Yanmar Start button

[alibaba 84]

Common problem I believe. Intermittent start on button push on Yanmar 3GM.

I've traced wiring and I already see a solenoid fitted. I by-passed the start button with a temporary switch and got starting first time every time, therefore likely the push button has corroded contacts.

To replace it is  around $110, but it is only an intermittent switch. Jaycar sell them for about 22 bucks.

I can't find the characteristics of the switch though, so does anyone know how much current goes through such a switch?

cheers

[CarpeDiem 527]

1 hour ago, alibaba said:

Common problem I believe. Intermittent start on button push on Yanmar 3GM.

I've traced wiring and I already see a solenoid fitted. I by-passed the start button with a temporary switch and got starting first time every time, therefore likely the push button has corroded contacts.

To replace it is  around $110, but it is only an intermittent switch. Jaycar sell them for about 22 bucks.

I can't find the characteristics of the switch though, so does anyone know how much current goes through such a switch?

cheers

Solenoid energizing coils don't take an enormous amount, I suggest looking at the model of solenoid and working backwards from there.

These are rated at 50A there's no way it be that.  I have one of these mounted in the engine bay to start a 29hp Volvo if the magic black box ever fails.

[marinheiro 364]

On 24/03/2021 at 2:17 PM, alibaba said:

Common problem I believe. Intermittent start on button push on Yanmar 3GM.

I've traced wiring and I already see a solenoid fitted. I by-passed the start button with a temporary switch and got starting first time every time, therefore likely the push button has corroded contacts.

To replace it is  around $110, but it is only an intermittent switch. Jaycar sell them for about 22 bucks.

I can't find the characteristics of the switch though, so does anyone know how much current goes through such a switch?

cheers

it will only be in the order of 5-10 amps

[aardvarkash10 1,103]

yup - mh is onto it.  Remote solenoids that are essentially just a big relay run at about 10A tops, probably half that or less, but depends on the solenoid in use.  The current is for a very short time and at a low voltage so its actually not too critical what the switch is within reason

A solenoid fitted to the starter is a different fish - it may pull 30 to 50A initially, dropping to about 5 - 10A once the pinion is engaged.

 

[alibaba 84]

Thanks folks- Repco had the deal, intermittent switch rated at 50a at 12v.

Hopefully problem solved.

[wild violet 38]

Mine did that just wiggled the plug by the motor and it would go.

[eruptn 105]

On 26/03/2021 at 1:29 PM, alibaba said:

Thanks folks- Repco had the deal, intermittent switch rated at 50a at 12v.

Hopefully problem solved.

What are the details, part number. Thanks

 

[alibaba 84]

The one I used in the end is part number 60099BL, it's a Narva brand, Repco have several different ones, and you should be able to find one which fits your cutout on the panel.

cheers

[alibaba 84]

aaah- intermittent start now getting worse. I've replaced both the start button and the relay.

I guess I now remove the starter motor for servicing? But before I do, has anyone got any other ideas?

cheers

[Psyche 794]

Have you shorted the relay to see if it starts every time? Might be a fault in the wiring to the relay/start button.

[ballystick 79]

The best way to check is to use a voltmeter and test the voltage from the source right through the circuit including the earth side while you are trying to operate the starter, if you have a wiring diagram it makes it easier. Think of it as a water supply trying to flow through a hose with restrictions. There are 2 parts of the circuit, the wiring to the solenoid on the starter and the main high current side, I think you are having problems with the solenoid side and someone may have added a relay to the circuit to fix a problem but it is not clear in your description. There is a lot on Youtube to help, see image showing some testing but there's more to it in the circuit

[chariot 244]

Had a similar thing years ago on a 25hp Isuzu instillation on our Cav 32. Was voltage drop from the battery. Previous owner said it had always done it. Change to heavier cable and never happened again.

[eruptn 105]

Had similar, the issue was a sticking bush in the starter motor. Best $50 spent, it starts so well now. Service the starter.

[wheels 544]

Yes these start swtiches eventually fail. Not Yanmars fault. It is common for most all. The trick is to find a switch with a good current rating. Not because it needs it. But the higher the current rating, usually the heavier the switch contacts.
The problem is caused when any coils magnetic field collapses. So every time you release the start switch. A very short duration, high energy back current (back EMF is the technical term) is created. The larger the collapsing coil, the greater that energy. This jumps the contacts of a switch and causes the contact to slowly erode away over time. The spark across the terminals can be reduced with the use of a capacitor across the switch terminals. But it is not commonl done.
$110 dollars I would be thinking ouch. That seems a bit steep. It's just an momentary ON/OFF switch.
https://www.repco.co.nz/en/globes-batteries-electrical/electrical-accessories/switches/narva-push-button-starter-switch-on-off-momentary-spst-red-led-contacts-rated-50a-12v-60099bl/p/A1209997

[alibaba 84]

Thanks wheels and ballystick and others- all of that makes sense.

With a bit more investigation, I note that the wire from the switch is heavy gauge white, and it disappears into the wiring harness. That makes sense because of the  heavy current it has to carry. It  then disappears into the wiring harness and emerges at the other end going to a little relay [ which I have renewed] attached to the bulkhead in the engine bay. Because the input wire into the relay from the switch is no longer heavy gauge white and is much lighter gauge red, I'm assuming that it was fitted as a after market device. so... a] there must be a junction somewhere in the harness joining heavy gauge white to lighter red, and that may be corroded and b] The wire from the relay to the solenoid is also fairly light gauge. which seems silly, since it too must carry a reasonably heavy current.

I'll test the voltage supply throughout the system as ballystick suggests with a view to putting heavier gauge wiring throughout to give the solenoid a real chance of receiving what it should. That should eliminate any wiring problems. If the problem then persists, it suggests the solenoid or starter motor itself.

Wheels, do I really need the relay if I fit heavier gauge wire directly from the switch to the solenoid? - using a heavy current rated switch as you suggest.

[ballystick 79]

The important wire is from the battery source to relay contact terminal (#30) and there from (#87) to the starter solenoid pull-in terminal. It can be a completely separate wire run beside the loom and should be a short as possible from a good fused source. The switch current wire to #85 can be quite small as the current is small. This used to be a quick way to fix automatic cars not starting when the gear selector unit developed high resistance and were expensive to replace.

[alibaba 84]

I've looked up relay connections and  half of them state that  the start switch goes to terminal 86, and terminal 85 goes to earth,  the other pair 30 goes to battery +, and 87 goes to the solenoid. The other half state these terminal pairs  are the opposite, ie 87 to battery and 30 to solenoid.Does that mean the the terminal pairs connections are interchangable? Ie 87 and 30 can be wired either way?

[CarpeDiem 527]

1 hour ago, alibaba said:

I've looked up relay connections and  half of them state that  the start switch goes to terminal 86, and terminal 85 goes to earth,  the other pair 30 goes to battery +, and 87 goes to the solenoid. The other half state these terminal pairs  are the opposite, ie 87 to battery and 30 to solenoid.Does that mean the the terminal pairs connections are interchangable? Ie 87 and 30 can be wired either way?

Unless the relay is diode protected it doesn't matter.

85 and 86, when given power, close the relay (turn it on). The negative can be on 85 or 86, and the switch that activates the relay can be on the positive or negative side of the circuit.  (A fuse should be on the positive side). 

Likewise the polarity of 30 and 87 don't matter. Generally, however, the load goes to 87 and the supply goes to 30.  Then with double poled relays the wiring is consistent and does matter, being supply on 30, loads on 87 and 87a. 

[alibaba 84]

Thanks for all the advice. I may  have found the problem. I traced the switch wire from the solenoid back to the ignition switch. The wire leaving the relay was of quite sufficient size I thought, but then I found at the back of the engine, someone had spliced a 3m length of thin red wire all the way to the ignition switch. Spliced again to thick wire at the switch but couldn't be seen behind the panel!

Replaced the whole length with decent tinned marine heavy duty wire. Can't make the fault reappear now. starts every time. I do know, from the previous owner, that the relay was fitted by a "marine electrician".

Ah well, at least it saves me removing the starter motor etc for refurbishment.

Thanks again