.

Be careful of the pressure when taking off the cap if engine hot.

Good Luck.
Dave Squire

Its not a myth that topping up a hot engine may crack the head, I once did that with a six cylinder BMW head when it had a coolant leak, and I was in a hurry to get home after work. Lesson learnt. (I still do stupid things though).
Dave Barrow

x2 Dave. The brother did the same with a V6 Renault.

If you're taking extra water as a precaution why not boil the kettle and fill a big vacuum flask? Then you could make some dry-packet soup or noodles for your lunch while you wait!

... or put the soup or noodles in the rad to stop any leaks!
Graeme Williams


Throw a raw egg into a leaking rad, said to stop a leak when the egg emulsifies and hardens passing out of a leak

Whether it works or not is open to guess-tion

My mate Dave swears it works

I note he only drives air cooled cars and so may never have had to test the theory…
Bill sdgpM

I've heard that oatmeal works well for sealing rads from a few that have tried it in days long gone but haven't tried it myself.
David Billington

Dave and Bill I've heard of both remedies but have never tried either. I prefer solder - I have succeeded twice with plumber's bar and a gas torch.

But for Colin I thought Sod's Law would apply. If he goes to all the trouble of taking a flask of boiling water and a pack of noodles Sod's Law dictates he won't need it to use any of it in the radiator.


This thread was discussed between 23/01/2016 and 24/01/2016

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