Help Lawn Tractor PTO/clutch Issues

[Muddy42]

I have been trying to run my 1990s Bolens ride on lawn tractor.  It has a Briggs and Stratton 16 HP Vanguard V twin engine.  The engine has PTO/clutch below it that is electrically driven - flick a switch on the dash and the PTO should engage underneath the engine.  Then the PTO would drive the cutting deck via a belt.  However, as you'll see in the video below, when I engage the switch the engine just dies. The machine itself drives backwards and forwards fine.  Please note, the cutting deck is totally removed for safety.

 

I have tried disconnecting the wires to the PTO and I get the same result, which makes me think the issue is electrical rather than something mechanical in the PTO itself.  I have bypassed various safety switches (seat etc.) but I think either there is another safety cut-off or the switch on the dash is faulty.

 

Annoyingly there arn't any markings for the PTO switch on the dash to help me.

 

Is it OK to test the PTO by wiring it directly to the battery?  Any if this works can I just fit its own switch and circuit?

 

Thanks,

 

[Muddy42]

Ive ordered a multimeter to see whats going on behind the pto switch.

[Husqvarna King]

I think these type of electronic mower clutches have air gaps that can be set with a feeler gauge. Remember similar with my old scag flail. Good luck I hate electrical faults 😦

[Mick Jones]

This sounds like it could be a safety switch/ circuit issue as you suspect. Not familiar with the Bolens set up to be honest but if you put 12 volt to the pulley clutch you should hear it "click" and pulley should not spin on the crank.

Can't see it doing any damage if the clutch is disconnected from the rest of the wiring and engine isn't running obviously.

 

[Muddy42]

 

58 minutes ago, Mick Jones said:

This sounds like it could be a safety switch/ circuit issue as you suspect. Not familiar with the Bolens set up to be honest but if you put 12 volt to the pulley clutch you should hear it "click" and pulley should not spin on the crank.

Can't see it doing any damage if the clutch is disconnected from the rest of the wiring and engine isn't running obviously.

 

 

Thanks yes, I'll give that a go.  I see a few hours ahead of me with the multi-meter and some replacement wire and switches!

 

11 hours ago, Husqvarna King said:

I think these type of electronic mower clutches have air gaps that can be set with a feeler gauge. Remember similar with my old scag flail. Good luck I hate electrical faults 😦

 

I don't think its the clutch itself, but I'll give everything a clean up and check just in case.  The whole clutch looks removable.  I had a lose oil filter last summer, so everything is covered in oil down there. Thanks

[Muddy42]

OK so wee update to this.

 

Using my multimeter and lots of continuity checking, I worked out that one of the safety cut-offs was interfering with the operation of the PTO circuit, so I've stripped the wiring right back to basics - no dash lights, no sensors, no headlights.  Now its basically the same as the attached Briggs & Stratton wiring diagram (but plus the two belt controls - drive and PTO).

 

However now the engine was having starting problems and was hard to turn over.  I wondered if the PTO might be siezed or causing extra engine load, as a related issue.  I loosened off the PTO completely and cleaning it out with a pressure washer, then dried, then WD40. The PTO was showing an electrical resistance of 3 ohms, which internet says is fine and it clicked on and off when hotwired. After this the PTO seems to turn freely, so I concluded that wasn't the issue.

 

So I turned to the V-twin engine.  It was still hard to turn over.  I could start it when jumping it from the car, but not from the 12v battery (which is a new mower battery by the way).  But I guess the car provides 48 amps rather than 32??

 

I don't have a feeler gauge, but the engine's valves didn't seem too tight.  When rotating the engine, I couldn't see/hear the operation of a compression release.  So I'm a bit stumped really.  Could it be a weak starter motor or some major issue with the camshaft and compression release?

 

Im just going to leave this post here and see if anyone has any bright ideas, while I do some more reading.  The engine is a Briggs and Stratton 16HP V-Twin model number 303777.

 

 

 

Edited Tuesday at 07:47 by Muddy42

[GarethM]

A car battery is 12v, so a duff battery on the mower that's sat for months without a balance charger sounds like it was the reason if your car started it.

 

And no a starter motor doesn't boost the battery voltage, 12v=12v just lots and lots of pixies.

 

From memory my tractor takes 3.4kw 12v so like 300A which is CCS (Cold Cranking Amps), also why cold weather beats the hell out of batteries.

[Muddy42]

14 minutes ago, GarethM said:

A car battery is 12v, so a duff battery on the mower that's sat for months without a balance charger sounds like it was the reason if your car started it.

 

And no a starter motor doesn't boost the battery voltage, 12v=12v just lots and lots of pixies.

 

From memory my tractor takes 3.4kw 12v so like 300A which is CCS (Cold Cranking Amps), also why cold weather beats the hell out of batteries.

 

Thanks Gareth.  Sorry I may have muddled things.

 

The battery on the mower is brand new - 12v and 310 CCA.  It turns the engine a bit with difficulty but doesn't start it. I was replacing a battery that was 10 years old and 12v and 300 CCA.  Actually the old battery doesn't seem perform much worse than the new one - I trickle charge the batteries a few times over the winter. 

 

No idea what CCA the car battery will have, but many more.  The car battery did jump the engine though.  I've checked and brightened up all the electrical connections.  Maybe I'll take apart and clean the starter motor aswell.

Edited Tuesday at 08:30 by Muddy42

[GarethM]

1 minute ago, Muddy42 said:

 

Thanks Gareth.  Sorry I may have muddled things.

 

The battery on the mower is brand new - 12v and 310 CCA. I was replacing one that was 10 years old and 12v and 300 CCA.  Actually the old battery doesn't seem perform much worse than the new one - I trickle charge the batteries a few times over the winter. 

 

No idea what CCA the car battery will have, but many more.  The car battery did jump the engine though.  I've checked and brightened up the connections.  Maybe I'll take apart and clean the starter motor aswell.

It's a lawn mower, not a 4 litre Perkins!.

But when it's cold disconnect the negative connection to stop battery drain.

 

The other simple parts is the solenoid, they do fail as they are a DC contactor that arc's every time it's cycled so wear out by burning away the metal contacts.

 

They are cheap to replace but to test, short the terminals and if it fires up you know what it is.

 

Plus redo the clutch, with brake cleaner. WD-40 will just attract dust and become a cutting compound and gum things up.

[Muddy42]

9 minutes ago, GarethM said:

It's a lawn mower, not a 4 litre Perkins!.

But when it's cold disconnect the negative connection to stop battery drain.

 

The other simple parts is the solenoid, they do fail as they are a DC contactor that arc's every time it's cycled so wear out by burning away the metal contacts.

 

They are cheap to replace but to test, short the terminals and if it fires up you know what it is.

 

Plus redo the clutch, with brake cleaner. WD-40 will just attract dust and become a cutting compound and gum things up.

 

Thanks. I will do clean the clutch if I get the engine running smoothly.

 

I replaced the solanoid two years ago.  Yes, I've shorted the two solanoid terminals and I get the same result.

 

When you say "not a 4 litre Perkins!", are you saying that 310 CCA, should be more than enough?

 

 

Edited Tuesday at 08:43 by Muddy42