Trim Pump Upgrade for Older Mercruiser

[stopher8]

I have a Mercruiser 165 L6 (1972 or so I think) and the outdrive falls down slowly after I raise it up. I've rebuilt both cylinders, and last night I removed the trim pump and disassembled. It didn't look too bad but it had older fluid in it that may have had a little water in it. If cleaning and reinstalling this pump doesn't cure my problem I'll need to buy a new pump assy. Can I upgrade to the newer style pump? Will it work the same? I think my pump now is a Prestolite.

 

[achris]

.... Can I upgrade to the newer style pump? Will it work the same? ....

Yes.

You will need to modify the hosing to accommodate the newer pump having the reverse lock valving internal..

 

[stopher8]

Would you care to elaborate? Is there a hose diagram I could look at? I believe the reverse lockout has been bypassed on mine currently. On the shift plate I do see a switch and a hydraulic fitting but nothing is going to either one. I only have 2 hoses going toward the transom from the pump, I assume to the lower manifold block that splits to each cylinder

 

[Bondo]

I only have 2 hoses going toward the transom from the pump, I assume to the lower manifold block that splits to each cylinder

Ayuh,... Welcome Aboard,.... This is also how a New style pump would be plumbed,....

 

[stopher8]

Ok, thanks a bunch!! I guess my next question would be wiring it. My current pump has two solenoids, I assume 1 for each direction. It appears the new pumps have only one solenoid. Am i correct in my assumption? As for the reverse lock, do I just need to run the coil positive through the reverse lock switch?

 

[Bondo]

Ayuh,.... With the New pump, ya run it's battery wire, 'n ground, the control wirin' plugs into the pump,....

You'll remove, 'n toss All of the reverse lock, 'n everything else in the return line,...

 

[achris]

Ok, thanks a bunch!! I guess my next question would be wiring it. My current pump has two solenoids, I assume 1 for each direction. It appears the new pumps have only one solenoid. Am i correct in my assumption? As for the reverse lock, do I just need to run the coil positive through the reverse lock switch?

This sounds more like someone has bypassed/disconnected the shift interrupt switch...

 

[fishrdan]

I upgraded the trim pump on my 72' 140HP. You will need to leave the reverse lock valve in place, but wire and plumb around it, I filled it with oil and capped the fittings. You will need to keep the hydraulic trim indicator plumbed, I just used another pump-manifold hose to include the trim indicator, so the hoses go; pump>manifold - manifold>trim indicator - trim indicator to pump. Most likely you will need new hoses as the pumps have different sized fittings. You will also need some adapter fittings from a good automotive or plumbing store. I'm not sure on the electrical as I upgraded the wiring and shifter w/trim switch when I upgraded the pump, it was plug and play for me green>green blue>blue, etc...

 

[stopher8]

Well...coming through the transom I have two BADLY corroded wires I'm guessing that's from the trim limit switch. They are just hanging and go to nothing. I need to pull off the bell housing to thread the hole for a new style aft mount cable, I have found an entire gimbal housing complete for a pre alpha but it has the trim sender and switch on the outsides of the pivot pins. Would I be better off to change over to this later style and save myself some later headaches? Will my current outdrive bolt up to this? I assume I'll need an alignment bar and transom seal kit to complete this. There are so many things bypassed, cut or rerouted on this boat I've gotta lotta work to do either way.

 

[achris]

You'll need the inner transom plate to go with that new gimbal housing, but if it's any later than 1982, forget it! How can you tell? The 1982 and later have the rear engine mount spacing at about 10", the earlier ones, 14"... If the one you're looking at is 10", don't even try to make the change, just too many 'gotcha's...

If it is the right one, then your drive will bolt straight to it. But you will need to fill 2 of the cutout holes and re-drill them an inch or so higher, and the middle section of the cutout needs to be widened slightly. Neither of those things should be a problem.

Chris.....

 

[8v-of-fury]

I too was looking to do this upgrade

As I see this thread has the fundamentals outlined, but no real resolve.. perhaps we can just start my questioning here.

I too have an early 70s 165 and Alpha drive. However i have the newer gimbal housing and drive already. Just have the old pump and single solenoid.

I have access to a few" gen II" pumps if you will, so the upgrade will be next to free for me.

I see that the hydraulics still go in to the sender on the transom as well as the device on the shift. I just end up elminatiing the hydraulics going to these and adapt the older lines to work on the newer pump?

 

[jbcurt00]

Closed

As I see this thread has the fundamentals outlined, but no real resolve.. perhaps we can just start my questioning here.

Perhaps you should check the helpful tip at the top of the page or the guidelines.

After 90days w no new posts, consider inactive topics for research only amd not to be posted to