1987 Merc 115hp Water Jacket

[kirbymac]

I am replacing my water jacket gasket. This is a straight 6, the last year they made this motor. I just have a few questions: 1) what gasket sealer should I use when installing the new gasket?, 2) what are the torque specs on the bolts for the jacket cover?, and 3) how big of a pain is this going to be to replace?<br /><br />Thanks,<br />Kirby

 

[jheron]

Re: 1987 Merc 115hp Water Jacket

I use permatex ultra black "SPARINGLY" on all water jackets... use red high temp on the inner exhaust plate IF you have to remove it.<br />Here is some good advice on the subject from Jeff G. over on the newsgroup...<br />The exhaust plate battle has been going on for a long time. I have posted <br />many times how to do the job that will fix the problem. Evidentially you <br />have not seen that post.<br /><br />You need to measure the inner plate block surface. If warped it MUST be <br />re-surfaced. A fully equipped machine shop can do this. IF the inner surface <br />is re-surfaced you must re-surface the outer block surface as well. If flat <br />leave it alone!!! Use a precision straight-edge.<br />After these two surfaces are done (if needed) you need to replace the inner <br />plate with a NEW plate and Mercury (ONLY) gasket. Use a high temp rtv <br />sparingly to seal, red is best not containing copper. Forget the epoxy deal <br />or any other sealer. Use Loctite 271 on the bolt threads. Chase the threads <br />with a good new tap. Torque to 200 INCH pounds.<br />Next place the middle plate on the block with no gasket. Look at the mating <br />surface from underneath the block through the exhaust. You will see light <br />around the edges. File the middle plate or have it surfaced until you see no <br />light. The middle plate high centers on the inner plate. That my friends is <br />the real culprit.<br />Once you get it right assemble the two outer plates and gaskets with some <br />black high temp RTV. Use a very light coat. Use some loctite either the red <br />271 or the removable blue. Either one will do. Now the exhaust problem is <br />permanently cured.<br />I have over 30 years on these blocks and have rebuilt literally hundreds. I <br />now have no water leakage problems even on my race motors which run very hot <br />and high rpm's.<br /><br /><br />This worked for me <br />Jon

 

[Laddies]

Re: 1987 Merc 115hp Water Jacket

When replacing the gasket on the water jacket cover, use a straight edge and make sure the areas around the spark plugs are preloaded about .015 if not you can use a press and carefully preload each on I use a little loctite 518 around each plug opening and nothing around the outside and no more than 85 in lbs of torque they are only 1/4" bolts

 

[kirbymac]

Re: 1987 Merc 115hp Water Jacket

Laddies, thanks for the clarification on the torque, I was beginning to wonder about the 200, it sounded a little high, but I think jheron was talking about the bolts that hold the middle plate block and not the jacket cover itself. Thanks again! So you are saying that the holes in the gasket around each plug use some loctite 518?? And nothing around the rest of the gasket? Also, do you loctite those 15 or so bolts that are in the face of the jacket cover?<br /><br />Kirby

 

[Laddies]

Re: 1987 Merc 115hp Water Jacket

I seal around the plugs but not the outside, thats where they ussally leak I avoid using sealers and loctite except in problem areas, god only knows that the things can be hard enough to get apart and clean up with out it. I never use RTV sealer on outboard powerheads--Bob

 

[emckelvy]

Re: 1987 Merc 115hp Water Jacket

Sounds like everybody's a bit confused here.<br /><br />Just to clarify:<br /><br />Cylinder block cover (the back cover over the spark plugs): 85 inch-lbs, 1/4" bolts.<br /><br />Exhaust manifold inner cover [water jacket] (over the exhaust ports): 150 Inch-lbs, 5/16" bolts.<br /><br />Exhaust manifold outer cover: 250 inch-lbs, 5/16" bolts.<br /><br />Hope this helps............ed

 

[Laddies]

Re: 1987 Merc 115hp Water Jacket

Hey Ed I'm not Bob

 

[Clams Canino]

Re: 1987 Merc 115hp Water Jacket

Ummmm I beg to differ on exhaust Ed.<br /><br />Exhaust outer cover 150<br />Exhaust inner plate 200<br /><br />You had it backwards.<br /><br />-W