Volvo 240dl station electronic problems, alternator?

  • Thread starter Thread starter Gilean
  • Start date Start date
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Gilean

Hi,
I've been reading a lot on alternator problems in this group. My
problem is similar to the ones I've read but just a little different
(of course).
Car: Volvo 240 dl station 1986 manual.
Problem: In a week time the car would start less well untill one day it
wouldn't. Couple of guys pushed me and it worked fine driving for 10
min to a mechanic.The mechanic measured a 12.65 V over my battery with
car running. He concluded that the alternator needed replacement.
After replacement the V was still 12,65. Both alternators were tested
outside the car and both the new and the old were good. The battery was
also good although empty. The mechanic put my old alternator in,
charged my battery and my car ran fine for a couple of weeks (also
after not using it for 10 days, so no leak while standing still I
guess). Then it started starting less easy again untill it wouldn't, I
got a push again, drove home (I think the engine almost stopped a
couple of times). The next day I went to my garage were I explained the
story. After checking it out they told me it was the alternator and
maybe also the alternator belt that needed replacement. Thanking them
for nothing I went home with an according to them fully charged battery
(altough they were a bit vague). A couple of days later I went for a
120 mile drive (each way) on the way back my dashboard fuelmeter and
engine-temp. meter slowly went down to almost 0 although fuel and temp
were fine. Also the speedometer only showed the right speed when I took
my foot of the gas (otherwise to low a speed). The overdrive stoped
working. To me it seemed the battery was totally empty and the
alternator was not keeping up. I stopped allong the road. The fuel and
temp went ok again but as I moved on everything stopped working as
described before.
Coming home the car wouldn't start.
The V over the battery with the car off is still just above 12. The
lights on the dash with key in position II work (I presume battery lamp
is alternator lamp).
Their are 3 wires from the alternator: Two red and one blue (thinner
one). I think they're ok but i'm no expert. (wich one is the ground?,
blue?)

A few things I did right before problems started occuring: I pluged in
a missing fuse (the one for back-up lights etc.) and replaced some
others. Since than the speedometer has been shooting up and down at
certain moments. This same day I replaced some speaker wire leading it
behind the dash. Since that day the "lights-warning light" also pops on
when I turn on the head lights. It goes of when I turn on and of my
direction lights. (:-?)
Since I thought I might have pulled some wires doing that I checked the
dash wiring. It looked ok apart from to loose wires of which I don't
know if I need them. 1: a solid blue one. 2: a red and white one. Does
anyone know what they're for. (I noticed there was another solid blue
one that was connected in combination with 2 other wires (black and
white and an other color if I recall correctly).

Hope anyone can help me I'm gonna be roadtripping for 3.5 weeks in 2
weeks, hopefully with this car.

Thanks.
Gilean.
 
Hi Gilean, please take a look at this link, it describes in detail the
charging system of a 740 (almost the same as the 240).
http://www.brickboard.com/FAQ/700-900/ElectricalStarting.htm

in addition to that link, check the ground connection to the alternator
(blue wire). If you have a volt meter, with the engine running and head
lamps on, check from the negative of the battery to the following points:
-blue, ground wire 0 to 0.1 Volt
-Thick red wire, should be 14 Volts.
-Third wire should be about 14 volts. The 3rd wire is what turns the
alternator on, it applies switched power through the battery warning light
on the dash board to the brush/regulator assembly, if the battery warning
light is burnt, the alternator will not charge.

Check the link, take the measurements, and report back.

Arnold
 
Hi Gilean, please take a look at this link, it describes in detail the
charging system of a 740 (almost the same as the 240).
http://www.brickboard.com/FAQ/700-900/ElectricalStarting.htm

in addition to that link, check the ground connection to the alternator
(blue wire). If you have a volt meter, with the engine running and head
lamps on, check from the negative of the battery to the following points:
-blue, ground wire 0 to 0.1 Volt
-Thick red wire, should be 14 Volts.
-Third wire should be about 14 volts. The 3rd wire is what turns the
alternator on, it applies switched power through the battery warning light
on the dash board to the brush/regulator assembly, if the battery warning
light is burnt, the alternator will not charge.

Check the link, take the measurements, and report back.

Arnold
 
Hi Arnold,
Thanks for the info.
I did the tests and this came up:
between:
- and Green (third wire) at first 12.1 V later when remeasuring after
thick red: 10.6 V
- and ground .05 V
- and thick red 10.6 V
Then some other measurements:
1. Voltage between the alternator power terminal and the battery "+"
terminal should be well under 0.2V (did not know what the power
terminal is)
2. Voltage between the alternator body and the battery "-" terminal
should be well under 0.2V : mine was .055 V
3. Voltage between the battery "-" terminal and the engine block should
be well under 02.V :mine was .006 V

So those last 2 look ok.
Then I started measuring while revving the engine:
- and green or thick red: 9.5V
then with the fan on high while revving:
- and green or thick red: 8.5V
hmmmmm I thought: interesting.

The V over the battery is also going down when revving. At a certain
point (I meassured this later on) 12.6 to 12.3 or so.

Then I remembered something else. The first time when they replaced my
alternator and put it back in. They left out one part which they said
wasn't important.. They thought it was a noize reductor but I don't
know. It's a small black box (lxwxh: in cm: about 2.5x1.5x0.7) with a
small metal plate with screw hole for connecting to alternator and a 3
cm black wire with a small plastic thing that says :AMP and looks like
is made to glide over something for electric connection. The black
little box says:
Germany
2,2microF 100V-
0 290 800 036
I wanted to send a picture but my server is down.

Thanks for all the help. I hope I'm on to something. I'm suspecting
there is something with my regulator or so, but shouldn't the voltage
go up above 14 then???

Thanks,
Gilean
 
Hi Gilean, I think that the control voltage is there to "turn on" the
alternator, that is the 12.1 Volts that you measured on the 3rd wire
(green). When you started the car, since the alternator is not producing
voltage, the electrical load keeps draining the battery, and that is why the
battery voltage keeps going down. The next step would be to remove the
voltage regulator/brush assembly and inspect the brushes. It is easily
done. This is a black piece located on the back of the alternator and held
in place by 2 Torx screws. If the brushes wear out, the regulator will not
be able to pass the voltage through the rings to the field to "turn on" the
alternator. The mystery piece you are talking about is a capacitor, it is
mainly there to help with ripple noise that would affect your radio, mainly
in the AM frequency band, it will not interfere with the electrical
operation of the alternator.
You were measuring earlier voltage drops which are helpful in
determining wiring conditions when the alternator is producing power, but in
your case it is not. My suggestions are:
-With the engine off, check the resistance from the negative of the battery
to the alternator housing, it should be zero ohms.
-Remove the green wire, and connect a 12V 5w bulb from the alternator
terminal where the green wire was connected, to battery + and see if the
battery voltage goes to 14V with the engine running.
-Check the regulator brushes.

How was this alternator tested outside the car? did they put it on a test
jig, or just measured for bad diodes?

Arnold
 
Hi Arnold,

This is what came out of the tests:

-battery to alternator housing = 0.0-0.1 Ohm
- I didn't get the bulb yet.

The brushes look like this:
http://www.ciezo.nl/~gilean/sp_resize.php?source=./gallery/Car
Parts/DSC03807 (Medium).JPG

On the short side?

Then I have an other question:
The fact that the V output with the new alternator was also 12.6V
doesn't that mean that it can't be the brushes (or any part of this
alternator for that matter)? What is left then? wiring (have I checked
that all with the test i did, what about the bulb test, is that
important, what do I test than?1)?

Both alternators were brought to an other garage then the one I was at
and then tested, so I guess it was on a test jig... I wasn't there
though , but I presume they're telling the truth about them both being
fine (otherwise they would've sold me an alternator).

Thanks again for your quick response.
Great help!
Gilean.
 
There should be a space between Car and Parts in the link.
Sorry for the mess
 
The third time with the picture link was the charm !
The brushes look fine, there is a lot of them showing. We are running out of
options here. The resistance to ground is fine, the only other advice I
have for you is to check the belt tension, tighten if necessary, disconnect
the 3rd wire from the alternator and connect a 5W bulb from the battery
positive (also available closer at the alternator) to the control terminal
(Where the green wire was connected), start the car and put some load on,
lights etc. And measure again. If the voltage measured at the alternator
output terminal (the big red wire at the alternator) comes to life 14 to
14.4, then the wiring to the battery charging light on the dash, (maybe the
light bulb is out) is to blame. If it remains dead, check your connections
at the alternator, and have it tested in front of you on a shop.

please report back, I am losing sleep over your problem.

Good luck

Arnold
 
Hi Arnold,

It seems to be very hard for me to reinstal the regulator. Is there a
special trick to it? Or should I just keep trying to find the screw
holes untill I go crazy (almost at that stage). I presume the brushes
should be pointing upwards. Do I glide it in and then upwards so I feel
pressure on the brushes? Any more things to be aware of?


Then something else:
I bought this, to do the bulb test cause they didn't have anything
else...

http://www.ciezo.nl/~gilean/sp_resize.php?source=./gallery/Car
Parts/DSC03817 (Medium).JPG



(again a space between ..03814 and (Medium)

Do you think it'll work with this piece of equipment?

Then I looked under the protective cap of the regulator and to me it
looked a bit funny... Is that black stuff supposed to be there as
protective cover or has something melted and leaked in there (I know
this is probably not the smartest question, but I'm losing sleep as
well, so checking everything):

http://www.ciezo.nl/~gilean/sp_resize.php?source=./gallery/Car
Parts/DSC03814 (Medium).JPG

I'm almost taking this alternator out and having it tested again (I
heard of a place where they do it for free). Is it easy to take it out?
But more important: also to put back in??? :-)

Thanks for the help again. I truly hope we're gonna beat this
quizmaster volvo.

Gilean
 
Gilean said:
Hi Arnold,

It seems to be very hard for me to reinstal the regulator. Is there a
special trick to it? Or should I just keep trying to find the screw
holes untill I go crazy (almost at that stage). I presume the brushes
should be pointing upwards. Do I glide it in and then upwards so I feel
pressure on the brushes? Any more things to be aware of?
Click to expand...
I have vague memories of the regulator replacement in the Volvo, but
normally the brushes have to be pulled back against the springs to get it to
fit. IIRC the Volvo regulator has tiny holes where straight pins can be slid
in to hold the brushes back, but on some regulators I've had to use thread
(often tied to the braided brush wires) run out to where I can keep tension
on it and then cut it when the brushes are in place.

Mike
 
Hi Gilean, I have not looked under the protective cover, but that black goo
could be epoxy to seal moisture out and make this regulator immune to
moisture and humidity. I would not be too concerned. You will have it
tested outside anyway. The tester looks, good, tie the red clip to the
battery +, (if you touch the tip of the tester to chassis, the bulb should
light up). Remove the green wire from the alternator, start the engine and
touch the tip of the tester to the terminal where the green wire used to be,
this should feed voltage to the field of the alternator, and the output
voltage should go up to 14.5 V.
If it does not, have it checked outside, I think it would be defective.

Good luck.
Arnold
 
Hi,

I did all the test, took the alternator to a test jig and... it was
fine.
Whilst there I thought, why not buy a new belt... replaced it and...
everything is fine..
I couldn't see the old belt slipping or anything like that.. but
anyways.. problem solved, thanks very much for all the help.

Gilean
 
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