1970 pre alpha tilt and trim pump

[Archer649]

My 1970 mercruiser has two lines on each cylinder so I'm assuming it is tilt and trim. my question is does the pump differ from the single line pump. I bought a prestolite pump that does not pump oil out of the down hose. I'm thinking it is a tilt only pump. I have the original pump (prestolite) so can I switch the pumps out because the motor is bad on the original one.

 

[alldodge]

My 1970 mercruiser has two lines on each cylinder so I'm assuming it is tilt and trim. my question is does the pump differ from the single line pump. I bought a prestolite pump that does not pump oil out of the down hose. I'm thinking it is a tilt only pump. I have the original pump (prestolite) so can I switch the pumps out because the motor is bad on the original one.

Howdy Archer

Sorry we missed your post. Not real sure about your question. The Prestolite pump has two lines out, one up and one down. The older systems used a reverse lock out feature and also check valves on the system. If your going to install a newer pump, there would need to be some changes. So if you could clarify what your wanting to do, one of us here should be able to help

 

[Archer649]

I have a prestolite tilt and trim pump on my 1970 starcraft chieftain that has two lines to each cylinder . The motor is weak so I purchased a pump that I thought was the same but when I installed it the out drive raised really fast and strong but in down mode it only went down part way. I checked the down hoses and there was no oil or pressure coming out. The feller that sold it to me said the weight of the out drive was supposed lower by it self with no pressure. I figured that mist be the tilt only pump with one line only to each cylinder. So I switched out pumps and used the good motor. Reinstalled and it worked properly in the up but part way down so I ran it up and down 5 times and motor stopped working. So I'm looking for a complete unit and my question is, is there a different pump for tilt or tilt and trim. Or is there only a tilt pump and a trim only pump hence the slow up and down on the trim?

 

[alldodge]

Being that old, you should have the check valves in line. The pump should push the drive down, and it might still have air in the line. As before there is also the check balls in the reverse lock out. You might be able to replace with the new style but I would see if Bondo or Bt Doctur might leand some insight

 

[Archer649]

My line from the reverse lock valve to the gimble is pluged.oil gets through the reverse lock valve but can't get through the gimble. Do I have to pull engine to replace line. I disconnected lines from rams and reverse lock valve and tried air pressure with no luck. So line is plugged or gimble block is pluged.

 

[alldodge]

Sure sounds bad, I think your going to need a full rebuild. This means to get to everything your going to need to possibility pull the motor to get to everything. With lines plugged might be the time to think about upgrading to the new design and remove the lock valve. Bondo any insight?

 

[Archer649]

It's the line going from the reverse lock valve to the gimble manifold. Reverse lock valve is working. Manifold is in the middle of gimble on the port side.

 

[Archer649]

Put everything back together . Left line loose at reverse lock valve . Operated down switch and oil coming out of the loose line. I left the lines disconnected at the cylinder and I tried hydraulic pressure to push oil through the line no luck. I think the manifold is plugged.

 

[alldodge]

While the manifold is plugged, there should be enough pressure to get something out the other side. It could be your pump is not putting out sufficient pressure

 

[Archer649]

I'm going to bypass manifold . Going to have a hose made to go through transom up top and down the outside of the transom. I can get a splitter and mount it above the Out drive and connect two longer lines to the cylinder. It should be a good temporary fix and maybe long term.