79 140hp trim problem

Jack Mears

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Oct 12, 2008
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64
I have a 1979 Evinrude 140 hp with power trim/tilt. It's not hooked up electrically. I manually tilted up motor to install lower unit by opening the hydraulic bypass screw. Now that the lower unit is installed, I lowered motor but the trim rods came up and don't allow the motor to return to the down position. Bypass screw still open.
Nothing in my service manual covers this situation.
Any ideas guys?
 

Joe Reeves

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Feb 24, 2002
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Re: 79 140hp trim problem

Jack.... That's the normal function of those trim rams. The only cure besides having the electrical setup operational is to have a battery available (any 12v battery, motorcycle, mower, car, whatever), temporarily disconnect the PTT electric motor at its plug connector, then connect wires directly from the battery to the electric PTT motor.
 

Jack Mears

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Re: 79 140hp trim problem

Thanks Joe
I only have 3 wires coming from the pump motor, no other at this time.
I assume the 3 wires would be: 1 wire from battery positive
1 wire for up
1 wire for down
I would connect the battery negative to the motor in an appropriate place.
If I have the battery positive connected to the red? wire then touch one of the other wires to ground will I get an up or down movement of the rams?

Mears
 

ezeke

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Sep 19, 2003
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Re: 79 140hp trim problem

The 1979 Trim motor should have three wires: one Blue, one Green and one Black.

The Black wire is the common ground. Positive voltage to Green lowers the motor; Positive voltage to Blue Raises the motor.
 

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  • 1979 PT&T Wiring.JPG
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Jack Mears

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Re: 79 140hp trim problem

THANKS EZEKE !!!

Thats what I need to know. Now I can get it down where it belongs and I can work on the powerhead.

Jack Mears
 

Joe Reeves

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Re: 79 140hp trim problem

Yep.... What Zeke said. Those units incorporated the 3 wire motor and incorporated a solenoid for the up mode, whereas the later models used a two wire motor and a relay system.

Your setup..... Neg bat terminal to black wire on elec motor, pos bat terminal to one of the other wires, normally green for up, blue for down.
 

emdsapmgr

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Re: 79 140hp trim problem

Do you have the special separate trim relay box required to operate the trim motor?
 

Jack Mears

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Re: 79 140hp trim problem

EMDSAPMGR:
No I don't have that box and I'm looking for the whole setup. All I have is the three wires from the pump and a length of zipcord from what I assume is the tilt indicator switch.
Any ideas where I can obtain this?
 

Joe Reeves

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Re: 79 140hp trim problem

Jack... This is the 3 wire setup. If you need the special PTT solenoid, contact me via email.

P-TILTWIRING.jpg
 

Jack Mears

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Messages
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Re: 79 140hp trim problem

Joe:
Thanks for that simplified drawing. I'll hook it up just to get the motor down so I can work on the powerhead.

For some reason the lower left piston has got hot enough to start melting the raised portion on the exhaust side of the piston. The neoprene water diverter was way out of place in this cylinder water jacket.
I initially thought the deposits on the piston and sparkplug were lead but after further examination I found it was aluminum off the burned piston. Wow- now I'm going to have to tear this engine down instead of just wiring it up and getting it running.
My biggest question was why did this piston start to melt down??? Was the water diverter the cause or was it too lean a mixture? If too lean, why would just one cylinder be affected when it's a two carburetor motor and assumably each carb supplies two cylinders?
This engine has .030 oversize pistons so it has been overhauled. The other 3 pistons are in beautiful shape (the crowns anyway) and the crosshatching is still apparent on the cylinder walls.
I need some advice before I tear it down and replace the bum piston etc.

Thanks
Jack Mears
Concrete, Wa.
 

Joe Reeves

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Re: 79 140hp trim problem

Two carburetors...... each having two barrels, one for each cylinder.

Each carburetor has two (2) high speed jets, two (2) slow speed jets, some have two (2) intermediate speed jets.

A partially clogged high speed jet would result in having just one cylinder run lean. The result would be (in time) pre-ignition which would lead to a melted piston.

Also, if a previous powerhead failure resulted in pre-ignition and small particles of steel became imbedded in the cylinder head...... and if someone reused that cylinder head rather than replace it...... those small particles of steel would glow constantly like a model airplane glow plug which would lead right back into that pre-ignition state. If that cylinder head is in that condition, replace it.
 

Jack Mears

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Re: 79 140hp trim problem

Thanks again Joe!

The heads on this motor look absolutely virginal. No sign of any previous damage. I wonder why the aluminum deposit on the piston and plug didn't adhere to the head.
Anyhow i'm going to pull the powerhead tomorrow and replace that bum piston and rings. I just finished pulling down a 78 140hp johnson which has a bad block. I have the carbs off of it so I'll send them out to a shop and have em' rebuilt. Upward and onward again. I hope.

Cheers-Mears:)
 

emdsapmgr

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Re: 79 140hp trim problem

If one water diverter is out of place, it can affect the cooling on one cylinder, causing it to run hot. It is possible for one cylinder to run hot internally and yet not get the outside of the head hot enough to set off the overheat warning horn.
 

RRitt

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Mar 30, 2006
Messages
3,319
Re: 79 140hp trim problem

jack,

i think you should check out a generic trim relay wiring harness. I think sierra
has a $50 kit and Ebay has gobs of used Mercury relay harness (same thing).

The wiring diagram above has down power running through switch. That means you are still
required to run #10 or #12 wire from motor to switch. It is far better to run a 3ft tail into
your engine and tap the starter circuit into a pair of headlight relays. Then you get
to run skinny #18-24 AWG from switch to relays while also having a lot less voltage
drop in cables. It is a vastly superior setup. That can be easily adapted to either
2w or 3w motors.
 

Joe Reeves

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Re: 79 140hp trim problem

Jack..... As "emdsapmgr" states, take a good look at those water deflectors. He has brought up a good point that had slipped my mind, a point that I've encountered quite a few times.

(Water Deflectors)
(J. Reeves)

Water deflectors are actually lengths of 3/8" outside diameter rubber hose, installed between the top cylinder and any cylinder beneath it, and also between the bottom cylinder and the block. The purpose of the deflectors is to have the water follow a definite path around the cylinder walls. Unfortunately the deflectors between the cylinders will at times swell sideways due to either a previous bad overheating problem, or simply due to age and salt corrosion. This causes a water flow restriction which usually allows the water to cool sufficently at low rpms but not at the higher rpms.

This hose material can be purchased reasonably at any automotive parts type store if you care to make your own, or you can purchase individual deflectors at any Evinrude/Johnson dealership at a somewhat higher cost.

Removing and installing them can be a hassle at times, but not always. I use a sharply pointed scribe with about 1/4" of the tip bent at a right angle whereas I can reach in, jab the tip sideways into the rubber, then yank it out. It's necessary to clean the seating surfaces where the ruber contacts the block with a small rat tail file to eliminate salt deposits etc. When installing the new rubber deflector, coat the deflector and the metal surfaces with WD40 which will act as lubrication to allow it to go in as easily as possible.

Make sure that you insert something into that deflector area before cutting and installing the deflectors if you make your own so that you will be certain that they are the right length and also that they will be seated properly. Usually a very small amount will be left extending about the block sealing area..... simply cut the excess off with a single edge razor blade.
 

Jack Mears

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Messages
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Re: 79 140hp trim problem

Thanks guys. I bought a new set of deflectors and put one of them in where it belongs using lube to get it in. I'm convinced that the reason that lower left piston started melting was the displaced deflector. That doesn't change the fact that I have to pull this powerhead down to replace that piston. UGH!
One good thing about this motor is that it's never seen saltwater. Makes it a lot easier to get apart.

Joe: Do you have any mixture knobs (2) for an Evinrude 5512 5.5 hp 1956?

Email me or call.
Jack Mears
 
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Joe Reeves

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Feb 24, 2002
Messages
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Re: 79 140hp trim problem

"Joe: Do you have any mixture knobs (2) for an Evinrude 5512 5.5 hp 1956?"

Sorry, I do not.
 
Joined
Apr 21, 2010
Messages
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Re: 79 140hp trim problem

The 1979 Trim motor should have three wires: one Blue, one Green and one Black.

The Black wire is the common ground. Positive voltage to Green lowers the motor; Positive voltage to Blue Raises the motor.
Do you have this schematic for a two wire T & T 140 ? Thanks !
 
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