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MG Midget and Sprite Technical - Update after HGF

Hi Fellas, good news:
The water / coolant is staying in the cooling and heating system but the heater was still air locked yesterday and no heat (each run I get a bit of heat then none). However the water in the header tank has each time I have come back needed topping up so I assume the coolant is going in the heater and will eventually fill it up. Do you reckon that's OK or should I try something else? (btw coolant goes all over the place with filler off and engine running).
Would be nice to have heater working by next winter :-)
And:
The oil is staying in the sump now the sump bolts are torqued up. The bottom of the engine and the underside of the car are drying out. No big patches of oil on the drive anymore and no drip in the garage last night.
Washer fixed pressure relief valve.
So:
Only oil container I haven't checked now is the diff as I haven't had time to get at it. Should my 1/2" drive fit it (seems a bit tight) or is it an odd size square drive?

At this rate of fix I will be driving the modern and back decorating the house soon (eek) :-(
Dave Squire (1500)

i used a 3/8"drive.. i had a 1/2" to 3/8"adaptor and it fit quite nicely.
Andy Phillips

Right; thanks Andy, no wonder my 1/2" seemed tight the last time I tried. Have 3/8 drive set anyway. Doh.

btw how did the doors go?
Dave Squire (1500)

not started them yet, spent the weekend on wheel bearings and fitting new wheels that didnt seem to like their new home...
however, got to go out for a blast down some backroads (just to test everything, you understand) so not a bad weekend really...
Andy Phillips

Sounds like you still got a head gasket issue

The coolant shouldnt be running out of the filler hole with the cap off....im thinking the coolant system is being pressurized by way of combustion....is it being burnt...white smoke out the tail pipe

The heater matrix...should fill up automatically....not over time...im guessing its clogged..or the heater valve has gone bad

How much water do you have to add each time you check it and how often do you check.it

Prop
Prop and the Blackhole Midget

Prop could be right. But also just be aware that if checked when cold, the expansion tank should only be around 2/3rds full. If you brim it, then it will expel the surplus out of the overflow as it heats up and builds pressure. Also, if you run it with the expansion cap off it will expand and overflow anyway. Then next time you look it will appear "low" again and you think it needs refilling. Again!

The way to get an air lock out of the heater core is to gently warm the engine up, then slacken the jubilee clip on the top hose and squeeze the hoes sideways to gently allow excess air (i,e, bubbles) out. Do this for a few moments until you are getting hot water out rather than air and then tighten the clip. But do take care of the hot water though - it can scald. To make this a little easier on mine I have fitted a shraeder type air bleed point to the top heater hose, but it isn't really necessary.
Guy W

Guy...

That has got to be the tip of the day, I like that

A Schrader valve in the cooling system

How did you actually do that...an old low side AC hose with the.valve built in???

Prop
Prop and the Blackhole Midget

Dave,
I'm not disagreeing with what Andy, Guy and Prop have put just adding to it

the drain and filler plugs may be a half inch square female socket but check first as they may have been changed to something else during the car's life

there are drain plug tools of various sizes and shapes (as per below) and a multi-tool drain plug but modern made multi-tool drain plug tools are next to useless

if you already knew this and what's next sorry, better to explain than not I feel, if you have a half inch square female socket then I think what Andy means is he uses a 3/8" to 1/2" adapter socket on his 3/8" drive handle

(i.e. on the adapter socket the 1/2" end is a male to go into the female 1/2" socket of the drain plug)

half inch socket bars and adapter sockets aren't strictly design for this purpose but if you have a spare bar or adapter you could file it down a little for an easier fit

the plugs only seem to go in a few threads so once you're passed the initial loosening there quite easy to undo

Guy has suggested a good method of expelling the air but it shouldn't be necessary, now you see why I suggest taking the matrix out to thoroughly clean it and of course check it

I don't know which way round the heater pipes go to the heater but could you perhaps fill the matrix from the hose that's at the higher point on the matrix(?)

and of course check that your heater tap is fully open (I think you mended the tap before(?))

I find these cars they find their own oil and coolant levels, mine is well below half in the expansion tank and if I put more in it just blows it off

talking of which check you have a pipe on the overflow outlet of the expansion tank to take the coolant below the car

just as a better explanation than I can give - a photo of a 3/8" (male) hex drain plug socket it can be used with its own bar to tighten (saves over tightening) or a 19mm socket can go over the top to loosen very tight plugs already fitted

Nigel Atkins

After driving around yesterday I can safely say the coolant and oil are both staying in the car. No need for top up of coolant yesterday. HG looks good.

I had the heater matrix out of the car a few weeks ago and cleared it out, put hot water in it and it worked for heat output just great, so it must be air locked somehow.

Thanks for all your help, its getting there.
Dave Squire (1500)

Dave,
well done

I must have missed the bit (or more likely forgotten) about the matrix coming out for its multi-flush and brush - did you do the JT suck test and renew both seals if rqd too

probably air then but Guy has given a good method, I know mine's a 1275 but I've always just followed the procedure in the DH and never had to do more than that

you did check the heater tap valve was and is fully opening when you refilled and warmed up - otherwise keep burping and/or filling it to get air out of matrix and coolant in, I want you moaning that the heater is too hot for summer use :)
Nigel Atkins

Another benefit of silicone hoses (as being mentioned on another thread just now). They are soft and pliable enough that the bottom hose can be firmly squeezed a few times to pump/force coolant around and dislodge any pockets of air.
Guy W

Just remove the cap and let the car ideal for about 20 minutes or so

You might try jacking the front of the car way up high remove the cap and let it ideal that way for 10 minutes

If you have new hoses and have an hour on the engine... give all the hose clamps a freash tighten....you would be surprised how lose they get

Prop

Prop and the Blackhole Midget

This thread was discussed between 29/04/2013 and 01/05/2013

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