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 MGB Technical - Starting Problems

My 66 B starts fine from cold but when I try to start it from warm or hot it will just not start. The engine just turns over and after some time ( fiddling with the choak etc ) it finally somewhat relictantly fires up. Once going it drives like a dream. Has anyone got any idears whats wrong.
Thanks
carl suthenwood

Carl - Our 66 was getting to be like that until I finally started tucking my throttle foot back against the front of the seat. Seems that I was unconsciously pushing down just a bit on the throttle when trying to start the engine, opening the throttle plate a bit and thus not letting the SU carbs do their own thing (which they do quite well without human intervention). Cheers - Dave
David DuBois

Ours used to do something similar, it would try to start cough and throw the Bendix out and then fail to fire. Not always and 100% fine from cold. Once running it went like, well a sports car. It has behaved itself since I reset the timing myself. As noted before I set it to 10 static and then advanced until it pinged and bought it back. This was a lot less advance than was on the car after its rolling road set up.
Stan Best

1. Check that the heat shield has still got it's insulation in place.
2. Check that the vacuum advance is working.
Allan Reeling

Carl,

I'll add that I've never used the choke on a warm MG. So, if by "fiddling with the choke" you mean that you use it to begin your starting attempt, that could be your problem.

Charley
C R Huff

Also, consider rebuilding the carburettors if your milage is above 40K, (assuming they have not been rebuild already?) The phenomenum of 'hot soak' of the carbs does seem to plague SU's, ie start from cold ok but, from hot not so good air locks etc. My old TR6 used to faulter when very hot, an air lock would develop at the high pressure fuel pump located in the boot. Later Tr's had a coil around the motor casing carrying overflow fuel to cool the motor.I made such a coil out of copper tube, from my old still,(no tax agents out there?)Only joking!!!. As Charlie said, start up from hot just don't touch any of the controls and if all set up well should fire. Check your plug gaps! If too wide, starting will be difficult at all times. Mike
J.M. Doust

I have had the same problem with my '66 since I bought her in '07, 1500 miles since, regular oil changes, 1 new set of Points, carbs oiled, same plugs but look perfect, a little run on but not bad, Battery has been dep cycled, but charges up well.
Never failed to cold start, even in freezing weather.
Runs sweet, pulls like a train, No issues. BUT, if I ever stalled at a junction, or pull up for Petrol, it
either starts instantly on the turn of the key ...or...if she doesn't fire instantly, the "Bendix" throws in & out & in etc. Early days this would not happen, it just would not restart, & I would nearly flatten the battery trying. The cure every time was patience. Wait 20 min's and all in order. BTW I never touch the throttle on restart.
Coil is not getting too hot. Prev' owner had this problem too I believe as he warned me about "fuel evap'" before my long drive from Norwich to Liverpool for the ferry.
Anyway my question is how does Heat effect the "Bendix"?

B.

B. G. Griffin

It's not the heat that is affecting the Bendix, but the fact that the engine is briefly starting and stalling. In the process, it throws out the Bendix just as it is designed to do, to prevent the starter motor from being spun by the engine at excessive speeds that would damage it. The engine is not starting either because it is flooding or just getting enough fuel to start and then die. RAY
rjm RAY

As said, you shouldn't need the choke on a warm engine, in fact it will likely flood it if pulled too far. I have to disagree with Dave in that with no choke and SUs you *will* need a smidgen of throttle, at least all my SU-equipped cars over 40-odd years have. With the choke out you don't need throttle as the choke mechanism (if set correctly) includes a fast idle cam to open the throttle a little anyway. But operating the throttle with SUs has no other ill-effects apart from perhaps causing the engine to rev too much too soon after starting manually, unlike on a fixed-jet carb where it is pumping neat fuel down the inlet. The American spec Stromberg with automatic choke *does* need a prod before cold starting to prime the choke and fast-idle, but hot starting should be the same as SUs i.e. still needing a smidgen of throttle.

I've never found air-locks or heat-soak an issue (with correctly adjusted carbs and timing, sound heat-shield, non-iffy pump and coil etc.) at least as far as temperatures in UK heat-waves get, and certainly not at the moment. If anyone is getting a situation where the car will not start, either hot or cold, then they should be finding out why i.e. what is missing.

The Bendix being thrown out implies that a cylinder is firing but the engine as a whole is not catching, which is almost certainly because you are *not* opening the throttle that smidgen on a hot start. I suppose it could also be that compression is pushing a piston down on the expansion stroke faster than the starter is trying to turn the engine, which will also throw the Bendix out, but if that were likely it would have been a lot more common with that type of starter.
PaulH Solihull

This thread was discussed between 15/03/2011 and 20/03/2011

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.