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MG Midget and Sprite Technical - Overheating?

I am having trouble finding a solution for this problem: 1972 1275 RWA with 28K (recon) engine, K&N's, Moss Sport Exhaust and manifold and alternator (fitted as I thought the problem could be electrical)upgrades. When driven, after the car warmed up, it was cutting out at lights and wouldn't restart until approx 1 hr cooling. Dismantled and cleaned up carbs and set tickover slightly high. Not cutting out at lights after that,but occasional chugging during driving, run on when switching off and wont restart if I switch off after warm up unless approx 1hr cooling.Gaps all checked on dist and plugs (No 3 adjusted). Thermostat tested with a bowl of boiling water. Loads of compression - unable to turn pulleys by hand without removing spark plugs. New water temp sender fitted at 24k doesn't get higher than 1/4 way from cold.
Last test drive the car was chugging on acceleration. Then it started dying and I had to drop through the gears with NO power to limp home 2 miles. Cut out completely: Tried in vain to start for 40 minutes, then jumpstarted it, as when turning it over, it wouldnt catch. Any help appreciated as I've only done about 80 miles ove the past two years because of this problem.
M A Pollard

I Forgot to mention, I've also added the white 1 inch exhaust wrap on the manifold and applied reflective foil tape to the fuel lines, heatshield and float bottles to try and prevent vapour lock, as I thought that might be the reason. That was prior to the last run and it made no difference, worse really because of the engine losing power in heavy traffic.
M A Pollard

Can it be a defective rotor or coil?

Flip
Flip Brühl 948 frog 59

coil or condenser are my bet or anny thing in the ignition circuit.

other wise there is a slight chance of a bad fuel pump
easy to check
just pull the hose of the carbs with the igniton on.
if the fuel comes rushing out you fine.

lose the wrap around the exhaust it only makes the head run hotter and leads to cracking of the manifold.
Onno Könemann

Removing the wrap is probably advisable since it hasn't made any difference. The rotor arm was replaced at 24k and the fuel pump was replaced as well. I also added one of those after market in-line pietzo spark units on sale from the Brum Classics show. I haven't checked the coil yet. Its all been fine for years, it just started playing up 2 years ago (80 odd miles ago).
What about the water pump failing? Could it be failing under load?
M A Pollard

It sounds like its running lean, i know if you go K&Ns it does lean out the carbs considerably

The other thing is it sounds like the ignition wire is getting shorted out, old wiring loom, errend screw, loose connection

Prop
Prop

MA,

I had a problem with my sprite cutting out if sitting stationary for to long and it not restarting till all cooled down, often about an hour. It was the coil and quite a new one as well, about a year old.
David Billington

sorry scratch the lean idea....just re-read

What about the rocker valve gap...it maybe to tight
Prop

Can you try a blow dryer to see what it is? Pump fuel lines, ignition, carb or?
My new! rotor caused the problem.....the 50 years old one was OK. The new ones cant manage the high voltage of electronic ignition especially if you open up the spark gap.

Flip
Flip Brühl 948 frog 59

I vote coil.

R
Richard 1500 5 speed

I think I agree with Richard. I had almost identical symptoms to these a few years ago, and eventually traced it to the condenser. I see that you've replaced yours, but it was an ignition problem all the same, and as mentioned above, any number of components can produce similar symptoms.

Best of luck,

-:G:-
Gryf Ketcherside

Thanks for all the help guys!
I'm going to try replacing the rotor arm and condenser
as well as testing with a spare coil. If successful, I might change over to the Lumenition optical with a sports coil. On the upside, at least its easy to move a midget when it breaks down.
M A Pollard

Remove all the rubish spark thingy's
The std a-series realy does not do anny thing more with it and it only adds to the list of posible failures
The std ignition should do fine and if you convert to electronic do it properly as you mention.

Never say a part is fine because it is new!!!
I have seen lots of new parts fail within a couple of miles (especialy ignition parts)

Today you have to search for good parts as the market has been flooded with cheap (oriental) crap because people always want the cheapest part.
When infact you eventualy pay less when you buy the expensive quality parts in the first place.
Onno Könemann

Just take it to a rolling road and it should get sorted. http://www.willfieldmotors.co.uk/index.htm
f pollock

This thread was discussed between 09/10/2009 and 10/10/2009

MG Midget and Sprite Technical index

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