Starter motor issue

Dear all,

So I changed my thermostat (see previous post if interested). When I came to start it up as part of the coolant refill operation, the engine turned but did not start. With hindsight this was not really surprising as (1) there was some light rain while I was working, and (2) some drips from the thermostat on to the distributor area. So probably classic damp problem caused the initial failure to start.

However before long it stopped cranking and I just got a sort of whirr and click. At that point my wife was getting tetchy so I had to leave it for a bit. A week later, the plugs and distributor appear dry. Same issue.

https://photos.google.com/photo/AF1QipMkeGfV3reNb3y_AKSKViNQOw7L09neKbJ1eGG8

Reviewed other posts and the “engine does not crank” checklist. Battery checked and topped up, no problems there. No change to battery voltage when trying to crank.

On visual inspection I don’t see anything immediately wrong. There is an exposed spade connection below with nothing connected, but don’t think that is anything new. You can see this in the middle of the picture, protruding to the left under the cable. https://photos.google.com/photo/AF1QipMPDERph6hxSNPKZvW64M5D7NiT_awOSKSv1k0B

Now, bypassing the starter relay and applying 12V, I got the whirr/click, same as with the ignition – although one time I got more than that, and it seemed to try to crank – something seemed to almost engage. But next time, whirr/click. See video.

https://photos.google.com/photo/AF1QipPRTm5Ub2Qq0CuqH6oHuza5D3WqrPbP0olA9xPb

I tried giving the starter motor a tap with a hammer (not very hard though), no change.

So before I go any further (which probably means getting it towed to the garage), appreciate any other thoughts.

Best regards

Nick Hill
XJC Series 2 4.2 (Canadian spec)
Paris

I can’t open any of the links

But from what you’ve written it seems that the starter motor is spinning but the drive gear is not engaging the flywheel. In that case that starter would have to come out for repair or replacement.

Cheers
DD

Thanks . Sorry, these links should work.

Google Photos


Clean the battery cables. Two up top and the ground down under. Each end of all three.

Don’t ask how I know!!!

Carl

Ok - but if when bypassing the relay, I get the same result, why would cleaning the terminals make a difference?

OK, so you asked anyway!!!

Because the starter is a large electric DC motor. it has a large task to perform, turning a good sized IC engine fast enough to start. that takes lots amps and all the voltage the 12 v battery can provide. Any dirty cable end can prevent that "energy’ from getting to the starter motor.

Plus. How healthy is the battery ??? Age, load test, etc…

Carl

After hearing the sound I’m not so sure the starter is actually spinning as I previously mentioned. I think it’s humming as it tries to spin.

Carl is right. Clean the cables, including the heavy cable at the starter itself, and the “+” post on the firewall. The starter is being ‘triggered’ by the relay but may not be getting enough voltage to actually spin and engage.

Cheers
DD

1 Like

Ok thanks. Will do that and report back. Just surprised that one second it’s cranking, then suddenly it’s not. But I guess that’s how it goes sometimes.

And in the mean time have the battery on charge.

there is a few things you should try first.

use a multimeter to test the battery after it has sat for 24hrs…it must read over 12.4V

you could also perform a “voltage drop test” across all the main cables, this will identify any wiring fault, bad terminals etc…you will need to Google “voltage drop test on starter system”

Cleaned battery terminals, earth terminal on the side wall, and the two voltage distribution terminals on the firewall.

I get 12.4v at the battery, falling to 11.8v or so on cranking. I was getting 12.3v after that.

No change in the symptoms so far, although I get fractionally more movement the first time I connect the solenoid directly to the positive battery terminal, bypassing the relay, it tries to turn a little more. After that, just whirr and click, as with the ignition key. But unable to do the full voltage drop test so far as don’t have the right multimeter here. Also hard to reach the right points on the starter solenoid from above, seeing as I have adult hands. Might have a crack at that tomorrow.

Nick,

from what you describe now it seems that

  • your starter relay engages every time you turn the key
  • your starter motor engages every time you turn the key
  • your voltage drops only from 12.4 to 12.3V once the starter starts.

The latter and the fact that the engine doesn’t turn over indicate that the starter motor turns free and the driven gear doesn’t engage to the gear wheel on the engine.

This sounds like a straightforward starter malfunction. The gear wheel on the starter should move freely on the shaft and be driven into the gear wheel of the engine by centrifugal forces upon operation of the starter. Once the engine turns faster than the starter the engagement will be opened and with the starter motor no longer spinning the starter motor gear wheel return to its original location. In your case the starter spins, but the gear wheel doesn’t engage.
Possibly some new grease on the shaft fixes the problem. Maybe the starter motor gear wheel set is worn out - as a consequence of the materials used it should be before the gear ring of the engine is, the latter being a worst case scenario.

But for the current scenario, I’m afraid, the starter motor will have to come out, either for replacement or for being overhauled.

Good luck

Jochen

75 XJ6L 4.2 auto (UK spec)

Thanks. To be clear, voltage across the battery drops to 11.8v or so when starter is engaged.

Agreed; Doug’s initial diagnosis in fact but the sound bite didn’t seem to match.

As mentioned, if the voltage at the starter terminal only drops 0.1 V that indicates that the starter isn’t loaded. Voltage drop at the battery doesn’t necessarily mean anything–could be a high resistance path to the starter. BUT, in fact, even with the starter unloaded, or even with the solenoid only, I would expect more than a 0.1 V decrease when trying to start. That’s odd. IMHO.

No, sorry I was not clear previously, voltage across battery drops circa 0.6v when starter engaged. From 12.4v to 11.8v.

Time for the starter to come out, if it’s been in service for years then you might find the armature has dropped onto the field windings.

No, I made the mistake in reading your clear post. But 0.6 volts isn’t much either. I’m pretty sure the starter motor isn’t mechanically loaded for some reason.

I watched one of my “You Tube” guys mess with a starter on a junk yard Chevrolet six. The Delco starter’s architecture is very similar to the Lucas seen here.
But, the solenoid housing was busted.

So, Johnathan did a “work around”. Applied volts to the post on the starter motor, not rthe solenoid’s post. Motor whirred, used arm to engage the drive. Engine turned… After some efforts, the old “stove bolt” purred.

Decades ago, our 71 Hornet had starter issues. Different architecture. Bendix drive. Whirr, but no crank.

A mechanical issue . Pinion teeth ground away !! Not hard to swap in a fix. . Fixes short lived… Quit buying cheaper after market pinions. Got the real thing. Solved…

Carl. .

Thansk all. Ok so here is the updated report following voltage drop test.

  1. Across battery terminals. 12.23 volts dropping to 11.7 on crank.
  2. Negative battery terminal to solenoid case. 0v , dropping 0.02v on crank
  3. Positive battery to positive solenoid. 12.2v dropping to 0.8v on crank [that’s what I wrote down, but it sounds wrong for the starting point voltage, should be zero, no?]
  4. Positive battery to positive starter. 0.02v on crank.

Now, I had topped up the battery a few days ago, when I was giving me 12.4v. But is it possible, given the above readings, that my battery has simply given up?

Thanks!

Nick

Can you just try a new battery? Or use cables to a second battery, that should help. I think that’s the easiest :slightly_smiling_face: