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MG Midget and Sprite Technical - Ongoing problem, advice please!

Guys

I look at the forum every day but haven't posted since I first brought up the problem I've got all the way back in October.

I've got a 1962 midget Mk1. Ever since I bought the car last year it will get up to a good running temperature (not overheating) and then die. I am then unable to start the car again until it has cooled right down.

I have replaced the coil and condenser, the fuel pump is new. Numerous people have looked at the car and can't find the problem. Just before Christmas a local mobile tuner came out who specialises in older vehicles and had the car running for ages while he checked everything - he told me he couldn't find anything wrong with it.

I have just had the carbs totally refurbished and balanced as well. My friend who balanced them had the car running for a long time. We then decided to take it for a run and it broke down after 100 yards! I have fuel getting to the carbs, the filler cap is venting and I'm still getting a spark (although my friend thought it was a weak spark). The plugs are good.

When the car dies it happens with very little warning - it will start to lose power and has trouble revving before dying rapidly.

I am desperate for a solution as I've already missed two club runs and have never been able to do more than eight miles in the car before it breaks down. Everyone who has looked at the car says it's a very good car but if that doesn't help if it doesn't work.

Help!!!!

Steve


Steve Osmond

Steve,

I think I remember that pic from before. Yes, it is very nice, and not being able to drive it must be frustrating.

I'll throw out a few ideas, but they will probably be things you have already checked.

Just to nail down the symptoms a little better, does it ALWAYS run well cold, and ALWAYS die as soon as it gets warm?

If it is more random than that, I might suspect a poor wiring connection somewhere, possibly even the ignition switch itself. You could try hotwiring it to see if it makes a difference. If you still have a Lucas regulator, check that the rivets holding the blades that the wires attach to are not loose.

Is the little flexible ground wire inside the distributor, which attaches to the points plate, in good condition?

Are all the little insulators associated with the points clean and properly installed?

I have heard that some of the new condensers are a bit of a crap shoot, so trying another one may be worthwhile. It would be nice if you could borrow one from a running car. Likewise, it would be nice to try a coil from a running car.

When you say it has spark (though maybe weak) do you mean immediately after it dies?

Good luck,
Charley

C R Huff

To add to Charley's advice, check the rivets that hold the terminals on the coil, they can loosen with age, pass current OK for a while then "fault" and go open circuit or set up a resistive circuit where it makes poor contact

This will make a spark become weak

Likewise check where the white/black wire enters the distributor mounted terminal. As above---ditto

And for all that there are people who never have condensers that need replacing there are dozens (allegedly) of us who have had new ones go U/S

as above--ditto

and inside the dizzy the rotor arms, even new ones can short internally to earth on the centre spindle

as above

if you have fuel available at the carbs immediately when it "faults" I suspect an electrical problem rather than a fuel based one

try Charley's hotwire sugestion too, old switches fail often enough (I think modern volts are stronger than old fashioned 1960s ones :-) )

And try usng a jumper wire from coil to dizzy, those external wires often wear out inside inhospitable engine compartments, cracking and breaking
Bill sdgpm

Just to add, you might try tracing down the white ignition wire from the key, to the tech and back to the coil...look at those bullet connectors carfully they like to corroad, esp there in the corner where the fuel pump connects into (mosture loves that area) and also look for that wire being pinched aka around the center console, also look for any screws that may have been accidentally screwed Thur the wire creating a bit of ground, also look for damaged wire...cracked insulation, bad hack-in, something creating a ground to the car body, in that positive white ignition wire...., just a freaky long shot, but try by passing the tach for a while, just to take that out of play.

and of course our old friend....Mr condenser, I'm not sure how he could be the culprit, but that's my 1st thought when something goes wrong with the ignition, or local puppies come up missing.

just another thought, what about a sticking exhaust valve ....they never stick until they get good and hot. aka no compression thus no bang bang

I do remember the car...did you HAVE a HEAT SHILD installed at the carbs?, I cant remember

Prop
Prop

I wish I was there, this should be an easy fix.

Steve I assume you are not too good with cars so we must do some basic things to help you sort it.

You need to establish if it is an electrical fault or if it is fuel.

Various ways we can do that but the easiest for you is to look at the rev counter when the engine dies. IUf the rev counter immediately drops to zero yet the engine is still running down then it means you have an electrical fault.

The brave amongst us will check if it is a fuel problem by feeding fuel directly into the carb throats whilst turning the engine over. You only need to pop in a few drops and the engine should run. Someone who is not too skilled at this can uy a couple of aerosols of carb cleaner and blast these into the carbs. If the electrical is fine then the engine will run on carb cleaner.

What I would say however is that a few years ago I sorted a newly finished car that was doing very similar things to yours. It turned out that the distributor was not gripped to well by the clamp on the engine. This was causing a bad earth for the dissy and so the car engine would cut out and then misteriously start up when cold??
Robert (Bob) Midget Turbo

I once had a pinhole leak in the top hose.

Car (Morris Oxford) would start and run fine till it warmed and the thermostat opened, then the top hose would spray a very fine jet of water at the distributor and the engine would die, not re-starting till it cooled and the distributor dried out.

Took a long time to fine that one and even then it was accidental!

Two things stand out from your description, the engine doesn't always fail after the same amount of running time and shutting the bonnet "encourages" it to break down.

Perhaps some kind of localised overheating causing electrical failure, wire grounding on the bonnet or water leak that only happens when bonnet is closed?

You seem to have covered all the obvious suspects. Time to start thinking of the weird ones!

AndyB
a borris

Steve, what part of Kent are you in?

AndyB
a borris

Bob "Various ways we can do that but the easiest for you is to look at the rev counter when the engine dies. IUf the rev counter immediately drops to zero yet the engine is still running down then it means you have an electrical fault."

A MK I runs the tach directly and mechanicaly from the dynamo. Except for the dashlight no electrics involved:-(

Bas Timmermans

Could be right Bas so guess it will need the petrol down the throat trick :-))

thanks Bas
Robert (Bob) Midget Turbo

Bob's tacho-trick might work if this is an early GAN2 Bas ! They have ventilated disc wheels but already an electronic rev-counter.
A beautiful car Steve but an irritating problem !
It seems that when the engine is running and the car is at a standstill everything is fine, as soon as the engine really has to work, it dies.
Vacuum advance pulling loose the internal ground strap in the distributor ?
Blockage in the fuel line preventing sufficient petrol flow to the pump (dirt in tank/ fuel hose clogged)?
(Is it still the mechanical fuel pump you use ???)

Nick, '63Midget
D.G.J. Herwegh

It sounds electrical, but I wouldn't rule out fuel. In particular, if the fuel system starts going horrendously over-rich then dying as the car warms up can be a result, and difficult to start will also be a problem. Has it got a heat shield? Heat from the exhaust onto the carbs can cause all manner of problems with similar symptoms.

A plug check is another useful way of getting a pointer to fuel or electrical. If the plugs are dry and unfouled, it indicates lack of fuel. If wet when the car dies, it is probably electrical. If very sooty then it could be over-fuelling.
A Walbran

Steve,

<< it will get up to a good running temperature (not overheating) and then die >>

Does it misfire before 'dying', or just stop?

If as it starts to lose power you back off the throttle completely, will it keep running?

Richard
Richard Wale

Does the inlet manifold have a heat-shield to protect it from the exhaust pipes?

A
Anthony Cutler

Gents

Thanks for all the prompt responses and suggestions. This is definitely the place to come for a good brainstorming session!

I will print off all these suggestions and take them with me when I manage to get to the car in the next few days (It's not at home at the moment)

I'll try and address all further questions now, sorry if I've missed anyone out.

AndyB - I live just outside Deal but the car is in Walmer at the moment. When the car does die it doesn't always do it after running for the same amount of time, it's definitely related to the ambient temperature and how long it takes to get up to 160.

Charley - It hasn't always run well from cold. I had one odd occasion just before Xmas when I started the car (the day after the Krypton tuner told me that there was nothing wrong with it) when it was running really rough. However, it usually runs really nicely cold and well right up until it fails.

Prop - The stanard heat shield is installed.

Bob - How did you guess I wasn't too good with cars! I bought the car with a view to learning as i went along but didn't expect anything like this from the word go. It's a GAN1 Midget, so if the others are correct (and I assume they are) then tacho function on dying won't be relevant.

Nick - It's still on a mechanical pump but it's a brand new one. Basically the car was restored with originality in mind and it's still positive earth. My friend checked the plugs the other day when it broke down and he said there they looked fine

Richard - It doesn't misfire before dying and it still dies if I back of the throttle.

Thanks again guys.

Steve


Steve Osmond

Nice looking Mk1 Steve. I'm sure you have enough advice above, but my input would be ignition related after reading your last post.

One very important thing to remember (and this is not a new problem), even a NEW part can be faulty, don't assume that because you have renewed a componant, it should work... That has caught MANY people out....

Mark.

My Mk1.


M T Boldry

Steve
Is the coil the correct one for the car and is it connectd around the right way-- Positive earth cars should have power onto the neg terminal of the coil and the pos. terminal to the distributor. Willy
WilliamRevit

>>>>>>>>>When the car does die it doesn't always do it after running for the same amount of time, it's definitely related to the ambient temperature and how long it takes to get up to 160.<<<<<<<<<<<<<<<<<


Now thats Extremely Interesting!!!

I cant help you directly, but Im sure someone else can pick up the ball and run with it.

The voltage regulator, for the dynomo, (genorator) is a mechanical one and requires constant adgustmment Im thinking every 30 degrees of ambiant air temp,(though doulbtful anyone actually does this) it operates sort of like a home heating/air conditioning thermostat... Im recalling this from old memory cells of reading the haynes manual, As I recall you have to clean some strange contacts with a "GLass Pen" (from A camara shop), push some knock outs in and out and there are like 7-9 diffrant wires feeding into this regulator box, im woundering if you dont have grimlins inside that voltage regulator box that need adjusting , or something is broken inside the box

when I bought my car, I had the regulator box/genorator...I messed with that stupid box for 3 months, and realized an alt. conversion was a better use of my time with built in regulator was a much better way to go. So drop-kicked the Reg. box deep into the woods for proper storage after making the conversion which is still in my top 5 modifcations

I think the regulator box is well worth a look for worn out, broken bits, or resident adjustment gremlins.

prop
Prop

Would the regulator cause stalling if it's faulty? All it does is to switch the charging circuit on and off as needed, right?

-:G:-
Gryf Ketcherside

Gryf....yes your correct, but Im thinking maybe a cracked housing/componete AKA. like around the 2 big and 1 small brown wires maybe its grounding out as the temp. fluctates, or maybe there is some kind of arking taking place inside the regulator. could be one of those terminals needs some glass pen work, because the contact is being broken when the guts move around doing there thing like a stat.

I just thought his statment about it dosnt stall, until the car comes on-line temp. wise was a Interseting statment....most likely it linds more credence towards the coil then anything, but that regulator is a pain, and remembering what was involved,

well...where there is smoke there is all ways fire, but then, that may apply just to me. LOL

Prop
Prop

Do you use the choke when starting and does it return when the cable is pushed in?

The only other thing I can suggest is run the car till it gets up to temp with the bonnet open (you may need to cover the rad!) and see what happens.

If it does die, run checks on the coil, condenser and carbs. Try doing this at night too, see if there's any stray sparks flying around the engine bay.

If I have a day off during the week (possibly tomorrow, Tuesday) I can pop over, not sure what use I'll be, but you can always cry on my shoulder.

Such a lovely car and you can't drive it, must be very painful!

AndyB
a borris

Gryf,

I think I initially brought up the regulator a few posts back. Even though I think it is unlikely in this case, I used to have a big Healey that would die if you let the engine get a little below idle speed. Then it would not restart until you wiggled one of the wire connectors on the regulator.

So, in my experience, yes a regulator can cause the car to quit.

Charley
C R Huff

I had an MGB that would do that. It turned out to be a cracked cylinder head right beside # 3 spark plug. When it got hot it would spray coolant on the distributer cap and kill the engine. It belonged to a young lady and she would call her dad and when he got there the car would start right up and run normally till it got hot again. Changed the head and all was well.
Sandy
Sandy Sanders

I am sure that Mr Anstead will be able to contribute to this one, he having experienced similar problems recently. The car ran like a dream for a while then died but was resuscitated each time by hotwiring. Whilst nothing appeared wrong with anything, replacing the Mk I ignition/lighting switch with another does appear to have cured the problem. Examination of innards of the old switch revealed nothing apparent but we wondered about the condition of isulation between terminals.
John
J R Clark

Due to work and other commitments I probably won't have time to look at the car until next week.

AndyB, the choke is fully returned after starting. Will try your other suggestions when I get the chance. If you e mail me on steve.osmond@btopenworld.com I'll give you my number and maybe we can arrange to meet sometime.

Cheers everyone - I've got plenty to be going on with.

Steve
Steve Osmond

Had this, would run until hot then die and not restart until it had cooled down, added to the heat shield and problem sorted, guess to much heat from the exhaust was boiling the fuel in the carb bowl?
Alex Sturgeon

Does the car have the original engine driven fan or an electric one?

Carl
C Bintcliffe

Guys

finally got to have a look at the car today. The car started okay but I only took it for short run - ambient temperature was higher today and so it didn't take long to get up to running temperature. So I parked the car on the drive and popped the bonnet with it running on tickover. Within about 3 minutes the car died but it didn't do is as quickly as I thought it has done when I have been driving.

I checked for any obvious signs but couldn't see anything sparking or shorting out anywhere however I'm still not completely sure it's not a fuel problem. When the car was running on tickover I was getting a steady dribble into the filter bowl but just before it died I'm sure there was next to nothing getting through. Shortly after dying though the filter bowl filled up quite a bit as though it was coming back from the carb float chamber.

On the electrical side I couldn't find any worn wiring as per suggestions and everything seemed to be connected connected good and tight.

However, when I removed the distributor cap a couple of the wires in the there looked a bit dodgy. Please see the pics below.

Pic 1 is with wires in situ pointing out what may be a problem and pic 2 is with wires moved to show another old looking wire underneath. I'd appreciate your input please.

Oh, and finally have a look at pic 3. Why has someone put that on the voltage regulator?

Regards

Steve


Steve Osmond

Pic 2


Steve Osmond

Pic 3


Steve Osmond

That black wire from the condensor is awful close to the cam lobes.
also check the flex line from the coil connection on the side as it could have an internal break. How about the braided black cloth covered wire that grounds the point plate. It could be broken or frayed.
Sandy
Sandy Sanders

whats with the rotor bug being chiped up really bad on the "BACK side"

is the reguator orginal...BMC??? If not Id start there.

also Id sand out the rubbing block...looks like something went spark, spark, ARC!!! that will kill the points rubbing block in a hurry.


I think Id certianly up grade to a pertonix chip and dump the points, you will be decades ahead


Prop
Prop

with that rotor bug being so badly chiped up, Id say spend the 2 dollars and buy a new one, it looks good but there could well be a fine crack running down its core and not opening up till there is heat, thus causing a "river of ground" from the stricker down to the dissy shaft... Ive seen it before

Dont trust the eyes, Ive never seen the crack that cause these problms

Prop
Prop

The dissy looks normal to me, so wouldn't worry too much about it based upon the fact that you left the car running and it stopped.

The problems identified by Sandy are not too unusual but do tend to cause problems when driving at ANY time and not only when the engine has been running for a set time.

The voltage regulator looks exactly like any knew regulator, even if it was aulty it would not cause this problem.

Pease do some tests to establish what the fault is.
Robert (Bob) Midget Turbo

Is the correct vented fuel cap fitted? Could be vacuum in the tank.
Rob Storer

Steve,
I don't see any mention of you having replaced the rotor arm. There were reports a couple of years ago of faulty rotor arms. They would appear to work OK, but as they heated up the insulation broke down - I think due to internal cracks under the rivet - and they failed. When they cooled down they would begin to work again.

I wonder if you have one of these "faulty" rotor arms.

Guy
Guy Weller

how was the coil temp. when it died...could you grip hold and hold on indefinatly....it should be warm, but NOT like grabbing a 40w light bulb.


prop
Prop

Hey robert,

just a thought, can you tell if his dissy elec. connections are set-up for positive ground, just re-reading and steve makes note he has positive ground....Im wondering if there is a mis-cross over somewhere...granted Id think lots of sparkies and flying stars would result, but who knows.


I dont know anything about positve ground other then how to spell it correctly..(sometimes, LOL)


Prop
Prop

great thinking rob


NON_vented fuel cap, that would get past the the carbs appearing to work okay, dont forget even a vented cap can get blockage.


Still as robert says a full dignostic orderly point by point break down is needed

Prop
Prop

The cap is easily checked. open up the cap just after the car stalled and if it does psssss its bingo start the car without cap and see if it runs. But the stalling proces of a non vented cap situation isnt sudden.

Most of the times its after/during rapid acceleration.
Bas Timmermans

And sort a putts putts down with lots of surging back and forth, and a little whizzing.

Prop
Prop

Gents

Thanks again for the input.

If the regulator is not what's causing my problem then I think I'll leave it for now.

The filler cap was checked some time ago and found to be okay.

It looks like it's back to square one again.

However.....

Prop, what you said about the coil was interesting. I can put my hand on the coil but wouldn't want to for too long as it's pretty hot.

I had discounted the coil because it was actually the first thing I replaced. I bought it from Moss and it was the second one I had got from them because the first one was leaking oil everywhere.

I may have to look into trying another one.

Regards

Steve
Steve Osmond

Fuel pump? I know you said it was new, but that doesn't always mean it can be assumed to work...
Andrew Noakes

Steve,
What about the rotor arm? Has that been replaced?

Guy
Guy Weller

Steve,

I Think your getting vary close! but the key is in the EXTREMELY HOT COIL!!!!

Did the 1st coil leak it oil because of over heating also, No doulbt this is why the car is dying after 20 min to 1/2 hour, the coil is cooking its self to death



I think the problem is one of 3 places.

A.) The regulater is not properly hooked up, and not funtioning properly....(not real likely)


B.) The points are set up for a Negitive ground and your car is a positive ground....Agian I dont know anything about positive ground

C.) there is a short/ground somewhere in the ignition wire set up....a screw penetration, a sharp piece of metal, a pinched wire, just worn broken insulation, improperly hooked up gauge, Next time it dies on you, start feeling wires under the dash and in the engine bay for heat, you might be able to even smell the wires cooking.

I would strongly suggest that you disconnect until you actually need to deal with the car....He have heard lots of stores of peoples wiring looms bursting into flames because of shorts in the wiring


Like I said..."THE EXTREMELY HOT COIL"....Is the key

Prop
Prop

Im sorry meant to say disconnect the battry.

prop
Prop

This thread was discussed between 03/05/2009 and 11/05/2009

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