Starter Gremlins

[Monty-4]

Hi,

I'm having some issues with the electrics, I'm re-wiring engine & accessories up after rebuilding the engine and respraying the engine bay. Rather frustrated I can't get the thing going after all that effort!

1. Wired everything up one evening, starter turned over fine, had spark, fuel and oil pressure but didn't run.
2. Figured out the timing was quite far out (~40 degrees).
3. Came back the next evening, moved the timing, starter wouldn't turn over.
4. Tried jump start pack and new battery.
5. Tried shorting Solenoid.
6. Took starter out, tested across the battery, worked.
7. Added second engine earth strap - from mechanical fuel pump blanking plate to engine tower.
8. Scraped some paint off behind where the solenoid mounts. Starter turned over once.
9. Cleaned up all the contacts I could find.
10. Entered state of complete despair.

The starter cable gets super-hot and tries to melt it's insulation where it meets the start motor if I hold the ignition on for any time.

[oliver90owner]

If a decent starter motor power cable is getting hot all the way along it there is clearly a very arge current flowing.

Timing shpould have nothing to do with the starter motor operation like that.

Is the engine hydraulically locked?

Solenoid passes current through the internals, from one terminal to another. There needs to be no contact with the bodywork for the high power current.

Starter is clearly taking a lot of current, mthe terminal has a poor connection or is shorting to earth.

Check spark plugs for a pot full of water.

Another possibility is the bendix is jammed in mesh, but you should have heard this when trying the starter motor, after replacement in the car.

[Monty-4]

Thanks for the response

I can spin the engine fast enough by hand (with spark plugs out) to hit over 50 psi oil pressure and still turn it over by hand with plugs in. That is to say I'm pretty sure it's not hydraulically locked, plus the little nub on the end of the starter turns easy enough by hand.

Could it be the starter brushes, or perhaps the physical earth between the starter motor body and bell housing isn't good enough?

[mogbob]

Earth straps first of all.
There should be two "original " straps fitted, excluding the battery earth ( more latter !)

One on the engine , straddling the engine mount tower i.e linking the engine block to the bodywork under a tower fixing bolt to the bodywork. The electricity jumps the rubber block through the strap. Clean metalwork , paint scraped away , around the bolt hole. Protect with copper ease.
Second on the gearbox ( quiet frequently absent if a clutch swop has been done by an inexperienced mechanic ) Part No WRC107.t'other end goes under a bolt fixing for the cross member / gearbox support bar. Again clean metal required.
Your "third strap" won't do any harm provided you've fitted the engine Tower end to a bolt that is body side of the rubber mount.
Battery earth .. the main one ... clean metal , tight bolt fitting.
All earth straps should not be frayed and pay particular attention that the clamp are " effectively " clamping. Some clamps appear to be working ok but in reality aren't " biting " firming. You sometimes, with new parts , have to file a bit off the 2 flat meeting surfaces , so that the nut and bolt can be tightened up. A multi meter drop test , before you proceed , might confirm and explain the cables getting hot.

Starter motor. I note you tested it off the car. Was the Bendix gear free to spin back freely , if you ran it down the shaft by hand.
Did you examine the electrical connections to the brushes and was there plenty of meat left on them ?
Starter fixing in bell housing , clean metal question again ? Hope you weren't over enthusiastic with painting the exterior of the engine block, gearbox ,etc.
All the lucar connectors on the ignition switch are " firm " and clean ?
A few bits to double check. Good luck with the hunt.
Bob

[oliver90owner]

Steady as we go! If it were earth straps causing the problem, I doubt it would be the feed cable getting hot - more likely the earth connections would be a high resistance problem, and so more likey to generate unwanted heat.

It would be far better to employ a voltmeter to search out where the voltage drops are occurring. It should only be across the motor and not across any connections.

Shorting across the solenoid terminals is usually sufficient to demonstrate the problem is likely in the starter motor, connections, or starter/earthing cables. The ignition switch connectios are immareial for this test/situation.

[Monty-4]

I get sparks when shorting the solenoid posts with a cable off-cut but no life from the starter motor. I've never seen an earth strap linking the block to the engine mounting tower before, perhaps my previous engine was missing it? Either way I've recreated it with my additional one.

Will have a look at the earth on the mating face of the starter motor, the gearbox earth strap and the perhaps remove the starter motor itself again to inspect the brushes if that get's me nowhere tonight. What really puzzles and frustrates me is it worked one night, and not the next!

I also noted the sidelights and indicators aren't working (headlights are) yesterday evening. I imagine this points towards a separate problem with a sidelight earth or the little inline fuse ('68 car)?

Edit: Quick sanity check - https://imgur.com/a/R2m2D. Additional two red wires feed an electric washer pump and power additional gauges. Additional blues go to electric water temp sender and a tach.

[Monty-4]

Gearbox to cross-member earth is indeed suspect. Will report back after replacement.

https://imgur.com/a/7uJwD

[Monty-4]

No change. Every contact and ground involved in the starter motor is clean and I also removed the starter and took some fine wet & dry to the brushes. Every cable in the circuit gets hot, all the way to the battery. It must be jamming or too tired to turn the engine over?

Any other ideas before I go and buy a replacement?

[oliver90owner]

Can't remember the last time I replaced an inertia starter motor. Usually bearings, brushes or bendix. It is easy to find if it is jammed in mesh. Rock the car in gear and watch and listen. It will throw the bendix out and jam or turn the starter until it frees itself.

You don't have the car in gear with the brakes on tight, do you? Even so, you should hear it try to operate at the first time of engagement.

[Monty-4]

I did double check today but given I can turn the engine by hand I think I would have noticed, I'm not that strong!

I spent some time trying to sort out the timing, check the carbs and start the engine on the crank handle today. I don't seem to have a reliable spark and also suspect the newfangled 'electronic' dizzy might be acting up.

At my wits end!

[SteveClem]

My solution on such occasions is to take the car down to my local classic friendly back street garage. They sort it out,quite cheaply,and tell me what the problem was. Then I know how to do it myself next time. Or,if I forget, I take it down to my local...etc etc.

[Monty-4]

Is the engine hydraulically locked?

Some more fiddling later, I think this might have been the case.

The carbs were flooding so I took those off, readjusted the floats, and removed the spark plugs to let any fuel evaporate. A day and a bit later and the starter turns the engine over fine but I just got backfiring through the carb. Rotated the dizzy about 90 degrees clockwise and the engine started! Unfortunately I then ran out of adjustment to get it at it's smoothest so I immediately shut it off and moved the leads back around a step. Now it won't turn over again! Plugs out again and battery on to charge, fingers crossed for tomorrow night.

[oliver90owner]

I was thinking of a pot full of water, not fuel.

If you have liquid fuel in the cylinders, that is very dangerous if the plugs are removed and the engine turned over - potentially catastrophic if there are any sparks or open flames nearby.

I have read of anecdotal reports of someone burning to death in the US - but that was apparently a gravity feed fuel tank. He operated the starter motor with the spark plug removed, dousing himself in fuel which was ignited by a spark or other ignitionn source.

[Monty-4]

Cripes! That was not a great deal of fuel, so little that I'm still not entirely sure of our hydrostatic hypothesis, but nothing else really changed between the attempts. Rest assured I'm rather cautious when it comes to disconnecting the battery and ventilating the area when there is a smell of fuel though. It's so well ventilated I can't work on it for more than 30 minutes at a time now as it's getting cold and dark so early (Scotland!).

[Monty-4]

Well well. Engine is up and running now. Starter appears to have stopped jamming for some unknown reason.