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1983 MERCURY 40 HP

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pritchettk

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"I have a 1983 merc with a bad

"I have a 1983 merc with a bad ring on one piston. For the shop to fix it all they want $700 I think I could do it my self, but my real question is. What other size powerheads would fit on that motor. Also, how hard is it to change out the powerhead if I get one that is just a 40hp identical to the one that is on mine? Is it very difulcult to change out a piston ring and hone the cylinder wall?"
 
"How do you know you have a ba

"How do you know you have a bad ring? A bad ring usually equals a bad piston, unless there stuck from carbon build up in which case you can spray engine tune into the spark plug hole, let it soak and sometimes free up the rings. If you can follow a service manual its not to difficult but you have to know what your looking for and do you have the tools required.

Cheers Spanaman"
 
Well the guy I bought the boat

Well the guy I bought the boat and motor off of had a shop take a look at it and they said it was a bad ring. I am not sure if they broke it down or just did a compression check. I guess there is really no way to check the piston unless you break it down.
 
"I have the same engine and di

"I have the same engine and did rings and main bearings over the winter. Remove the exhaust cover, left side of engine veiwed from behind. Inspect the piston, cyl's, and rings from there. Thats probably what the shop did. Using a small screw driver push on each ring, it should spring in and back like its under tension. If it doesn't have some give and return to its normal position then that ring is broken. The only way to change it is to remove the powerhead and do a complete tear down. You will need a Merc manual for this. Email me with any ?"
 
Well I bought some penetrating

Well I bought some penetrating oil and I will try that and i hope thats all it is. If not I guess I will look at the rings. I dont really want to spend a lot of money fixing it when I see 50 hp and other 40hp's go for around $3-800
 
"If you don't fix iy, I su

"If you don't fix iy, I sure could use it.
There are 3 rings, it won't be easy to get the oil down there, and make sure that piston is all the way up or down, if not the oil will run out the intake or exhaust ports. good luck"
 
"Well I am trying to get the e

"Well I am trying to get the exhaust cover off and there are 2 more bolts down below and I can't reach them. Do you have to the the whole powerhead off before you can take anything off? I can't even get the cylinder head off, the bottom 2 bolts have no room to come out all the way."
 
"4 bolts in the back that hold

"4 bolts in the back that holds the bracket that supports the top cowl, shapped like a ( u ) but upside down. then the same in front, that will let the lower engine cover loose.
removing the cyl head does nothing but exposes the water jackets, this engine is cast and does not have a cly head like a car"
 
"aww ok, thats how to get the

"aww ok, thats how to get the lower cover loose man I was wracking my brain trying to figure it out. I was like well it looks like it comes off some how but couldnt find no bolts to it or anything."
 
I got the whole powerhead off.

I got the whole powerhead off. Now I have to figure how to disconnect the steering cable and all the goodies off the block so I can get in there. I can see that the top piston has a few small small little scratches in it. But the rings are kinda springy when you push on them. So I dont know. I guess I am just going to finish tearing it apart and get in there and see whats wrong.
 
"Keven, if all the rings sprin

"Keven, if all the rings spring back it doesn't need to come apart unless you just want to. Did you turn the flywheel and check the other piston? Small scoring is normal, no air filter on these. When removing all the goodies, tie wrap all the linkage togeather so it doesn't fly apart. If you take the rods of crank, be carefull, 16 needle bearings per rod, 29 per piston pin, and special tool required."
 
Well from where I am now I can

Well from where I am now I can only see like 1/4 of the pistons. The bottom piston looks fine but I cant see the other 3/4 of either piston. I never ran a compression check on it my self. I guess I should have but I did'nt want to mess anything up worse than it already is. What do you reccomend?
 
"Keven, you can take the intak

"Keven, you can take the intake/transfer cover off the other side. Then you can look at the pistons and rings from that side."
 
"<font color=""000000""><font

"<font color=""000000""><font face=""arial,helvetica""></font>We are trying to locate a stator for our 40 hp Mariner. We think it was built by Yamaha. The serial number is
676 L50635. We are having a very difficult time finding any information on this motor. Can anyone give us some suggestions?</font>}"
 
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