outboard teardown

[90bayliner90hpforce]

Hello all. my name is Marc. Ive been lurking here for months and wanted to thank you for all the great info this site has to offer to boaters like myself
i just finished my tear down yesterday thanks to swicks great video........
ill start with the history of my boat.
I bought a 1990 bayliner capri 18 foot that came with a 1990 90hp force outboard (model# 906x90c and serial# 022573). When i bought it the guy told me that he could only get the engine started with the choke on, and couldn't get it to stay running without the choke on..
I brought it to a well know marina shop here in town and got them to do a carb kit and clean and adjust everything. Boat ran very very well after that. i was hitting 34mph with two people in it. Then i started getting starter probs.. bought a new starter and i was back in business. This past weekend i go on the water with my son and let him drive a bit. As hes driving full pin, the engine suddenly made a weird sound and lost half power.( what i mean is that even with the throttle wide open i couldn't even get 5mph.
i bring the boat back home and start searching the site for answers. i fall on Swicks issue and i headed back outside to check my engine. Compression on both first and second piston was 144 and 0 on the third . Wouldn't you know it, i too have a bad piston in the lower cylinder.
As mentioned above, i tore the sucker apart to see if there was more damage. From what ive seen so far im lucky because the cylinder walls are not that badly scratched and i might get away with honing.
Before i bring it in to the machine shop i was wondering if you can help me with a few issues i have and look at some pics i took.
1- when looking around i noticed a chunk of the water sleeve missing at the edge of the middle cylinder . Is this bad??(see pics) Can i fix this with something?
2- When i removed the piston shaft caps i noticed that the needle bearings didnt stay in there cages like Swicks did in his video....is this normal??(all three were like that)
3-how can i tell if this has been bored? (what do i look for)

I think thats it for now friends...im sure ill have more after work to ask....Thanks again in advance for all your help.
i will post pics in next post

 

[90bayliner90hpforce]

Re: outboard teardown

 

[90bayliner90hpforce]

Re: outboard teardown

 

[RogersJetboat454]

Re: outboard teardown

Hate to say this guy, but it looks like your bumming with that chunk missing out of the middle holes casting. A head gasket would have a real hard time trying to keep water from entering that cylinder with nothing but the cylinder liner to support it and seal against. That's about the area that most head gaskets have a fire ring which doesn't do as much to seal the cylinder as the gasket material its self.

As far as fixing it, I don't think that's going to happen. A talented welder may be able to add material back, but then the block would need to be decked some how to be sure the repair is level with the rest of the deck surface, and there is always the risk that the heat from the process of repairing it may distort the shape of the liner.
More trouble, and probably more expense then it's worth. You would be better served to find a block or power head in better shape.

 

[tater76]

Re: outboard teardown

Oh the humanity!! I hate to see damage like that. This is a perfect example of what running lean will do. Now, I am on the fence with the chunk missing on the cylinder. Rogers makes some valid points about the welding, but if it were me I would JB weld that. Gasp!! Yes I know what you are all thinking, but I'm cheap so I do what I have to do.

As for the cylinders???? they look pretty gnarly to me. That was a massive amount of aluminum rub off, and would be very difficult to remove. All of your pistons show scuffing too, and will need to be replaced. So, lets assume you want to go forward with the build of this block. The cost of 3 new pistons, boring the block, and fixing the chip on the sleeve would be anywhere from $600-$900 depending on who you know.

To answer your other questions, if your motor had been bored over, the pistons would likely have a stamp of the oversize on the crown. Your needle bearings are supposed to be loose. They switched designs in later force engines like Swick's. See my pm to you.

 

[90bayliner90hpforce]

Re: outboard teardown

wow...... didnt want to hear that
i looked real quick for a possible block and would you know it i found someone right here in town who is selling parts off one...i will go look at it to see if its a good candidate for a rebuild..... should i be able to tell lots if i take off the cover that covers the top of the pistons and look inside????? will that be enought to gamble on?
Thanks for the answers guys....looks like its going to be a real fight to win this one....

 

[jerryjerry05]

Re: outboard teardown

Shot!!!
The replacement,if it's complete,grab your starter and do a comp test.
Then maybe buy!!!

 

[90bayliner90hpforce]

Re: outboard teardown

Thanks Jerryjerry. I will do that.. If everything isn't there can I get a good judgment from the cover??

 

[RogersJetboat454]

Re: outboard teardown

Thanks Jerryjerry. I will do that.. If everything isn't there can I get a good judgment from the cover??

By the cover, do you mean the head? Yes, if you are otherwise not able to perform a compression test, pull the head and have a look down the cylinders while rotating the crank.

 

[Frank Acampora]

Re: outboard teardown



Well, the bottom piston is toast and the cylinder needs to be rebored. That missing chunk of aluminum though---- the head gasket is larger than the bore and part of the sealing ring does seat againt the aluminum. With no repair even a brand-new head gasket will fail.

Getting a welder to fix it will cost more than a used block. You can TRY grinding it relatively square then shaping a piece of aluminum to fit in there like this one. JB weld in place, but no guarantee it will work.

Best to buy a used block.

 

[90bayliner90hpforce]

Re: outboard teardown

what year block will fit

 

[90bayliner90hpforce]

Re: outboard teardown

Hi guys....
Alright, I found an engine ( I think it's an 89) ...believe it or not it's in real good condition..but two things are different on this one then mine.........
First the cover that the spak plugs screw in has the same bolt pattern but mine has fins on it and mine seems thicker by a bit.
The other is the exaust cover.. Mine has fins and this one don't plus mine has two extra rows of bolts running down the center of it.....
Can I use this engine with mine to build one... Maybe use the new block bored with pistons and use everything else off mine since I know everything else on mine was good.....
Also. Is it good to use two separate halves ( block from one and the intake from another.. Will it seal good???
This guy let me take it home to check if I could use it or not......what a good guy
Thanks again guys

 

[Frank Acampora]

Re: outboard teardown

NO NO NO! These blocks are pinned then line bored to maintain alignment of the bearings. Blocks and covers are matched units. Yeah, you might find two separates that are close and "get away with it" but the only way to use a different front cover is to mill .010 off it and re-line bore it.

Newer blocks had a smaller exhaust chest and larger water jacket so they appear to have two rows of bolts on each side.

However, If you are certain it is a Force engine it will bolt to your leg. It sounds like it is a slightly older unit and will swap.

Just look closely at the linkage and controls. If it has Mercury cable mounting in the lower shroud it will have different linkages and you must use a Mercury Control box. A couple of photos of the inside front of the lower cowl would help if you can get them

 

[90bayliner90hpforce]

Re: outboard teardown

Thanks frank...
All I have is the engine no foot or cowl.... Everything is exactly the same..from carbs to throttle cable linkage to wiring except a purple thermostat wire that I don't have on mine.
Can I use everythin from this doner but put my carbs, stater coil packs and such....
They all look the same..what I would do is get this doner block bored .10 new pistons rings rebuild doner block and intake as one( so I don't miss match and use my stuff to finish the build.....
I'll try and brought a camera for pics, mines at work...but like I said, they look the same apart from the two things

 

[90bayliner90hpforce]

Re: outboard teardown

Edit.....purple wire is for tachometer

 

[Frank Acampora]

Re: outboard teardown

Why do you want to bore the donor block? If all three cylinders need boring and pistons, it will cost more than buying a good block.

If the new block is not scored, don't bother boring it unless it is out of tolerance--the machine shop can tell you that. Tolerance is .002 for wear, taper, out of round, or barrel shaped.

From what you say, it does sound like the new block will be a direct swap. Is the purple wire separate and coming from a temperature sender on top of the head? Most newer stock engines did not have sensors, just overheat switches mounted in a well in the head.

edit: OH! Purple wire in the cable. All had that and yes it is usually for tachometer signal.

 

[90bayliner90hpforce]

Re: outboard teardown

Thanks again frank...
The reason behind my thinking is I just didn't want to take a chance with anything..I went threw all this work with tear down and cleaning of everything plus I don't know the history on this doner . I was hoping with the block bored or at least honed with brand new pistons and rings and all my nice clean parts( carbs, stator ect....) off my engine that I'd have a reliable outboard for awhile
Cost wise I'm looking at about 300 for pistons and rings by wiseco and all other stuff like gaskets and things I already needed for the rebuild.
What would you do if you had my good working engine but no good block and this doner engine with what seems to have good cylinder chambers but no history...
Thanks a lot frank

 

[Frank Acampora]

Re: outboard teardown



First -- I'm tighter than a crabs ***hole and that's water tight. If it were mine I would use it as-is if it were OK.

Now that you have the experience I would assemble the new block onto your leg and check compression ratio. Anything over 120 (wet) and I would finish installing carbs and electronics and run the engine.

Remember that block that I did port work on? I didn't bore it. I did hone it simply to remove machining burrs and because I installed different pistons than were in it originally. On the 5 cylinder 150 I simply re-honed and installed new pistons to replace the two damaged ones. It has good compression on all cylinders.

 

[90bayliner90hpforce]

Re: outboard teardown

Thanks frank... I will do that in the morning and relay back to you.. Thanks again, I couldn't of pulled this off without you and the others that are eager to help someone in need.

 

[90bayliner90hpforce]

Re: outboard teardown

Just one more thing.....what do you mean wet? Do I spray oil in there....