Intermittent Starter Motor Pausing Issue - Alfa Romeo Bulletin Board & Forums
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post #1 of 16 (permalink) Old 05-26-2016, 06:31 AM Thread Starter
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Intermittent Starter Motor Pausing Issue

My 1974 Spider (with SPICA) has been having an intermittent "pause" in the starter motor turnover while starting the car. If I were to show the sound it's something like. hmm-hmm-hmm-pause-hmm-hmm-pause-pause-hmm-hmm-hmm and eventually it starts.

So, it always starts turning over but I hear pauses in the cycling. Sometimes, it just starts right up with no pauses and turns over fine.

The big clue is that if it's doing the pause thing, if I put my foot on the gas pedal, it pauses more. Somehow, the accelerator is linked to the pauses and makes it worse.

The battery is at 12.5V and I can start the car with headlights on. I cleaned the battery terminals, neg cable to ground mount, pos cable to alternator thoroughly. I cleaned the switch wire to starter motor.

I removed the starter motor and dissembled it. I removed the brushes and lightly sanded the commutator which looked fine. The brushes looked fine and had plenty of meat left. I lightly lubed the motor bearings. Using a spare 12V battery, I bench tested just the solenoid and it was fine. I bench tested the motor and it was rock solid turning quickly with no pausing. I sanded the starter motor back and the metal gasket and the engine where the starter mounts to ensure a good ground. I reinstalled the starter motor.

The issue still persists.

To add some more info, I know I have an extra rich setting on the SPICA and need to tune it. I see black soot on the exhaust pipe and black smoke when it's cold out.
The compression leak-down test is not great at: 105 100 125 130. That's a future project.

Any ideas before I buy a new starter motor?
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post #2 of 16 (permalink) Old 05-26-2016, 08:10 AM
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Poor contacts in ignition switch? Uneven compression? Poor ground?
It's really hard to tell on the bench, with no load, how the starter will be when installed. They spin great when they're just turning themselves. I've been fooled more than once.
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post #3 of 16 (permalink) Old 05-26-2016, 08:48 AM
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My suggestions:

1. Disconnect the Spica Cold Start Solenoid wire and tape it out of the way. Attempt to see if that solves the problem.

2. Use a jumper cable between the engine block and negative battery cable. If the pausing disappears, it's likely that your engine ground strap is not making a good connection. Check that the battery ground cable is clean and tight to the chassis connection.

3. Rig a test light to the ignition switch side of the starter solenoid. If the light flashes off when the pausing occurs, it's likely that the ignition switch is the culprit.

4. Rig a test light on the cable from the starter solenoid to the motor itself to see if the current break is internal to the starter solenoid.

5. The big copper contactor bar in behind the plastic cover on the solenoid gets burned and can cause intermittent conditions.

The gas pedal has no interface with the starter unless the linkage is rubbing against wires.

John Stewart
74 Spider
91 164S

Last edited by Roadtrip; 05-26-2016 at 09:00 AM.
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post #4 of 16 (permalink) Old 05-26-2016, 09:05 AM
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Also check ignition timing. Perhaps if it is too far advanced it might be trying to fire early on occasion? It is even possible that one lobe on the distributor rotor is opening the points a few degrees earlier than the other lobes (so even if it is timed correctly on #1 another cylinder could be firing early). Yee Old Fashioned distributor machine can test for that.

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post #5 of 16 (permalink) Old 05-26-2016, 09:15 AM
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Quote:
Originally Posted by Roadtrip View Post
The gas pedal has no interface with the starter unless the linkage is rubbing against wires.
On a spica car, the throttle linkage is a long way from the starter and its associated wiring. But if the starter is OK and the state of engine tune is the issue, then yes, the throttle position could effect how the engine cranks.

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'67 Duetto
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post #6 of 16 (permalink) Old 05-26-2016, 09:27 AM
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True. Unless previous owners have done some "creative wiring." That's why I try not to assume that everything is factory stock when diagnosing these old cars.

John Stewart
74 Spider
91 164S
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post #7 of 16 (permalink) Old 05-26-2016, 09:37 AM Thread Starter
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Thank you all for your replies. I did install the Centerline ID405 Electronic Distributor last month. It's possible that this behavior is coincident with that change.

I timed it with a timing strobe gun and got it running pretty well. It was definitely better out on the road.

Could this intermittently be affecting the starting if it was timed slightly off? I could try retarding the timing slightly but that may affect road performance.

And yes, a previous owner did modify the car by putting in "racing" cams. Not sure if this is an issue. I think the starting wiring is OK.
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post #8 of 16 (permalink) Old 05-26-2016, 09:41 AM
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I had a similar issue with a "rebuilt" Bosch starter on an older BMW. Every time I took it out to bench test, it worked fine. I put it back in and it was intermittent. I finally took it out to bench test and gave it many cycles. I noticed sparking under one of the bolt heads that holds the back cover on. It sandwiches a current path under the cover and was not clean enough or tight enough to make a good current joint. I drilled and tapped the hole to the next size larger thread, cleaned the contact surfaces well, and put it together with NoLox and snugged the new bolts really tight, problem solved.



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post #9 of 16 (permalink) Old 05-27-2016, 11:43 AM
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Pull your spark plugs so there's no compression at all. Crank it and see if the problem persists.

Put your plugs back in, but pull the center wire from the diz. Crank it...

That will narrow it down.

Steve Bock
'77 Spider with SPICA
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post #10 of 16 (permalink) Old 01-02-2018, 08:46 AM
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Where you all ever able to resolve this issue? I just bought a 1978 spider and it has the exact same issue. I'll follow all the tips and hints given to help diagnose, but I'm curious if you ever resolved this.
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post #11 of 16 (permalink) Old 01-02-2018, 09:56 AM Thread Starter
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@shadowdd6 Congrats on your 78 Spider purchase!
I live in Massachusetts and my Alfa is in deep sleep mode now but as I recall, it still does the pause intermittently. It usually happens if I am cranking for a long time now...when I have fouled plugs.
It doesn't affect the drivability of the car so I chalk it up to Alfa charm at this point.

Some things I would recommend if you haven't done these already:
- Add the electronic distributor
- Add some Marvel Mystery Oil to gas and oil once a year.
- Do a basic tune of your SPICA if you have one in this car. There is a guide available on this site.
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post #12 of 16 (permalink) Old 01-02-2018, 10:49 AM
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In post #4, RoadTrip mentions the copper shorting bar inside the solenoid. If you can access this, try reversing it on the shaft so there is at least a fresh set of contacts on the bar. I did this years ago, and the cranking speed increased quite a bit.

Maybe your problem is intermittent contact with the shorting bar.


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George Schweikle

1976 Spider (Dedicated Autocrosser, "SPICA, No Carbs")
1991 Spider Veloce (Retirement cruiser)
Scuderia Non Originale
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post #13 of 16 (permalink) Old 01-02-2018, 12:10 PM
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Quote:
Originally Posted by ihart View Post
Could this intermittently be affecting the starting if it was timed slightly off?
When the timing is off - particularly when it is too far advanced - it will slow the cranking speed, but not intermittently. So my guess is that timing isn't the issue.

I like the theories about worn "shorting bars" in the solenoid. Don't like the theories about something in the ignition/start switch unless you hear the solenoid clicking when the starter does the intermittent thing.

Jay Mackro
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'65 Guilia Sprint GT
'67 Duetto
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post #14 of 16 (permalink) Old 01-02-2018, 02:08 PM
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I know that some of the Bosch solenoids can be taken apart and the contacts can be refinished. The other problem could be worn out armature bushings.
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post #15 of 16 (permalink) Old 01-02-2018, 03:59 PM
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Thanks everyone for the fast responses! I'll definitely follow all these leads. I'm only 7 days into my first Alfa purchase, and first project car so all these things are new to me. I look forward to exploring though!
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