merc 50hp head cover removal

[krypton]

Hi, has anyone had any success with removing the head cover from a merc 500 without having to remove the whole block ?<br /><br />It's a 1969/70 Merc 500, 4 cylinder and has a little hole in the middle of the thread of the top spark plug that is causing lots of water to exit at the base of the spark plug when in use.<br /><br />I would like to remove the head cover so I can get the hole repaired but I dont really want to be taking off the whole block but looks like I may need to because the lower bolts on the cover are kinda hard to get to(the lower cowling is in the way).<br /><br />Would putting some silicon rubber around the base of the spark plug be a temporary fix to stop that water coming out ?<br /><br />thanks.

 

[scruffy_fish]

Re: merc 50hp head cover removal

Been there. <br />Purchased a 500 and went to change the spark plugs that were coverd with rust. Found silicone all around the base, what a mess.<br />Bite the bullet and fix the leak!<br />First get a hammer impact wrench for the bolt heads. Next soak the bolts with WD40 or other good solvent for rust for a couple of days. The screw threads go through to the back so apply WD40 at the back side also.<br />After a good soaking heat the bolt head with a hot torch flame, immediatly use the impact tool and give it a shot. This should loosen the bolt.<br />Repeat for all bolts. <br />The lower bolts you won't be able to impact so use a breaker bar.<br />When you replace the cover make sure you use a good gasket cement and the surfaces are flat and clean. Also replace bolts with stainless steel ones and anti seize compound.<br />It sounds harder than it is, good luck.

 

[krypton]

Re: merc 50hp head cover removal

Hi Scruffy, thanks for your reply. Did you manage to do this job without removing the whole block ? There is barely enough room down the bottom of the cover to get the #4 spark plug out. <br /><br />Cheers.

 

[rodbolt]

Re: merc 50hp head cover removal

hello<br /> if the bolts actually come out then yes there is usually enough room. the lower trim is removable to gain access to the power head mounting nuts. but usually they are badly corroded. usually you will find not only the cover is damaged but the top of the cylinder jug as well. to repair the cylinder jug I use JB weld and a flat file. but anymore I just refuse to work on them that old. its a matter of economics.those were good old motors so good luck and keep posting

 

[krypton]

Re: merc 50hp head cover removal

Hi rodbolt, thanks for your help. <br /><br />"the lower trim is removable" ... I didn't think the lower cowling was removable unless you remove the whole block ? If there is a way to take this off without removing the complete engine then that would make the job a whole lot easier. I am still waiting for a manual to arrive at the local library but until then are you able to tell me how I take that lower cowling off ?<br /><br />Apart from the water coming out the sparkplug the motor is a great runner and pushes my 14ft glass runabout along nicely at 25mph this is why I really want to fix this.<br /><br />Cheers.

 

[scruffy_fish]

Re: merc 50hp head cover removal

I was faced with the same delema. Decided to try and remove the water jacket cover as I suggested in my earlier post. I figured if it didn't work, I would have to remove the power head anyway. It did work and saved me the hassle of removing the power head until another time.<br />I already had a snapped off bolt before I got the motor and had to drill and retap that, but if you take it slow, and with a little luck my may have success. Go for it..