Random cranking issue, M57 diesel 2003

[jonbmw]

Hello

I'm having a issue with my 2003 3.0d (520k km, 320k miles).
This issue has been appearing for about 2 years, on and off, but has recently started happening a lot more frequently.

Issue is with starting the car. When starting to crank the car, it sometimes cranks a few times and then suddenly stops, makes kind of hissing noise from the engine. Then i can crank again and start the engine. But depending on the car's mood, i might have to do it a few times to start it. This happens about 50% of the time now. I'm suspecting a starter issue, since the engine works and starts fine when this problem does not happen.

Does anyone have any clues as what might be causing this? I have not pulled any codes yet, but since this issue has been going on for a while, the car has been to the shop and i've read codes myself a year ago, but there wasn't anything wrong. One shop I went to last year for suspension work, said the starter needs replacing, but i would like to be sure before i spend cash on that.

[andrewwynn]

Most likely correct assessment.

Common failure mode of a starter is to pull more and more current as it fails. It presents with the symptoms you described.

Get a measurement of the current draw when starting.

It should be in the range of 225-275A. When failing they can be 350-400a.

225a is my gas 3.0 on cold start, 185a on immediate restart. I'm suspecting the second attempt the engine has enough oil in the right places to get that drop in torque required.

It can take years to slowly fail and the only symptom is it cranks slower and take longer to start (though it will often take out an aloder weaker battery so more often than not people replace the battery first not realizing it was the starter not the battery in the first place. )

Start the car with a fully charged battery but also jumper from another running car.

If it starts fast almost certainly the starter.

[Moments]

Instinct says starter too.
Big kudos for you running at 320k miles - you also make my E53 seem like a youngster at a mere 180k :-)

[jonbmw]

Originally Posted by andrewwynn

Most likely correct assessment.

Common failure mode of a starter is to pull more and more current add it fails. It presents with the symptoms you described.

Get a measurement of the current draw when starting.

It should be in the range of 225-275A. When failing they can be 350-400a.

225a is my gas 3.0 on cold start, 185a on immediate restart. I'm suspecting the second attempt the engine has enough oil in the right places to get that drop in torque required.

It can take years to slowly fail and the only symptom is it cranks slower and take longer to start (though it will often take out an aloder weaker battery so more often than not people replace the battery first not realizing it was the starter not the battery in the first place. )

Start the car with a fully charged battery but also jumper from another running car.

If it starts fast almost certainly the starter.

I will try to get a hold of a meter to measure the amp draw.
But regarding the slower cranking, I can't say that I'm noticing this. It's more like cranks fine or cranks fine just for a sec then stops. It will only crank slower when it's winter time or battery is low from not driving (it has a parasitic draw somewhere...).

I will also try to fully charge the battery and jumper when starting. I'll see if this makes a difference.

[jonbmw]

Originally Posted by Moments

Instinct says starter too.
Big kudos for you running at 320k miles - you also make my E53 seem like a youngster at a mere 180k :-)

Thanks for the input!

It's been in the family since the beginning of it's life. I've driven it for the last 8 years and 100k km or so. It's now finally starting to show signs of breaking down, since I live in the European equivalent of the rust belt and the mileage does not help the case

[jonbmw]

Starter was replaced, starts up faster now and the issue has not come back in 5 days. Seems like the starter was the culprit, as suggested. Thanks.

[andrewwynn]

You didn't notice the slower start because it takes years to get slower so it's normal. How people usually notice is when they meet up with somebody with the same model but newer car (or newer starter). Sadly more often than not they've already replaced the battery thinking the slower cranking is from weak battery. Hope your problem is fully resolved. That's a great engine you should have at least a few more years in that car.

[Clavurion]

Originally Posted by andrewwynn

You didn't notice the slower start because it takes years to get slower so it's normal. How people usually notice is when they meet up with somebody with the same model but newer car (or newer starter). Sadly more often than not they've already replaced the battery thinking the slower cranking is from weak battery. Hope your problem is fully resolved. That's a great engine you should have at least a few more years in that car.

Same thing as with leaky injector which makes the start gradually slower (rail pressure build up is slower). When somebody comes to diagnostics I can say from the first start if there is a worn injector and start takes more cranks than it should.

[wpoll]

Originally Posted by Clavurion

Same thing as with leaky injector which makes the start gradually slower (rail pressure build up is slower). When somebody comes to diagnostics I can say from the first start if there is a worn injector and start takes more cranks than it should.

Interesting... Would there be other indications of a worn injector?

Things like checking the selective mass adjust values in INPA and/or the smooth idle tests etc?

[Clavurion]

Originally Posted by wpoll

Interesting... Would there be other indications of a worn injector?

Things like checking the selective mass adjust values in INPA and/or the smooth idle tests etc?

This mentioned leak off problem indicates worn internal sealing. You can measure leak off with measuring hoses and cups (I've used 20 ml syringes). Usually good injectors are below 20 ml leak off @ 2 min idle.

Correctional values (smooth running control) tells more about the condition of injector nozzle (fuel atomisation properties).