1976 Mecruiser 351W Trim System

[orttauq]

I have a 1976 American Eagle (ABC) with a 351W. It has the old style trim system with the 56046A1 trim indicator sending unit mounted in the engine bay. It has been disconnected and both hydraulic lines are just open. I posted about changing to the new style (senders on gimbal ring) but that involves replacing almost every part of the outdive after pulling the engine. I have tested all the related components and/or found NOS parts and I think I can get this all working EXCEPT I can not find anywhere the routing of the two open hydraulic lines. I have the two service manuals that cover the drive unit but it just shows how to test.
Can anyone help with how the lines should be run? The trim system work but requires holding both buttons to raise and lower the unit and the gauge does not work.

Really appreciate the help! THANKS

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[kenny nunez]

If my memory is correct the white plastic low pressure line goes from the pump to one side of the indicator ram cylinder then out to the reverse lock valve where the grey hose goes to the trim block at the bottom of the gimbal housing.
There is a bleed screw on the top of the indicator ram cylinder to bleed out the ram. I am not sure which side of the cylinder the plastic hose from the pump goes. You may have to switch it to get the indicator to power the trim gauge in the right direction.

 

[orttauq]

Thanks Kenny. So as it is now there are two braided steel hoses from the bottom of the pump to down under gimbal-a high pressure loop for trim rams in and out. Then these two disconnected plastic hoses go from a seperate port on the pump to the trim cylinder to the lockout to the gimbal housing-a separate hydraulic 'system' from the high pressure lines to the rams. Sound right?

 

[kenny nunez]

It looks like the reverse lock valve has been by passed. The incoming line between the trim indicator and the valve uses 1/8” npt male X 1/4” female compression fitting like on the lines hanging off the trim indicator. Originally there was a 1/8” npt male X 1/4” female 90* compression fitting. Someone eliminated that fitting and bypassed everything. It may have been a leaking reverse lock valve that made someone change the routing.

 

[orttauq]

It looks like the reverse lock valve has been by passed. The incoming line between the trim indicator and the valve uses 1/8” npt male X 1/4” female compression fitting like on the lines hanging off the trim indicator. Originally there was a 1/8” npt male X 1/4” female 90* compression fitting. Someone eliminated that fitting and bypassed everything. It may have been a leaking reverse lock valve that made someone change the routing.

THANKS for your time on this!!
You can't see it in the 2nd picture but the one line coming straight out (parallel to red wire) from the cylinder is just open; not connected to anything and yes, I did find a port on lockout that is open too. When I removed the cable plate (?) two springs and a check ball fell out of the open port on the reverse lockout. There is also micro switch on the lockout that is shot. Seaway Marine in Lynnwood, Wa has the switch, I have not looked for the lockout.
I have not removed the trim pump from the engine bay but I have not found where the low pressure line would connect.
I have all the electric sorted except the limit switch at the top of the outdrive; just need to sort the hydraulics.

 

[bbook83]

THANKS for your time on this!!
You can't see it in the 2nd picture but the one line coming straight out (parallel to red wire) from the cylinder is just open; not connected to anything and yes, I did find a port on lockout that is open too. When I removed the cable plate (?) two springs and a check ball fell out of the open port on the reverse lockout. There is also micro switch on the lockout that is shot. Seaway Marine in Lynnwood, Wa has the switch, I have not looked for the lockout.
I have not removed the trim pump from the engine bay but I have not found where the low pressure line would connect.
I have all the electric sorted except the limit switch at the top of the outdrive; just need to sort the hydraulics.

Good luck trying to find the limit switch at the top of the outdrive. I’m glad you found the lockout switch at Seaway, but last I checked, neither they or anybody else has the trim limit switch. In my experience with my ‘1974 Jolly Roger (cousin to the American) with MC1 Mercruiser, the switch will not last long. I have been pushing both buttons for at least the last 25 years to trim without problem. You get to know your boat and you will know when to stop going up.

 

[orttauq]

Good luck trying to find the limit switch at the top of the outdrive. I’m glad you found the lockout switch at Seaway, but last I checked, neither they or anybody else has the trim limit switch. In my experience with my ‘1974 Jolly Roger (cousin to the American) with MC1 Mercruiser, the switch will not last long. I have been pushing both buttons for at least the last 25 years to trim without problem. You get to know your boat and you will know when to stop going up.

Right, I am not finding the limit switch so I am thinking maybe a magnetic proximity switch solution. Epoxy a rare earth magnet to top of outdrive and the sensor in the gimbal ring. Might need a relay but I think it will work.

 

[kenny nunez]

Try using a little compressed air to move the piston in the trim sender cylinder. It probably still works and should move the trim gauge. If it does just connect it back in the hydraulic system. The drive may stay down at idle in reverse. Finding a good reverse lock valve are pretty slim.
In the wiring diagram just connect the purple and blue wires together so that only one button will raise or trim the drive.

 

[orttauq]

Thanks, I did that and the cylinder does work. Lockout switch is on the way too.

 

[bbook83]

It pays to periodically look again for NLA parts. If you google mercruiser part number 45942A1, you will see two listed for sale. A bit spendy for a switch.

 

[orttauq]

Yeah, I found those but a little too much $$ for a switch that is known to not last. But then again restoring an old boat will always be hard on the wallet.

This is why I am thinking a type of prox switch. Just need to determine if the OEM switch is NO or NC.

 

[orttauq]

I removed the trim pump today to sort the hoses and found that it has ATF fluid in the system...how scr*w*ed is it (am I)?

 

[kenny nunez]

The only thing that atf will do is foam. Power steering fluid does not, just try to purge as much of the atf out. Try to post a picture of the bottom of the pump where the hoses connect.

 

[orttauq]

It could be PS Fluid. It is red and pretty light weight so I figured ATF. Sticker on reservoir says regular engine oil so knew it was not right. Standby for a pic.

 

[Alumarine]

I removed the trim pump today to sort the hoses and found that it has ATF fluid in the system...how scr*w*ed is it (am I)?

I've used Dexron ATF for a couple of decades with no issues in my trim pump.
Being red it's easier for me to differentiate between that and engine oil if there's a leak.
I'm not sure why it would foam. I've had a number of vehicles that required Dexron for the power steering pump.

 

[orttauq]

I've used Dexron ATF for a couple of decades with no issues in my trim pump.
Being red it's easier for me to differentiate between that and engine oil if there's a leak.
I'm not sure why it would foam. I've had a number of vehicles that required Dexron for the power steering pump.

Good to know that I will not have to be replacing all the seals. Thanks!

 

[orttauq]

Here you go @kenny nunez I am guessing the plugged port is where the low pressure line to/from trim sender goes.

 

[kenny nunez]

It looks like someone replaced the down port fitting with an inverted flare style. Originally it was a compression style for the plastic lines like hanging off the reverse lock valve. If you replace the fittings on the trim indicator cylinder with inverted flare style you will be able to re connect it in the system. With a short inverted flare style line, it does not even have to be a flexible type. NAPA sells 3/16” steel lines with the flare fittings. You just have to select a line long enough and connect from the pump to the cylinder and connect the line that was on the bottom of the pump. There is a bleed screw on top of the cylinder so you will have to cycle the system to clear the air from it.

 

[orttauq]

My guess was wrong on the plug in the above picture. There is a hex adjustment screw under that plug.

 

[orttauq]

I think the fitting was changed to a inverted flare style because the SS braided line from the outdrive was routed directly to the pump.