DIY Swivel pin, powerhead and lower unit?


Old 11-16-08, 09:03 AM
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Join Date: Feb 2008
Location: New Haven, CT
Posts: 107
DIY Swivel pin, powerhead and lower unit?


I have a 19' open bow sea ray with a 1990 135hp mercury outboard 2-stroke.

My experience in auto/marine mechanics is null.

Situation: I bought this boat used recently. I took it out for the first time and while on the water the engine started to overheat. This was due to the water pump failing for not being replaced by the previous owner in two years.

Since I was effectively stranded, I tried to push the boat a little further to try to get to dock, this caused a bit of white smoke, this i knew was bad - but the next day i turned on the engine to make sure it ran and it did.

I took the boat in to get diagnosed - i knew the water pump had to be fixed but they found some other issues:

-In the lower unit, they found water in the gear case, they said this was due to the propshaft being bent from presumably an old accident. He spun it for me so I can see that the shaft was indeed bent. So this has to be fixed, then the water pump will be replaced, and then the lower unit would have to be resealed.

-Hub spun in the lower unit - i dont know what this means, im guessing it means its worn out?

-They said the 'swivel pin / "knuckle" also needs to be replaced, they shown me how rusted out the thing is and said it was dangerous - i dont know the extent of this but I understand that in order to fix this the entire unit would have to be dismantled in order to replace it.

-You can see melted tubes on the power head due to its overheating. Also, the little sticker on the powerhead which, if melted, indicates that the power head should be replaced is in fact melted off. However, the engine does indeed run. They indicated that while it does run, there is no garuntee here that water wont break into the thing while running in the future and thus ruining the engine.

Ok, all this said - I would say that, if i did extensive research, i probably could fix the lower unit.

The powerhead, my father gave me a bit of confidence that this could be done DIY, however I am skeptical as this is a crucial part of the engine - IS the engine, so idk.

The swivel pin......I dont know, I cant even find information on this. Also, I do not have the ability to take this engine off the boat myself and then also have it sit in my basement where it is warm in the winter - its a distance from the driveway.

They quoted me $2700 for parts and labor - $1500 of that is parts, with 12 hours for labor 8 for the swivel pin and 4 for the lower unit- this does not include the powerhead.

Does that estimate sound reasonable, particularly the labor hours?

They did list all parts required but alas, no serial or part numbers to them.

I am willing to learn and it sounds like a fun project, but i am low on confidence, would you say any of this is DIY?

Any tips, comments?
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Old 11-16-08, 09:58 AM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
Ok this is a big project and most can be done at home with no special tools but some will have to be done by someone with special tools.
The gearcase or at least the propshaft is better off being done by someone that has the propper tools I wouldn't take it to a dealer but find a smaller shop that you feel comfrortable with. That way if you have other small questions they might be willing to help.
But just remember when a tech is on the phone or answering a customers questions the time it takes to give free advice is time they are loosing when they can be making $. I don't mind helping a person out "heck I enjoy doing it here" at work it's a different story I get paid by how much work I get done.
I would break it up into small projects, first remove the gearcase and bring it in to have the propshaft replaced and the prop rehubed you can do the impeller at home. This is something that you should learn to do so it can be done at regular intervals.
At some point you should do a compression test and or a leakdown test to find out what shape the powerhead is in.
Start there and ask a alot of questions like I said it's a big job but you can do it a mercury service manual will help a lot and save you a tone of time.

Good luck Chet
Old 11-16-08, 01:15 PM
badeyeben's Avatar
Join Date: Dec 2006
Location: Southern ILLINOIS
Posts: 944
Clymer has a decent manual for repair procedures for about $30.
A quick search on the net (1990 mercury 135hp) got me several rebuilt powerheads for $3300 and 2 complete running engines on craigslist for $ 3000 in west palm beach. One left hand and 1 right hand.
The way the economy is going boats and motors are being sold for quick cash. I just read in the paper where a guy abandoned a $200,000 boat because he could not pay the slip fees. Check around there may be some great motors for sale in your area for what you might pay for the repairs. Keep the old one for parts or rebuild it to sell later or as a backup.
Just something to consider.
Old 11-17-08, 05:24 AM
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Join Date: Feb 2008
Location: New Haven, CT
Posts: 107
A few thoughts:

most important issue to me:
power head:

I read a bit about the compression testing and a bit about this leakdown test. What I would like to confirm is the life of the powerhead.

Lets say the tests do not work out well. It looks to me as though worst case scenario is replacing the head gaskets. Is it possible that this is not the worst case scenario? Head gaskets are relatively cheap compared to an entire new powerhead - I do not see why I would get a new powerhead if at worst all I need to do is replace the head gaskets. For example, is it possible that the housing could be cracked letting the compression fail, or in the water - water would leak through?

What more can you tell me about that?

No comment on the swivel pin, this is the most expensive estimate so I was hoping to hear a comment about this. Is this something that is doable at home? How difficult would you say it would be to remove the engine off the boat? Id imagine I would need more than myself....

gearcase = lower unit? fortunately it already is taken apart so I could just send that over.

Propshaft - i do not have special tools (by special you mean something I could not buy or ought not to?), wouldnt even know what to get outside of a local hardware store. I am not sure what you classify as a dealer as I bought used. I went to a small mom and pop harbor who is a lisenced mercury sales and this considered a dealer or just a local shop?

To the water pump/impeller, yes I believe I can do this myself as well so consider this item checked off.

The impeller - it has been difficult for me to find the part anywhere, all i can find is some generic named impeller and there is no indication of which one is correct, which is why i brought this in the shop in the first place
Old 11-17-08, 05:28 AM
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Join Date: Feb 2008
Location: New Haven, CT
Posts: 107
one other comment.

I read this online:
"Compressor should be at least 2hp and deliver 90psi. "

Why the 2HP? Ive seen air comressors that are 1/2 hp or 1hp and deliver higher than 90psi.
Old 11-17-08, 10:29 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
hopefully I can finish this without loosing it all and throwing the computer across the room! Man I hate computers tonight.

Ok I think you have compression and air compressor mixed up. A compression tester screws into the head where the spark plug goes. They are available on the internet or from a local parts store. What it will tell you is how much air each cyl. is compressing. What you would be looking for is less than 10% differance between all the cyl.

A leak down tester pressurizes the cyl at a specific pressure and can tell you what % is leaking.
A air compressor is used for this test.
Both of thest tests will indicate the condition of the motor.

For the swivel bracket you will need to pull the powerhead (motor) from the midsection to remove the top mounts. It makes it easier to do with the L/U off.

You are better off getting a manual first then this all will make more sence.

What year and serial # is the motor and I can get a part # for the impeller.
Old 11-17-08, 10:43 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
If the motor is severly overheated it will show up on a compression test. It could be a head gasket but it can also start to melt pistons. It would need to be ran a long time for any major damage to occur.

The propshaft should be done by someone qualified, there is more to it than just sliding a new shaft in. The gearcase will need to have new seals in it as well.

I see it's a 1990 135hp I can't think of the merc part # tonight it's too late I will post it tomorrow.
Old 11-18-08, 05:34 AM
Thread Starter
Join Date: Feb 2008
Location: New Haven, CT
Posts: 107

I will get the lower unit fixed up by marine mechanic I had originally look at the boat.

This is what I am imagining at this point:

I will get the lower unit fixed by the mechanic. So lets say the lower unit gets fixed. They put the lower unit back.

So then I would need to remove the lower unit and the power head in order to get the swivel pin fixed. Now, all research on doing this aside - can one person reasonably handle taking the power head off and anything else? I'm talking strength.

More importantly - is this something someone can pick up? As I do not know anything about engines, I would be learning as I go - and thats fine with me unless the work on the swivel pin / power head is more of an art than work.

well I guess what I am wondering is, I imagine that a piston, head gasket, anything in there can be replaced part by this the wrong assumption?

"It would need to be ran a long time for any major damage to occur. "

when you say this, what is defined as long time? additional background: stranded after overheating. sat there let the engine cool a bit, moved again, sat and let cool - moved again, sat and let cool. Finally my last try before getting towed the engine started to fizz out white smoke (as in hot air It seemed). This was over the coarse of 4 hours but the engine ran maybe 1 - 3min on each interval.
Old 11-18-08, 04:23 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
The impeller kit part # is 817275 a-2

The powerhead can't be lifted by hand a engine hoist is the best solution.

It's hard to say how hot the engine got without looking at it. Did you have alarms going off and you let it cool untill it went off then repeted? You did mention melted tubes so that sounds like it was prity hot. Was there a stream of water out the back?

Did you find a manual?
Old 11-19-08, 05:22 AM
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Join Date: Feb 2008
Location: New Haven, CT
Posts: 107
"a engine hoist is the best solution."

would this also be applied to repairing the power head if need be, or can that be repaired without lifting it off the rest of the engine? I would not have such a thing so it would probably be best to take the engine into the shop to fix the swivel pin.

Did you have alarms going off and you let it cool untill it went off then repeted.

ahh yes i forgot to mention that. yes I pretty much turned it on when the bell stopped going off at me, then move it till it started beeping again.

At my last attempt it was beeping and i kept pushing the engine and then i said that this probably isnt worth it. No, there was no water coming out of the engine, thats why it was overheating. the impeller after seeing it most definatly had to be replaced.

I have not had a chance to find a manual yet at home. I am in the process of reinstalling my laptop. i do have one of them repair manuals

this might not be the right one but it looks like this: if it is not the right one it would be because my engine is a two stroke:
Seloc Mercury/Mariner Outboards 1990-00 Repair Manual price comparison
Old 11-19-08, 05:02 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
From what I could tell that manual looks correct. It will help a lot and what that doesn't cover I or someone can fill in the blanks or go into more detail.

What I think I would do is take a compression test first I would guess it should show about 125 psi give to take 15psi but they must all be within 10% of each other. I think you can pick one up for about $25. Then you will know where to go from there.

If the internal components of the engine are damaged you will need to lift the powerhead off the midsection, but if the headgasket is blown it cab be repaired by just removing the head.

There is a good posibility that no damage occured and it was just steem that you saw out the tell tale. A compression test is your next step and it can be done without the gearcase on.

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