1990 fORCE 90HP Engine Questions

[HAMMER1111]

Hello All:

I am new to the boat world and have a few questions about a boat I just got. I was lucky enough do get a boat for free. A 1990 Maxum 17' bowrider. Hull and interior is in great shape. May need to put rings in the engine but not sure yet.\

Questions

1. When the engine is in the up position it creeps down. Does the pump have an internal check valve or does the seals in the cylinders need replacement? I cant find a breakdown of the pump anywhere on the net.

2. I noticed that the 1 cylinder does not have hydraulic lines attached and no hole for lines. Is that a helper cylinder only?

3. What do you think is the best thing to do about the engine. Should I attempt to break the block and install new rings? Should I buy a used powerhead? Money is tite but I never took a block apart. I can fix all other problems with cars and trucks but never had an engine completly apart like that. Any feedbackI would appreciate.

Thanks

 

[Jiggz]

Re: 1990 fORCE 90HP Engine Questions

If you can post pics of the problem about the tilt and trim system (I believe this is what you are referring to about the engine creeping down) it will make it easier and probably get more direct responses addressing the problem. As for changing rings, first you need to do a compression test on all cylinders to identify which cylinder has a problem. If compression tests are no good, the next step is to search this forum on how to replace pistons and or piston rings. And then you should already have a knowledge on how to remove the head to do an open and inspect. From there you can make an assessment on what your next step will be. If the cylinder is gouged so bad, you might not even need to replace rings but instead more like about changing power heads.

 

[pnwboat]

Re: 1990 fORCE 90HP Engine Questions

The one cylinder that does not have any hydraulic lines to it is a shock absorber.

Most folks that are mechanically inclined are able to take the block apart and re-assemble. Hardest part is finding a machine shop that does outboard blocks. Most automotive machine shops are not inclined to do machine work on an outboard block. Average cost for boring an outboard cylinder is $30 - $40 range. Also, removing the wrist pins from the rod requires a press. Preferably a hydraulic press. Forged replacement pistons like the Wiseco brand have "floating" wrist pins, so no need for a press, but you need special wrist pin bearings. The stock ones won't work with the Wisesco pistons.

 

[HAMMER1111]

Re: 1990 fORCE 90HP Engine Questions

I removed the trim and tilt last night and found that the one seal in the hydraulic is not as wide as the cylinder grove. Some investigating tells me that it will leak past the seal if that is the case. Yes after the removal I did figure out that the other is a shock only. I will try and find seal today at the store. I still doent know if there is an internal check valve on the pump. If the seals are good then the pump may be the problem. CORRECT.

For the compression test I may be crazy or the tester I bought from harbor freight the other day doesn't work. I tested each cylinder and found that none of them have compression. It bouncing at 30 psi only. I have to maybe hook it to my lawn mower to see if the tester is bad. I am in luck as there is a machine shop close to me that does car engines. I will stop by today and ask if they do boats.

You mentioned that I can inspect the pistons by removing the head only.-Is this true?

Thanks

 

[jerryjerry05]

Re: 1990 fORCE 90HP Engine Questions

Start with the profile?Location?
You might be close to someone who can help.
Then a compression test.
There are some shops around the country that will do a bore job, most wont.
I have to travel about 35mi. to get to one here.
Gotta make sure what motor your working on too.
Possible it's been changed?
The drift down is usually the hyd. pump in the T/T unit.
They sell new junk units from china or a guy(RRitt) on here rebuilds the OEM units.

 

[Frank Acampora]

Re: 1990 fORCE 90HP Engine Questions

The O-ring inside the tilt cylinder and the trim cylinder is normally a bit smaller than the width of the groove it rides in. As long as it contacts the cylinder wall it will seal. Typically a bad O-ring will cause the engine to drop rather quickly--less than 30 seconds. A bad seal inside the pump will also cause the engine to drop. It starts slowly and accelerates as the O-ring wears and dissolves until the engine will drop in seconds.

 

[HAMMER1111]

Re: 1990 fORCE 90HP Engine Questions

I changed the seals in the cylinders last night so Im good to go with them. I disassembled the pump but no good. The interals of the pump dont look good. I think I will have to buy one because one of the ears on the hydraulic cap is eroded and the plastic pump housing that the cap srews into is cracked and will not hold. I did see them on ebay. Also if anyone needs o-rings I found a company in Whippany NJ. F&S distributors. They have millions of o-rings and gaskets. Much cheaper than the web. There is a machine shop down the street from me that will bore the engine. Funny I found all these companies within 1/4 of a mile from my office.

Also can you explain one more thing on the tilt and trim
You guys stated that one cyl;inder is a shock and one is the tilt. I guess the 3rd cylinder at the lower portion of the engine is the trim??? The shaft is not that long and when I did lower the engine it looks like i pulls the engine closer to the boat. But how do you know when to stop pushing the trim down in the water. Does it stop automaticly or to you have to watch the gauge?

If I find any other companies in Jersey that I feel can us boat owners better deals than the web I will gladly post them.
I do apprieciate all the feed back.

 

[pnwboat]

Re: 1990 fORCE 90HP Engine Questions

Yes the third cylinder is the trim. The piston in the trim cylinder is larger than the tilt cylinder. It exerts more pressure that the tilt cylinder, but moves much slower. I just look at the motor. When the motor stops moving, I know I've reached the limit. The only thing that stops the motor from going any further when trimming down or tilting up is the trim or tilt cylinder bottoms or tops out. It doesn't automatically stop. As long as you hold you finger on the tilt/trim switch, the pump will keep trying to push the fluid into the hydraulic cylinders.

 

[HAMMER1111]

Re: 1990 fORCE 90HP Engine Questions

Im back

Pulled the engine yesterday and just about done with taking it apart. I documented everything along the way and feel comfortable at this time and my luck that I was filming the tear down with my phone and my phone broke. Hope I have a good memory...Now I get to the crank shaft and found these odd looking bolts on the connecting rob. Its not a 7mm or 6mm 14 point socket and its not a torks??? Does anyone know what socket size I can use on them. 10 more min and I can have this done and to the machine shop tomorrow.
Also I will post pictures of the pistons that are fried. Im wondering if its from overheating the engine.

Thanks