Saab Central - Technical Help

Classic Saab 900: Starter Trouble

Diagnostics, Removal and Repair

Thanks to 'Deniss', for writing & supplying this comprehensive article.

I own a 1987 Saab 900 turbo 5-sp (SPG), 16-valve engine.  My starter trouble began with occasional no-starts while the car was hot, such as when I would be running a lot of errands around town.  I would turn the ignition key, and there would be nothing but one click heard under the bonnet (no turn over).  If I let the car sit for a bit, it would crank and fire right up.  She would always start when cold or even warm without hesitation.  When I asked about this problem in the forum, some people said it could be that the battery needs charging (if the voltage output is insufficient, i.e., under 12 V), some said the battery cables could have deteriorated and thus would provide higher than normal resistance when the car is hot, some said the electrical connections at the battery and at the starter could be dirty or the grounding could be faulty, some said the ignition switch/relay could be faulty, and some said the starter solenoid could be sticking.  By the time I got to testing these things, my car wouldn't turn over at all, hot or cold, so I tried to narrow down the problem logically, with the help of SaabCentral community. 

Initial Diagnosis

Here's the order of things you can try to narrow down the cause for your no-start condition:
  1. Using a multimeter, measure the voltage across the positive battery terminal and some good ground on the engine.  It should be over 12V, preferably around 12.5V or more.  If below 12V, charge your battery and see if the car will start.
  2. Check whether the battery cables are good.  With your multimeter, measure the resistance across the grounding point on the radiator crossmember (follow the fat blue cable from the battery) and the negative battery terminal.  It should be very small, if any, else remove the cable and clean the relevant electrical connections (using some medium-grit emory paper), including battery terminals, and repeat the test.  If that does not help, replace the blue battery cable (~$35 on eEuroparts.com).  Now, trace the red battery cable to the terminal in the back of the starter solenoid (called terminal 30) and measure the voltage across terminal 30 and a good ground on the engine.  Your meter should read battery voltage.  If it does not, clean connections at the battery and at the starter with some emory paper and repeat the test.  Replace the cable if still no reading.  If you do get a good voltage reading, measure resistance across terminal 30 and the positive battery terminal.  Make sure your connections are clean.  If your meter reads significant resistance, replace the cable (~$40 on eEuroparts.com).  See if the car will start.
  3. I suggest doing the same sort of cleaning with other grounding points under the bonnet and the other branch of the red battery cable, which provides power to the cabin, etc.  But at this point this is probably optional for your no-start problem.  I went through all the grounding points I could find under the bonnet and cleaned them to make sure no grounding gremlins are after me.
  4. Now, if you look at the electrical connections on the back of the starter solenoid, you will see there is a fairly small gray plastic spade-type connector with a small black wire running from it connected to the solenoid.  That's terminal 50.  Disconnect the spade connector from terminal 50 and connect a voltmeter between this connector (yes, the connector and not terminal 50) and a good ground.  Prop the volt meter up on the intake manifold so you could see its reading from the cabin while you turn your ignition switch all the way to START position.  At this point, your voltmeter should read over 12 V (battery voltage).  If it does, then your starter motor or starter solenoid is at fault.  If the voltage is significantly lower or none at all, your ignition switch/relay or related wiring could be to blame - make sure you address this problem separately.  To test this, bypass ignition switch relay by wiring terminal 50 directly to the positive terminal of your battery (but take caution when you make this electrical connection because starter might fire up immediately).  If this still does not fire up the starter, then either your starter motor has gone bad or your starter solenoid is sticking.
  5. Grab a hammer and smack your starter solenoid with it (but make sure you hit the solenoid housing only and not anything else).  I read that this is a known remedy for a faulty/sticking solenoid.  Fire up your starter either with the ignition key or wiring terminal 50 directly to your battery as in the preceding step above.  If it will crank now, good - you've narrowed down the problem to a sticking starter solenoid (and maybe also your ignition switch/relay if they were bad in the previous step).  Perhaps this would be a good time to remove your solenoid and clean it to prevent it from sticking in the future or even replace it in case its connections have eroded badly on the inside, so you don't have to do this job twice.  If the starter still will not crank, we need to do one more test.
  6. There is a thick wire strap running from the back of the main starter motor housing to a connector in the back of the solenoid - let's call it terminal 70, for the lack of its official name.  We will want to disconnect red battery cable from terminal 30 and connect it directly to terminal 70 to test whether the main starter motor is bad.  When you do it, be extremely careful!  If your starter motor is good, it will begin spinning immediately when you touch terminal 70 with the battery cable.  But since your solenoid it not engaged, the starter gear will be disengaged from your flywheel, which will cause the motor to spin extremely fast.  So do this test very very briefly so you do not damage your starter motor in the process.  If the motor spins, then your solenoid needs to be either cleaned or replaced.  If the motor does not spin, then you need to replace the whole starter motor assembly.

Starter and Solenoid Removal

So you need to remove the starter assembly from your car.  If you narrowed your problem down to the solenoid, you could try and just remove the solenoid by itself - there are 3 philips flathead screws holding it to the starter motor housing, but I did not see that possible.  The access is difficult, the screws will be on very tight, and it is really easy to shear off the philips head pattern.  In fact, even when I removed the starter from my car, I had trouble removing the solenoid screws.  If you still want to try removing just the solenoid, follow the steps below as far as needed to get enough access to the philips screws and then use a rachet with an appropriate philips driver.  Press hard and at the right angle, or you will shear off the bolt pattern.  (Regular screwdriver did not work for me).

Take the following steps to remove the starter from the engine:

Repair

Solenoid

Now that the starter is out, there are several things you could do with it.  If you narrowed the problem down to the solenoid (most common cause), you need to simply replace it.  To remove the solenoid, first remove the thick wire from the back of the solenoid that leads into the starter motor housing.  Then, remove the 3 philips flathead screws.  Use a rachet with a philips head driver here and press down as hard as you can.  Anything else will shear off the philips pattern, as I found out from experience.  In fact, I had to drill all three screws out.  It isn't very difficult because you only need to drill out the head of each screw you messed up, but make sure you drill pilot holes of increasing sizes for every screw.  This is what the inside of the solenoid looks like:
Inside of solenoid housing
Plunger
The cylindrical space inside the solenoid (above) is filled by the plunger (below).  There is a spring that is fitted between the bottom of the plunger and the gold-plated button inside the solenoid (shown above).  The plunger hooks onto a lever inside the starter motor housingengagement lever
which is used to engage the starter motor gear into mesh with your flywheel.  Often, just thoroughly cleaning the plunger and inside the solenoid will solve the problem of a sticking solenoid. 

Now, let us check the contacts on the back of the solenoid:Solenoid contacts
Clean all these contacts.  In its unenergized state, the plunger inside the solenoid is all the way forward, the gold-plated button inside the housing is depressed, and there should be an open circuit across terminal 30 (battery power supply) and "terminal 70" (starter motor power cable).  At the same time, there should be a closed circuit across terminal 50 and "terminal 70" with some small resistance.  This is where the solenoid draws its earth: through starter motor brushes and windings, not through solenoid housing.  When power from the ignition switch flows to terminal 50, the electromagnetic force causes the plunger inside the solenoid to retract.  When the plunger retracts, it moves the starter gear forward to engage the flywheel
starter pinion retracted
starter pinion engaged
and presses the gold-plated button inside the solenoid housing (see picture above), which creates a closed circuit across terminal 30 and "terminal 70" and makes the starter motor spin. After you clean the plunger, the insides of the solenoid housing, and its contacts, re-attach it to the starter motor housing with 3 bolts and re-install the wire strap that powers the starter motor from the solenoid.  To test, use jumper cables to connect a positive battery terminal to terminal 30 on the solenoid and a negative battery terminal to the front of the starter motor housing.  Now carefully and briefly power up terminal 50 by connecting a jumper between terminal 30 and terminal 50.  Caution: if the starter motor will spin, it will generate large amounts of torque and will be difficult to hold in place, so before doing this test, lay it against the wheel of your car and step on it.  Do not run this test for more than a couple seconds, or you will damage your starter motor!

If this procedure does not fix the problem, solenoid windings may be damaged or its contacts could have eroded.  Replace the solenoid.

Starter Motor

Since you removed the starter from your car, it might be a good idea now to take it apart and clean/lubricate the mechanism of your starter motor (but only if you found your starter motor to be healthy during the diagnostics!)  It is an easy procedure, but prepare to get really dirty. 

First off, unbolt the solenoid from the starter motor housing and set it aside.  Let's have a look at the back of the starter motor housing:
back of starter motor
As circled in red in the picture above, the two rods that hold the starter motor housing together each have a 7-mm nut on them.  The nuts are offset into the washers.  You will need either a 7-mm deep offset box-end wrench or a 7-mm socket that has a hole in it large enough for the rod to slide through it.  For me, 7-mm socket with a rachet worked just fine.  Loosen the nuts just a little for now, perhaps by a turn or so.  Unscrew the two philips screws and gently remove the cap from the back that you see in the picture.  There will be a washer and a locking ring-clip sitting on a shaft.  To take the ring clip off, push on it from its open end and as you do it, wedge a screwdriver blade on the opposite side to pry it off.  It should come off fairly easily.  Now, undo the two rods all the way and take them out, but rest the front of the housing on the floor so that it does not drop.  Pry the back cover off, and you will see something like this:

brushes-magnets
That's 4 small magnets with the winding strap attached to them, sitting on the set of small brushes.  At any circumstances, do NOT allow the ring that houses the 4 magnets to slide off the brushes.  It is possible to re-install it if that happens, and I was successful at it, but it requires a lot of patience, strong fingers, and plenty of manual dexterity.  It is easier to just not remove it.

Now, let us remove the front of the starter motor housing.  Lay the motor housing on its side, and carefully start wiggling the front section.  You will see a rubber piece where the lever arm driven by the solenoid is housed.  Pry it off carefully, as well as the orange plastic pivot attached to the lever arm.  Once free, you will be able to slide the front of the housing off, exposing something like this sticking out the front:

ring gear

Grab this assembly, and pull on it to decouple it from the rest of the assembly, and it will come off in one piece, shown above.  That's ring gear and clutch gear.  Remember the location of the off-white plastic housing you see here with respect to the main motor housing (black).  I believe there are flat divots to match.  This is another shot of this ring gear assembly from the other end (with black plastic cap covering ring gear removed):

ring-gear-exposed

There you can see that flat divot on the off-white plastic housing that I mentioned.  It should align with the orange plastic pivot for the lever arm, the rubber piece, and the main motor housing.  Now that ring gear is off, you will see starter motor and its pinion (where my hand is, in front of the coil windings):
starter motor pinion

So now, you can connect all the dots of the inner workings of your starter motor.  Play with the ring gear assembly to see how it works - it's fun!  In the picture above, you can see that I took the motor out of its housing, but there is absolutely no need to do that.  I did it out of curiousity and to clean things up a bit, but it is not worth the trouble really. 

At this point, inspect all the gearing and see if it is in good condition.  I bought some nice, viscous Lithium grease and lubricated all the gearing to make it smooth and try to prolong its life.  That includes motor pinion, ring gear, clutch, and front starter gear and shafts.  Grease the gearing liberally and work the gears through the grease, but make sure you wipe away any excess grease.  Make sure the clutch is well-lubricated, but that the excess grease does not make its extended and retracted positions stick!  Same for the outermost gear that engages flywheel.  Clean up whatever you can, but be especially careful with the coil windings of the motor because you do NOT want to scrape any insulation from those wires.

Now, we can put everything back.  I will assume you did not take out the motor from its housing.  If you did, you know what the force of those magnets is, so when you put the motor back into its housing, hold in the ring assembly of those 4 magnets on the end so it does not slide out while you put the motor back in.  Put the black plastic cap back on the ring gear and slide the ring gear assembly back onto the starter motor pinion, making sure that the divots in the housings align, as I pointed out before.  Now, you can put the front part of the starter housing back on, taking care to align its bolt holes with the two threaded rods we took out earlier.  Put the rubber piece in the housing and press the orange plastic pivot into it to secure the lever arm.  Screw the rods in by hand and turn the motor to rest on the front of its housing and re-install the back plate, the washer, the ring clip, and the cap, securing it with two philips screws.  Now tighten the rods with a 7-mm socket and a rachet.  To reinstall the solenoid, hook its plunger into the lever arm and slide solenoid housing onto the plunger, remembering to put the spring under the plunger (or your starter motor may not disengage from the flywheel!).  Re-install 3 bolts to secure solenoid housing to starter motor housing.  Installation of the starter back into your car is the reverse of the removal procedure outlined above.

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