Johnson T&T Bench Test How To??

[kyudizky]

Hope this isn't in the category, but have seen other T&T questions here so....

Looking at buying a used trim unit for my '84 90HP Johnson, its a two wire unit, one blue wire and one green wire.

Can it be tested (make it go up and down) while not installed on a motor/boat (bench tested)? Can i connect it to a battery out of the boat, if so, which wire goes to which pole on the battery?

Thanks for the help.

 

[RRitt]

Re: Johnson T&T Bench Test How To??

yes you do not need a boat to test. If you have a 5000psi hydraulic gauge you can even test against drift down.

I doubt that a 1984 unit is 2wire. More likely it is three wire with ground connecting through frame. Some motors have three bolts on top. Two opposite bolts hold the motor together and a third offset bolt (usually 5/15" hex) is there for a ground wire.

In which case connect that to ground. The blue wire is usually up and the green wire down. If you connect blue and green at same time in any fashion you can burn out a 3w motor pretty fast. Even both to positive - or one positive and one negative - or both negative. One of the two wires MUST be simply left open.

 

[kyudizky]

Re: Johnson T&T Bench Test How To??

In the picture attached, my unit does not have the hex bolt for a ground wire, and the insulated wire coming out only has 2 wire in it, one green and one blue. So how would I test it, how do i ground it?

I plan to sell the unit as I have no use for it anymore. It worked when I took it off my boat, but want to be make sure it still does b/c I do not want to sell it as a good working unit if in fact its not, I have been on the bad end of that deal before and don't want to do that to anyone else.

Thanks for the help iboaters!

 

[ezeke]

Re: Johnson T&T Bench Test How To??

If there are only two wires on the trim motor, reversing polarity reverses the direction of the tilt.

Connect the blue wire to the battery ground and the green wire to battery positive, then switch.

The standard trim motors were changed to two wires during 1981.

The newer motors are called permanent magnet field motors. The Arco site pdf shows the differences: http://www.arcomarine.com/xhtml/tech tilt trim motor tips.pdf

 

[kyudizky]

Re: Johnson T&T Bench Test How To??

I tried touching the 2 wires to the battery terminals and it just popped and sparked. So that means the motor is not working???

 

[BigB9000]

Re: Johnson T&T Bench Test How To??

or the trim unit is all the way up or down.

reverse the wires, and try again.

 

[RRitt]

Re: Johnson T&T Bench Test How To??

I swear i'll never fully figure out J/E. When I look it up in one place it tells me the 1984 90Hp should be the two ram system and when I look it up in another I find the three ram w/ loop.

At any rate ... off boat and no special tools? Hmmm ....
If rams are bad they will generally drift down at any pressure. You could just hang a cinder block on the thing and come back a day or two later. If the rams have a problem then the block should move. Take a piece of string and a fishing weight. Hang it 1/2" off ground. Come back few days later and see if the string is touching ground.

The pump is harder to test but only take a few minutes. You just hook it up to a pressure gauge and run the pump. With your typical $8 worth of harbor freight tools I would probably take the looper loose and hook my pressure gauge there. Easy to get to and autoboys should have the fittings needed to connect your pressure gauge. It should deliver and hold pressure per spec. If it has an internal leak it will show up instantly. I don't know the spec. Ezeke probably knows or has link to correct pressure reading. But even if you don't know exact pressure it's not a big deal. The system has enough sq inches to do much bigger engines than 90HP. You'll be interested in pressure bleed off more than absolute numbers.

 

[bob johnson]

Re: Johnson T&T Bench Test How To??

I tried touching the 2 wires to the battery terminals and it just popped and sparked. So that means the motor is not working???

to me it means that those two wires are shorted to each other somewhere along their path... it maybe inside the motor.

the 1988 70 hp i have has a two wire trim setup and touching the wires one to a pole on a battery either drove the unit one way or just hummed the motor.....switch the wires and the unit went the other way like ezeke says...if it is at the end of stroke it still shouldnt spark on the battery.

the sparking is the negative and positive are shorting to each other..

or you have a bad connection...press hard or dont press at all!!! dont dilly dally with the wire on and off the post!!!!!!!!!!!!!!!!!!!!!!!!1

good luck

bob

 

[srikid]

Re: Johnson T&T Bench Test How To??

Nice info. Thanks.

 

[RRitt]

Re: Johnson T&T Bench Test How To??

I tried touching the 2 wires to the battery terminals and it just popped and sparked. So that means the motor is not working???

your motor does not look the type to have problems. the seal around cable looks decent, the jacket isn't cracked, and there is no rust around the sealing washers. The only hint of impending motor failure that I see is the rust colored stain around the wire nut. Trim motors pretty much last 100 years or until water gets inside --- which ever comes first. Yours just doesn't look like it is leaking yet.

If you take off the three phillips head bolts the motor will lift off. This will expose the pump and fluid so you need to have a safe (out of the way) place to put the system and a way to keep debris out (latex gloves?).
Try the motor by itself. If it is dead then you have to take it off to replace it anyway.

 

[kyudizky]

Re: Johnson T&T Bench Test How To??

RRitt,
The motor was a '84 J90MLCRD (manual trim) so trim unit was not original to the motor, I have no idea what year he unit was from.

Once it started to spark/pop, I too the wires off the post immediatly and didn't try again, so I'm thinking I didn't press down hard enough.

Gonna try it again tonight. This may be a dumb question, but would it hurt anything to just pop the hood on my truck and test it on my truck battery, without unhooking the truck cables?

 

[BigB9000]

Re: Johnson T&T Bench Test How To??

Once it started to spark/pop, I too the wires off the post immediatly and didn't try again, so I'm thinking I didn't press down hard enough.

Gonna try it again tonight. This may be a dumb question, but would it hurt anything to just pop the hood on my truck and test it on my truck battery, without unhooking the truck cables?

For a long time i didn't have a relay/switching system to control the PT&T, so I had wires hanging, and just connected them to the batter. everytime it sparked.

When I bought the motor, I popped the hood of my truck to test it.