Tilt/trim pumps

[Frank Acampora]

OK, RRitt. I need your help. What is wrong with these two pumps? They will raise the engine but not lower it. Do they require a second check ball and spring at the rear (down) side of the pump? Also, the front of the check valve keeps popping out. Can I stake it to keep it in or is there a good glue? Is This the source of the problem?


Everything else works fine. Motor turns in both directions and cylinders are moving freely since I can lower the engine if I remove the front check valve and let them bleed down

 

[RRitt]

Re: Tilt/trim pumps

It has threaded check valves. If the threads of lower casting are no longer capable of holding in check valves then the lower casting is ruined and the VB should be culled for parts.

When working on threaded check valves you have to be 3x more careful when removing the cap. No wiggling motion that might stretch the aluminum body. You also need to keep a modest inventory of check valves culled from bad cores. If a check valve does not fit together snugly during reassembly, then replace it with one that does. You can use the middling strength press-fits on the rear check valve of smaller engines so core attrition is not unbearably bad. Wash all parts in laq thinner prior to assembly so that they are 110% oil free and use a droplet of locktite red on the seat. heat dry needle down on a rack so that none of the locktite seeps into spring chamber.

failure to reverse direction can be caused by too thick fluid. wait 10 minutes and see if the excess pressure bleeds off.
if it is not a fluid issue and you know the bottom end is good then you're going to have to crack open the gearplate. Use precision ball bearings throughout. check the hole in regulator seat for roundness or distortion. drop two small washer into spring toer to isolate springs coils from your set screw. use your calipers and (after assembly) make initial adjustment of 5/16" spring compresssion.

 

[Frank Acampora]

Re: Tilt/trim pumps

Thanks!

I did not want to use the pump on the right because it was dirty BUT---I took it apart, cleaned it, and didn't find anything that appeared to be wrong. I pushed the shuttle out of the body to be certain it was moving freely. I assembled everything and set up the spring compression to 5/16. Mounted it on the reservoir and this one works.

This particular engine is the one I modified with a thicker exhaust plate and bypasses in the piston skirt. It is important to me to have the trim working properly so I can compare it directly to other engines on my test hull.

I will examine the pump on the left at a later date.