screwed alternator and rev counter problem... HELP!

[GoLfMan]

started the mk1 up today and took it for a drive with its new suspension in it handles brilliant but the engine didnt feel that fit for some reason and when i got back smelt a burning smell.... the alternator had gone and sapt all charge from the battery while it was at it!

also my rev counter was acting weird! bouncing up and down like a yo yo whats wrong?!?!!?

[ontarv]

if alt died rev counter would play up
as your bat drains, less power gets to coil
and eng power drops due weaker spark and signal
for taco comes from coil so can get wacky!!
vn commy alt fit in without to much hassle thats
what i run, 85 amps as well !!

[h100vw]

All probably down to the alternator at this stage. Get that sorted before chasing any other snags.

Keep in mind that the alternator output may have gone way over 14volts and fried a few things too.

Gavin

[GoLfMan]

cheers for the quick replies fellas...
so a VN commodore alternator ey, do go on

[ontarv]

yep vn go on ok. really easy if your has air pump
i had to modify my top mount to fit alt off of a 77 with
air pump then neighbour give me niosy vn one
fixed and fitted pully and fan off golf alt and
wired in .. simple alt has three wires
signal , light , power to batt
see pic

[GoLfMan]

mines a 77 Golf... mite just get a new VW alternator

[ontarv]

does it have a air pump ?
mines a 76 , i had to make top mount to
fit a 77 alt but it was'n't putting out enough
so i fixed the vn one , and was the same shape and offset
as 77 one give or take a washer

[GoLfMan]

air pump?! that fan on the front of the alternator... yeh it does

[brackie]

Air pump

Josh.. I reckon the "air pump" being referred to is the emission control device. In '77 new regulations forced VW to install these (useless) contraptions to try and burn any NOX left after combustion. Most people just ditched them.
My advice would be to just relpace the alternator with a good 2nd hand one (guys..somebody must have one ) The diodes are probably done or the regulator isn't regulating. Bosch alternators have a regulator integrated with the brush block so it may be worth putting in one of those as a possible cheap and easy fix.
Ontary's advice about checking out everthing in case overcharging has happened is good advice.

[GoLfMan]

Josh.. I reckon the "air pump" being referred to is the emission control device. In '77 new regulations forced VW to install these (useless) contraptions to try and burn any NOX left after combustion. Most people just ditched them.
My advice would be to just relpace the alternator with a good 2nd hand one (guys..somebody must have one ) The diodes are probably done or the regulator isn't regulating. Bosch alternators have a regulator integrated with the brush block so it may be worth putting in one of those as a possible cheap and easy fix.
Ontary's advice about checking out everthing in case overcharging has happened is good advice.

gotcha mate, yeh my 77 hasnt got the emission control stuff as we changed the engine and couldnt get it back on... but correct me if im wrong here but pre-1979 cars dont require emission control?!
ill advertise in the parts wanted section and see if i get any bites... i think this alternator has been on the way out for a while as it was whining pretty bad for years!

[syncro]

... but correct me if im wrong here but pre-1979 cars dont require emission control?!

Yes it does but who checks anyway?

[blackgti1.8]

gotcha mate, yeh my 77 hasnt got the emission control stuff as we changed the engine and couldnt get it back on... but correct me if im wrong here but pre-1979 cars dont require emission control?!
ill advertise in the parts wanted section and see if i get any bites... i think this alternator has been on the way out for a while as it was whining pretty bad for years!

Yes they do - that aforementioned airpump
(all cars after June '76 until ~ '79 sometime...)
After that they magaed to ditched the airpump in favour of a more passive
scheme...

The < '79 cars had a double crankshaft pulley 'cos they had to drive
that airpump, as well as the alternator. I think that the outside one drove the
alternator, which was a hassle, since that required a different alternator bracket...
Anyway, I assume from your comment that you have a 'normal' pulley,
so I wouldn't worry about it - like Brackie says, no-one give a rats-xxxx