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Make: Maruti Suzuki

Model: 800 hatchback

Engine: F8B MPFI

Battery: Exide 35AH 2.5 year old Rated OCV 12.92

Location: Nagpur, India. Daytime Temp about 44C

Background: Around November/December 2017 minutes after after encountering a sudden level change at speed the engine cut out. This was diagnosed to be a stripped timing belt; the original having lasted close to 70000Km.The clutch has also been replaced as per inspection and replacement schedule. Occasionally upon starting, the engine would suddenly race, and shudder violently at random but never reproducible at the workshop. Similarly there was an occasional instance of what felt like a misfiring plug in both cold and hot start; also not reproducible.

The problem: The evening before last the vehicle served a short run; a few Km. Yesterday morning on a cold start the starter turned but the engine cranked very slowly thud thud and died. Subsequently the starter whined but the crank did not turn. It sounded like ... https://vocaroo.com/i/s1SiqOpBShQ5#

With the battery showing 12.86V I put it to charge around 8H by which time it had come up to 12.9. Upon the third attempt the engine fired. Putting the multimeter against the battery with the engine running showed the voltage at 13.62V. However occasionally this would fall all the way to 3V, and then recover.

Driving the car to the workshop where the Bosch starting system tester was applied showed all good. In one instance when the alternator was tagged bad, racing the engine had the alternator reported good on all subsequent tests. The master mechanic even pulled the battery ground without killing the engine albeit the engine did balk a little when the terminal was reconnected.

The master mechanic recommended a wait-and-watch policy; which I am not comfortable with. His take on the recording was that it sounded like a timing issue.

My questions: What can I do to reproduce this problem? The occasional drop in the voltage has me leaning in favour of a faulty regulator, or alternator assembly being the cause; how can I confirm this with only a basic digital multimeter at hand?

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    For future reference, I wouldn't call someone a "master mechanic" who pulls the negative lead to the battery while the car is running. It's a very good way to fry your alternator. The battery acts as a buffer to the charging system, which helps prevents power spikes to the alternator. Taking the negative lead off can cause a power spike which can fry the electronics in the alternator. You could use this method in the past to check power output, but is no longer a good idea. I would not go back to this "mechanic" in the future if I were you.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    May 15, 2018 at 12:22
  • Point taken. Also, potentially quibbling, but the alternator output is already going all over the place ... Albeit 'nicely'
    – Everyone
    May 16, 2018 at 11:48

1 Answer 1

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This sounds like a poor or loose connection or a broken cable somewhere.

You need to check, inspect and test each cable and connection between the battery and the alternator - including all the ground cables / connections. When testing the cables you need to pull or stretch them to check they are physically ok.

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  • Then I need to get hold of the wiring diagram?
    – Everyone
    May 15, 2018 at 9:06
  • Not necessarily - I would just follow the cables ...
    – Solar Mike
    May 15, 2018 at 9:27

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