Another diagnostic challenge (answer posted)

[Jeremy airjer W]

I ran into this a couple months ago and was reminded of it again tonight at work. It was a late model SAAB.

The symptom is it makes a grinding noise in park and neutral with the engine running. As soon as you put it in reverse or drive the noise goes away.

All the clues and info you need are in those two sentences. What do you think.

[Macgyver55]

The real question here is does it grind in Park or not grind in Park.

If you meant that it grinds in Park and neutral but nowhere else I'm thinking a sticking ignition switch, causing the starter to be engaged only when the neutral safety switch alllows it to engage?

Heading up now to put in the dock and boats, hopefully the answer will be here when I get back.

[theoilman]

I saw an IH V345 in a truck do something similar over 20 years ago. A real head scratcher on it too. It turned out to be broken front motor mount bolts allowing the lower pulley to drag on a crossbeam, but only under specific engine torque - I forget now which conditions caused it to grind and not grind but it was a really weird combination.

[Jeremy airjer W]

Sorry it has been changed to drive or reverse.

[Tom7227]

  airjer said:

Sorry it has been changed to drive or reverse.

Don't know what it is but another $200 in diagnostics just was added to the bill because the wife couldn't get the symptoms straight when she took it in.

[Jeremy airjer W]

Funny!

[Big Buck Buster]

If I were to take a guess at it without hearing it, I would say the trans pump.

BBB

[Scott K]

I would say it is normal, and that is what you get when you buy a SAAB

[Jeremy airjer W]

  4wanderingeyes said:

I would say it is normal, and that is what you get when you buy a SAAB

That's a given but laughable non the less!

[fivebucks]

I think I would have to call in to The Tappert Brothers, Click and Clack.

[Scott K]

  Macgyver55 said:

The real question here is does it grind in Park or not grind in Park.

I'm thinking a sticking ignition switch, causing the starter to be engaged only when the neutral safety switch alllows it to engage?

This makes sense, I will go along with this.

[katophil]

cracked fly wheel

[katophil]

well?

[deadeye]

Ditto the cracked flywheel.

Those cars always end up being a saab story.

[bak2MN]

Nice pun deadeye. lol.

[Jeremy airjer W]

This one happened to be a stuck ignition switch like a couple of you mentioned. Since the starter circuit can only be completed with the transmission in park and neutral it would grind in those two gears. Once in drive the circuit is open and the grind goes away.

[Big Buck Buster]

Interesting!

[deadeye]

Huh. Makes sense to me.