Ford Focus tdci - Slow cranking/no start when engine is hot

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Fri 25 Jul 2014 13:27
Ford Focus tdci - Slow cranking/no start when engine is hot - jerrican

My Ford Focus 1.6tdci 2005 (Mark II) frequently turns over very slowly, and often won't start, when the engine is hot after driving for 30 mins or more. Voltage at terminals drops from 13.5v to 9v or less when cranking.

However, it always starts readily when cold (within a couple of seconds) and can then be turned off and restarted several times without hesitation.

When symptoms first appeared intermittently a few weeks ago, I had the battery (3+ years old) and charging tested with the engine hot - all was reported OK. Unfortunately (?) there were no symptoms on that occasion.

So which is more likely - bad battery and bad battery test, or lazy starter motor when hot?

Thanks in advance for any views which will be appreciated.

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Fri 25 Jul 2014 15:10
Ford Focus tdci - Slow cranking/no start when engine is hot - elekie&a/c doctor
Could be any or all of the above problems.You need to find somewhere that can actually carry out accurate tests on the battery and starting and charge systems.I doubt if any of the quick fix places are capable.
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Fri 25 Jul 2014 20:25
Ford Focus tdci - Slow cranking/no start when engine is hot - Peter.N.

Check the voltage at the starter when cranking, if its much lower than the battery voltage you have a poor connection somewhere, possibly on the starter terminal a this will expand and lengthen when hot, it could also be a poor earth connection to the starter you can check this by measuring the voltage between the negative battery terminal an the starter housing. If all that test out OK it probably the starter.

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Sat 26 Jul 2014 18:48
Ford Focus tdci - Slow cranking/no start when engine is hot - jerrican

Thanks for those thoughts. I have taken some more measurements and broken/cleaned/remade a number of electrical connections en route to the starter as a basic check, but having seen now that access to the starter motor is awkward and has to be both from above and underneath, I'm inclined to try and find a good electrical specialist. Problem is reproducing the symptoms reliably for him to examine, so meanwhile I'll leave off the underneath engine cover and see if cooling the lower part of the engine compartment (where the starter is) relative to the top (where the battery is) makes any difference.

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Sat 26 Jul 2014 19:33
Ford Focus tdci - Slow cranking/no start when engine is hot - madf

My guess is that the insulation on the starter motor coils in breaking dwn under heat.

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Thu 31 Jul 2014 18:49
Ford Focus tdci - Slow cranking/no start when engine is hot - jerrican

It was the battery.

Running with the lower engine cover removed, so cooling the starter motor more than the battery, made no diffierence - which suggested that it was the hot battery that was failing. Added to that, it is cheaper and easier (for me) to get at than the starter motor. So I changed the battery - and all is now well.

When I fully removed the battery, I saw a Motorcraft label on the back - presumably it was original fitment from 2005 and a 9 year battery life is not to be complained about! Had I realised it was that old, I wouldn't have raised the issue here - but many thanks to everyone for your help.

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