924Board.org

Gram · Posted: Thu Jun 09, 2005 11:35 pm Post subject: Starter problem

Yesterday the 924 developed a new problem. Sometimes when I try to crank it the starter just spins over quite fast. No clunks, nothing, just a whirring noise. Next time I try it it's fine and starts it normally. Any leads please.? Maybe it's just gunked up and due for a clean. Solenoid?
_________________
'82 924 NA Euro (hers)
'98 Audi A4 TDI (ours)

Smoothie · Posted: Fri Jun 10, 2005 2:08 am Post subject:

The solenoid acts in 2 steps, (1) its' electromagnet pulls the piston in, which levers the drive gear out to engage the flywheel. That'd be the clunk. Then (2) as the piston reaches the end of its' travel, it closes a switch that activates the motor. Obviously that's the whirring.
To get the whirring without the clunk, the switch would have to stuck in the closed position. Being very gunked-up, could cause that and a major gunked-up-edness would also immobilize the piston, explaining the lack of clunk, so yes - a cleaning -might- help.

The brass colored pin at the center of the solenoid here is the switch that gets pressed in by the piston to activate the motor. If the pin is stuck in the in position, you'll get the whirring without the clunk - http://pg.photos.yahoo.com/ph/smoothies931pics/detail?.dir=bdb3&.dnm=8f3a.jpg&.src=ph

Showing internal pieces of the solenoid - the switch is at bottom-center - http://pg.photos.yahoo.com/ph/smoothies931pics/detail?.dir=bdb3&.dnm=1329.jpg&.src=ph
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Gram · Posted: Fri Jun 10, 2005 2:31 am Post subject:

Thanks Smoothie. I was reading your other posts earlier, re cleaning up the solenoid. Looks like I'm in for a job...
_________________
'82 924 NA Euro (hers)
'98 Audi A4 TDI (ours)

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

"gunked-up-edness"

I just looked that word up in the Factory manual. It says:

A state of gunky; to be gunked; Usually found under the engine around the starter.

Not to be confused with "f***ed-up-edness", which is usually associated with the fuel or electrical system.

Good word smoothie.

Smoothie · Posted: Fri Jun 10, 2005 6:28 am Post subject:

I can't help it if the dictionary in my mind contains a few more entries than the printed version.

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

numbbers · Posted: Fri Jun 10, 2005 9:05 am Post subject:

Often, your problem is caused by the starter drive unit. As the solenoid kicks the drive gear in the starter forward, the gear is given a spin, so it will easily mesh with the teeth on the flywheel. The unit with the gear on it, is the starter drive. It is a racheting mechanism that locks the drive gear in only the direction of rotation of the engine, so that if the engine kicks back, it will not damage the starter. If the rachet part of this mechanism fails, the starter will crank, but the drive gear does not turn, resulting in the wirring noise you describe. Starter drives used to be available seperately for American engines, but now, you have to replace the complete starter.
_________________
1980 924 Turbo