Won't Start: Makes "Whrrrrrr- Thunk!" sound

[lomotpk]

Teh car is an '84 930.

Turn the key, all lights come up, battery checked out OK.

Try to start, engine does not turn over. Instead you hear a 1 second long "whrrrrrr" sound followed by a Thunk and then nothing.

Solenoid? Starter motor? Any Relays I need to look at?

All ideas, suggestions, musings will be seriously considered and followed up!

Busted in Boston

[targa911man]

Whirring from front or back?
Front--fuel pump is starting but cutting off--several things could cause that--does not necessarily mean the pump is defective. But I doubt you would hear a "thunk" when it stops.
Rear--starter gear is not engaging--could be a problem with the starter or the gear itself. Might be jammed. Probably not solenoid or it wouldn't start to begin with.

[lomotpk]

The Whrrrrr is in the rear.

If the gear is jammed, is this something one can 'un-jam' and then things will be OK. Or, is jamming a serious checkbook oriented failure?

[targa911man]

I am have never worked on a 930, but it is certainly one of the easier fixes on a 911. I guess whether unjamming it will cure the problem will dfepend on what caused it. Most it will cost you for a DIY replacement is $150-$180 for a new starter. There is a trick on getting the top mounting bolt on the starter out on a 911/915 tranny, but I don't know if it will work on the 930 with the different tranny. You lay under the tranny and reach around to where the bolt is. You can get the wrench on it and have decent room to loosen and remove the bolt.

[lomotpk]

UPDATE.

I charged the battery (it was low).

Now when I try to start it, the lights (dash, glovebox, etc) go OUT and there is a buzzing sound from the rear.

Is this the sound of a dead starter?

[vash]

buzzing? or fast clicking sound?

[lomotpk]

buzz.

Definitely not a clicking sound.

[sammygon1]

Sounds similar to the problem I had. It was caused by the teeth on the flywheel being ground down. The starter would spin (whurrr sound) and maybe catch a broken tooth (clunk sound) engine would not start. I would pull the starter and check in the hole with your finger to see if the teeth are ground down. It could just be the starter though. Sam

[vash]

disconnect the battery first. you can peek into the hole the starter set in with a mirror.

[Doug Steinel]

Perhaps a few teeth on the flywheel are damaged and those teeth happen to be in line with the starter teeth when you try to start it. Try turning the engine over with a socket on the belt nut so the flywheel moves a few degrees. Then try to start it. If it starts, then I would think you should expect an intermittent starting problem until you replace the flywheel.

[lomotpk]

CONCLUSION:

I let the battery charge all night, AND I hand turned the motor this morning and Whooooomm! it starts as if there never was a problem.

However, I didn't follow good diagnostic procedure so I cannot tell you if it was the battery of the flywheel teeth. My suspicion is the battery.

Thanks to you all, once again proof that the internet works.

Lomotpk

[john70t]

The battery and connections should always be the first thing to check in starting problems.
Sometimes if the bendix is sticking and not poping out to engage the flywheel, a few loving taps on the starter with a hammer will free everything up.