Engine driven Lincoln poopin' out!

[Flinty]

I've got an old Lincoln welder with an Onan 16hp twin, circa 1972. When I rev the engine the ignition cuts out. Purrs like a kitten at idle. Ignition cut-out has been verified by a timing light. Points ignition. Carb freshly rebuilt. Any ideas, you guys? I'm stumped!

 

[TBurow]

need some more info, does it have an external 12v coil or is it powered by magnets on the flywheel? if it is a 12v coil does it have power when the ign is cutting out? have you checked to see if the coil is arcing internally, takes alot less power to idle. replace the condenser, a third of points problems are caused by a bad condenser.

 

[Flinty]

Sorry, we were walking out the door and I wanted to get on the forum. The system is a ext. 12v coil and it is new(the coil). The power supply to the coil is constant and unwavering as I checked it with my volt meter and reved the engine. How do I check the condenser or is it cheap enough to just replace? How do I check if the coil is arcing internally? I have run it with the points cover off and you can watch the ignition malfunction, i. e. when the points close a small spark is generated, as I increase the rpm the sparks don't keep up, they are intermittent and the engine coughs and sputters. When the throttle blade is returned to idle it picks right up again. Thanks

 

[GHarman]

How about a low oil shut off switch? Have one on my P220-G Onan engine driven Miller welder. Went out within the first 10 hours of operation! Greg

 

[Flinty]

I'll have to check that. It does have a switch but it powers the hrs meter, maybe I missed a wire that ties it into the ignition. I'll bypass it and see what happens. We have a generator that will lope erratically when the low oil switch engages. Thanks for the input!

 

[Hoefler]

Sounds like a condenser. If it acts up after it runs a while, i would suspect the coil as well.

 

[B.G. Smith]

I believe these engines have a pushrod that runs on the cam or crank and operates the points, make sure it is not sticking in the bore ro worn out. bg

 

[Flinty]

Well, I took the points out and lubed the little shaft that actuates the points, then I replaced the condenser. It worked! This machine now runs and welds just fine. Once again, my TDR membership has paid for itself. Thanks for the quick responses. Jon.

 

[DValentine]

I have a Lincoln with an Onan I think is from the mid 60's. I have a book on the engine if you have anymore questions. Cummins truck shops carry Onan parts.

Dave

 

[tgordon]

Onan is/was one of the owners of Onan. Other sources for parts, your local JD, MF, IH dealer as they all along with others used them in their lawn tractors. Glad to hear you got it running, if the engine ever needs anything internal be ready to repower/replace the engine as major parts are NLA or priced at vverrrry high:{ But until then they are one great engine.

 

[fest3er]

... I have run it with the points cover off and you can watch the ignition malfunction, i. e. when the points close a small spark is generated, as I increase the rpm the sparks don't keep up, they are intermittent and the engine coughs and sputters. When the throttle blade is returned to idle it picks right up again. Thanks

Hmmm. Even though you've fixed the problem, a little more info never hurts; I figure if you know *how* something works, it'll be easier to determine *why* it doesn't work properly when it malfunctions. I hope this isn't TMI, though.



If I recall correctly, breaker-points-based ignition systems spark when the point contact is broken. I believe it is done this way so that the coil is at full voltage when spark is demanded, thus producing a strong spark at the outset that 'fades out' as the voltage drops. A second spark is created when the points make contact again, but this one is weaker, and it 'fades in' as the coil voltage rises. Breaking the points at maximum voltage ensures consistent spark timing across the RPM range.



The coil is a transformer. And like all transformers, the primary (spark) circuit only does something when the secondary (points) circuit is changing. One, that's why it doesn't spark after the points have been closed: the change stops. Two, that's why transformers don't work on DC voltage: when the input doesn't change, there's no output.



The condensor (capacitor) stores a certain amount of energy; when the points again make contact, the condensor supplies a lot of current momentarily so that the coil is rapidly brought up to maximum again; but it isn't as good as breaking the contact at maximum voltage. The little wire that feeds the points can't supply enough voltage and current to do the job by itself; the condensor is an 'able assistant'. If the condensor is weak (not quite shorted out), it sinks too much voltage/current to ground, thus starving the coil.



N

 

[Flinty]

Makes sense to me, this welder was a 'gift' from a friend. Given to me because of my mechanical abilities. This thing was an electrical train wreck when I got my hands on it. The ignition switch was left on frying the coil, a quick trip to Harley-Davidson got me into a new coil for $35. Hrs. meter was shorted out, oil switch was wired wrong. It wouldn't charge the batteries. Parts had been lost for the points set-up, thereby grounding the points to the chassis. (I had to fabricate the replacements) The carb and gas tank were full of varnish. It's been like peeling an onion. $200 and lots of 'spare' time later and no working welder. My wife's patience was wearing thin along with my mad money. So you can imagine my frustration by the time I finally had this thing running but not functioning. By the time a fella gets engrossed in a project he kinda gets sick of staring at the stupid thing. Starting from square one and getting another unbiased point of view from you guys jarred me out of the rut I was in. BTW I always thought the condenser was actually a capacitor, thanks for clearing that up. And thanks to everyone that paid attention to my rinky-dink problem. Jon

 

[Philip]

If this is one of the 200/225 amp boxes. That is a 12 HP Onan. I put many hours on one of the same year model.



If I would have found this post earlyer I would have told you about the push rod. Been there before. LOL

 

[Dieselnut59]

I would relplace the points with a Pertronix "Ignitor" system. I have done this on MANY old distributers. You can take a worn out distributer, install the "Ignitor" in place of the points and it will run like a charm. Nice thing about them is it goes right in where the points were, eliminates the condensor, is moisture proof and has no "air gap" setting. It is a "Hall effect" system, with a magnet that slips down ver the lobes where the points ran and a "pick-up" that mounts where the points mounted. Trash the ground wire from the points to the coil and hook the wires from the ignitor unit to the coil. It is a simple, neat and very reliable installation. I have done hundreds of these on forklifts, old trucks, generators, construction equipment, etc. These units make a world of difference in how well an engine runs. They make a "cold natured" engine less "cold natured", fire plugs that otherwise foul out (rich or oil burning situations) and fire down to lower rpm's.

Their website is www.pertronix.com

You will need the model number of your distributer. We sell their products if you are interested. PM me if you decide to order one.