Diagnosing poor starter motor

[Ian Geary]

Morning all

Focus 1.8 tdci is a reluctant starter in cold weather. (Fine above 6 or so degrees). Engine turns but won't catch.
I can get it to start by using short bursts of starter, with pauses in between, which will get the engine to catch on about 4th go.

Other adults in my household however have demonstrated just churning the starter against the non starting engine will flatten battery after 10 or 15 seconds. (Which I then recharge with a trickle charger)


Glow plugs newish - made no change. Bosch battery good on my load test, but a few years old now. Newish alternator makes 14+ volts.

Car runs well otherwise, just got not with zero advisories, on 115k miles original starter.

Internet led me to poor starter. Don't have osiloscipe to check actual revolutions, but internet says the starter probably isn't as lively as it should be.

I've taken starter motor off this morning (thankfully straight forward)

Solenoid moves freely
The cog (dog?) Slides easily, but shows some inevitable wear on the teeth.


Can anyone advise what else I should be looking at?

A general clean up of the carbon? Clean up the electrical terminals?

I'm tempted to throw £160 at a new/exchange at ecp because of course I've not thought ahead to get one cheaper from internet.

But given I've got sod all else to do, I wondered if there was some pH secret to bringing a starter back to life.

Thanks

Ian

[Ian Geary]

Well, I've fiddled a bit more and removed the coils from the housing.


Tbh there's no real smoking gun..ie missing brushes, broken magnets etc

Apart from inevitable dust I have no way of telling if any of it isn't functioning.

There is a wear mark where the copper windings have been rubbing on the plate that separates the motor from the cogs.

Guess I will just clean it up, put it back together and see if it makes a difference.

[finlo]

Although your glow plugs are new have you checked they're getting voltage to them?

[stevieturbo]

If you did not know or test the glow plugs....it was kinda pointless changing them

If you have no means of testing the starter, seeing what current it pulls, checking cranking rpm ( which lets face it, isn't difficult to make an assessment by ear ) etc etc....tearing it apart seems a bit odd.

If the battery is known good, all cables and grounds are good...and the starter is slow. Then likely it is a problem.

So is it cranking fast or slow ?

Or record/monitor voltage at the starter during cranking.

[Ian Geary]

Fair enough, thanks for the replies.

Taking it apart passed the time I guess. At least it confirmed nothing obvious was wrong.

No, I didn't test the glow plugs before changing them...they were so cheap and easy to change, i did it on the off chance a year or two ago (the his has been a long running problem, but the wife now uses the car for work in the morning so it's gone up the list of things to fix)

I think I will have to get more technical and record voltage, current draw etc, as well as checking out the glow plugs.


Ian

[stevieturbo]

Ian Geary said:

Fair enough, thanks for the replies.

Taking it apart passed the time I guess. At least it confirmed nothing obvious was wrong.

No, I didn't test the glow plugs before changing them...they were so cheap and easy to change, i did it on the off chance a year or two ago (the his has been a long running problem, but the wife now uses the car for work in the morning so it's gone up the list of things to fix)

I think I will have to get more technical and record voltage, current draw etc, as well as checking out the glow plugs.


Ian

It still doesn't answer the simple question....is it turning over fast or slow ?

And taking it apart if you're not doing that sort of thing every day...you simply may not see anything wrong. It doesn't mean there is not anything wrong.
maybe a windings issue, maybe a magnet issue, maybe brushes etc ? Most may not have a huge red flag showing something wrong.

But basics first.

Check battery cables, grounds, and how fast is it cranking ?

[Smiljan]

Battery going flat in just 10-15 seconds of cranking. That isn't a healthy battery.

[Matt_E_Mulsion]

I had a very very similar problem with a 1.8 tdci in a Transit Connect, that wouldn't start when the ambient temperature dropped cold over the course of a few winters.

I tried everything to keep it going, new battery, new starter, new glow plugs, which all helped for a while, but I eventually came to the conclusion that the fuel pump was struggling to build up enough pressure to get the van to start.

The way I combatted this problem was to fit a small tube from the air box up to and poking out of the scuttle panel in which I would spray a bit of easy start down the tube whilst cranking the engine. This was enough to get the engine to fire on the cold mornings.

This worked for a winter or two before the van completely gave up the ghost. It wasn't worth even thinking about repairing the fuel pump before let alone after it completely packed up.

[Penelope Stopit]

Armature drive end bush has worn causing armature to rub on the magnets, commutator end bush will also now be worn but nothing like the drive end bush that has a very high load on it

Magnets may now be weakened and could also be cracked, does look like there are small pieces of magnet floating about in the yoke

You might get away with replacing the bushes

Moving on

Smiljan said:

Battery going flat in just 10-15 seconds of cranking. That isn't a healthy battery.

Is correct, unless the failing starter is putting a massive load on the battery which is doubtful

A good battery should operate a good starter for minutes

Don't know what load your tester is putting on the battery, starter in cold weather could be drawing 200 Amps or more

[Penelope Stopit]

None of the above means the engine starting problem will be solved once sorted, there could be other problems

One stage at a time though, sort starter, charge battery and allow it to cool then have it discharge tested with the correct load. Auto electrician or Halfords battery test????

[Mave]

stevieturbo said:

It still doesn't answer the simple question....is it turning over fast or slow ?

But basics first.

Check battery cables, grounds, and how fast is it cranking ?

Agreed. If the starter is turning over at a decent speed, then I wouldn't start off assuming a starter problem.

[Penelope Stopit]

That's a shame, seeing this topic active got me thinking that the OP had posted back, have attempted to save the fitting of a faulty starter motor

Was a touch late posting to the topic though, very likely been fitted by now

[Belle427]

Could point to fuel pressure problems which are not uncommon on these engines.