Lotus Elan

Possible Alternator Issue

PostPost by: GHill » Mon Aug 28, 2017 9:18 am

Morning All

So yesterday took the car out and the right light came on the tacho and then the indicators and tacho, fuel gauge, battery power, engine temp gauges all stopped working. Didn't ruin the drive of course but after lots of sticking my arm out of the window the car got home no problems.

So this morning I set out to trouble fix. Problem 1 was a simple 15 amp fuse, so that was swapped and voila the gauges all work again - one issue that remains is the red light is still on the tacho and I noticed that the battery charge gauge is showing 'not charging' confirmed with a quick measurement at the battery.

So... to the forum, what would you do next? I'm assuming the problem is the alternator i.e. not getting charge from the alternator back to the battery.

Alternator is turning...

img_0615.jpg and
Alternator in action


Tacho red light is still on...

img_0620.jpg and
Tacho red light


Battery not charging...

img_0616.jpg and
Battery gauge


Was expecting the battery to have a higher voltage with the engine running...

img_0617.jpg and
At the battery


Cheers Y'All

Regards
G
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PostPost by: William2 » Mon Aug 28, 2017 9:41 am

Yes, I would definetly put my money on an alternator problem. Battery voltage should be showing at least 13 volts.
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PostPost by: john.p.clegg » Mon Aug 28, 2017 11:12 am

12.28V

What was the battery voltage before you fired it up ? you should be looking around 14V when the alternator kicks in ( Lotus fitted a larger pulley so as to not over-spin the alternator ).

John :wink

P.S pull the small wire off the alternator and
1 check you have around 12v on it ( no engine running ).
2 Check when you earth this wire the red light comes on.
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PostPost by: GHill » Mon Aug 28, 2017 12:23 pm

Thanks All

So my favourite type of lotus problem, the intermittent problem.

Went to the car to check and look what I get now...

img_0621.jpg and
Battery charge


img_0623.jpg and
Battery charge


img_0625.jpg and
Battery charge


So I will keep an eye on it - happy motoring everyone.

Oh all I did was remove the wires from the back of the alternator gave the connectors a quick rub with a green scrub pad and reconnected.


Cheers
g
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PostPost by: LaikaTheDog » Mon Aug 28, 2017 6:01 pm

same problem with my alternator turned out to be a frazzled internal regulator...in the alternator... most days it would be fine....then nothing... took a LONG time to track down
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PostPost by: jono » Tue Aug 29, 2017 3:50 pm

Had the same thing with a fairly new alternator.

Changed the diode pack, it lasted a month and went agian.

Fitted a new alternator from a reputable supplier - only ?38 and been fine ever since.

IME not worth the hassle opening it up and soldering in the new bits, just buy a new alternator and I think your problem will be solved.

May be wrong but it worked for me.
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PostPost by: GHill » Sat Oct 28, 2017 8:55 pm

Hey Gang

So this weekend I replaced the alternator in the plus 2 (alternator purchased from Paul Matty). However When I started the car, still no electrics to the following and I need your help and advice to track down the problem:

The following aren't working

- The tacho gauge
- The indicators
- The engine temp gauge
- The fuel level gauge

The following are working

- The speedometer
- The windows
- The hazards
- The lights


Any ideas, all thoughts appreciated.

Regards
G

PS posted a little ode to petrolicious video's - a bit naff but very much enjoyed making it - gave me a whole new respect to video makers.

https://www.youtube.com/watch?v=vuFA36hfgk4
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PostPost by: The Veg » Sat Oct 28, 2017 10:18 pm

Loved the video!
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PostPost by: mbell » Sat Oct 28, 2017 10:37 pm

- The tacho gauge
- The indicators
- The engine temp gauge
- The fuel level gauge

The gauges run from the 10v supply, the tacho is 12v but I think that power is taken off the input to the 10v regulator. The indicator flasher is below the tacho and probably gets power from the same place. The connect is also very easily dislodged from the flasher.

So I suspect you have a connection issue with the line feeding those items. Have a look round under the dash trim above the diver left leg.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: GHill » Sun Oct 29, 2017 7:18 am

Cheers

Will definitely take a look - I did have a look yesterday and all the connectors looked to be on so I will give it another go. Any suggestions where to look after that?

@The Veg, thanks

Cheers
G
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PostPost by: bob_rich » Sun Oct 29, 2017 6:33 pm

Hi

Which wiring build do you have? year of the car should help confirm that. On my +2S 130
the gauges you mention are fed from the +10V but the indicators are not . though the pick up point for the indicators may come from the input (+12V) side to the regulator. Did you blow the fuse again? Depending on the model and the wiring loom the rear screen heater and brake warning light may be fed from this fuse as well.

To blow a 15A fuse, (how did it look? was it black well blown or just looks like the fuse wire in the link just fell off.)
Unless you have a very odd fault only the rear screen heater fault would draw a current that may given a fault to clear a 15A fuse.

To clear a 15A fuse may take a lot more current than 15A and it could be this that damaged the alternator rectifiers
in the first instant. Could give a bit more help if the actual wiring build model was known. ( car type and year and body number would tie this down)

If you do have a intermittent fault then remove the wires to all suspect points, replace the fuse with say a 2A then add the gauges back one by one. if /when the fuse blows then the las added gauge would be the suspect. For the rear screen. the rear screen heater would need a bigger fuse . Try fusing this separately with an added fuse link form the battery from the battery with a 15A fuse.

Hope this helps best of luck

Bob

Hope this helps
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PostPost by: GHill » Mon Oct 30, 2017 8:12 pm

Hi

For clarity I have a 72 elan plus 2s 130

Yes the bloody fuse blew again (holds head in hands)

The fuse looked frazzled but connected

I've put a 35amp fuse there although I like the idea of the 2amp then connecting one by one

Thanks for all your help

Took her out today for a good run

Cheers
G
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PostPost by: bob_rich » Mon Oct 30, 2017 10:32 pm

Hi Again

It looks like your circuit may be the same as mine so the circuits of the fuse thats blowing are likely to be as described in my last post. PLEASE DONT fit a 35A fuse ! ! From my own experience ( as a retired electronic engineer) I don't think the individual wires in that circuit would cope with 35A for an extended period. have you got the original 10V voltage regulator this may have a internal fault. The 10V regulator is a bimetallic device that switched slowly on and off to produce an average output of 10V for the gauges . So a fault to earth on any gauge (or the 10V regulator itself ) could reflect a short back to the fuse. Also disconnect the rear screen heater for the time being to eliminate that. The flasher is connected to the input side of the regulator so there could be a fault in that circuit or perhaps the indicator stork has a problem or one of the indicator bulbs has a short to ground.

another trick I have used to find a fault is to replace the fuse with a bulb. It has to be a big one such as a headlamp bulb. when the fault appears the bulb will light limit the current and while the bulb is lit you can go around the circuits and see which one is causing the bulb to light. this would wok well with the gauges and regulator as the circuit generally take less than 0.5 Amp. not so good with the rear screen heater and indicator It needs to be wired across the fuse link position and make sure the bulb is suspended somewhere where the heat cannot do any harm.

Its all a bit of a nuisance but this trick it does eliminate damage and possible burnt out looms

best of luck

Bob
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