PT1418 starting and solenoid

[davesisk]

OK guys, I finally got outside and was going to replace this solenoid switch that's mounted to the right side of the frame. I had ordered a new one from the fact'ry. When I got out there, I realized that the one on the tractor has 3 poles, and the one PT sent me only has 2 poles. Doh! Wrong part....

I'm positive the issue is this solenoid, because if I tap on it with a wrench, it'll eventually start.

From talking with my father-in-law, this sounds like a Ford solenoid. It's cylindrical in shape, says "Jumbo Solenoid" on top, and it has 3 poles. If you were looking at it like a clock-face, then at 9am there's a large pole with a cable from the positive battery terminal and a 14-gauge (ie. small) green wire with fuse attached, at 12 noon, there's a 14-gauge black wire, then at 3pm, there's a large pole with a large power cable going back under the engine (presumably to the starter).

Can anyone help me identify this as something I can simply go get from an auto-parts store?

TIA,
Dave

 

[Charlie_Iliff]

Dave:
The two basic types of solenoids I have played with have two small wires, to activate the solenoid, and two large, to carry the current to the starter. The other small pole, on some, as I recall is to supply full 12 volts to the coil, bypassing the ballast resistor, on old points and coil systems. Perhaps I am misremembering something, since I assume your Briggs is a magneto system and wouldn't need the auxiliary positive wire.
I think you can be sure that a parts store solenoid will work, if it has the same poles. Marine stores also have them. You need intermittent duty high amperage. It is the type used on a Ford, since GM usually had theirs mounted on the starter.
Ignition/starter solenoid gurus, please chime in.

 

[MossRoad]

Isn't it a standard Briggs item that a small engine/lawnmower shop would carry?

 

[davesisk]

Just an update here. A neighbor who used to be an auto mechanic came by yesterday, and helped me do some troubleshooting. He validated that the "won't turn over" problem is indeed the solenoid. (He took a look at the part PT sent me, and he said it's an oil-pressure switch. Oops! <g>)

For the surging problem, he also took the air filter housing off and had a look at the governor with me, although he couldn't really tell whether it's mechanical or pneumatic, it appears to be mechanical, and a little part with a spring and an adjustment screw is completely loose (like a screw came loose and fell out or something).

He helped me find the model number on the engine (B&S 42H), and said order an engine manual and a carb and/or governor rebuild kit. Sounds like good advice, and I intend to take it.

I'm going to get the "damned old tractor" patched up and running great yet....!

Even with these issues, I used it to unload 1/2 pallet of retaining wall blocks, and to pull up two small stumps (wrapped a chain around the end bar on the lift arms and stumps, then pulled 'em up with the lift arms!)

Dave

 

[Keoke]

Dave, the unit you describe is a relay rather then a solenoid.
Yeah, I know mechanics call them solenoids but Ford calls it a relay. A straight solenoid does mechanical work only (eg. car door locks). A combo relay/solenoid such as on GM starters closes the circuit but is also used to engage the starter drive.
The Ford type relay you have is kinda of half & half (relay/solenoid) unit.
It has the moveable core, like a solenoid, but it does no mechanical work like a true solenoid either.
Relays have fixed cores and moveable armatures and are used to close heavy current circuits with a small trigger current.
Bottom line, ask for a Ford starter relay and don't use the small terminal marked with the letter "I" which is used as a ballast resistor bypass while cranking on older Fords .
The other small terminal is marked with the letter "S" this is your guy for triggering relay.
Don't forget that this relay needs a good ground in order to work.
Also, don't forget that the trigger wire coming to relay is very often in series with any number of safety switches, all of which have to be closed first in order to power up relay.

cheers,

 

[davesisk]

Finally got this issue resolved! Called PT to tell Don I had recieved the wrong part. He said the right part was back-ordered, so I went to Carquest to see if I could find a match. Came home with a starter solenoid for Bobcat/Bolens/Toro/Wheelhorse tractors, put it on, and now it cranks everytime!

Now, I've still got the governor and/or carb problem, but at least it cranks reliably!

Thanks for the help and suggestions, you guys!

Dave