Rebuilding a couple Merc I6s. Some questions.

[Sean777]

So, first off, hi everyone! New to the site, have been roaming around reading up but I'm at a point now where it's time to ask some questions. This is my first foray into marine engines really, so I'm learning fast.

To make a long story short, I picked up an inline which was running and slowly seized, the previous owner saying it was probably seized mains from "not enough oil". Before I got it apart, a "parts motor" inline popped up for sale so I scooped it, believing it should have good crank/mains. My thoughts, take 2 motors, make one motor, everybody's happy.

After doing some research I think I've figured out that one motor is an older 1400; having WMK-9 carbs, the other is an older 1150, having WMK-10, both with the old style fuel pumps on the side of the powerhead and the older big red coil above the fuel line. The 1400 had been rebuilt fairly recently because it has a bunch of new gaskets.

When I tore the motors down, I realized that both of them had good cranks/mains/rods. The 1400 had one piston that was heavily scored and was really tight in the bore. I noticed that the reeds for that cylinder were slightly open. I'm thinking that maybe whoever rebuilt it might have put the reeds in backwards or bent them and they weren't sealing. Thinking that might have caused the cylinder to run really lean and starve for oil?

The 1150 was seized and when I got it apart it looked like the #1 piston was seized in the bore from sitting. I got the crank out after some effort and it looks like the bores are good, though the pistons/rings are shot.

Now my dilemma; I was hoping to use the boost port pistons from the 1400 with the crank from the 1150, take the good carbs and electronics from the 1400 and assemble one good motor. But now I have 2 good cranks, 1 good block and one that would be good with a bore/hone, and 2 incomplete sets of different pistons.

I'll try rebuilding the 1400 first and see what good parts I'm left with and decide whether it's worth rebuilding the 1150 or not.

I'm putting the motor onto a 70's 14' fiberglass runabout type of boat, so I'm not looking for all out power. I'm more into it because I just think this motor is cool and it's something fun to do. Like anyone, I'm looking to keep costs reasonable, but I'll pay a couple extra bucks to make sure the motor's nice and reliable.

On to my questions:

1. Is there a complete rebuild kit I should pick up, that will have all the gaskets I need to rebuild the whole powerhead?
2. What pistons should I be looking to get? High-dome or low-dome, 2 ring or 3? Does anyone have an affordable source?
3. I don't have a manual yet (on the way), but does anyone have a list of all my service tolerances so I can start measuring things?
4. How am I going to get the crank/pistons back into the block?

I'd be curious to hear anyone's opinions on my project, tips or tricks, things to look for, suggestions for parts sources...

In the meantime, please enjoy this picture of a couple cranks sitting on my workbench (yay!).


Cheers!
Sean

[Mark75H]

There are a number of ways to get the pistons back into the block. Milkdud has some pretty good pics of his method. I'm a hose clamp kind of guy.

The reeds standing slightly off the cages will not affect the motor while running as long as its not more than something like 2 reed thicknesses. Just seeing a little gap is insignificant.

High dome pistons are hard to come by. Merc supplied low domes as replacements when they stopped putting them in new motors.

Hope you spent money on a Merc factory manual; others are basically worthless.

140 on a 14 footer is going to be a handful.

[Raceman]

First, the "early 1400" was a one year only engine in 1972. It would NOT have had boost port pistons. The first inline with the boost port pistons was the '73 1500 and the boost ports and corresponding trench in the cyl wall were essentially the only differences between these two. Is your 1150 powerhead black also? If not, you could have some interchangeability issues with the mid section you plan on running. Look at the bottom of both blocks and compare the exhaust outlets and be sure they both have the same number of studs. Pro Marine sells all different piston configurations. If you're going to use it in a recreational ap you'd be better off with the low domes. 2 ring pistons were used on the 4 cyl 850's only and there's no reason to use 'em in the inline, although they wouldn't help or hurt it. I've used both and couldn't tell any difference. It looks as though you disassembled the flywheel instead of getting a proper puller. You'll need to get the right tool to remove the rest of it from the crank. First thing you need to determine is exactly what you have. Serial numbers would help with the identity.

[Raceman]

And also, just FYI, the bottom ends don't seize from lack of lubrication. The pistons will stick to the cylinder walls long before that happens.

[Mark75H]

Beat ya!

[Raceman]

Beat ya!

Yep, you out drew me again. I'm glad it ain't a gunfight.

[WillDiver]

here's a like to the hose clamp method described, and includes a video of the special Merc tools.
http://www.fiberglassics.com/glassic...-power-rebuild

hope the link comes through.

Will

[Sean777]

Sweet about the hose clamps!

The boost port pistons in the 1400 are not original as they look almost new and are 2 ring. Looking into the block I can see some FOD in the crown of 2 cylinders. I just was going by carb ID, they may be something else completely.

Both powerheads are black. The S/N on the front of the 1400's lower part where it mounts to the transom (not sure what you'd call it) was 7112406. But that being said I don't think it necessarily matches the powerhead. Both motors have a number stamped on the side of the starter motor bracket, part of the lower case. Would this be the powerhead's S/N? I don't remember the numbers off hand but will check next time I'm at my shop.

I managed to get one of the distributor drive pulleys off with a 2 jaw puller but the other was on too tight and I need some long fine thread bolts to use my other puller.

Damn I bought the Seloc. Should have known it'd be useless.

[WillDiver]

potential source of parts, in addition to ebay..
http://forums.iboats.com/showthread.php?t=438822

Will

[Raceman]

Both powerheads are black. The S/N on the front of the 1400's lower part where it mounts to the transom (not sure what you'd call it) was 7112406. But that being said I don't think it necessarily matches the powerhead. Both motors have a number stamped on the side of the starter motor bracket, part of the lower case. Would this be the powerhead's S/N? I don't remember the numbers off hand but will check next time I'm at my shop.

I managed to get one of the distributor drive pulleys off with a 2 jaw puller but the other was on too tight and I need some long fine thread bolts to use my other puller.

Yes, those are the serial numbers. I've never disassembled an inline flywheel, but have been told that phasing is important. I could be confusing this with V6 information because I heard it a long time ago, but in any case, if you can figure out the position of the flywheel in relation to the piece it mounted to it would be best to put it back as original.

[Sean777]

I think I'm up the creek in that respect, I didn't think I'd need to make note of the position of the flywheel. Hopefully I can sort it out.

The blocks have the serial numbers 7001176 and 7010980. The former had the WMK-9 carbs and the latter had the WMK-10 carbs.

Thanks for any insights!
Sean

[milkdud]

Ive heard your not suppose to take the flywheel apart as well.

If the flywheel has the timing stickers and the .4xx number on it you can just find TDC and then the .4xx BFTC then line up the flywheel to the correct bolt holes.

C

[Sean777]

Looking at Maxrules.com, my second serial number 7010980 comes up as a 73 1150.

The first serial number 7001176 doesn't show up anywhere. That powerhead was bolted to the midsection with the S/N 7112406, which comes up as a 78 1150. The WMK-9 carbs ID it as a '72 140hp, and it has the old style fuel pump and ignition.

So who knows WHAT it is!

[Sean777]

I think I can save 4 of the 6 pistons from the 1150. I don't suppose anyone has a couple spare original non-boost-port pistons kicking around they want to sell?

[milkdud]

You can use the boost port pistons in the older non boost port motors. Mercury only made boost port (power port) pistons as replacements after a certain time to be used in both motors.

C