1984 Mercury inline 6 115 hp outboard - power head removal

ab59

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Looks like I have been locked out of the search venue here so I will try to ask for the information I need. I need to replace the lower crank seals on my 1984 Merc " Tower of Power " 115 hp outboard . Can I pull the power head without removing the carburetors ? Would like to just remove the cowls and drop the lower and replace the seals with the motor hanging , Is this possible ? I have access to a manual but it does not really go into detail about this. No I have never separated a power head from the lower before , but I am willing to learn.
thanks, A.B.
 

Faztbullet

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Unbolt cowling supports,unplug the wiring, remove battery cables and grounding straps, disconnect shift are, disconnect fuel line, unbolt and lift off with everything attached..
 

ab59

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Thanks for your response --Great , looks like I'm half done already. No shifter and cables are loose . Thanks , I will begin tomorrow if I don't get smoked out again.
 

Chris1956

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Lay it on a bench. It will be real hard to pull the endcap and torque it back (with the crankcase bolts you will need to loosen), if she is hanging. The block is able to be carried by one person. If you remove the spark plugs, she can be laid on her back.

Try to install 3 crankcase seals if you can fit them.
 

ab59

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Thanks for your reply Chris 1956-- I will most likely take your advise and lay the power head on it's back . I was not too thrilled about trying to do my work on a suspended head but trying to make this as quick and simple as I can.
I read somewhere that there is a gasket that goes bad on the old " tower of power " motors after sitting , that will let water leak into the spark plug wells . Would you know which gasket this might be ? I can't find the article that I saw the information in so I'm kind of working in the dark here. I need to order all the parts I need today if possible and would be nice to order everything I need to do the job. Just not sure of what I need.
thanks-Bruce
 

Chris1956

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I never heard of a gasket going bad if the engine sat. Also, your engine block is a one-piece casting. The cylinder head and crankcase are one piece, so the head cannot leak unless it is cracked.

The water jacket over the cylinder head can leak and often does. A little silicone over the leaking part usually fixes it.

You will need 3 lower endcap seals, an oring and perhaps a gasket, but I am not sure. You might check the lower main bearing, and see if it is bad. Pull the end cap and feel it for play.

Clean the fuel recirculation fitting on the lower part of the block and make sure the rubber hose is sound.
 

ab59

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I now have the cowels and power head unbolted . I just read something on an old post about there being 8 bolts on the power head , I have only found 6 . Is there a difference between a 1973 power head and my 1984 power head bolt pattern or am I missing two bolts somewhere ?
 

racerone

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There are 8 studs I believe.----So you should have 8 nuts ( 3/8 thread ? ) on your work bench.---Find each one.
 

ab59

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forgot to sign in before my last comment so I guess it didn't post --thanks for your reply--- I figured it out , nuts were just different on the last two so I kept missing it.. One her back on the table now . Trying to figure out how to get the cap off without removing the cover. Is there a puller for this ?
thanks --Bruce
 

Chris1956

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You will need to remove the bolts on the end cap, plus loosen the surrounding crankcase bolts. It should then be loose enough to remove it.

Try a putty knife to start to remove it.
 

ab59

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Thanks for your reply Chris 1956 it helped me out ! The cap came right out with the scraper and a couple of screwdrivers , thanks , I did not think it would be that easy . I took a picture of the seals as removed , still in the cap and want to make sure that they are in there correctly . I'm still not positive that these seals are the problem but if they are I want to be damn sure that the new ones go in correctly . Lemme know if the old seals were installed correctly if you would. The bearing seems to be solid with no play . Thanks-

DSC00381.JPG
 

racerone

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Looks to be correct.----Position / location of the 2 seals may be important.----How do the sealing lips look ?----What was the motor doing that led you to replacing these seals ?
 

Chris1956

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Look at the end of the crankshaft. Often the seals will wear a groove in it. Try to position the new seals, where there is no groove. If you take out 2 seals, and replace with 3 seals, they should contact "virgin" crankshaft.
 

racerone

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Doubt the seals are really bad here.----They lasted 36 years.----I see no need for 3 seals.
 

ab59

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Ok guys , first thanks for your replies -- Racerone -yep two seals and they looked a little funky at the lip in one or two places . I am going back with three as that is what I intended to do as per Chris1956 and others .I got a little froggy and crushed one of the new seals so I ordered another one. This just was not one of those times where a bigger hammer was a good thing, lol. Shaft has no discernable marks and the lower bearing feels good and solid .
Racerone- you asked about why I pulled the power head . The po said that he replaced three pistons along with new gaskets and something else that escapes me right now . After he got it back together and did a link and sink he put it on his boat and found that although the motor ran good on muffs , on the water it would not perform and bogged down badly and would not plane the boat. He brought it home from the lake and put it up for sale.
When I bought the motor , I ran a compression test and it came back 125 -130 across all six cylinders. I started and ran the motor and put the problems on the site and got a few opinions but most pointed towards water intrusion through the bottom seals. I don't remember the cylinder that the plugs came out of but two showed a washed clean look .
 

Chris1956

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Bad crank seals would usually only allow water into the bottom 2 cylinders. If the water appears in the top 4 cylinders, it is likely a warped or holed baffle or a holed inner water jacket cover.

Of course, a warped or holed baffle or holed inner water jacket cover could allow water into the lower 2 cylinders as well, but the crank seals are a much easier fix, and would need to be ruled out.
 

racerone

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Is there not a recirculation hose that pumps oil / whatever to the top bearing on this engine ?----Would pump water up there too.
 

ab59

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Well I hope that the lower seals are the problem . If the problem persists upon reassembly I may just sell the jet and part the motor out . I have 2 1/2 inline 115 hp motors .
 

ab59

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Thanks everyone, I have finally received the midsection gasket and the power head is now attached to it's new midsection With Power Trim ! Torqued up what I could and firmly snugged the rest. Now I have to figure out where the solenoids bolt down for the PT and slip the jet back in and it's test time. BTW , just to be sure I'm not screwing up again , there is NO gasket that goes between the lower and the bottom of the midsection , Right ?
 

Chris1956

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There is no gasket between the gearcase and midsection.

The crowleymarine website may give you a hint where the PTT solenoids go.
 
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