1990 90 hp mercury trim HELP!!

[philipjames5k5]

So I shredded all kinds of things in my old trim motor, so I went to change the trim motor, and I figured I would clean the trim manifold, but when I took the four bolts out and lifted up all kinds of parts fell out. Now I do not know what goes where. I've tried to make this as easy as possible. Please let me know what else you guys need to help me. I could not find a schematic view of the pieces inside the manifold.

 

[achris]

Re: 1990 90 hp mercury trim HELP!!

That's not good.... Also because Merc never intended the pumps to be repaired, they are a 'replace' item, so there are no diagrams in the Merc manuals...

The good news it they are likely not a Merc designed and built pump, but one they just buy in. You might be lucky and find out who made the pump and they may have manuals for it...

Chris.....

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

put gears back into same holes and same direction in order to avoid binding or wobble.
make sure to lubricate when assembling so that the gears don't burn.
pistons go into holes with the sharp needle down and fat needle up.
make sure pistons slide easily. If there is even the slightest binding then the pump won't work.
place ball bearings on base and springs into holes. press down lightly on spring and it will catch into place.
while holding pistons in place, lower the gearplate down onto manifold.
finger tighten the three short bolts and verify that gears spin freely.
install rocker arm.
tighten each bolts in pattern similar to torquing cylinder head.
frequently check that gears spin freely while tightening.

This model pump is extremely finicky about rebuild. Everything has to be perfect or the pump will have difficulty reversing directions. If you just clean them and put everything back together then the failure rate is going to around 30%. Everything has to be perfect. If it is then your rebuild failure rate will drop to about 5%.

 

[philipjames5k5]

Re: 1990 90 hp mercury trim HELP!!

Ok Im not home near my boat today. Are the ball bearings in the actual pump because I did not see any with this manifold

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

the two in question sit loose on top of the manifold as you lower the gearplate into place. watch the springs as they make contact and keep everything straight with jewelers screwdriver if needed. the third BB is made from delrin and sits on top of a spring, underneath an oring seal. It is a common point of failure, but I doubt you have the capacity to repair if anything is wrong ... so just make sure the bb and spring are free inside hole and that seal lines up as you assemble.

 

[philipjames5k5]

Re: 1990 90 hp mercury trim HELP!!

I am out of my league here. Is the gear plate this shiny cylinder in my pictures? I have no ball bearings, what you see in the picture is what I got. So Im hoping that the bearings you speak of are on the pump itself.

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

be patient and I'll try to put up some pictures. I just started a batch of these. Looks like about 50 in this batch. Everything is done in steps so that each specialized tool only gets set up and put away once. It could be the end of week before i get to the pictures you need. If you finish before then, please post a note and I'll work through without losing time on a photo session.

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

did one just for you. no words just pictures. there is so much more to it than pictures can convey. However, these should show you what goes where. Just make sure that every part and every surface is perfectly shiny, smooth, and new. Apply assembly lubricant to everything.

 

[Archer59]

Re: 1990 90 hp mercury trim HELP!!

Nice pictures. I had mine apart last month. There were shards of filler plug throughout.

Make sure you blow air through every spot you possibly can. In pic #2 there are two springs under the two symmetrical circles. ( I didn't take them apart ) I used a can of air with the spray tube to depress the springs and spray. I had one that was sticking until it did this. When you bolt the two pieces back to together make sure you can spin the gears after tightening. I had to play around with bolts until I got it right.

Good Luck,

 

[Archer59]

Re: 1990 90 hp mercury trim HELP!!

RRitt,

In pic 2 how do the two silver discs holding the spring in the manifold come off? Small hex key in the hole and pry? Mine is working fine now (knock on wood) and didn't take those apart.

Thanks.

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

you can buy a set of hooks, picks, and probes. I used a dremel & drill stock. Each hook, chisel point, and extractor is shaped for a specific task. When you do them 50 at a time it pays off. When doing 1 you would just end up with a tool bench covered in small tools.

if I needed a one-off then ... i would probably just cut a notch into the end of a small hex shaft. When finished, cut square and turn it back into an allen wrench.

 

[philipjames5k5]

Re: 1990 90 hp mercury trim HELP!!

RRitt
If this unit fails when I replace it, can I buy the unit you have pictured? Also in picture 5 are those orings in the two little holes? You are very helpful thank you

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

RRitt
If this unit fails when I replace it, can I buy the unit you have pictured? Also in picture 5 are those orings in the two little holes? You are very helpful thank you

LOL. The exact one in pictures may not work. I only did that one so I could take pictures for you. I did not do any detail work and my failure rate without detail work is around 30%. With detail work it drops to around 5%. The rebuild takes about 90 minutes per pump with detail. Most important part is that the rocker arm and pistons must slide perfectly. There should be so little friction that the rocker arm will move and push down the pistons by just spinning an allen wrench with your fingers. If you lightly tap a piston it should depress and pop back up with any catch or hesitation. Or. put another way, the rocker arm mechanism should work fine in both directions just pumping air as you spin a drive shaft between your fingers. If it does that then you failure rate will be 2-4 per every hundred rebuilds.

But the problem is ... how do I know which one or two out of every bucket will fail? It takes more time to assemble, test, dis-assemble, and clean than it does to do a full system rebuild. If I could figure out a cheap way to test then I'd already be selling full rebuild kits on ebay. I guess if you accept the 1/20 risk of wasting your time and postage then I could pull one from inventory. There is no way to price efficiently guarantee it won't be the black sheep.

all standard orings used in gearcase are shown in picture 1. No orings are visible from top of a finished manifold/pump assembly. The side valve takes 3 @ #011 and 1 @ #006.

 

[philipjames5k5]

Re: 1990 90 hp mercury trim HELP!!

Ok so I never took apart the bottom part of the manifold like you showed in your first picture I am missing the derlin ball and o ring. So what I have pictured in the original post and the picture attached in this post. Any hints on where I can get the plastic ball? looks like that and the o ring are the only things missing.

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

7/32 delrin balls come in bags of 100. local grainger is probably the best bet.
However, I think you could get away with a 7/32 metal hardware store ball bearing on this port.
I am thinking that the hole in aluminum plate is very small. A perfectly round ball may not be needed.
i can't remember if it is a size #006 or #008 oring.

 

[philipjames5k5]

Re: 1990 90 hp mercury trim HELP!!

RRitt,
Sorry for all the questions, is there a way to find out the oring size or does it matter if its a #006 or #008, and I have had zero luck finding 7/32 delrin balls in hardware stores and online for that matter

 

[RRitt]

Re: 1990 90 hp mercury trim HELP!!

try using a 7/32 metal ball bearing from your local ace hardware. I think it might work.
or this
7 32" inch Loose Ceramic Balls AL2O3 Alumina Oxide Bearing Balls 11924 | eBay

yes, orings need to be precise. BN70 rubber needs to be compressed between 10-20% in order to work properly. It needs need to be of quality material to last. I think the releif seal is #008 for your pump.