Yep, i have had problems with a couple of those in my time - your one was in good shape compared to the mess i have found in one or two of them. You can use a meter to diagnose the issue, just measure the voltage drop from one side of the switch to the other whilst under heavy load - cranking for instance. In the past i have measured a 7v drop across those switches. 7 from 12 does not leave much for starting your engine! But your so right, adding bypass cables, extra relays and solenoids to a circuit that used to work is obviously not the way to fix the fault - the engine used to start ok with the original circuit, so obviously all that is needed is to fix that fault, do the job properly and there is no need to add anything.
Thank you, I have this exact engine and never knew about the fuse. I've had a starting problem for 15 years and even rebuilt the starter once. My Yanmar mechanic said this fuse is never a problem. Mine had a ton of corrosion and now the starter works perfect. I love your "old school" knowledge
Thank you, Replacing this switch fixed my non starting issues . one time the engine would start . next time you try to start it Nothing not even a click. I checked through a lot of wires cleaned terminals . nothing. I replaced the isolator switch after finding this advice . and bingo . now we are good to start every time . I have a Yanmar 2YM15 engine.
2:21 That fused connection only applies power to the B+ terminal. Power directly from the battery does not run through that wire (obviously) it's supplied 100% via the cable run directly from the positive terminal on your battery to the positive terminal on the starter solenoid. Only thing that matters with that fused connection is that it engages the solenoid on the starter. The solenoid is a relay. That is what engages the Batt+ connection.
You've got to remember that the starter pulls 100 amps and the glow plugs 60 amps (on a 4 cylinder engine). At that, you will lose 1.6 volts of battery voltage for every 0.01ohms of contact resistance- that's not a lot; that corrosion will have much higher resistance than that even if a normal multimeter won't show it. A low ohm meter that can measure milliohms is a good investment for anyone who does this kind of work regularly. It will tell you how good your earthing points and cable joints are too!
I prefer to measure under load, the analog meter I bought when I was 14 is a lot easier to use for this than the digital meters, especially the older or cheaper ones that update slowly.
Good video - I learnt to my cost years ago that 'continuity' is fine for low current but means nothing when you are dealing with lots of amps - a hair thick single strand of copper will give you 0 Ohms on the meter but try passing serious Amps
Hi, Me too, I have found those cheap isolators to be absolutely hopeless. Completely useless especially in a marine environment. I did not know about that fuse though so thanks for that. I have found on a few occasions that when these engines crank but do not start, it is caused by a lack of compression, either stuck piston rings or those exhaust valves.
I have the 3 cylinder Yanmar. It’ll start every time but sometimes requires repeated pushes of the starter button, that gives a “click” each time. Do you know what that might be?
While your point is taken, I respectfully disagree. This component should prove defective with a "voltage drop" across it (under cranking load of course). Ohm meter is useless for this type heavy contact / heavy gauge circuit. As you correctly pointed out, even a few ohms under heavy current draw will result in a significant voltage drop. As you well know. No disrespect intended. I love your videos and feel a bit sheepish disagreeing with you.
I applied the same checks for my Tohatsu 8hp Outboard with Electric Start and Remote gear and throttle Replaced old cut off switcht Replaced Corroded Key/Start Switch Remote (tohatsu make) key was rusted and bent !!) Lubricated spindle with Duck Oil where starter dog spins and moves up to engage flywheel.. All works fine now seemed expensive 50 quid for Tohatsue key and starter switch but it is high quality msinly ruined by by me not lubing and bent rusty key !! So lesson learnt regular lube/maintenance in future saves lost trips and 50 quid...
Yep, i have had problems with a couple of those in my time - your one was in good shape compared to the mess i have found in one or two of them. You can use a meter to diagnose the issue, just measure the voltage drop from one side of the switch to the other whilst under heavy load - cranking for instance. In the past i have measured a 7v drop across those switches. 7 from 12 does not leave much for starting your engine! But your so right, adding bypass cables, extra relays and solenoids to a circuit that used to work is obviously not the way to fix the fault - the engine used to start ok with the original circuit, so obviously all that is needed is to fix that fault, do the job properly and there is no need to add anything.
Thank you, I have this exact engine and never knew about the fuse. I've had a starting problem for 15 years and even rebuilt the starter once. My Yanmar mechanic said this fuse is never a problem. Mine had a ton of corrosion and now the starter works perfect. I love your "old school" knowledge
Thank you, Replacing this switch fixed my non starting issues . one time the engine would start . next time you try to start it Nothing not even a click. I checked through a lot of wires cleaned terminals . nothing. I replaced the isolator switch after finding this advice . and bingo . now we are good to start every time . I have a Yanmar 2YM15 engine.
well done glad it helped
Hi not a motor guy but nice to stop in learn a tip or two, always learning new things to us, thank you for the share, Lance & Patrick.
2:21 That fused connection only applies power to the B+ terminal. Power directly from the battery does not run through that wire (obviously) it's supplied 100% via the cable run directly from the positive terminal on your battery to the positive terminal on the starter solenoid.
Only thing that matters with that fused connection is that it engages the solenoid on the starter. The solenoid is a relay. That is what engages the Batt+ connection.
You've got to remember that the starter pulls 100 amps and the glow plugs 60 amps (on a 4 cylinder engine). At that, you will lose 1.6 volts of battery voltage for every 0.01ohms of contact resistance- that's not a lot; that corrosion will have much higher resistance than that even if a normal multimeter won't show it. A low ohm meter that can measure milliohms is a good investment for anyone who does this kind of work regularly. It will tell you how good your earthing points and cable joints are too!
I prefer to measure under load, the analog meter I bought when I was 14 is a lot easier to use for this than the digital meters, especially the older or cheaper ones that update slowly.
Good video - I learnt to my cost years ago that 'continuity' is fine for low current but means nothing when you are dealing with lots of amps - a hair thick single strand of copper will give you 0 Ohms on the meter but try passing serious Amps
Every day see them day in day out and he’s right but in some cases the windings are braking down in the starter motor and causing a lazy starter
Hi, Me too, I have found those cheap isolators to be absolutely hopeless. Completely useless especially in a marine environment. I did not know about that fuse though so thanks for that. I have found on a few occasions that when these engines crank but do not start, it is caused by a lack of compression, either stuck piston rings or those exhaust valves.
Another good one POC! Thanks for sharing your experience!
Always beneficial to watch your videos. Common sense engineering.
I have the 3 cylinder Yanmar. It’ll start every time but sometimes requires repeated pushes of the starter button, that gives a “click” each time. Do you know what that might be?
Watch the video from start to end . I went to a lot of effort to make it !
While your point is taken, I respectfully disagree. This component should prove defective with a "voltage drop" across it (under cranking load of course). Ohm meter is useless for this type heavy contact / heavy gauge circuit. As you correctly pointed out, even a few ohms under heavy current draw will result in a significant voltage drop. As you well know. No disrespect intended. I love your videos and feel a bit sheepish disagreeing with you.
5 year old post, and still spot on!!
thank you
some people are just plane thick
I applied the same checks for my Tohatsu 8hp Outboard with Electric Start and Remote gear and throttle
Replaced old cut off switcht
Replaced Corroded Key/Start Switch Remote (tohatsu make) key was rusted and bent !!)
Lubricated spindle with Duck Oil where starter dog spins and moves up to engage flywheel..
All works fine now seemed expensive 50 quid for Tohatsue key and starter switch but it is high quality msinly ruined by by me not lubing and bent rusty key !!
So lesson learnt regular lube/maintenance in future saves lost trips and 50 quid...