Strange cranking over fault.

[ah]

When I crank my engine over on the key,it turns over as if I’ve got a flat battery and then if I turn it over again seconds latter it turns over as normal,any ideas ?

[sweep]

Could be a starter motor issue thats if your battery is ok? I had it on my 325 when it was warm.

[ah]

I had the battery checked and it's fine ,the starter motor i about 5 years old.

[martauto]

Is everything tight and with very clean connections ?? Old hat I know but ......well over the years it`s bit my arse more than once.

Mart.

[ah]

I think so but not had a good look,I can’t help thinking it’s something to do with ignition barrel area,have you got any ideas.

[martauto]

I think so but not had a good look,I can’t help thinking it’s something to do with ignition barrel area,have you got any ideas.

Don`t know much about that area, sorry, one for the boffs I think.

Mart.

[Brianmoooore]

If a cylinder or two was partly filling with coolant when the car was parked up you would be trying to crank the engine over against a compression ratio of several dozen to one, which would slow it down until the coolant was expelled, but then the engine would misfire until the plugs in the affected cylinders dried out, so, fortunately for you, I doubt if this is the problem.
Much more likely is a poor connection in the starter secondary circuit (the large battery cables, the engine to body earth strap and even joints between alloy and iron), or a faulty starter motor.
Feel all the wiring joints after cranking, and see if any are hot, indicating a poor connection. Wouldn't hurt to remove the earth strap and refit it.
A starter motor is essentially two motors working together, and if a carbon brush for one of them (there are two pairs) is sticking in its holder for some reason a problem like yours can occur. The reason can be something as simple as a build up of carbon dust and other dirt, so worth a bit of dismantling of the motor to check before spending money.

[ah]

Thanks for the advice Brian, the first bit was a bit worrying ,were you implying head gasket.

[Brianmoooore]

It would be a failed head gasket or cracked cylinder head, but it won't be the problem with your car. After having my peace disturbed by hordes of hungry relatives, friends and their offspring descending on us over the last few days, and being dragged off 'shopping' several times in the days before, I was in the mood for winding someone up a little. I'm not the greatest fan of Christmas!

[ah]