Merc pre alpha trim pump thread sizes help

[Jakecsam]

Okay so I have a 1980 Chris craft Catalina 25 with a Mercruiser 260 & a pre alpha drive. It has the….
66397A1 76812A4 Reverse Lock Valve Shift and the trim pump that is currently installed on the boat is a MerCruiser 79271A4. I have the two braided metal hoses ran from the outside manifold nicely, but someone has been in here before & seems to have played around. So as it sits right now I have the 2 hoses coming from inside, the 4 connected at the rams all good, a pump that works but no fittings on the pump. I was going to bypass the reverse lockout so I put some plugs into the ports on that and wanted to straight shoot the two hoses from transom right to pump, problem is there’s no fittings on the pump & I’m assuming they’re two different thread sizes. I work at a marine shop so I have tons of stuff laying around I can make work so just wanting some advice on what would be my best option ? I can still run the reverse lockout, would just like some direction possibly ? Thanks in advance.

Also I do have a set of the newer style black & grey hoses that fit into a newer style manifold on the t plate (7-16 inverted flare as opposed to the older braided ones I have that I think are 3/8)
Also have a few other different style trim pumps laying around ( I added photos to this post ) and maybe one of those could be plug and play ? But also hoping I can just get the old existing one plumped properly, seems like a spring and bearing ball might be missing any help is appreciated

 

[Bondo]

Ayuh,..... Welcome Aboard,...... What I'd do is use the new style plastic tank pump, the black 'n grey lines to the manifold at the transom,......

 

[kenny nunez]

Since the trim block on your gimbal housing is 3/16” female. Remove the block and make up 2 steel 3/16” lines about 6” long with a 3/16” flare nuts on both ends that will screw into the trim block. Or 2 mercruiser stainless braided lines like the ones that attach to the rams. With 2 1/4” female NPT unions and 2 3/16” female to 1/4” male and 2 1/4” flare female to 1/4” male connect the black and gray lines up to the pump.
I did that exact set up last year for a friend. The new style pump has the reverse locking valve built in so you should not have any problems with the drive raising in reverse. Just be sure that you have the lines connected correctly for pump rotation up-down.
Either new style pumps will work so the choice is yours which one is in the best condition.
Good luck.

 

[Jakecsam]

Ayuh,..... Welcome Aboard,...... What I'd do is use the new style plastic tank pump, the black 'n grey lines to the manifold at the transom,......

That’s where I think I was gonna go, how’s that for wiring ? I’ve already got wires from the old style pump up to the helm with the old style three button switch. I’m assuming I’ll have to re rig all the wiring eh ?

 

[Jakecsam]

Since the trim block on your gimbal housing is 3/16” female. Remove the block and make up 2 steel 3/16” lines about 6” long with a 3/16” flare nuts on both ends that will screw into the trim block. Or 2 mercruiser stainless braided lines like the ones that attach to the rams. With 2 1/4” female NPT unions and 2 3/16” female to 1/4” male and 2 1/4” flare female to 1/4” male connect the black and gray lines up to the pump.
I did that exact set up last year for a friend. The new style pump has the reverse locking valve built in so you should not have any problems with the drive raising in reverse. Just be sure that you have the lines connected correctly for pump rotation up-down.
Either new style pumps will work so the choice is yours which one is in the best condition.
Good luck.

That old old one that’s on the boat seems to work good… I’m just having a hard time with the fitting part of it, I have two steel braided lines ran inside from the old school gimbal manifold I just can’t seem to figure out what size I need to be able to connect the two braideds straight to the pump ? Or should I use the reverse lock out ? Also I think a spring and bearing may have fallen out, I’m assuming that’s pretty important

 

[Bondo]

That’s where I think I was gonna go, how’s that for wiring ? I’ve already got wires from the old style pump up to the helm with the old style three button switch. I’m assuming I’ll have to re rig all the wiring eh ?

Ayuh,....... Should be the same,....

 

[kenny nunez]

On the bottom of the old style pump the brass elbow is 1/8” NPT, remove it and get a 1/8”NPT male to 3/16” inverted flare so that you can connect the low pressure “down” hose to the pump. The other port is the “up” high pressure side. This will work but since there was reverse lock valve you might experience the drive raising in reverse.
The 3 button control will only work if the wiring and “ear muff” switches are good. Most times just pressing the middle and top buttons to raise the drive.
Wire colors, green is down and blue is up.
Does the old style pump actually run? You will be better off with the newer style pumps.

 

[Jakecsam]

Oh yeah the old one runs no problem. The other pumps I have have been on a shelf for god knows how long. Figured because the old one still works, just needed to figure out the fittings deal. Maybe I’ll just run it as it was meant to be, with the reverse lockout line at the top to the pump etc etc. I think I’m overthinking it at this point lol

 

[kenny nunez]

Models after the one you have eliminated the reverse lock valve and added an extra ball and spring in the valve block. This was adjustable but very critical, it had to be adjusted with the Mercruiser test kit.
Since you mentioned some balls falling out the valve it will most probably leak.
On the model you have the reverse lock valve had a micro switch which kept the pump from running in the up direction, by passing the switch would cause the one of the rams to explode if someone tried to raise the drive while in reverse.