trim cylinder issue

[DFWcobalt]

Apologies for resurrecting this one but having a similar issue with my VP outdrive; holds trim on the trailer just fine, but under load the prop thrust pushes her right back down.
Local shop said they couldn't find any leaks, but I can assure you that the outdrive will get pushed down. No oil visible on the drive cylinders, or under the drive when on the trailer.
I suspect the check valve in the pump. Any way to diagnose this with certainty? Would a leaky check valve just allow pressure to escape, or would/could there be a tiny leak somewhere on the pump and oil would go into the bildge?
thanks

 

[Scott Danforth]

moved your post out of an old thread

you have a leak at the cylinder. its bypassing the piston.

find a different shop, get your cylinders rebuilt or rebuild them yourself.

 

[DFWcobalt]

Thank you very much!

I'm quite sure the rebuild will be way cheaper than the local cobalt shop asking for 5k to replace the pump and both cylinders!

 

[Lou C]

I did the ones on my old Cobra a couple of years ago and as long as you can get the end cap off it’s not a hard job. Parts cost was $52 per cyl.

 

[Scott Danforth]

$75 for a rebuild kit, takes about an hour

If you don't have the pin spanner, it's about $40

 

[DFWcobalt]

Best source for rebuild kit? DP-SM

Also, how do i bleed any air from the system post-rebuild?

 

[Scott Danforth]

I use five-stare marine out of Florida

if you look at the link in my sig (near the last few pages), I go thru the rebuilding process.

take care when re-inserting the piston so you do not cut the piston seal.

Thank you very much!

I'm quite sure the rebuild will be way cheaper than the local cobalt shop asking for 5k to replace the pump and both cylinders!

BTW, that is not a "repair" that is a parts cannon firing parts swap

hydraulic piston seals last about 15-20 years. thats why hydraulic cylinders are rebuildable.

 

[Bondo]

Best source for rebuild kit? DP-SM

Also, how do i bleed any air from the system post-rebuild?

Ayuh,...... Just run it up, 'n down a few times, keeping the tank full,......

 

[DFWcobalt]

Would a pin spanner used to chuck an angle grinder work on the trim cylinder? Seems to be the right size, just not sure how much torque it has to hold to bust the end caps free

 

[Bondo]

Would a pin spanner used to chuck an angle grinder work on the trim cylinder? Seems to be the right size, just not sure how much torque it has to hold to bust the end caps free

Ayuh,.... Sounds like it oughta work,......

til it don't,....

 

[Scott Danforth]

Would a pin spanner used to chuck an angle grinder work on the trim cylinder? Seems to be the right size, just not sure how much torque it has to hold to bust the end caps free

only if it fits.

this is the pin spanner that I had to use on my VP cylinders. I also had to modify it to fit around the shaft.

 

[Scott Danforth]

these can work, however are more expensive than the correct ones.

these do not work that well, however I have used them. just takes 3 hands. still more expensive than the correct ones (I got mine on amazon)





I picked up one like the one on the right, then modified it like the ones in the middle.

 

[DFWcobalt]

Got a proper spanner and got after it. Super easy so far. Waiting on UPS for new parta.

 

[DFWcobalt]

I just got my kit from five star. It includes six very small o-rings, and my teardown did not find any of these. Any ideas where these might go?

DP-SM. Five star kit fsm0007.

Thx

 

[dypcdiver]

Probably the hose end seals to the cylinder, make sure you get the old ones out as they are very small and a bit difficult to see.

 

[DFWcobalt]

Zoomed in on my pic and I see one line with one and one without.
So assuming each line gets one (4 total) and five star sent two extras?

 

[Lou C]

You dont even have to remove the cylinders from the transom mount to do this job, as long as none of the trim hoses are leaking!

 

[DFWcobalt]

Too late now

How the heck do i keep the split rings in place when i try to put the assembly back into the cylinder?

 

[DFWcobalt]

Well sh*t. Project halted.
One of the rings got pinched and broke

 

[Lou C]

Ok when I did my Cobra cylinders in the instructions I got with the BRP kit there is a trick using a tin can to compress the split rings without damaging them. I’ll see if I can find pix of what I did.