Starter relay failures

[busheytrader]

Anyone had issues lately with starter motor relays?

At just over 40 years old the original one failed. At about 9 months and not many miles the replacement from one of the electrical specialists failed.

Bad luck maybe?

Adam

[Beans]

So far I never fitted a new relay to one of my cars in over 30 years.
I had one starter relay failure some years ago, but that was 30+ years old when it failed.
I replaced it with a second hand original Lucas starter relay (in my case easy as I have a few spares)

[saabfast]

My car had a failed start relay when I bought it (in 2006), started it by means of a screwdriver across the solenoid and starter connections! I replaced it with one from Robsport and it has been fine since. Take care, there have been several reports recently of ones supplied by Rimmers being incorrect and not working.

[Beans]

Since my starter relay failure I always carry a short wire in the car with two spade connectors.
Very handy to short circuit the start circuit in case the relay fails (and the spare refuses service)

[busheytrader]

I changed the starter relay for a new one but no joy. I've checked the ignition switch in its various position with a multimeter - all ok. I'm working my way through the loom tomorrow if the garage hasn't turned in to an oven.

The headlight lift relays both click noticeably when activated. Should the blue starter relay do the same or is it silent? There's no solenoid noise covering it at the moment.

[saabfast]

Make sure he relay has EXACTLY the same diagram, there are subtle differences with the incorrectly supplied ones. One thing I did when waiting for a new relay was remove the cap and pinch the contacts to start the car (it will dangle below the glovebox when released). If you do that with the old one and it works it is possibly a fault in the circuit from the ignition lock, if it does not it might be time to get the meter out and go around the circuit.

[busheytrader]

The issue looks like it was the earth connection beside the fuse / relay box.

I recently replaced the Lucas ignition drum (the insides fell apart) and starter relay so checked them with a multi meter. No issues. Starter motor and it's solenoid worked fine off jump leads.

I unscrewed the earth connections to check, they looked clean but dull so brightened them up with some Scotchbrite anyway. Reassembled, turned the key, all works again. It must have had just enough resistance to disable the relay.

[FI Spyder]

I did have starter problems. Being new to the car and connections clean and seeming good, I replaced the starter with a gear reduction starter. That didn't solve the problem. I found that spraying the solenoid connection (by fuse block) fixed the problem (for a while), then it would fail in an increasing frequency. At one point I took the solenoid (by fuse block) apart and the contacts in the 35 year old, 100,000 mile (at that point) solenoid looked brand new, put it back together. Then I found that the 12V distribution clamp by the battery was loose and when I wiggled it the car would start. Problem kept getting worse. I thought I would remove the cable going from the battery to starter so the distribution clamp could be put in a vise and tightened. On doing that the battery clamp fell off the wire (itself being clamped to the wire). The lead clamp had expended so that even though the clamp was tight, it still couldn't make good contact with the wire. I folded half the strands back on itself (to make the wire thicker) and cut the others off and now the clamp could grip the wire tight. No problem starting after that after years of tracing down what seemed to be a moving cause of no start. The moral of the story is assume nothing and any connection in the starting circuit can cause a problem from solid to intermittent. And oh, it still is using that original starter solenoid (now 40 years and 120,000 miles old and held together with heat shrink).

[busheytrader]

Ok, the issue came back......the starter relay wasnt clicking

Long story short, the connector above the bell housing / below the fresh air plenum needed its contacts cleaning. I don’t think I’d cleaned it out for over 30 years since I converted the car to V8.

This part of the loom has the red white wire dedicated to the auto gearbox inhibitor switch. A manual car doesn’t have one, hence the looped red white wire bypassing the switch that isn’t fitted. Unfortunately this is the wire that powers the starter relay from the ignition key and runs through several connector blocks, including the dirty one under the fresh air plenum.

[dursleyman]

This is the villain described above

[Beans]

The wire strands from this loom have a tendency to oxidise inside their insulation.
That's because this loom is rather exposed to oil and engine blowing through the transmission tunnel.
So check visually (blackened copper strands) and with a multimeter (resistance).

[busheytrader]

Yes Russ, that’s the culprit.

40 plus years on from a loom accommodating both manual and automatic gearboxes, I can see why owners recreate the red/white wire bypass loop inside the cockpit. No problem with the reversing lights, switched through the same connector. I last cleaned out that connector when I converted to V8, more than 30 years ago.

The wiring on my DHC’s loom for the heated rear window, that was never there, came in useful for powering the V8’s fuel pump.