Why is my car not starting - intermitently?

Nobbie1967

chrisw said:

Crankshaft sensor breaking down intermittently?

This sounds likely due to it occurring when it’s warm after use. For some reason this is a common failure mode. They startup fine from cold, but then fail to restart after stopping for a short time. Not sure they throw a code either so easy to miss.

Goudy

Sounds like it might be a battery issue.

It's not uncommon to have an intermittent starting issue if the battery is getting old and flaky.

When they are completely knackered, a battery won't even energies the starter relay properly, so you just get a series of rapids clicks from under the dash, but when they are starting to lose power they react differently under different conditions.

The cars electronics will use different strategies to start the engine under different conditions, hot or cold and quite often a weak battery will show up on one particular strategy, more often than not when warm starting.

It sounds counter intuitive as you've think cold starting would be the issue but the battery would have had time to recover a little when left overnight or a good few hours.

Repeated warm starts after a cold start in the morning just isn't allowing the weak battery to recover, hence the warm start issue.

How old is the battery? If it's five years or older I would just replace it anyway.

Is it the correct battery? Someone asked me to look at their recent new used car once and it had a smaller battery than is should have had. That caused all sorts of issues, poor starting and faulty electric steering waring lights were the big issues.

Have you had the battery checked properly.
This check should involve it's ability to store and deliver amps, as it's these amps that really start the engine.
Just checking the volts doesn't really tell you much unless there is a dead cell, it needs an amp test, a local garage should be able to test it for that.
  

twopenny

Thank you Goudy. The battery is about 3yrs old.

I went through a phase of it not starting and the 'busy' garage put in new battery, then starter motor, then alternator.

Frankly I would have expected them to check the alternator first but it is what it is.

Plugs were replace 6yrs ago.

To me  it's as if the fuel is evapourating in the pipes or something. Then I turn the engine a few times and wait 5mins and alls back in place.

Up late last night doing YouTube but there's so much flouncing and presentation on there these days that real information is scant.

I will ask them to check the plugs, especially the one where I spilt oil. It turns and sounds like one is not sparking properly - or that could be my imagination.

It could be that some of the sand got in somewhere and has take a while to cause problems. I've only just noticed it in hinges and on the engine in small amounts. Could have fallen from somewhere it got blown into.

Ask to check battery, and all the other things mentioned on here as a list.

It would at least eliminate things.

It's all very well attaching it to a machine but in my experience a mechanic can do better by looking and listening.

I guess though that it means when it starts well alls fine so it's

I'm going to see if I can get a recording of the sound when starting/not starting. Not sure if the phone will do it from inside. If not I'm going to have to nab a stranger when it won't start and get them to turn the ignition while I'm under the bonnet At least I know no one will try and steal it!

The car is a lifeline to me and I don't want to wait till it doesn't start at all - and I can't just leave it on the drive forever more..