1976 888 (MC-1) Trim/Tilt pump/line leak

[ratdude747]

Been fighting a hydraulic issue the last two weeks.

Last weekend I found my drive I had raised the night before had fallen. Massive lagoon of oil in the bilge under the pump. Found the high pressure line was loose and was able to finagle a wrench down there to tighten it. Adding some 10W-30 and it was back to working and I was able to enjoy my outing as originally intended.

Last Wednesday I found more oil in the bilge under the pump and the fitting loose again. Tightened it up and verified trim is still working.

Today I went to raise the drive and it just puked frothy oil all over under the pump. The line is tight... Haven't taken a wrench to the fitting yet.

Attached is a picture of the pump... but it's a bit hard to see under all the wiring.

In this picture pulled from another thread:




...this pump is a "C" (based on the reservoir shape and fill plug)

Bad line? Or bad pump? Or do I need to pull the pump to find out?

Edit- I'll note that at least as currently installed, the line in question is a white fabric covered line, similar in construction to the external lines (or an automotive brake line), not tubing with compression fittings like the other internal lines. Also, this line runs from the pump assembly to the reverse lockout valve.

 

[ratdude747]

If it is the pump unit, it seems that I can upgrade to a newer unit somewhat easily since I'm already on a 2-solenoid setup... just would need to bypass the reverse lockout valve.

Wondering if maybe that's the way to go since the valve and pump are both wildly obsolete...

 

[ratdude747]

Found this thread with a similar issue and what appears to be the same pump:

Mercruiser 165 4.1L trim pump leaking

Hey all, newbie to boats and the forums! I have some general automotive expereince so I can work on things. I bought a 1978 Sea Ray SRV-195 with a Mercruiser 165 4.1L straight six with the MC-1 (I think MC-1?) We were getting ready to move it and went to put the trimp up and it wouldn't go. We...

forums.iboats.com

May just be 4 bad o rings? The high pressure line is soaked but the low pressure line is dry.

Pump access isn't super great (as it's under a sun deck... I have to lean very far!

 

[ratdude747]

Some findings:

• I have my lines backwards in the earlier posts (braided line to transom, compression fitting nylon line to reverse valve)... But it doesn't matter:
• The pump bracket was only attached to the bilge shelf with the three front bolts, which allowed for easier flipping of the pump assembly:
• Popped the dogbone plate out...
• ...and sure enough, a torn o ring:

Well... Seems like this isn't to bad of a fix if these o rings are still available or cross-reference to something that is. Something I deal with all the time at work (cross-referencing/reverse-engineering oddball and obsolete parts.

 

[kenny nunez]

You can match up the “O” rings at any auto/hardware store.
Be sure to put a straight edge across the mounting holes on the mating surface. You will see the plate is bowed, so just take a file or run it over a belt sander to flatten it out. Stick the “O” rings to the bottom of the pump with some heavy grease then bolt it up.

 

[ratdude747]

You can match up the “O” rings at any auto/hardware store.
Be sure to put a straight edge across the mounting holes on the mating surface. You will see the plate is bowed, so just take a file or run it over a belt sander to flatten it out. Stick the “O” rings to the bottom of the pump with some heavy grease then bolt it up.

Noted. The bolts were loose... makes me think that's what did it in. Was hoping to not have to remove the plate (to avoid having to mess with the compression fitting while everything is flipped), but if not, it is what it is. I do have some machine shop access via work and a shop that I do business with if push came to shove.

Edit- per some cross referencing, these are dash 012 O-rings. Nothing special...