Starter motor turns too slowly when hot (won't start)

[Jim Hughes 0]

Done a quick search and nothing exact or similar.

 

1.8 16 V KR series.

 

Been struggling with this problem for too long now and could do with some advice. Over 12 months ago I replaced the starter motor with a new reconditioned unit due to slow turn over when hot, (replaced gearbox bush at same time) not much improvement but would start well when cold and only just start (slow turn over) when hot. Leave it for half an hour and it would start no problem.

 

Replaced battery with a new one 6 months ago and this made a small improvement, then about 6 weeks ago after standing for over a week would not start at all. Turned over way to slow and fouled the plugs. I was not convinced it was the starter motor as I'm on number 4 now! (I've owned the car 12 years)

 

Replaced all positive/negative cables to starter/battery and all earths & added extras, replaced gearbox bush again with VAG bush, greased shaft well (bush end). Put it all back together and the problem was solved, turned over rapidly when cold and hot, never has it been so good - I was a happy fella :D

 

Now after 4 weeks of bliss the problem is back with avengence. Starts ok when cold, turns over too slow when hot. The only option is to leave it to cool or get a bump start - this is starting to get very embarrasing. :mad2:

 

Read some other probs on search and they mention about solenoid and live trigger, the solenoid is clearly getting it's signal and operating as the starter is turning the engine - all be it slowly, it's almost as if the engine has massive compression when hot, or its a temp related resistance issue. :shrug:

 

I'm completely out of ideas now and would appreciate any suggestions. :help:

[dr_mat 0]

As you say, this is very odd. I might want to check the battery output voltage when cold/hot. Perhaps there's a circuit that's dragging the voltage down when the engine is still hot?

[Wullie 1]

I had a similar problem inasmuch as the starter would turn over slowly. Turned out to be the brushes in the alternator which were worn and only producing enough charge to keep things going. Fitted a new regulator brush unit and all is well now. Cost about £10 from ECP, their part no 414 44 0050. Original part no 069903803D. It's an eaasy fix as well, two philips screws secure it. They will be tight so it may be easier to pop out the alternator as access to the rear one is awkward. If you have the means to check the alternator output is should around 14 v just after starting dropping a bit after the charge used to start the car has been replaced. (Only way I can think to say it.)

[dr_mat 0]

There is no excuse for not having one of these for this kind of money:

http://cgi.ebay.co.uk/Digital-Multimete ... 0620214836

 

Stick it on the 20V DC range, stick the contacts on the battery posts and read ..

[Jim Hughes 0]

Thanks for the advice folks.

Stupidly I'd not even thought of alternator! (It's a J plate car @ 120K on the original) :cuckoo: You do tend to go down blind alley's sometimes. I have a Multimeter so will do some checks later.

[Jim Hughes 0]

With Multimeter across battery posts engine not running - reading 11.99 Volts.

 

Engine running reading - 13.80-98 Volts.

 

And now the worst bit! the engine is now starting fine when hot :mad2:

[dr_mat 0]

Lol, well there you go! Problem solved! :)

Just like Schrodinger's cat, you simply had to LOOK at the problem and it would resolve itself .. :)

[Jim Hughes 0]

I've been out today for a few journeys and it has been no trouble at all (starting hot & cold)

 

Fact: the car is not a daily user, and truth be told when it does get used it does not travel huge distances, last week it had been stood for a few days idle in freezing temperatures, yesterday when I had the trouble it took a while to start and when I think back I had the heater fan on full for the whole journey before it let me down. I'm begining to think that the extreme cold could have had an influence here, and, with the previous history I've had over this problem - I've jumped to the wrong conclusion. :roll:

 

However: My understanding is that the hardest start should always be the one from cold.

 

I've got a spare fully-charged battery and jump leads in the car from now on, so hopefully will be able to rule out a few obvious issues.

 

Still, thanks again for all your advice. :wave:

 

I will update with any developments.

[Supercharged 2]

Jim - change the brush pack on the alternator - at 120k miles they will be worn.

 

You can even do just the brushes themselves - couple of quid from VW

[davidwort 0]

stuff that is an issue when hot is usually something like the starter or solenoid as they're electromagnets and weaker when hot, but as you've done those... :scratch:

 

have you checked the timing, just to make sure, if it's been over advanced it will be a bugger to start, not sure if that would be more of a struggle when hot though

alternator output seems OK, perhaps try a heavy discharge tester on the battery when the car is hot

[mattkh 0]

I've been out today for a few journeys and it has been no trouble at all (starting hot & cold)

Hi

You mention not the ignition switch. When was it last changed ?

[Jim Hughes 0]

Hi again.

 

Supercharged - I'm going to change the Alternator brushes asap, if they are worn (probaby) they will be short in length and they will be at the end of the 'spring push' giving possible intermitent results.

 

David - Timing: I had the car booked into the only garage I trust, only to find that they had chucked out their timing light as they had no customers with the old type ignition on their vehicles, except me :nuts:When I was doing the poss/ neg leads and gearbox bush work I noticed that one of the vac pipes related to advance /retard was disconnected, but as I fixed this at the same time as the other issues I was not sure it was related. I will endeavour to find somone with a timing light.

 

Matt - Ignition Switch :? hmmmm.... like I say I've owned the car 12 years from 60k and to the best of my knowledge it's never been changed. Is it a known problem area? Very, very, rarely I've turned the key for ignition and nothing has happened ie no turnover but I could count on two hands the amount of times this has happened.

 

Still many thanks again for all your suggestions :notworthy:

[Supercharged 2]

I'd kind of ruled out the ignition switch as the 12V signal from this just energises the starter solenoid so I don't think that would cause it to turn slowly - if it wasn't engaging the flywheel then it would run fast I think with no resistance (?)

 

That said, the original ones do go wrong and they've been improved now using a Polo 6N part (black in colour) so well worth adding to the shopping list to keep the car reliable - I'd say the low miles is the only reason it's still working tbh - £20 ish from VW

[Jim Hughes 0]

Hello Folks,

 

Just thought I'd update this one for the memory banks. I visited the dealers with regard to changing the Altenator brushes, drew a blank to be honest (they wanted exact details) to be able to supply the exact parts - which would mean taking the Alternator off, or I was being fobbed -off. I was just about to buy a new Alternator off Flea Bay when I decided to try a different battery - instant result.

 

I've been disconnecting the battery when left over night, and left for any considerable time, all is well - car starts no problem-at-all, hot or cold.

 

I can only be left to conclude that there is a current draw on the battery when not in use, (usually, no more than a few days). There has been just enough amps to effect one start, but after a short run it has not been enough to replenish the charge in the battery, hence no ' hot start' .

 

I must admit I suspected this a long while back :cuckoo: but with a multimeter connected in 'series' at idle (no electrical circuits on) there was no-more draw than 0.5 Amps. :shrug:

 

Any way - never mind that, hope you have a good Christmas and all the best for 2011 :salute:

[Jim Hughes 0]

The battery I replaced over 6 months ago which I had ruled out as not being a 'cause' as IT WAS BRAND NEW. Assume.

Assume - Never Assume Anything, As It Makes An Asse of Me and U! :cuckoo:

 

I returned the above back to the car a few days ago and it would not turn it over at all. :eek:

 

I went back to the supplier of the battery with ALL the evidence, they said: " Yup we've had a lot of trouble with that make of battery, it looks like they are ALL sh1te - we'll get you a new one from a different manufacturer"

 

FFS :censored: :mad2: :bad-words: