engine wiring anomalies (c900)

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

John B - 10 Jul 2005 23:31 GMT

While conducting a routine oil change this afternoon, I noticed a couple of
strange things with the wiring on the intake side of the engine.

First, the main cable from the battery's (+) terminal has a serious insulation
problem near where it connects to the starter. It looks like the insulation is
cracked and possibly a little burned and/or melted. The insulation on the
neighboring wire looks a bit damaged as well. Photograph here:

http://home.ccil.org/~rotten/DSCF0130.JPG

Next, I happened to notice a wire connected to the intake manifold at one end,
and nothing at the other end. It looks like a ground wire for something, but I
don't know what. Photograph here:

http://home.ccil.org/~rotten/DSCF0131.JPG

Opinions on these issues welcome. I'm especially wondering about the battery
cable, as I certainly don't want the broken insulation to spread down the wire
and short the battery. The car (a 1992 900 NA) is running very well, FWIW.

Thanks,

John

Reply to this Message

MH - 10 Jul 2005 23:53 GMT

> http://home.ccil.org/~rotten/DSCF0130.JPG
Looks like melted insulation, maybe from cranking too long, or a locked
up or otherwise faulty starter motor

> http://home.ccil.org/~rotten/DSCF0131.JPG

That is a non OEM cable, my '91 900 does not have it.
Also the round yellow terminal on the thin yellow starter relay cable is
not original. Maybe it had some issues with the relay or starter motor
in the past. Has it ever been replaced?

Signature

MH
'72 97 '77 96 '78 95 '79 96
'91 900i

Reply to this Message

John B - 11 Jul 2005 00:33 GMT

> > http://home.ccil.org/~rotten/DSCF0130.JPG
> Looks like melted insulation, maybe from cranking too long, or a locked
> up or otherwise faulty starter motor

Hmm, ok. The starter motor died (after a long illness) and was replaced within
the last year, so it could be that. I suppose I should just spring for a new
battery cable. If that's the case, you'd think the guy putting in the new
starter would have noticed, but you never know. It would have been in his
interest, as he could have charged me parts and labor for a new battery cable.

>> http://home.ccil.org/~rotten/DSCF0131.JPG
>
> That is a non OEM cable, my '91 900 does not have it.
> Also the round yellow terminal on the thin yellow starter relay cable is
> not original. Maybe it had some issues with the relay or starter motor
> in the past. Has it ever been replaced?

Yep, that's probably from putting in the new starter (which I had done at an
indy Saab place). If the mystery wire from the intake manifold isn't OEM, then
it might well be part of an aftermarket security system the car used to have.
I've found (and removed) assorted remnants of it from all over the car over the
years. I guess I just never noticed it before.

Thanks for the very helpful reply.

John

Reply to this Message

Charles C. - 11 Jul 2005 00:27 GMT

> While conducting a routine oil change this afternoon, I noticed a couple of
> strange things with the wiring on the intake side of the engine.
[quoted text clipped - 11 lines]
>
> http://home.ccil.org/~rotten/DSCF0131.JPG

I would say this is an earth (negative line if you like). Most probably
used to connect another component to the manifold and thus to the
negative line.

> Opinions on these issues welcome. I'm especially wondering about the battery
> cable, as I certainly don't want the broken insulation to spread down the wire
[quoted text clipped - 3 lines]
>
> John

Signature

Please remove _removeme_ to reply.
Work: http://www.somis.dundee.ac.uk/
Hobby: http://www.egothor.org/

Reply to this Message

Paul Halliday - 11 Jul 2005 08:19 GMT

> While conducting a routine oil change this afternoon, I noticed a couple of
> strange things with the wiring on the intake side of the engine.
[quoted text clipped - 5 lines]
>
> http://home.ccil.org/~rotten/DSCF0130.JPG

Simply put, get that changed immediately. I had a situation where my radio
would go off periodically. Luckily I have a voltmeter gauge in the car which
showed the voltage to drop dramatically. The car did not stall.

I found the problem almost immediately - the live wire from the battery had
bared off on the turbo battery shield and had welded itself to it. Once the
car had been made safe, electrically, I found a number of blue scorch marks
on parts of the shield and a perfectly round blue scorch mark on the turbo
elbow. A lucky escape ...

> I'm especially wondering about the battery
> cable, as I certainly don't want the broken insulation to spread down the wire
> and short the battery. The car (a 1992 900 NA) is running very well, FWIW.

Don't risk it ... Just get it replaced.

Paul

1989 900 Turbo S
http://saab.go.dyndns.org/

Reply to this Message

Craig's Saab C900 Site - 12 Jul 2005 05:52 GMT

>While conducting a routine oil change this afternoon, I noticed a couple of
>strange things with the wiring on the intake side of the engine.

>First, the main cable from the battery's (+) terminal has a serious insulation
>problem near where it connects to the starter. It looks like the insulation is
>cracked and possibly a little burned and/or melted. The insulation on the
>neighboring wire looks a bit damaged as well. Photograph here:

>http://home.ccil.org/~rotten/DSCF0130.JPG

Given the current that a starter draws it's highly likely to be a
combination of heating due to the terminal resistance where the cable
attaches to the solenoid going up just due to age and contact degradation,
and also due to that end of the high-current cable being the closest part
which is near the heat of the engine when running.

Additionally, the end of the insulation is a point where contaminants,
moisture, etc. will 'wick' into the multistrand copper cable over a period
of time so that's probably part of it too.

>Next, I happened to notice a wire connected to the intake manifold at one end,
>and nothing at the other end. It looks like a ground wire for something, but I
>don't know what. Photograph here:

>http://home.ccil.org/~rotten/DSCF0131.JPG

>Opinions on these issues welcome. I'm especially wondering about the battery
>cable, as I certainly don't want the broken insulation to spread down the wire
>and short the battery. The car (a 1992 900 NA) is running very well, FWIW.

I agree that the small wire coming off the intake manifold is an earth for
something. Check the alternator to make sure it's connections are all in
place, but to save the wire causing any shorts take it out and replace the
bolt. Then, with the wire kept safely somewhere in case it is needed, have a
look to see if there's anything nearby which looks like it's had a lug come
away.

Regards,

Craig.

Signature

Craig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia
Craig's Saab C900 Workshop -- For all Saab C900 Enthusiasts world-wide!
http://www.saab900classic.net http://www.saab900.org c900@lios.apana.org.au
Come and explore our site, and check out our web-forums, mailing list, etc.

Reply to this Message

John B - 12 Jul 2005 15:00 GMT

> Given the current that a starter draws it's highly likely to be a
> combination of heating due to the terminal resistance where the cable
> attaches to the solenoid going up just due to age and contact degradation,
> and also due to that end of the high-current cable being the closest part
> which is near the heat of the engine when running.

Ok, thanks. I've ordered a new battery cable, which I'll put in this weekend.

> I agree that the small wire coming off the intake manifold is an earth for
> something. Check the alternator to make sure it's connections are all in
> place, but to save the wire causing any shorts take it out and replace the
> bolt. Then, with the wire kept safely somewhere in case it is needed, have a
> look to see if there's anything nearby which looks like it's had a lug come
> away.

Yes, definitely a risk for shorts. While I was photographing it yesterday I
accidently drew a spark from the hot terminal of the alternator. I've snipped
off the wire, and I'm pretty sure I won't need it for anything.

Thanks.

John

Reply to this Message