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MG MGA - Starting puzzle.

When I had my 3-bearing mgb engine fitted, the car usually started up from cold ok but if I tried to start the engine from hot, it was a different story.

If I pulled the starter switch when hot, it would act as if the battery was flat and only crank the engine for half a turn.
Then after 3 or 4 pulls, the engine would suddenly crank freely and start up easily.

Well I have just changed the engine for a 1950 cc unit with even higher compression and i decided to refit the same inertia starter motor to see how it copes.

I did spend time in cleaning up all the starter cable and battery connections, but I have found that the same puzzling hot startup issues remain.

Is it excess fuel in the cylinders that is causing a temporary hydraulic lock?
Is it because the engine is too far advanced? (although it runs great with no pinking with 32 degrees advance at 3500 rpm)
Or do I need just to go out and buy a high torque type starter?

It is not a major problem as the engine (so far) has always restarted, but I would be happier if it fired up straight away so that I can be rid of that "Will she fire or won't she" feeling.
Cheers
Colyn
Colyn Firth

Colyn

I could have written much the same a few years ago, but as much with cold starts as hot. The problem disappeared totally with the hi-torque pre-engaged starter I fitted. However, I am not convinced it was just the change in starter that cured the problem, but as much to do with the starter switch. Its change of use from taking a full load from the battery to merely transferring a small load to the integrated starter solenoid has more to do with it I suggest.

I took one of those starter switches apart. You would be amazed at the carbon build up and arcing with associated high resistance. The little copper disc inside the switch can rotate a bit under vibration bringing various bits of burnt up carbonised metal into contact when the starter is pulled.

Steve


Steve Gyles

Colin
try and get an original switch instead of a modern report. There's a world of difference. I always grab them if they are cheap enough at a jumble, and I have replaced a few of the repros on other cars to resolve this problem.

If you get stuck I think I have two or three originals in a box, though Bob probably has one more locally!
dominic clancy

I did say "pull the starter" when really I should have said that I push the starter! Sorry.

In fact my car has a push button starter with a solenoid where the original MGA switch was fitted.

So it could be a bad solenoid maybe.

It also has a battery isolator switch in the main cable positioned under the dashboard which I suppose could be have high resistance.
Colyn

Colyn Firth

Since going 1800 I have experienced it but only a couple of times and only when hot. I have standard starter and standard original pull switch.

Interestingly my starter almost completely failed a couple of weeks ago, it just turned the engine very slowly and then stalled. Electrics were all fine so I just replaced it with one I had on the shelf and all is fine. After looking at the starter I am pretty sure it was a brushes issue and when I looked at how to change brushes I lost the will to do it. Unfortunately the bit of paint still on the replacement is green so perhaps it came of my first Morris Minor (803 cc), did they have same starter?

Enjoyed the MGCC MGA Register North Weekend event. First time my car has been out of Scotland since I finished core rebuild in 1979. Unfortunately as I tried starting to drive home the engine fired briefly then dead. It turned out 2 year old coil had failed, but I had a spare so quick change, but spare is same type as one that failed! At least I was fixing it in the glorious sunny Raven Hall car park.

Paul
Paul Dean

I once had a similar problem with a racing midget. Starter would spin the engine fine when cold, but really struggled when hot.

I swapped the starter for another (secondhand) inertia starter and never had the problem again.
Dave O'Neill 2

This thread was discussed between 10/05/2016 and 11/05/2016

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