Replacing 15.5 ohv engine with 18 twin

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  #1  
Old 11-07-09, 04:44 PM
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Replacing 15.5 ohv engine with 18 twin

I am having some difficulty with the wiring change when swapping out a 15.5 OHV briggs and replacing it with an older 18 HP twin.
Have two sets of wires coming out of the frame and only one set to connect to the Engine.
The man I got the engine off indicated that the single wire coming from the engine was a kill switch wire..
Anyway I have a Red and orange one plug and a black and blue on the other , These come from the frame..( there is also a plug to the lights but I know where they go.)
The Engine has an red and black wiring ( which I assume is the alternator lead)
I thought to connect the red and orange lead to the red and black ( but an after thought is that the wiring is totally different for both engines.
The Mower is a Sears and has safety features with off switch on the seat and with the blade drive..
So My question is.. What is the difference with this change from single 15.5 OHV to a 18 twin .. Its not the twin v...
 
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Old 11-07-09, 04:54 PM
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Without knowing exactly what mower or engine you have, I'd say the single black wire on the engine is the kill wire and should connect to the wire on the harness that is grounded when the key is off and the brake pedal is locked down and blades are off, and open when the key is on. The 2 wires coming from under the flywheel are alternator wires. The red one should go to the wire that goes through the ammeter to the battery. The black one runs the lights.
 
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Old 11-07-09, 06:02 PM
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Engine type

The engine taken out was a Briggs 28N707 type 0173-01 single cylinder ..( which looks like the two wires (black and blue) were to the solenoid)
The other wires by default would be to the Alternator.

The new engine is a Briggs 422707 18 hp twin power type 1510-01
The plug on the engine which the frame plugs connect to are black and red ( which I think come from the alternator.
The single black wire from the engine would be the kill wire which was not an item on the other engine unless the black wire that is in the blue black plug is also a kill wire.

The mower is a Sears 42 inch Hydro model 917256530

Anyways I tried to start the engine and there was no enable to the solonoid to fire up the starter..I have set the brake and set the blade actuator lever. But still no action from the solenoid ..
I wondered if I am missing something in my preparation..
 
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Old 11-08-09, 09:03 PM
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Do you have a volt/ohm meter?
 
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Old 11-09-09, 05:06 PM
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yes

Yes I do have a Volt Meter and was in fact in the process of trying to determine what was receiving current.
So far I have determined that the relay is receiving the main supply and the red line feedback to the switch does supply current. I was not able to determine that the white wire from the switch does when the switch is turned to start. But then I am now not sure which lead is the relay initiator. I see only one fuse which is a 30 amp inline which is ok.
There is a line to the altenator (this was mentioned as one of the wires with a plug from the frame) which has 12 volts in it, but I think this is the feedback to the battery in order to charge .
So any other tips would be appreciated.
 
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Old 11-10-09, 12:07 AM
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On the solenoid (relay), there should be your 2 large cables on the large posts, one with a small red wire with the fuse in it also. Then on the smaller spade terminals, there will be a black and a white wire. The black is ground and the white is the trigger wire for the solenoid which should supply 12 volts with the key turned to start as long as the brake pedal is pressed and the blades are off.
 
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Old 11-11-09, 04:58 PM
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Blade unit out

Will the start process be interrupted if I have the blade unit out of the mover? In other words I only have the engine installed and have yet to install the blade unit.Does the power get interrupted if the blade unit is out?
If so that might explain why I am not getting a start power to the solonoid.
 
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Old 11-12-09, 05:30 PM
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No, just be sure the PTO is turned all the way off.
 
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