Ignition switch problem

[davesisk]

OK, so, the ignition switch on my old PT1418 started sticking in the start position a couple of months back. Recently, it finally stopped starting the tractor in the start position, so I've been using a screwdriver to short the two posts of the starter relay. Not something I'd like to continue doing, so I decided to replace the ignition switch.../w3tcompact/icons/grin.gif.

So, I call PT to order a switch, and they suggested that I just pick up a generic 5-pole ignition switch from any lawn equipment store. They said any brand should work. OK, did that.

I had offered to help a neighbor move 5 cubic yards of topsoil he had delivered Saturday, so I went out to replace that switch first. I switched them out and hooked the 5 wires to the same positions, and no dice. In fact, it blew the 20 amp fuse in the fusable link going from the switch to the remote pole on the starter relay. Doh! The switch apparently did NOT have the same internal connections as the old one.

So, a neighbor who's good with automobile engines came over to try and help me troubleshoot it. We discovered the fuse blown, and no fire going to the spark plugs. We replaced the fuse, and the new switch immediately blew it again. Assuming that the switch had the same internal connections but the pole positions were different we tested the new switch with a circuit tester, and cut the old switch open with a grinder. Based on this testing and prodding, it doesn't look like the new switch is wired the way the engine expects. When there's voltage on the starter pole, there's no voltage on the coil pole. So, we decided to try running a wire from the starter relay pole to the coil input. We tried that once, and I smelled burning wire and saw a little smoke come out of where we think the coil is. Curses! I've got what should be the right switch ordered from PT, but know I'm wondering if I've cooked the ignition coil. Since it's buried under the engine shroud, I'm expecting that it's going to be tough to get to. Perhaps I should just carry it down to a Brigg's and Stratton repair shop if it doesn't work after installing what is theoretically the correct ignition switch? What do you guys think?

Thx,
Dave

 

[Charlie_Iliff]

Dave:
It sounds as if the switch you got is for a system which uses a ballast resistor to hold down voltage to the coil primary when the engine is running. The coil pole is connected to a large ceramic resistor, then to the coil. For starting, those systems put the full available voltage to the coil while cranking, so they shut down the high-resistance ignition circuit and bypass it. My recollection is that this is usually by a wire from the starter solenoid which is hot when the solenoid pulls in, but cold when the starter is inactivated. (I'm not looking at a diagram or anyone's text, so I'm not confident that there aren't other ways to get the full 12 to the coil during starting.)
My recollection is that the main reason for the ballast resistor was to reduce points burn during normal running, but the full voltage is needed for starting, especially if the starter draws a lot and the battery isn't big.
All that being said, I don't have a real suggestion. I'd bet your Briggs is magneto, although I don't know for sure. If so, I don't think it uses any battery current at all. The wire from it is probably the kill wire, which the switch should ground to shut off.
As with other electric composents, if you let the smoke out, you may have to go to the friendly Briggs dealer to get components with a fresh supply of smoke.

 

[davesisk]

Hey Charlie:

Well that at least sounds encouraging (like in I probably didn't cook any wiring after all.../w3tcompact/icons/grin.gif). I guess I'll see when I get the new switch from PT...

Thx,
Dave

 

[Charlie_Iliff]

Dave: I'm not altogether sure I meant to be encouraging. Even though I think the wire coming from the mag is a ground wire, it is to the primary coil. One end of that coil is grounded. If you put 12 v to it, I suspect the coil got pretty hot. If enough smoke got out, it may now be shorted internally. B & S store will love you. Fortunately, B & S parts are amazingly cheap.

 

[davesisk]

Ah, I see. You're correct, B&S parts are very cheap. My biggest issue is that I have a feeling the coil is pretty darned hard to get to. I'm guessing that it's under the engine shroud, and the only way to get the engine shroud off is to take the engine out! Ouch! Keeping my fingers crossed over here...

Thx,
Dave

 

[davesisk]

I got the switch from PT, and installed it. This time, I made sure I had clear instructions and knew exactly how to hook it up.../w3tcompact/icons/smile.gif. The switch appears to be the correct one and work as intended.

Unfortunately, it's still hosed. Apparently, we did indeed damage something by mucking around with it. Most likely the magneto/ignition coil. I've got a B&S repair manual around here somewhere that I ordered, and I'm going to try to see how difficult this is to replace. Hopefully, it's pretty easy. But, I have a feeling it's not because it's hard to get to.

Dave

 

[davesisk]

Good news and bad news. I talked with a B&S mechanic today, and you have to take the engine shroud off to get to this magnetron. I'll have a look if it's still daylight when I get home, but I believe this does mean taking the engine out in this case. Curses!

That's the bad news. The good news is that I found a certified B&S repair shop that 1) is certified to work on this particular engine, 2) knows how to work on hydraulic equipment (they rent Toro Dingo's), 3) is familiar with Power-trac's (the guy said they tried to become a dealer once), and 4) can come pick it up, fix it, and return it to me (the pickup/delivery is a mere $40).

But there's still a little bad news. I have to get the tractor out of the backyard and to a spot in the driveway where they can actually load it up. My hydostatic drive pump doesn't have (or, at least, I can't positively identify) the tow ports found on newer models. So, I'm going to have to build a dolly with big pneumatic casters to roll it around front. I think it would take many men to actually roll it from the area it's in (even on a dolly), so looks to me like I need winch as well.

Harbor Freight to the rescure. I picked up a 2000 lb 12V electric winch ($49, and has a plate to hook to a hitch ball), 4 10" pneumatic casters (2 swivel, 2 fixed), 4 3 ton jack stands, and a small 2 ton floor jack. Some of this I've been needin' anyway, so might as well get it now when I really need it. I've got enough 4x4's at home to build a 4' by 8' dolly, then jack up the tractor, and slide the dolly under it. Hook the winch up to the hitch ball on the tractor, and pull it using the trees in the backyard as anchors.

I think while I have this thing at a repair shop, I'm going to have them look for more hoses that need to be replaced, install the fittings to bleed the hydrostatic pump (have to just dump the oil in the engine compartment currently), install fittings in the tow ports if they do exist, etc. I'd like to get this thing where it doesn't always have something broken, at least for 6-12 months or so.

I think one of my issues may be that the tractor spends a lot of time sitting there instead of being used (especially now that I have a 8 week old daughter). (And, I suppose it being almost 13 years old also might be a factor.../w3tcompact/icons/smile.gif.) I reckon I need to get out and give it some more use, even if that means loaning it to a couple of neighbors whom I trust. It's one of those things where I want it to work when I need it, but I don't need it every week.

Which brings me to another question. I've thought about having this same repair shop see if a B&S Vanguard diesel will fit in this machine. It's expensive, and I'm not sure that it's worth it though. Consider that the tractor spends most of it's time sitting, then some light use maybe once per months, and gets the crap beat out of it maybe once every 3 months, do you think I'd gain anything by this engine switch? In general, which "sits" better, a gasoline engine or a diesel? I'm thinking the answer is a diesel, but I'm not really sure. Any guidance?

Dave

 

[Charlie_Iliff]

Dave:
Sounds as if your PT is helping you collect all sorts of essential equipment.

<font color=red>which "sits" better, a gasoline engine or a diesel?</font color=red>

Neither "sits" well, but gasoline deteriorates a lot more cheaply than diesel. Diesel's advantage (if there is any -- trigger flame war # 3, after religion & politics) is in a lot of hours of fairly constant use. Then it saves on fuel & wear, but it takes a lot of hours to make up for the initial differences in cost.

 

[davesisk]

Charlie:

<font color=red>Neither "sits" well, but gasoline deteriorates a lot more cheaply than diesel.</font color=red>

So, you mean that if you compared a gasoline engine that's been sitting for awhile (maybe gunked up the carb, etc.) with a diesel that been sitting for awhile (what problems?), it's cheaper to fix the damage done by sitting gas than sitting diesel? Or did I interpret this completely wrong.../w3tcompact/icons/grin.gif. I actually thought the opposite was true, but that just shows ya how much I actually know about engines...

Thx,
Dave

 

[Charlie_Iliff]

Dave:
You interpreted it right, but I wasn't just referring to things gunking up and needing cleaning, adjusting, etc. When an engine sits, there is also a lot of corrosion which leads to high wear rates when it is run next. In aircraft, for instance, when an engine has a recommended time between ooverhaul of 2000 running hours, there is an assumed number of running hours per month. An airplane that sits most of the time is often lucky to log half the number of hours before overhaul is needed.
My comment about gasoline engines doing it cheaper wasn't intended to suggest that they deteriorate at a different rate, but that gasoline engines are far cheaper to buy and far cheaper to rebuild or replace. I suspect that you can put four or five new Briggs engines in your machine for the cost of a diesel conversion, so letting one of them rust a bit doesn't cost as much as letting a diesel one sit and rust, even if the diesel lasts longer.