trim pump question

[Fishermark]

On the project boat I am working on?. (An early 70?s vintage SeaRay with a Mercruiser inline 6 and pre-alpha outdrive).

Taking a break from the engine work - (waiting for a new coupler to arrive). Decided to work on the trim and tilt mechanism. After wiring it up and topping it off with fluid, it only works going ?up? not ?down.?

I downloaded the appropriate manual (looks like I did so just in time - I see from another post that the online version has been shut down - is that true?). According to the manual I have a high pressure, large reservoir pump. As noted in the picture below, there are quite a few ?extra? parts that I am not familiar with from my Alpha experience:

Now when I say it doesn?t work going down, what I mean is the pump motor runs, the drive simply doesn?t move. I loosened the trim lines and pushed the unit down, hooked it back up and again, the outdrive will go all the way up to the trailer position, but will not go down at all.

Suggestions???

On a related note, the trim pump calls for ?MS rated 20W oil.? I noted that there was red fluid in the pump currently, which I took to be transmission fluid. I topped it off with transmission fluid. Is it safe to assume that it should work with this - even if that is not the technically correct fluid? (In the manual, it mentions installing a new pump and saying the ?oil in the pump will mix with automatic transmission fluid in cylinders with no ill effect.?) Having said that - what is MS rated 20W oil??

One last note,: in order to get the outdrive in the down position, I had to remove the down trim lines as mentioned. Even then, the outdrive didn?t go down on its own - I had to push it down, and it seemed stiff. Is that normal?

 

[Fishermark]

Re: trim pump question

By the way, I should probably start a new thread for this, but I also found what I believe is the engine serial number metal tag - I can see on the engine block where it had been riveted on, the tag was in the glove box of the boat. Can anyone help identify this engine:
serial number: 2917271

Boat serial # 70-190 I/O 454

 

[Haut Medoc]

Re: trim pump question

I'm guessing that the rams are corroded......
There is alot more power/pressure on the 'up' than 'down'.....
You might try moving them up & down several times & see if that helps....​

 

[Don S]

Re: trim pump question

I would bet you have pump problems. You need to hook up a gauge to the down side, you should see between 650 and 1000 psi.

 

[Fishermark]

Re: trim pump question

The rams show no obvious signs of corrosion - in fact they look pretty good. The seals could be hardened I suppose - but they go up easily enough.

I saw the pressure reading in the manual Don - I don't have a gauge, (I know that's not your problem ), I may try and pick one up. But I think you may be right. I removed both down hoses from the rams and operated the pump. Oil came out, but it didn't "seem" like it was under very much pressure - certainly not 650 - 1000 psi.

What about the serial number? Can you help me identify my engine more precisely?

 

[Fishermark]

Re: trim pump question

Back to the question of oil - what is the right oil to use?

Just what is 20W MS rated oil? Inquiring minds want to know!

I have a jug of clear trim pump oil from wally world - it is thin - probably less than 20W - in fact, about the same consistency as transmission fluid. If no one has a better suggestion, I guess I will keep the transmission fluid in it.

 

[Fishermark]

Re: trim pump question

One more point on the trim pump pressures.... the manaul also states the "up" pressure should be in the 2700 - 3000 psi range!

Since it takes more pressure, theoretically, to raise the drive than to lower it, and since it goes up just fine... doesn't that rule out the probability that the pump is bad

 

[Don S]

Re: trim pump question

The downside has only 1/3rd that pressure. When going up, it will only need those pressures when under heavy loads. In your driveway, it won't need more than a few hundred pounds to raise it.

The MS oil is a VERY OLD oil classification. Use 20W oil, it will work fine.

 

[rodbolt]

Re: trim pump question

the MS was an API rating best I remember. mostly applied to non-detergent oils.
same as SC,SJ,SD and so on.
not sure you can still find an oil with an MS rating in 20wt.
but I saw many of your units both with and without the trim sender that had down issues. like DonS said, about the only way to isolate it is to use the pressure tester.
or the poke-N-hope method.
in our salt pond it was mostly the cap ID was corroding down against the trim shafts and locking the shaft in the ram cap.
occasionally we would have a bad main,shuttle or check valve in the pump assy.
I dont think much is still avalible for it anymore.
I have hd sucess with standard trim and tilt fluids.
biggest thing was some early oil detergent additives tended to attack the orings and would settle out forming a mud that would clog small ports.
man I am feeling old

 

[Fishermark]

Re: trim pump question

man I am feeling old

Hey, I resemble that remark!

Thanks for the additional info rodbolt - is this the same rodbolt who has been posting for a long time - did you redo your screen name?

 

[Don S]

Re: trim pump question

Yea, it's our same ole (OLD) rodbolt, he's just down in Venezuela fishing and forgot his password to get in.
I know this because I ask the same thing a week or two ago.

 

[Gary H NC]

Re: trim pump question

The new updated version of RodBolt...When is RodBolt 2.0 being released?

 

[Don S]

Re: trim pump question

Release date for 2.0 depends on how BIG and how MANY fish he catches while he's down there. Shoot, he may forget about Kitty Hawk.

 

[rodbolt]

Re: trim pump question

wow
you guys are hard on an old man, think Ill go get nother glass of Santa Theresa Rum. about the best in the world
I outta bring ole DonS back a bottle
but yep, forgot my password so I had to re register.
I dunno which is worse, loseing my eyesight or forgetting what I was looking at.
think Ill get another glass and ponder, or wonder, HMMMMM

 

[Don S]

Re: trim pump question

HEY, no drinking and having fun while answering questions on the board. You know better

 

[rodbolt]

Re: trim pump question

o
I fergit
CRS is terrible. now where did I place my glass
no real big fish this time,13.5 was it.
but peacock bass are nasty and Payara are even worse

 

[whywhyzed]

Re: trim pump question

If the trim pump is running freely when activating DOWN (i.e. it doesn't sound like the electric motor is working too hard), then I suspect the DOWN relief valve, #16 on the diagram has a piece of crud in it the ball is stuck open.... or the ball,spring or seat is damaged in there... allowing the oil to take the path of least resistance back to the reservoir through there, rather than go out through #11 and out to the cylinder...

I can see those tricky buggers did some neat things with this system btw... That sender cylinder is also a pressure intensifier due to the imbalance of effective areas..which is part of why you don't need much pressure for DOWN... that sender "slave" cylinder is going to boost it to the trim cylinders...but it will also decrease the volume (by an amount equal to the displacement of the rod that sticks out to work the sender) to slow down the DOWN travel of the trim and give equal or near equal speeds extending and retracting the trim cylinders..... as well as working the sender....cool system but why so complex beyond me.... none of my Mercruiser boats ever had that sender cylinder deal...must be only certain year range had that

 

[rodbolt]

Re: trim pump question

actually very few had the trim sender option as it was rather pricey. most trim systems typically dont use much pressure for trim down as gravity and prop thrust tend to do just fine, in fact a few systems use no pressure for down just gravity and prop thrust.
usually with the above system if it would not go down it was a mechanical binding,especially if you could stand on the cavitation plate and it worked fine then.
but the only way to tell for sure was with the presure test manifold and guage assy.
last parts I needed for that setup were NLA from merc.

 

[Fishermark]

Re: trim pump question

Well, since it's rare, here's a picture!

Maybe I'll take it onto Antiques Roadshow and make enough money off of it to replace it with something I can actually get parts for!

If I cannot clean up and eliminate the rams as the problem, I may take it somewhere so they can pressure test the system. I looked online, and the pressure test kit (Mercruiser pn 91-52915A6) is something like $300 - more than I need to spend on a tool that I would use very little!

 

[Fishermark]

Re: trim pump question

Well, I think I found the problem. After removing the hoses from both rams, one moves back and forth by hand easily, while the other is STUCK. I cannot begin to move the ram in and out. If I hook up the one ram that is stuck to the outdrive, I can physically move the outdrive up and down - but just barely.

The funny thing is it looks okay, but obviously the o-rings inside are hardened and stiff.

Here's a picture of the ram disassembled:

The brass looking piece, (called a rear bearing in the manual - it's like a floating piston), is supposed to slide back and forth fairly freely.

I have the rebuild kit with new o-rings, etc. But the problem is that bearing / piston is stuck and I cannot slide it off. I will tackle it tomorrow, but in the meantime... any ideas or tips on getting it off without damaging it?

Also, according to the manual - there are two o-rings inside that piston.... any basic tips or "gotchas" I should watch out for when reinstalling the o-rings, etc. I know to lubricate them well. Just wanting to make sure I am covering my bases in advance.