Trim cylinders leaking after cap replacement, backstory given, advice/experience?

[SweetD]

Hi Folks,

Under the category of "it's always something":

Earlier this Spring, I had a trim cylinder leak on my 2005 Johnson 90hp with the common Showa model trim/tilt. I replaced both trim cap assemblies with new aftermarket replacements that can be found on eBay, after reading positive reviews and contacting the seller, who assured me the aftermarket parts are high quality and they use them in their own business, which is rebuilding trim/tilt units. They had these parts, including all of the o-rings/seals, manufactured for their use. So they now also sell the parts on eBay and Amazon.

Anyway, I installed the caps back in the first week of June. Everything went smoothly and I'm sure I installed them correctly, including torquing to spec. I also replaced both trim rods with used, but in excellent condition, rods from a freshwater motor. My original trim rods were getting pretty corroded and I didn't want to risk re-using them. The "new" ones have no corrosion, pitting or nicks at all.

This weekend I noticed I have a small leak out of both caps at the wiper seal where the rods push through. It's not leaking when not actuated - i.e. - it "stops" leaking when sitting for a bit. I'm getting a couple of drops leaking immediately when actuated down then up. Of course as the motor is used in real time, it gets actuated frequently and hence more leaking I am sure.

Am I correct in that the inner o-ring in the cap should not be allowing fluid past? The wiper seal on the outside is there to help prevent debris/water from ingress into the cylinder, and not stop fluid leaking out? If so, I'm guessing the inner o-ring seals are not sealing correctly against the trim rods.

Finally, has anyone had this experience? I'm not interested in faulting the seller or his/her business - aftermarket parts are buyer beware. I'm kicking myself for not going with OEM in the first place to save a few bucks, but that's water under the bridge now. For those with experience using aftermarket trim/tilt seals vs. OEM, will OEM parts likely make the difference for me? I'm not sure what else I can do at this point other than give OEM a shot and put my tail between my legs for wasting some dough.

Thoughts?

Many Thanks

 

[jakedaawg]

Personally I would take the caps and rods to your local hydraulic place...every large town has one or three...seals are seals, hydraulic is one place where OEM doesn't matter. There are only a few places that make all that stuff. Let a pro hydraulic guy take a crack at it. You will be surprised how inexpensive it is. I.E.: Volvo penta TNT cylinders, I take them to my local guy and they come back perfect for $65. He charges me an extra $15 over what would be a $50 dollar job because they are metric. He hates metric.

 

[SweetD]

Thanks Jake for the feedback and idea, I may have to resort to it.

I made a quick video this evening showing how loose the new aftermarket inner cap seal fits over my old trim rods, which are of course the same as the new trim rods. Now, the seal is not actually in the cap of course, but watch how easily it falls up and down the rod - I would think the inner seal should be a tighter fit, like the wiper seal is that I also show. What do you guys think?

https://photos.app.goo.gl/1cScwFjV3FF5bE896

Thanks,
Dave

 

[dingbat]

Throwing money (OEM) parts at it isn’t the solution.
You need to know exactly what is going on and why.

Wipers don’t seal. Their purpose is first line of defense for external contamination entering the system.

Did you replace the piston seals while you had it apart?

Did you measure old and new seals? You could be dealing with a metric to SAE issue

 

[SweetD]

Throwing money (OEM) parts at it isn’t the solution.
You need to know exactly what is going on and why.

Wipers don’t seal. Their purpose is first line of defense for external contamination entering the system.

Did you replace the piston seals while you had it apart?

I'm not looking to throw money at it, which is why I am asking for anyone's relevant experience with this issue. I have seen many instances over the years where OEM parts/seals/whatever do make a difference in all kinds of different equipment. In this case, the aftermarket parts are supposedly used in many tilt/trim rebuilds by a professional shop, the same shop that sells the same parts to the general public. So it seems strange they would not work in my case.

Yes, every seal was replaced with new, aftermarket seals. The new cylinder caps are also aftermarket as mentioned. Everything is new.

Another note, I went down to the boat for a few minutes tonight after work and actuated the tilt/trim. It didn't leak, and I actuated it fully twice. But, it has been sitting unused for just under 24 hours. Didn't have a lot of time to mess around this evening.

Did you take a look at that vid I posted above? Those inner cap seals seem very loose fitting to me. Wish I had an OEM one to compare.

Thanks for your input.

Dave

 

[jakedaawg]

They look a little loose but seals, in my experience, are determined by careful measurement. Then, once you have consulted the book with your dimensions, you buy the seals, backers, and wipes, install them and viola, they work. I honestly have never just put a seal on a ram without it being in the groove of the gland or whatever.

 

[dingbat]

Yes, every seal was replaced with new, aftermarket seals. The new cylinder caps are also aftermarket as mentioned. Everything is new.

Another note, I went down to the boat for a few minutes tonight after work and actuated the tilt/trim. It didn't leak, and I actuated it fully twice. But, it has been sitting unused for just under 24 hours. Didn't have a lot of time to mess around this evening.

Did you take a look at that vid I posted above? Those inner cap seals seem very loose fitting to me. Wish I had an OEM one to compare.

The OEM didn’t make the parts, they spec’d them.

Seals and o-rings are built to industry standard sizes and tolerances. Measure the old part, select the matching seal or oring.

Seals often/usually swell when exposed to many kinds of petroleum based fluids. Could be the seal was expected to swell and simply sized accordingly.

 

[SweetD]

So just an update, I went down to the dock after work tonight and actuated the tilt/trim several times. After four times down and up the tell-tale leak occurred. I'm not sure what to do but get another set of seals and redo the whole thing. P.S., that's not wear on the top of the trim ram, it's residue:

 

[SweetD]

The OEM didn’t make the parts, they spec’d them.

Seals and o-rings are built to industry standard sizes and tolerances. Measure the old part, select the matching seal or oring.

Seals often/usually swell when exposed to many kinds of petroleum based fluids. Could be the seal was expected to swell and simply sized accordingly.

Good info. Can you clarify on your statement "the seal was expected to swell and simply sized accordingly"?

Do you mean that it swelled to its expected dimension, which isn't where it needs to be? My understanding is that o-rings/seals are usually designed to deform when pressurized, in order to seal. Perhaps the seal is just not swelling/deforming to spec?

Thanks,
Dave

 

[dingbat]

Good info. Can you clarify on your statement "the seal was expected to swell and simply sized accordingly"?

Do you mean that it swelled to its expected dimension, which isn't where it needs to be? My understanding is that o-rings/seals are usually designed to deform when pressurized, in order to seal. Perhaps the seal is just not swelling/deforming to spec?

Thanks,
Dave

orings are used in pressure and vacuum, static and dynamic applications. The only difference being the compression rates with are controlled using the size (wxd), shape and tolerance of the groove which it mounts.

Seals are sized to shaft size. Min. and Max. shaft tolerances apply.

The other issue is the difference in cross sections between metric and SAE o ring. The sizes are so close, yet outside allowable groove tolerance, that you need calipers or a micrometer to determine which is which.

The only way to get to the bottom of the problem is to start measuring parts.

The first thing to check is the cross sections. Quick way to rule out a inch/metric mismatch.

Oring and seal lube is a must when assembling hydraulic components.

The swelling of materials is a known and quantified in documentation but.... I know of no application that you would purposely under size a part to compensate

 

[flyingscott]

Inside that cap should have been an o -ring with rubber backing rings i believe. Did you install those correctly. They are usually formed to the oring. That is the seal it is leaking past.Did you lube the orings before you put them in.

 

[SweetD]

Thanks dingbat. I would hope that when someone is selling a replacement seal kit for a specific use, they would properly size the parts.

flyingscott - the seals came pre-installed with the caps. They actually had a dab of silicone grease on the assembly already, and the instructions said to spread that grease on the inner part of the cap. I also lubed the shaft and the inside of the cap with the hydraulic fluid (ATF, Dextron 3) as suggested. I had no trouble installing the caps to the rods, they went on smoothly and didn't jam at all.

Here is a picture of the inner seal from the aftermarket kit I have on hand. I'm assuming the same type/size seal was used that was pre-installed into the cap. It looks like what you describe with the integrated backing rings, but the "rings" stand proud of the diameter of the center "o-ring", effectively forming a channel it seems:

 

[SweetD]

Update, I spoke with the owner of the company from where I bought the caps/seals. He was totally reasonable. He told me they sell a hundred seal sets per month during the boating season, and use all of their own aftermarket caps and seals on all of the rebuilds they do, and they seem very busy.

They have sent me a new set of cap assy's and I will carefully install them once again. Hoping this solves it. If not, may send in unit for full rebuild. I will update.

 

[SweetD]

OK, I broke the system down, emptied the fluid, cleaned it out, put the new seals in the caps, and put it back together. Bled the system, all is working. Of course the "working system" part was never the problem, it's the "leaking system". Didn't notice anything unusual, seals looked good and fluid looked clean and free of water.

I don't have high hopes to be honest because ultimately I didn't really change anything, but who knows. I feel a bit like the old definition of insanity. I guess I'll find out soon enough.

If it still leaks, I'm not sure what to do but have it rebuilt or find a nice used unit, which is difficult I think.