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.
Reviewed other posts and the âengine does not crankâ checklist. Battery checked and topped up, no problems there. No change to battery voltage when trying to crank.
On visual inspection I donât see anything immediately wrong. There is an exposed spade connection below with nothing connected, but donât 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 â although one time I got more than that, and it seemed to try to crank â something seemed to almost engage. But next time, whirr/click. See video.
But from what youâve 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.
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 "energyâ from getting to the starter motor.
Plus. How healthy is the battery ??? Age, load test, etcâŠ
After hearing the sound Iâm not so sure the starter is actually spinning as I previously mentioned. I think itâs humming as it tries to spin.
Carl is right. Clean the cables, including the heavy cable at the starter itself, and the â+â post on the firewall. The starter is being âtriggeredâ by the relay but may not be getting enough voltage to actually spin and engage.
Ok thanks. Will do that and report back. Just surprised that one second itâs cranking, then suddenly itâs not. But I guess thatâs how it goes sometimes.
use a multimeter to test the battery after it has sat for 24hrsâŠit must read over 12.4V
you could also perform a âvoltage drop testâ across all the main cables, this will identify any wiring fault, bad terminals etcâŠyou will need to Google âvoltage drop test on starter systemâ
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 donât 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.
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 doesnât turn over indicate that the starter motor turns free and the driven gear doesnât 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 doesnât 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, Iâm afraid, the starter motor will have to come out, either for replacement or for being overhauled.
Agreed; Dougâs initial diagnosis in fact but the sound bite didnât seem to match.
As mentioned, if the voltage at the starter terminal only drops 0.1 V that indicates that the starter isnât loaded. Voltage drop at the battery doesnât necessarily mean anythingâcould 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. Thatâs odd. IMHO.
No, I made the mistake in reading your clear post. But 0.6 volts isnât much either. Iâm pretty sure the starter motor isnât mechanically loaded for some reason.
I watched one of my âYou Tubeâ guys mess with a starter on a junk yard Chevrolet six. The Delco starterâs architecture is very similar to the Lucas seen here.
But, the solenoid housing was busted.
So, Johnathan did a âwork aroundâ. Applied volts to the post on the starter motor, not rthe solenoidâs post. Motor whirred, used arm to engage the drive. Engine turned⊠After some efforts, the old âstove boltâ 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. SolvedâŠ
Thansk all. Ok so here is the updated report following voltage drop test.
Across battery terminals. 12.23 volts dropping to 11.7 on crank.
Negative battery terminal to solenoid case. 0v , dropping 0.02v on crank
Positive battery to positive solenoid. 12.2v dropping to 0.8v on crank [thatâs what I wrote down, but it sounds wrong for the starting point voltage, should be zero, no?]
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?