Stumped by charging problem(diesel

zaph · 15th January 2020, 21:22

I just fitted a second new alternator, a Bosch refurb unit and this is also refusing to charge(12.8 ish volts at battery posts), just like the last one. Running with new belts, new tensioner pulley, new tensioner and new idler pulley.

I suspect it is the new supposed quality crank pulley, which is infact junk, because of the flutter between the crank pulley and alternator.

However before I throw yet more money away, is there anyway I have missed which could be causing under charging?

trikey · 15th January 2020, 21:24

It wont be the crank pulley, if the alternator is not charging then its a faulty unit.

zaph · 15th January 2020, 21:54

Quote:

Originally Posted by trikey

It wont be the crank pulley, if the alternator is not charging then its a faulty unit.

Two brand new alternators that are both faulty? Either I am extremely unlucky or something else is going on. Unless sellers are selling alternators that won't work with an 05 75.

The belt flutter between the crank and the alternator is huge, I have seen some videos of Rover 75 belts, with faulty pulleys. Mine aint making the noise but something is not right because non of them look like mine. it feels like there is a twist in the belt between the crank and the alternator.

Other option is a fault in the wiring loom, which is causing the alternator to under charge.

I would hate to have to scrap a car over such a ridiculous fault but I can't keep throwing money at it and at the moment it has me beat.

MarkS · 15th January 2020, 23:36

I apologize for asking the obvious but you have got the routing of the belt correct as shown below ?

https://the75andztclub.co.uk/forum/s...84&postcount=4

Is the belt the correct length ?

https://youtu.be/WcP9_ecUFM4

Have you checked the (5A?) alternator fuse in the internal fusebox and have connected the low power connector to the alternator ?

zaph · 16th January 2020, 11:52

Quote:

Originally Posted by MarkS

I apologize for asking the obvious but you have got the routing of the belt correct as shown below ?

https://the75andztclub.co.uk/forum/s...84&postcount=4

Is the belt the correct length ?

https://youtu.be/WcP9_ecUFM4

Have you checked the (5A?) alternator fuse in the internal fusebox and have connected the low power connector to the alternator ?

It is correctly routed, two new belts, same fault.

I will check the fuse but wouldn't that lead to zero charging, not low charging?

RogerHeinz57 · 16th January 2020, 13:21

Sorry to add this of it seems a bit cheeky, but often diagnosis techniques follow the route to the most expensive option, and disregard more obvious checks that should be done first, and far easier in practice to achieve.
Battery connections need to be good and tight.
Checking of earthing to the body also. Could be worth connecting a jump lead to the negative side of the battery and connecting the other end to a good engine earth, and or to the body, following this take readings with a good meter.
Check the ends of the wiring between the starter and alternator link cable as these can suffer with corrosion issues the same as body earthing points.
The jumpy belt tension won't be helping matters, but assuming the charge rate remains the same during most engine speeds that problem can be dismissed.
Hopefully it turns out to be something easy to fix after spending much time and £ so far.
Good luck.

pletevl · 16th January 2020, 14:02

Try another multimeter, mine under reads when it's battery is getting low.

Pete.

zaph · 16th January 2020, 16:49

Partially fixed it. Pulled the earth by the gearbox, one look at the bolt showed the problem. It was actually spark eroded at the top. Cleaned the bolt and all the surfaces, now all is well.

Alas the belt is still jumping around a bit too much for my liking. So I think that warrants further investigation.

MarkS · 16th January 2020, 17:40

Sanity restored ?

COLVERT · 16th January 2020, 19:15

Quote:

Originally Posted by zaph

Partially fixed it. Pulled the earth by the gearbox, one look at the bolt showed the problem. It was actually spark eroded at the top. Cleaned the bolt and all the surfaces, now all is well.

Alas the belt is still jumping around a bit too much for my liking. So I think that warrants further investigation.

Does that mean your alternator is now charging as it should ??--

15th January 2020, 21:22	#1
zaph Avid contributor Rover 75 Join Date: May 2015 Location: Leeds Posts: 135 Thanks: 0 Thanked 17 Times in 11 Posts	Stumped by charging problem(diesel I just fitted a second new alternator, a Bosch refurb unit and this is also refusing to charge(12.8 ish volts at battery posts), just like the last one. Running with new belts, new tensioner pulley, new tensioner and new idler pulley. I suspect it is the new supposed quality crank pulley, which is infact junk, because of the flutter between the crank pulley and alternator. However before I throw yet more money away, is there anyway I have missed which could be causing under charging?

15th January 2020, 21:24	#2
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,760 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	It wont be the crank pulley, if the alternator is not charging then its a faulty unit. __________________ Lest we forget..

15th January 2020, 23:36	#4
MarkS Gets stuck in Rover 75 Diesel Tourer, called Perseverance Join Date: Nov 2011 Location: Bournemouth Posts: 664 Thanks: 189 Thanked 157 Times in 108 Posts	I apologize for asking the obvious but you have got the routing of the belt correct as shown below ? https://the75andztclub.co.uk/forum/s...84&postcount=4 Is the belt the correct length ? https://youtu.be/WcP9_ecUFM4 Have you checked the (5A?) alternator fuse in the internal fusebox and have connected the low power connector to the alternator ? Last edited by MarkS; 16th January 2020 at 01:45..

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16th January 2020, 13:21	#6
RogerHeinz57 I really should get out more....... A Reasonably Priced Car Join Date: Jan 2014 Location: Burton Latimer Posts: 2,530 Thanks: 408 Thanked 1,064 Times in 712 Posts	Sorry to add this of it seems a bit cheeky, but often diagnosis techniques follow the route to the most expensive option, and disregard more obvious checks that should be done first, and far easier in practice to achieve. Battery connections need to be good and tight. Checking of earthing to the body also. Could be worth connecting a jump lead to the negative side of the battery and connecting the other end to a good engine earth, and or to the body, following this take readings with a good meter. Check the ends of the wiring between the starter and alternator link cable as these can suffer with corrosion issues the same as body earthing points. The jumpy belt tension won't be helping matters, but assuming the charge rate remains the same during most engine speeds that problem can be dismissed. Hopefully it turns out to be something easy to fix after spending much time and £ so far. Good luck.

16th January 2020, 14:02	#7
pletevl Posted a thing or two rover 75 cdti(rhd), MG ZR(lhd), MG TF(lhd), MG TF(rhd), mini mpi (lhd), Renault megane III (awful) Join Date: Mar 2014 Location: East of France Posts: 1,278 Thanks: 124 Thanked 114 Times in 93 Posts	Try another multimeter, mine under reads when it's battery is getting low. Pete.

16th January 2020, 16:49	#8
zaph Avid contributor Rover 75 Join Date: May 2015 Location: Leeds Posts: 135 Thanks: 0 Thanked 17 Times in 11 Posts	Partially fixed it. Pulled the earth by the gearbox, one look at the bolt showed the problem. It was actually spark eroded at the top. Cleaned the bolt and all the surfaces, now all is well. Alas the belt is still jumping around a bit too much for my liking. So I think that warrants further investigation.

16th January 2020, 17:40	#9
MarkS Gets stuck in Rover 75 Diesel Tourer, called Perseverance Join Date: Nov 2011 Location: Bournemouth Posts: 664 Thanks: 189 Thanked 157 Times in 108 Posts	Sanity restored ?