Tilt / Trim Force 50hp - Slow Leak

[N2Motors]

All,

I'm new to the site and still learning and while I see a ton of info on tilt and trim issues, I'm still confused. I have a slow leak down issue on my 1990 Force 50hp and I am not sure how to fix it.

I've seen people reference o-rings or bleeding it out, etc.., but I'm just now sure how to tackle this and before I starting taking things apart, I'm hoping someone can point me in the right direction.

Appreciate everyone's thoughts.

 

[RRitt]

Re: Tilt / Trim Force 50hp - Slow Leak

on the side of your motor is a pump assembly. The pump assembly is built from two halves - a motor and a pump. In earlier years, the pump is called the valve body in order to avoid confusion. Bleed down is caused by the valve body portion of your electric fluid pump.

If your valve body is round with four phillips head mounting ears then it is prestolite.
50HP won't have too much back-pressure from the force of propellor. you should get 3-7 years out of the chinese product. It's still a crummy product but it is cheap and works well enough for a 50HP. If you have the time to wait then rebuilding the oem is superior.

If your valve body is square with a 10mm bolt or socket head in each corner then it is either Eaton or Oildyne. Eaton and mercury did not get along well and the entire product family was superceded to Oildyne by 1995. If it is eaton or oildyne, then I do not know how to advise you. The tall skiinny motor eaton is easy to fix. the short squat motored oildyne is a PITA.

post a picture and we will know which of four possible system you have.

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

Thanks for your feedback. I also caught wind via the forum you are they expert on this matter so I'm all ears!

I just took a look and based on your assessment, I have the prestolite variety. I guess that's good????

I should also note that I experience leak down on both the trim piston and the tilt piston. Not sure if that helps us isolate the problem any further within the valve body.

Also, is it not possible for an o-ring within the pistons (NOTE - not sure if this is the right vernacular here...) causing this?



View attachment 178563View attachment 178564View attachment 178565

 

[jerryjerry05]

Re: Tilt / Trim Force 50hp - Slow Leak

Your pics won't open for me.
RRitt rebuilds them.
The leakdown is usually the pump and will need to be rebuilt. Get it apart and send it to RRitt.
He used to have a site on e-bay???

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak



jerryjerry05 et. al. I'm trying again with the photos. Hopefully this will work now.

Thanks

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

Guys,

I decided I'd just open up my valve body. It came apart surprisingly easy (as if it had recently been taken apart. I recently purchased the motor) as nothing was stuck or corroded. All the tubes and tube ends seemed in good shape. Granted, it is a fresh water motor.

I've attached some photos. A couple of comments on the photos/tear down.

1) I did not see any small rubber gaskets or o-rings within the valve body (not including the large pop-can size one that seals the valve body to the motor. Is this normal?

In one of the holes (where the small spring goes - see screw driver reference), I found little black pieces not sure if this is the remains of a gasket?

In one of the large holes (see screw driver reference) I found some brown sludge. Not sure what this might have been.

Finally, In the oval slots where the two silver balls sit, I've noticed some potential wear in the metal. Is that normal?

Appreciate everyone's feedback! Thanks

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

All, Any thoughts on the condition of my valve body? I'm feeling lonely! Appreciate everyone's expertise.

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

All,

I'm continuing to add to this post I as read and re-read other posts on the subject. I've finally figured out where the o-rings go and have taken apart the very bottom of my valve body. I'm noting two different colors of o-rings which may indicate someone previously tried to work on this. One thing I found suspicious is the black o-ring almost has a separate sleeve type ring (by sleeve type I mean relatively flat ring vs. a round o-ring) on top of each other. I cannot imagine this is to specs.... You'll notice in one of the photos I placed the o-ring ajar a bit. When I popped this valve out the sleeve type ring was essentially on top of the black ring that is still in place.

A) Is it possible the sleeve type ring slid down from somewhere else along the metal? I'm doubting this.

B) Did someone not have the proper o-ring size and simply try to double it up? In this case, it would appear to be 'extra' assuming I find the right ring.

The green rings in the photos look 'OK' in the sense that they do not appear to be cracking or disintegrating. Whether or not they are of proper size is a different question.

Now that I am at this stage, does anyone know what size o-rings I should have and where the best place to order them is?

NOTE - there is also one black o-ring on the center metal piece, but this is hard to show in photos.

Thanks much!!!!!

 

[pnwboat]

Re: Tilt / Trim Force 50hp - Slow Leak

You're almost there. Attached is a further breakdown of the check valves. There is a very small O ring inside. If it is leaking, your motor won't stay up. You have to pry off the cap of the check valve to get to the O ring inside.



If you notice that there is a small spring and a plunger with a small nipple on it. The small O ring fits over the nipple.

Another picture of the dis-asembled check valve. This is an earlier version but I'm pretty sure it's the same as yours. Note: the small plunger and spring are reversed as far as the way they are assembled. First picture shows proper orientation. Also note the plier marks on the cap and the body of the check valve.



Here is the plunger with the small nipple. Whats left of the original black O ring and the new red replacement.




Part number of the replacement O ring.




Hope this helps.

 

[RRitt]

Re: Tilt / Trim Force 50hp - Slow Leak

pnwboat has your answer.
those little red seals are why your system bleeds down.

the green seals in your previous post are not normal and mean that somebody already tried to fix it. Green is usually a silicone and it does not work very well with the combination of petroleum, water, and pressure. Standard BUNA or VITON is your best choice. I think the sizes you need to replace green orings are #012 and #015. The outer ring should be hardness 90 if you have the choice available. The inner one should be hardness 70 (most common flavor). Just put the top half back together exactly the way you found it. don't change the post height adjustment or use cheap grade balls or anything else. Just apply tiny bit of vaseline as pre-lube and put it back exactly the same. If you have some engine assembly grease that would be better.

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

RiTT & PNWBoat,

Thanks so much. Your feedback was incredibly helpful. Question regarding the plier marks on the check valve? Does this mean the check valve is wrecked? I tried prying the cap out as well as use some pliers, but I have not been able to budge the cap up to this point.... particularly as I didn't want to mark up the cap. If I know a couple of marks are OK, I can obviously try a bit harder.

Thanks!

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

RRitt,

Forgot to ask a point of clarification. Are you suggesting a replace the exisiting silver balls with new ones? Also, where should I apply the pre-lube once I'm ready to re-assemble. Thanks

 

[pnwboat]

Re: Tilt / Trim Force 50hp - Slow Leak

The check valve pictured is probably OK, but just wanted to point out that they are made out of aluminum and easily damaged. Sometimes warming the check valve up a bit helps to get the cap off. Be careful if you suddenly pop the cap off. The spring and plunger will to shoot out of there if you're not careful.

I usually replace the check balls with type 316 stainless steel alloy ones. You usually have to purchase them in bulk though. Make sure you measure the original ones carefully.( McMaster-Carr ) Not sure what the original ones are made of, but I've seen some that were really badly rusted/pitted. If the check balls show any signs of pitting on the surface or corrosion then they should be replaced. If not, it's probably OK to re-use if you're in a pinch. Pre-lube should be applied to all the O rings and surfaces that the O rings seal against. Also dab some on the gears.

 

[RRitt]

Re: Tilt / Trim Force 50hp - Slow Leak

RRitt,

Forgot to ask a point of clarification. Are you suggesting a replace the exisiting silver balls with new ones? Also, where should I apply the pre-lube once I'm ready to re-assemble. Thanks

if they are rusty, otherwise no. the risk of getting low metal grade or low precision does not justify replacement. i have a 60/40 mix of tranny fluid and vaseline and a small brush. I make sure to get into the gear teeth and then just paint a thin coat over the whole plate. the hard part is getting the balls to stay in place. You can ruin the VB if you pinch one and put dimples into the aluminum. assemble upside down with a good light and keep your eyes on the BBs.

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

Thanks guys! This is all great stuff. I'll order parts tonight and add to the post once I complete the work. Hopefully I'll be able to report a successful fix!

 

[N2Motors]

Re: Tilt / Trim Force 50hp - Slow Leak

Guys,

A bit of an update here. Unfortunately I have to report only partial success. Whereas before the slow leak would cause my motor to drop completely within 5-10 minutes, I'm now have a motor that will drop about 3/4 over a week. I've posted a part of the tilt mechanism so you can see how far it has fallen. Again, this is after about 1 week.

Interesting to note that after a week, it does not seem to drop any further. In the picture I have posted, I had it all the way up, but in other examples of me testing, I would raise it to different levels and I seem to get similar results (drops a bit and then stops).

Any thought on my prognoses. Could it still be working air out of the system? Could I not be using the right oil (I ended up using regular hydraulic oil)?

Appreciate your thoughts.

 

[DAN M VAGOS]

Re: Tilt / Trim Force 50hp - Slow Leak

I to have a force 50 that's leaking to and I can't get over how helpfull this post was. I pulled my valve all apart and found only one seal on one plunger and a collapsed spring so I think I found my problem lol. Thanks agen

 

[pnwboat]

Re: Tilt / Trim Force 50hp - Slow Leak

N2motors, check for leaks around the hydraulic screw in fittings on the valve body and the Trim/Tilt cylinders. If no leaks, then I would suspect the "O" rings in the Tilt cylinder may be leaking. That is the tall cylinder with the hydraulic line attached to the upper left portion of the cylinder. Maybe RRitt will chime in and give us his thoughts.

 

[RRitt]

Re: Tilt / Trim Force 50hp - Slow Leak

It is most likely still the check valve.

Generally speaking, there is no need to rebuild Force rams until you see cracking or hardening of the top seal on tilt piston. If you do see any deterioration of top seal then rams should be rebuilt asap. Sometimes in saltwater, galvanic corrosion will push up the center seal on trim piston first. Galvanic corrosion under center seal is a serious problem and should be fixed before fatal. It will eventually push out the aluminum retainer and ruin the brass centering ring. With the exception of 120-150HP engines built by mercury-force, internal seal failure almost never happens. When it does it is usually the result of water getting into oil and hardening orings.

 

[jerryjerry05]

Re: Tilt / Trim Force 50hp - Slow Leak

Hope i'm not doing something wrong again??
I have some NLA parts for a 50 trm/tilt. Willing to trade???If needed contact me.
Have you done the leakdown test?
It's in the manual?
With out doing that your guessing, RRitt Knows!!
Profile?location? You might be close to someone who can help.