Starter whirrs but doesn't turn engine over, whats wrong?

BottleNose · 03-11-2007, 06:17 PM

Trying to start a long-stored '67 911...the starter whirrs just like when you start a 911 normally, i.e. it doesn't make any straining or binding sounds. But the engine is not actually turning over.

Back in auto shop class I remember something called the starter bendix, which moves the starter's gear onto the flywheel to crank the engine. Is there a way to access this part and perhaps try to free it up? I'm guessing it's just stuck due to sitting for so long. I already removed the starter.

Thanks for any ideas.

Joe Bob · Joe Bob's Garage

Sounds like the solenoid is not kicking it out....or it has a broken shaft. Pull the starter and bench test it.

BottleNose · 03-11-2007, 07:00 PM

How do I bench test it? Can I just hook it up to a car battery?

I have an extra starter from a newer 911 with an identical looking solenoid, should I try swapping them?

RoninLB · 03-11-2007, 08:57 PM

solenoid plunger either stuck or jammed. If mine I'd have it completely rebuilt.. might as well bring the alternator and regulator in for testing also..

Jack Olsen · 03-11-2007, 09:07 PM

Try a gentle tap or two with a hammer. Sometimes that'll loosen it up and buy you a little more time.

Swapping the starter is not a very enjoyable job. It's up on the high side of things, under the seat. Get used to the idea that you're going to be hugging a transaxle for a while.

David E. Clark · 03-12-2007, 01:46 AM

Here is a terrific article that should help.

Starting and Charging System Troubleshooting

GarryW · 03-12-2007, 03:34 AM

Make sure there is a ring-gear on the flywheel. I make that mistake in my early days and it sounds like you described. Good luck!

glenncof · 03-12-2007, 11:14 AM

I have had the same problem once with a weak battery.

Early_S_Man · 03-12-2007, 11:35 AM

A starter from a later 911 could be either SR-17 [what came on the '67] or SR-68 ... either will fit and work fine on your engine.

SR-17X rebuilt starters aren't very expensive, ~$40 or so.

BottleNose · 03-13-2007, 01:28 PM

This is very strange...I swapped the entire starter for a known good one I had around. SAME EXACT problem and noise! The starter was from a 1969 911E rustbucket parts car and always cranked it over fine. I only removed it a month ago.

I took the starter back out again...by the way, it's much easier with the pax side rear wheel removed...and peered into the hole. The ring gear looks just fine to me, no worn or missing teeth. Both starters sounds like it is just spinning its gear without contacting the flywheel/ring gear.

I took pictures of the flywheel/ring gear and a sound video of the noise, would it help anyone to post them? I read the linked article but couldn't find any advice for my type of problem. Any ideas?

john walker's workshop · 01:59 PM

ya got the wires on right?

BottleNose · 03-13-2007, 02:54 PM

I think so...just the way I found them. Two yellow wires merge together and are plugged onto one tab, while two large wires (one going to the battery and one to the alternator I assume) with washer-spade connectors are held on with the large bolt and nut.

This car has been sitting for at least 10 years. Would this make any difference? I can turn the engine easily at the crank pulley.

911pcars · 03-13-2007, 05:28 PM

Per the illustration in Ron's post, when the solenoid energizes, the lever goes to the left. This results in two actions:

1. A copper disc electrically connects the battery cable to the starter motor circuit and energizes the motor.

2. At the same time, the bottom of the lever moves to the right, moving the overrunning clutch/pinion gear to the right along the motor shaft into mesh with the ring gear.

If the motor rotates, this indicates the lever has moved and the mechanical motions are as designed. However, if the overrunning clutch is malfunctioning (slipping), the motor will rotate but the pinion gear can't drive the ring gear (crank).

It's curious that both starter motors you tried result in the same symptom. If the starter is okay, I would suspect some missing teeth in the ring gear in the area the overrunning clutch/pinion gear would be. However, you verified the ring gear teeth are intact.

So the question is, "Is the overrunning clutch in both starter motors okay?" If available, this part can be replaced or have the starter checked out by an automotive electric shop/rebuilder.

Sherwood

BottleNose · 10:23 PM

I moved the crankshaft a couple of turns to make sure there weren't worn or missing teeth causing the problem. Is it possible that the starter or the ring gear is out of alignment? Here are some pics of the ring gear.

http://forums.pelicanparts.com/uploads10/IMGP45651173939040.jpg
http://forums.pelicanparts.com/uploads10/IMGP45671173939266.jpg

And a sound/video recording of the weird noise the starter makes. Skip the first 20 seconds of the video...just me walking around to the drivers seat to start it.

The noise is identical for both starters.

Is there a specific way to "bench test" these starters to make sure the overrunning clutch is working properly? Is it simply a matter of connecting a 12V + to the large nut and grounding the starter motor? How many volts do you send to the tab where the yellow wires connect to trigger the starter on?[img][img]

911pcars · 03-14-2007, 11:14 PM

If you can get to the pinion gear, try to manually rotate it in the opposite direction of motor rotation. If the overrunning clutch is okay, you won't be able to rotate it relative to the motor shaft. If you can, that's the problem, a slipping overrunning clutch.

A bench test should confirm the pinion gear is moving outward as designed.

Sherwood

bazar01 · bazar01's Garage

I listened to the video, and it sounded like the starter is engaged to the ring gear when the car was started.
The starter will spin faster than that sound when the pinion is not engaging.
The car is not firing though. But it sounds like there was compression but battery sounded weak.

304065 · 03-15-2007, 07:51 AM

I don't hear any grinding noise which would be the case if some enterprising mechanic accidentally fitted a VERY early cup-type flywheel which had the 356 gear pitch. The odds of that are near zero. Of course the ring gear is an integral part of the early cup-type flywheels pre-1970.

I'm with Sherwood: if the motor turns over freely, I believe there is an internal fault with the starter pinion either not moving all the way, or the clutch is toast.

As Warren says, an SR-17X (the X stands for eXchange, a bosch remanufactured part) can be inexpensively had at most FLAPS, as these were used on the 914 also and carry a VW/Audi Stamp next to the bosch part number.

Gunter · Gunter's Garage

Quote:

Originally posted by BottleNose
I think so...just the way I found them. Two yellow wires merge together and are plugged onto one tab, while two large wires (one going to the battery and one to the alternator I assume) with washer-spade connectors are held on with the large bolt and nut.

This car has been sitting for at least 10 years. Would this make any difference? I can turn the engine easily at the crank pulley.

Wiring sounds good.
Aside from the starter issue, there are certain procedures to follow when bringing a long-stored car back to life.
Don't compound the problems, do a search.
Just turning the key is a bad mistake.

glenncof · 03-15-2007, 08:30 AM

Quote:

[i] Is it simply a matter of connecting a 12V + to the large nut and grounding the starter motor? How many volts do you send to the tab where the yellow wires connect to trigger the starter on?[img][img] [/B]

There are three connections. Ground, +12V constant to large lug, and +12V to solenoid (which is the on/off control). I suggest using a known good voltage source or monitor voltage with a meter.

Have you put a voltmeter on the battery ? The voltage sould stay at about 12V since the starter is not engaging (which draws the big current).

I would also check both terminals for 12V with meter grounded at the starter. This would be to detect bad connections. If battery voltage is holding up, lower voltages here would indicate bad connections.

It's a '67 so corrosion is not unlikely and two starters with identical symptoms is low probabliity.

BottleNose · 03-15-2007, 03:00 PM

I can in fact turn both starter's pinion gear the opposite direction! Looks like I have two bad old starters. I will check the voltages at the starter connections, but I think I will check out a rebuilt starter locally.

Thanks for all the advice guys!

>Aside from the starter issue, there are certain procedures to follow when bringing a long-stored car back to life. Don't compound the problems, do a search. Just turning the key is a bad mistake.

Oh yes, I know! I did my research on this board and followed the proper procedure (marvel mystery oil in cylinders, fuel system flush, replace fuel lines, boil fuel tank, etc.)