2084 engine swap
 

I have access to a 18hp kohler from a 2185.
Would this be a direct bolt in to replace a 20hp in the 2084?
Here are the specs for the 18hp replacement engine:
Model- CH18S
Spec- 62509
Disp- 624
Serial- 2633908137

I thought I read I will need the drive shaft out of the donor 2185, is that correct?

I was looking through my service manual and the crankshaft hubs where the front PTO mounts looks to be different diameter between the two engines, if so I can't use my PTO on the replacement engine, which comes without a PTO.
Can anybody verify the crank differences?


Thanks.

2084 should have a CH20 in it. The CH18 should be a direct swap. You would use the 2084 drive shaft.

and 2084 muffler/ shrouds.

I will be replacing the CH20 with the CH18.
From what I understand swapping the carbs will make the 18hp a 20hp, is that correct?

The 2084 has a 60" Haban deck, if swapping the carbs will indeed make the 18hp a 20hp would you advise doing it or will the 18hp handle the 60" deck just fine?
I only cut grass with this tractor.

Thanks.

You can probably just swap the carb from your 20 to the 18. 18 may be a bit challenged pulling a 60. You could give it a shot and see how it behaves. If it has enough power then leave it alone.

I'm not clear on the carb swap Sam.

Is that the only change to make a 18hp into a 20hp?

Thanks.

Carb swap is from what I understand the only difference, your results may vary. :beerchug:

Remove (unscrew) the throttle limit pin on the side of the carburetor and re-adjust the governor for wide open throttle, its now a 20HP.

The PTO on the 18hp donor engine has two black wires coming off of it. From what I can tell 1 is power and 1 ground, which is switched.
The 2084 has 1 wire going to the 20hp PTO.
My question is do I just run a separate ground wire off the 2-wire PTO and does it matter which wire on the PTO I ground as they are both black coming out of it.

Thanks.

Doesn't matter what wire you use for ground.

WOW! I've been following this thread and am impressed with the knowledge shown by all involved. You guys know your Cubs.

The CH18 is in the 2084 and running nicely. Pretty much a direct bolt-in procedure. When I picked up the donor CH18 the seller also gave me the PTO, muffler and drive shaft along with the engine which he said has 466 hrs. on it. Just had to invert the PTO so it would clear the lower muffler shield and run a ground wire for the PTO as well as to make a male to male spade connector for the power side of the PTO. I put new crankshaft seals in it and cleaned the starter drive.

I wont know till spring how it handles the 60" deck under load but running it with no load the deck sounded more "powerful", for lack of a better description, than with the tired CH20 that was in it that had 1050 hrs. on it.

I will probably rebuild the CH20 this year when I get time.

Thanks for all the help.

Relay wiring questions
 

On my 2084 on the right side attached to the bolt that holds the grill to the frame just ahead of the starter there is a relay. The relay and wire colors don't match any wiring diagram in my service manual which is for a 2082 that MTD told me would work for the 2084.

Anyhow here are the 4 wire colors going into the relay:


Black- goes to ground on starter bolt.
Violet- to a spade lug on solenoid switch.
Violet- it is spliced to a red wire coming off the harness that may have been cut off from the plug in connector that is screwed to the engine above the starter.
Red- goes to the large terminal that the battery cable connects to on the solenoid.
What is this relay for/what does it do?

Also on the replacement CH18 I just installed in this tractor there is a blue wire coming out of the harness connector that is screwed onto the engine above the starter that has a female spade connector on it. What is this wire for?

The tractor starts, runs, and the PTO engages but the safety switch must be by-passed because I can start it without pressing on the brake pedal and I'm just trying to get the wiring straight.

Thanks.

The relay is for the starter. It's a starter relay. Added by either a PO or a dealer. DO NOT remove it. They are a good deal. They take the load off the ignition switch for starting. Makes the ignition switch last longer.

The other blue wire..... If I understood that right, it is grounded. If that is correct, my guess would be it used to plug into the harness and ground somewhere else. Now, it grounds right there. If I misunderstood that, sorry.

Hope that helps.:beerchug:

JMech, you are correct about it being just a starter relay that was added on.
That explains why I could not find it in any wiring diagram.
As far as the blue wire I asked about, that wire would go to the spade terminal on the solenoid if there was not a add-on relay and the red wire which was cut to connect to the relay would be in the connector on the engine feeding the blue wire.
The blue wire on the original CH20 was cut off so close to the connector it was hard to see it.

Thank you for the help.

I have used the starter relays or boosters as they are called and they do a lot for the ignition switch and if all of the safety switches are closed then the power goes from the battery directly to the solenoid and bypasses all of the old corroded safety circuit where resistance can build up to 30 amps or more. To me they are almost an item like a fuel filter for older mowers. To see the difference on a cold startup just jump the batt + to the solenoid terminal and see the power of your old battery compared to the OEM method and the current going through all of the old connectors and safety switches and then to the solenoid.:beerchug: