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 - Radiator bleed help?

Hi all,
Looking for your help again!
1972 midget Mk III , 1275.
Replaced all the cooling system whilst in lockdown, including all hoses, water pump, radiator thermostat etc.
The car runs OK, and the coolant temp goes to the middle of the gauge between C & H, so happy with that, and there are no leaks.
To initially bleed the system , I started the car with the expansion tank about a third full of coolant, the radiator brass cap OFF, then added coolant to the rad. A couple of spits happened, I added more coolant to the top, then put the radiator cap back on.
Have I done enough, or should I bleed the system " further down " by removing the hose at the heater tap and double checking there is a coolant flow?
Is there anything I have forgotten or should have done?
If anyone has a sound bleeding method ( you know what I mean!!) for me to try I'd be very grateful.
Cheers & stay safe
Colin
colin frowen

Colin,
you only need to follow the instructions in the Driver's Handbook, you can add on whatever other tricks or tips you want to those but you shouldn't need to. It's as simple as the instructions below, I've never done any different and never had to.

One thing to remember is to fully open the heater tap, the expansion tank is normally filled to half way as it will find it's own level if that's too high by going out of the overflow pipe when the car is hotter.

Once the car is fully cooled down or cold, check the heater tap is fully open, top up the expansion tank to half and run the engine up to fully warmed, leave to fully cool down to cold see if expansion tank needs topping up at all, anywhere from third to half will be fine but I like half until summer weather is here.



Nigel Atkins

Oh, and, I forgot just check for leaks before starting the engine, whilst its running and after you switch it off.

After the first proper road run I also like to check all jubilee clips, you need to slightly loosen them before nipping them up again (or actually tightening them) to make sure they operate properly.

The only places I get leaks, well weeps, are from the thermostat housing gasket and tap mounting where although the paper gaskets alone should be enough I've found I have to add Hylotite Red 100 as the best sealant to stop the weeps (even though I shouldn't need to supplement the paper gaskets I've found I have to sometimes).

The heater tap itself on mine also weeps a little but I'm fed up with changing that so put up with it, I don't know how many single drops of coolant the expansion tank holds at a third full but it must be thousands.



Nigel Atkins

Hi Nigel,
Many thanks.
Surprisingly , I do actually have that manual( but like a twerp, I didn't refer to it - D'oh! )
Many thanks- it LOOKS like I've done the right thing for a change!
Cheers
Colin
colin frowen

Colin,
I'm sure what you done was fine, more effort than needed, but fine.

If you check the expansion tank when it's cold and its at third full then you could leave it at that (other than checking for leaks and heater tap was open).

I'd check again for coolant level, leaks or weeps and jubilee clip tightness after the next drive and leave it at that.
Nigel Atkins

Not disputing what Nigel says, but if my expansion tank is as low as 1/3rd full after a full heating and cooling cycle, I it has drawn that water back into the rad as the coolant contracts. At that point I would add a little to the expansion tank as I think it is getting a little close to the bottom of the suction pipe at which point it would start to draw back in air - I like to keep it between 1/2 and 3/4 full, though not more than that as it would then just overflow when it next expands.
GuyW

Nigel, if your heater tap's weeping, have you checked the state of the plinth?

Mine had a weep in that vicinity that I couldn't trace and persisted no matter how often I tightened things. When I did a full engine strip down I found that the thread inside the plinth was corroding to nothingness and had obviously been doing so for some time as it looked as though a PO had tried to stop it with putty or similar. The plinth seemed to be made of Mazak or something similar

Fitting a new plinth has cured my heater tap's incontinence, though there may still be a weep somewhere else that I have yet to find.

C Mee

Colin,
Guy is quite right, the 'good book' says expansion tank to half-full so that's what you should do - but if it drops to a third and stays there don't worry leave it there, it'll go up a bit in warmer weather.

If you want to fill to 3/4 that's fine but if it drops to half or a third and remains there don't worry leave it there, it'll go up a bit in warmer weather.

Once you've run the car in summer you find the level you and it likes and not need any top ups.
Nigel Atkins

Colin,
thanks for your thought, I'm on my fourth heater tap, second or third plinth, third lot of studs, second head skim.

The first lot of studs that came with the car had a stud that came lose, so the next lot I stud-locked in, my mate couldn't get them out with a torch but he must have loosen the jar lid because I got them out using PlusGas and double nuts. I did snap one stud by being impatient and not leaving the PlusGas to soak overnight as I always suggest to others, but I got it out, my mate's an engineer so obviously I had to show him up.

The tap pedestal he machine lapped level it's the shim washer above the pedestal that leaks this time, OK on previous tap as I smattered all in Red 100 but this time I didn't use it there, I made the mistake of following the "you shouldn't need to" mantra.

The tap itself leaks, it was an under warranty replacement from the manufacture/supplier for the one supplied that leaked, previous to that lasted 10 years, blamed on my engine or the rad cap but not the heater tap.

I know next to know of mechanics but I am very experience in problems with over-priced old cars called 'classics' and professional specialist that deal with them.

And having to drain and refill the coolant has happened many times on this Midget for many reasons - but still every time I check the 'good book' to make sure I do the refill as per book I'm easily distracted, forgetful and my mind does switch and double switch on me, as my wife says "no, the other left").
Nigel Atkins

Formerly, as photos, tap pedestal and shim (washer) with Red100, no leaks (other than tap itself), former studs. Stat housing with Klingersil gasket, no leaks (studs too short and so were the replacements). All the rust is concours genuine.

Now the pedestal and shim washer without Red100 leaks (as well as tap itself) and the higher (no really) paper gasket did leak until I added Red100.

What I like about Red100 is that you don't overtighten nuts but if the nuts are/get too loose and a weep starts as the Red100 is semi hardening you can just nip the nuts down a little without dismantling and the Red100 will fill the space and stop the weep.







Nigel Atkins

Red 100 - sounds like the old red Hermatite that I dont think is made anymore. Pity, as it was good stuff to use on loose threaded joints like the diff plug. I've not found anything that works as well.
GuyW

I've hyperlinked to it a few times before, see link below for details.

It's made by Hylomar the same lot that make the Universal Blue but I find the Red100 much better with coolant - and remember I use the highly leak finding coolant 4-Life! (or 4-Now as far as it goes for me).

Red100 - https://hylomar.com/en/hylotyte-red-100/

Universal Blue - https://hylomar.com/en/universal-blue/

Nigel Atkins

The Red100 is improved on the Hermetite Red if you look at the 'TYPICAL PHYSICAL PROPERTIES' on Red100 linked page.

'warrick' posted elsewhere Dec 18, 2008 -
"Hermetite Red was withdrawn from the market by ICI some 2-3 months ago.
Hylomar Limited used to manufacture this semi hardening gasket & jointing compound for ICI and we have since launched our own product - Hylotyte Red.
I hope this helps."
Nigel Atkins

Yes, I use Hylomar Blue, and I have probably seen you mention this Red 100 before, but not appreciated that it was a Hermatite replacement. Sounds like I need to find a tube.

It really annoys me that Halfords have drifted away from useful car stuff. I see they have now cleared their shelves of oil and air filters - and thermostats and radiator caps. It means that stuff like this that they used to stock now has to be bought on line and it's an expensive way of buying odds and ends. Not strictly true as there is s local indie motor factor but they are limited for the smaller consumables.
GuyW

Speaking of Halfords, my local one a mile away has closed after 40 years of my custom. Nearest one is now 9 miles away.
Bill Bretherton

If you cannot find Blue or Red Hylomar locally any more, try:
https://www.merlinmotorsport.co.uk/m/hylomar or page 121 of: https://tridentracing.co.uk/wp-content/uploads/catalogue.pdf (both Merlin Motorsport and Trident Racing Supplies are helpful and I find it quite tricky not to be tempted to make my postage more worthwhile with some other goodies, such as fasteners etc)

I feel the same frustration as few independent local motor factors exisit and Halfords not stocking so much useful stuff. One big motor factors I tried near me tried to sell me silicone sealant when I asked for Blue Hylomar and I had to explain what Blue Hylomar is as they had never heard of it (needless to say I walked out empty handed).

Last tube of Blue Hylomar I bought in person relatively recently was from the very helpful Ayrshire Motorpart in Girvan, who also good for Yuasa batteries (my Sprite one is apparently often on lawn tractors) and wiper blades. http://www.ayrshiremotorpart.co.uk/ Shame I am not often passing them.

Cheers
Mike





M Wood

This thread was discussed between 19/05/2021 and 20/05/2021

MG Midget and Sprite Technical index

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