520 coil roast

[htopjimmy26 3]

Hi guys, I know it's been a while but I've been out hunting horses and found a good one if I can fix it. I found a 1996 520h at the kinda local dealer that the owner didn't wanna fix with a 48inch deck you could eat off of and 400hrs. The problem is that the coil is melted on the -neg side where the module? hooks to it. I did some snooping and this just doesn't add up, the white plug where the engine harness mates with the tractor harness has 1 crispy pin where a white wire turns red and goes to the batt side of the voltage regulator, but still has continuity??? The rest of the connections look good and the fuse box ain't super nasty. Did it over charge and cook the coil through the ingition module? The regulator doesn't look all melted or discolored. I haven't pulled the flywheel off yet to see what the module looks like but would appreciate the voice of experience. I'm a little scared of just putting a coil on and watching 85$ melt before my eyes :C. Thanks, Dana

[htopjimmy26 3]

Just tested the batt and thats good hasn't anyone had a similar experience?

[Save Old Iron 1,563]

Dana, I have not yet had this same experience with my 520, but i'll throw in a few comments that may help you along.

"Krispy connector"

This is caused by long term effect of corrosion within the connectors causing a resistance to the current flow from the stator into the battery. High current x increased resistance x time = heat and a burned, crispy connector shell. I have seen this many times on tractors, computers and even on some costly medical equipment I have serviced in the past.

Usually replacing the metal connectors within the shell is the only long term solution. If the shell has deteriorated, the entire shell may also need replacement,

Burned Coil

check out the diagram below showing the ONAN engine wiring,

Notice there is nothing within the wiring ( other than the fuse) to limit the amount of power being drawn by the coil and ignition control module. If the coil is melted, either the coil itself is shorted internally or a defective ignition module is causing the coil to conduct current when it should not. Both these conditions will overheat the coil.

I hear you on your concerns over the the $$ aspect of Onan repair. The parts can be pricey and "guessing" can get expensive very quickly.

Given your situation and your concerns, here is how I would proceed,

1. Repair the +12v connection on the krispy connector.See if the tractor at least starts and runs. If the tractor starts, quickly check the B+ voltage from the rectifier to the battery. If it is significantly over 14 - 15 volts, shut down the engine and correct the issue - most likely its a bad regulator assembly or regulator ground connection.

If the engine does not start ....

2. Check the coil assembly and ignition module per Onan service manual procedures.

Replace any parts necessary.

3, Always check for wiring issues. Pinched wires, bared wires missing insulation, burned or "krispy" wires, poor previous repairs, etc.

Some of the issues you have can already be attributed to corrosion on electrical connectors, so carefully inspect ALL the electrical connections which support the ignition circuitry in your tractor. If one is bad - suspect ALL connectors and wiring junctions.

I believe the 520 has a decal in the battery area warning not to run the tractor without the battery in place.

And don't underestimate the damage a previous owner could have cause by trying to jump starting a dead battery,

I have seen one occasion where someone hooked up a small arc welder to jump start his tractor. Guess that's why he called me on my day off to help him get his tractor fixed.

I would have yelled at him - but I use his welder on occasion!!!!

Best of luck

[htopjimmy26 3]

Thanks for the reply Chuck, I have done some more snooping/diagnostics and hooked up the battery with a new used coil and no sparky. I guess the ignition module just sends a 12v burst to the coil every rotation, so I checked that and no 12v I did have some minor volts but not 12[thats on the -neg side of the coil] so I pulled a zillion screws out and managed to pull the front cover far enough out to see a big hole burnt in the module so I got me a used one of them sans hole I just have to figure out how much more stuffs gotta come off before I can get the flywheel out. :thumbs2:

[Save Old Iron 1,563]

Dana,

I believe the output of the ignition module is only 1.5 volts - not 12 volts.

Also, the low oil pressure switch could be causing no +12 to the ignition circuit unless you have the +12 jumped directly to the coil.

Did you repair the Crispy connection yet in the engine harness ?

That "not so bad" fuse holder may not be doing you any favors either.

Probably best to take all the engine skins off and make sure the rear cylinder fins are not obstructed.

If you need a service manual - send me your email address. I can help you out on that .

Chuck

[htopjimmy26 3]

It runs! I got the flywheel off this afternoon and found the ignition module all blown up like an alien busted out. Chuck, thanks for the offer I just found my service manual I bought for my 416 I kinda forgot about. I got it running and checked the batt voltage at full tilt and got about 13volts at the cables, I cleaned up the bad terminal a little but it could probably used a repair, some strands are damaged. Is it possible to buy the terminals and remove them from the connector repair and replace? Also the gauges work intermittently and no lights so I have a little more tshooting to do. The P.O. was definatley not a tractor guy or a maintenance guy either. There is no grease on anything, the air filter was a disgrace, tranny had 1mm of oil on the dipstick and he had the deck hitch rod for the mid hitch on backwards . I guess I'll take another look at that fuse block and see if and of the fuses have power. Thanks again for the help Chuck. , Dana

[Save Old Iron 1,563]

Your welcome Dana,

as far as the connector repair - yes - the shell and male / female connectors can be replaced.

The problem with older (molex says old is over 5 years or 25 insertions !!) is the terminals no longer fit snugly together.

A TEMPORARY fix may be to squeeze the female terminal together to decrease the diameter. Sliding a small jeweler's screwdriver between the shell and the female terminal will distort the connector enough to provide better contact. Again, a temporary measure more to confirm the terminal IS THE PROBLEM rather than to CURE THE PROBLEM.

Given the environment this connector is in ( high vibration, heat, dirt, moisture and even battery acid fumes) its probably better to remove the connector entirely - now I will count to 10 to allow all the purists out there to stop screaming.

Clip the wires. strip, solder and heatshrink each wire and problems will be eliminated. Given that you perform all your own repairs, future component replacements which are attached to the connector should pose no significant issues for you.

If you choose to replace the connector and terminals, here is a great website describing the material and tools you will need and the techniques you will use to replace the terminals.

http://www.marvin3m.com/connect/index.htm

As payment for my help - send me your 2 stage blower. I'll consider us even.

:thumbs2:

[Save Old Iron 1,563]

P.S.

If its possible, I would love to see pictures of the meltdown - coil and trigger module.

[htopjimmy26 3]

Well, Wifey cleaned out the fridge after I threw the module in the trash, I looked for it but I ain't goin in after it. I do still have the coil and will try to link a pic later. I guess you were right about the fuse block, the fuses all tested good but 1 showed signs of melting a little and had oxidized so I said time for all new and Voila all gauges work and I now have head and taillights. I am still up in the air about the burnt pin in the harness, I may just chop it out and wire it direct but for right now everything works! I shouldn't brag but I now have a 1996 520h with 400hrs on it with a pristine 48in deck for a total of 720$ invested Thanks again, Dana

[htopjimmy26 3]

Chuck, I gotta tell ya that the 2 stage is probably more of a lawn ornament than an actual snow blower. It takes all a 16hp tactor has got to run and is sooooo heavy that without loaded tires, 2 link chains, 100lbs a wheel in weights, and maybe another 150or 200lbs in suitcase weights on the back, plus equally large operator most tractors will go nowhere. This blower I think was really designed for the 520 specifically as my 416 will barely power it, ohh and the chute plugs ALL the time. I have entertained the Idea of possibly modding it to fit on one of the C195s and using a box blade as a counter weight but I think I would need wheel weights for a 15in wheel, Got any of them? P.S. I would also accept any extra C195 rear PTO kits you may have kicking around :thumbs2:

[Save Old Iron 1,563]

Glad it all worked out with a minimum of guessing and money down the drain on expensive parts.

Regarding the 2 stage blower , You probably get the same soggy snow we get down here in the Albany area.

Since this will be my first year using Wheel horses to do any "winter work", I'll see how things work out.

Right now I'm trying to get the time to at one of the three tractors I bought this year to run ..... because next year the Wheel horse tiller attachment I bought will be given a good workout.

If I can get the c160 or the C81 running before the snow flies, the 37" single stage blower I bought this year will also be given its time to shine !!!

If not, its plow time.

p.s. how much did the ignition module cost ?? Have you located a good source for Onan engine parts?

[htopjimmy26 3]

Chuck I get wet snow, dry snow, drifting snow, mealy snow and pellet snow and lots of it, ever heard of the Tug hill plateau? That's where I'm at. If I were you I'ld take the single stage blower and hook it to your highest HP hydro tracor and you'll love it. All the stuff I have and I snow blowed with my C160 and single stage, worked great. What do you have for tractors? I see you don't have them in your sig. I bought used reluctor[stator], pickup[module], coil and voltage regulator off a JD 420 on Fleabay for 68+ship . For new stuff this place doesn't look badOnan parts.

[Save Old Iron 1,563]

Dana, I am soooooo familiar with the Tug plateau. I spent nearly 30 years as a field engineer for several health-care companies repairing medical equipment. I used to travel the whole north country circuit - Lowville, Govenour, Massena, Ogdensburgh, Canton Potsdam - to all the hospitals in the area. Those long 2A.M. trips home in 12" snowfalls still fresh on unplowed route 11, 12 and 30, those bring back memories.

As far as my equipment, I picked up a backblade for my JD850 off craigslist a few months back. While picking up the backblade, the owner said "need anything else?"

Well, there was a pristine WheelHorse tiller sitting in his garage - "How much?"

$150 he said and I went home with more than I came for.

Now I need to buy my first Wheel Horse tractor !!

A week later another craiglist ad netted me a c160 hydro, c81 8 speed with 42 rear and side discharge mowers and a spare Kolher 12hp engine for $200. All are supposed to have "governor" issues with unstable idles - haven't pieced them back together yet to see what is what. Originally I did not want both tractors but now see that would have been foolish to pass up that deal.

Well now I guess I could use one to till and the other during the winter if I had plow blade and chains (thus the madness begins).

A week later,another craigslist ad said a blade, chains and wheel weights were available locally from a 520h.- $200 bucks - so I went to the address and the owner said no, you don't understand - that's $200 for the weights, blade, chains AND THE 1988 520 tractor!! Seems he just wanted to get out of home ownership. Where he was going was too small for the 520.

Left there quick and in a hurry - with the 520.

So now I have to piece all these tractors back together in hopes of using one tractor this winter and the other to till the garden in the spring.

That kind of brings me up to date.

But I do so miss the 2 A.M. trips home in the snow . NOT !

Catch you later and good luck with the 520.