24v Starter PITA

[Knucklehead]

Hi all,

Now starting to understand why folk changed over to 12v starter systems.

Hoping somebody on here can give me some more things to try for my 80 that is not cranking before I have to admit defeat and get it recovered to a garage for the first time.

Turn the key and get the loud clack clack clack from the starter. No sign of engine turning.

So far I've had fresh batteries load tested just in case, fitted new starter motor, tested Starter Relay and 12/24v voltage relay as per FSM, took Starter Relay apart just in case but looks like new inside, checked all connections are clean and tight. Still nowt.

I did notice however when turning the key the voltmeter inside goes from its normal just over half way at rest to near zero when I crank the key. Fairly sure it barely dropped when starting before this all happened.

I had wondered if I could take the 2 batteries out of the vehicle, connect them together using jump leads giving 24v, use third battery to apply 12v to the small Starter spade terminal 50 and then touch the 24v directly to the Starter terminal 30 that the battery cable normally attaches to?

Not being too great with electrical stuff not sure if it's a good idea to try and directly crank the starter motor this way or maybe i'll electrocute my ass.

Any thoughts how to further trouble shoot would be much appreciated. Hate not being to fix stuff myself.

Cheers,
Dave.

 

[Towpack]

I've had the clack clack clack or, machine gun sound as some call it, when one or both of the batteries have been low but if yours are good it sounds like a bad connection somewhere limiting current which amounts to the same thing really. What voltage are you getting at the main starter terminal? You should have 12v with everything off and 24v when cranking. I'd be very cautious regarding the test with two batteries off the vehicle. Obviously what you DON'T want is 24v going into the 12v wiring loom. I would disconnect both the 12v wire at the starter solenoid AND the main power lead to the starter itself. With the batteries linked, connect - to earth at or near the starter and the 24v + to the main starter terminal. Then take another + feed from the first battery (at 12v) and touch the 12v spade terminal on the solenoid and the engine should crank but will not start. If it doesn't it means either the solenoid or starter itself are at fault.

 

[Chris]

Also get a jump lead, connect it to one of the engine lifting points at one end and somewhere sound on the body / chassis at the other. The only earth to the starter is via the engine earth strap.

 

[Knucklehead]

Cheers fellas. Unfortunately currently working on this single handed so cant check 24v at starter terminal when being switched on but definitely getting 12v at rest. Also getting correct voltage at the voltage converter terminals for both batteries looking at the FSM.

Think I will try the direct 24v using your suggestions and at least see if the new starter turns the engine.

 

[Knucklehead]

ok chris you are a star. Thought would go for easiest option so connected a jump lead from the lift hook to my bull bar and bang off she went.

Sooo this tells me somewhere in that engine bay is a bad earth? Maybe I just drive it with the jump lead attached!

 

[Grimbo]

Common thing when people are looking at electrical problems is to forget the earth side of the circuit draws as many amps as the + side .....
Also voltage is just that .....a potential voltage.....it could show 24 volts as I suspect yours would have done but not be able to draw any amps ......amps is what allows the circuit to do any "work" so to speak ...... if you had of been able to get a tester on it and watch as you tried to crank the 24v would have dropped off as it rattled and failed to start .

 

[Knucklehead]

Unfortunately the lecky side is not my strong point. I can see one earth strap running down from the number one battery and attached to the engine block. Doesn't look too easy got at to clean up if it is that earthing point. Thinking there are a number of earths could be at fault and might just be easier to add another one somewhere.

 

[Chris]

Yes that's the earth strap. I actually ran an additional earth on mine for good measure. Glad to hear it fired up.

 

[StarCruiser]

Battery connections can also be cracked or otherwise poorly mated. Worth checking. Not easy on your own but sparks from a connection under load during start attempts will often give notice of where the problem lies.

 

[StarCruiser]

Make sure any earth strap goes from the engine to the battery not to the body. The body to battery connection is much smaller than the battery to engine earth. Re making the factory one is favourite. Additional earths if taken elsewhere can route current through low current wiring if an earth strap breaks unless the additional one follows the exact same path as the original. Toyota did what they did for good reason.

 

[Knucklehead]

Cheers.

I had previously checked all the connections for the batteries and the various relays and they seem sound.

So if I understand correctly my options are to replace the original battery to block earth strap as this is likely the problem or run a same size strap from number 1 battery neg terminal to the engine block?

The end of the original strap is buried deep in the block and looks a bugger to get at the securing bolt so thinking leave the original in place and run another one.

Is there another good place on the 1hdt engine to attach a new strap to?

 

[frank rabbets]

The idea is to get to as close to the starter as possible with the earth strap. I have 2 x on my 1995 80, both standard.

 

[Chris]

Just to point out that my additional earth strap is as big if not bigger than factory and does indeed go to the battery.

IIRC the block earth is not buried deep in the engine. It goes past there and terminates very low down where it can be reached very easily.

 

[Knucklehead]

Think might take it to an auto electrician for extra straps as likely i'll make things worse!

Just had a look again and the earth connection on my no. 1 battery has a thin wire to the inner panel and then the thicker cable runs down and terminates against the engine block side just above the front engine rubber mount and under the exhaust manifold. Wouldn't fancy trying to swap it out.

Cheers.

 

[StarCruiser]

A 12v conversion might, depending on size of starter (I believe they are lower power, something like 2.7 Kw rather than 4.5Kw, correct me if I’m wrong) require an uprated set of cables. Chris, I never had any doubt.

Essentially anywhere on the block will be sufficient. There is so much metal to conduct the current, it far exceeds the cable for conductivity. Just consider heat and vibration, so route well away from hot bits, support well and make the terminations well by crimping (cue debate on soldering versus crimping) and supporting by covering where they meet the cable with thick heat-shrink. A good size bolt of at least 8mm is best and make sure the surface where it connects is machined flat and brightly cleaned before fixing with a bolt and washer. If you can lay your hands on a dished type spring washer, also called a medium contact washer or Belleville washer, and use that, so much the better. Why? Because it takes up the minute movements due to the dissimilar metals expanding and contracting and will keep tension on the joint.

 

[StarCruiser]

It’s probably worth tracing the cable and inspecting it. Sometimes salt can rot a cable from inside. Usually this gives a bump in the insulation. Yours may simply have come undone or fractured the connecting terminal. It may be possible to put a new terminal on.

The skinny wire to the body is the one I was referring to earlier

 

[Knucklehead]

Thought should upload pic of the earth cable Im looking at to make sure. The other end of the thicker cable is what I mentioned terminates directly to the block below the manifold. Very hard to check what state the cable is actually in as real awkward to get at.

Sounds like having more than one extra earth cable does no harm so could have one from the starter motor securing lower bolt (seen an old cruiser starter motor diagram that had a strap directly to the starter bolt) and then one from battery neg. to the block.

Probably easy enough to find a spot on the block to terminate a cable, maybe the bolts holding the lift eye on, but where would I attach it to the OEM negative cable connection and what gauge of cable?

Maybe could run it past the battery and attach to the existing inner panel connection though would be a lot thicker than the current cable in that spot.

Advice appreciated as usual.

 

[StarCruiser]

Needs to go to the battery connection. If it’s to the body you are then using that skinny cable in the circuit. Not ideal. If for any rare reason you needed to crank for more than the usual 1 second, that cable would get very warm/hot. You either need to replace the battery terminal with a bolt type (bit of a shame as the original looks good) and crimp a ring terminal to the skinny cable and make up a cable to the block at least the same section as that which you are replacing. Or, cut the existing cable to the block and crimp splice a fresh bit on with a ring terminal on the end, to go to your chosen bolt. Heat shrink the crimp splice (butt crimp) with thick heatshrink. Adhesive lined is best.

 

[Jake the Peg]

It’s also worthwhile going round the earth cables and cleaning up all the connections, it may save you some other faults developing

 

[Knucklehead]

Many thanks for pointers. Think it’s worth a go. What’s the worst can happen