Newbie tune-up '69 Merc 75 (7.5 HP)

[saltyfries]

I bought a 14' Lund with a 1969 Merc 75 (7.5 HP) a couple of weeks ago. Engine serial is 2534336 which makes it a 1969 according to my research. The owner said it would need a "tune-up" and so far, except for some leaky oil seals in the gearbox, I guess everything I have found falls into that category. I've ordered a new impeller, oil seals, fuel pump re-build kit, plugs, and a tune-up kit. I'm starting with replacing the points and condensers and will post pictures as I go so if you see anything wrong with the way I'm doing things please let me know.

Starting with the manual starter, I removed the large top nut. I discovered that this nut has a left hand thread. Then, I removed the three phillips screws which hold the starter to the engine block and removed the starter.

Next, I improvised a pulley puller from a steel disk and some nuts and bolts (picture attached). Using a rectangular bar and a wrench, I removed the flywheel RH nut from the flywheel. Then, using the puller I applied pressure until I felt a sharp pop. I removed the puller, removed the flywheel, and discovered that the shaft is tapered in addition to being keyed.

More to come...

 

[saltyfries]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

Continuing...

I screwed an extra nut onto the main shaft and removed the plugs to make it easier to turn. Then, I removed the cover protecting the points/condensers. I turned the shaft until each follower made contact with the high point on the cam and then in turn checked the point gaps with a feeler gauge. Gaps measured .009 and .013. Nominal should be .020.

At this point, I opened my Sierra tune-up kit and studied the contents. Everything appears to match well except that I found a small capsule of what appears to be grease and a small square of black paper (picture attached). Can someone tell me what these are for?

 

[Laddies]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

Take the pill and the papers for wiping up. NO there is grease in the capsule put a tiny bit on the inside of the point arms for lube.

 

[saltyfries]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

Take the pill and the papers for wiping up. NO there is grease in the capsule put a tiny bit on the inside of the point arms for lube.

LOL...

By "inside of the point arms" do you mean the part that actually rides on the cam? If so, should the grease be renewed on a regular basis? Also, there is a piece of felt which wipes the cam, but on mine it only touches the high point of the cam. Should I replace it? I just looked it up at Doug Russell and they do carry it, but I don't really feel like paying the $30 minimum to get it.

Thanks

 

[Laddies]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

Don't worry about the relubing in most cases it don't get done the first time, I think it just gives a little time for break in on the original startup till the arm and cam seat and I certianly would not pay the money the want for a wiper as all it does is wipe excess lube off from the arm being over lubed.

 

[saltyfries]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

I installed the new points and condensers today. No reason to post any pictures on that because installation is pretty much just a reversal of disassembly. I tried to set the gap exactly at .020 but found that it would move slightly every time I tightened the screw, so I erred on the larger side figuring that the followers would wear in slightly. I put a little of the grease which came with the tune-up kit on the cam and the followers of the points and turned around the felt wiper to take advantage of the unused side. I put some theadlocker on the posts which secure the wire terminals to the points. Replaced the flywheel, tightened the flywheel nut to 35 ft. lbs., and re-installed the starter mechanism. It was then that I realized it was unnecessary to remove the nut on the starter, duh.

Tomorrow I will pull the water pump and/or remove the carb for cleaning while I wait for more parts from Doug Russell.

 

[saltyfries]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

I removed the two nuts securing the gear box to the lower leg. Pulled the gear box out and using a screwdriver pried out the copper water intake tube. I removed the two nuts holding the water pump and slid the top of the water pump down the driveshaft. Then using a screwdriver, I carefully, so as not to damage the gear box casting, pried out the water pump. As I'm doing this, milky white oil is dripping from the gearbox, so I know I have a problem. The last picture shows the underside of the water pump. I'm no expert, but that seal doesn't look good to me. Also the picture shows the impeller, clearly bad, and a drive shaft bearing beyond. The bearing rolls smoothly and doesn't seem to have excessive play, but there appears to be a little surface rust around the casting where the water pump o-ring seats. Is this OK? How do I remove the inner water pump seal without damaging the plastic pump housing?

Thanks

 

[Aqualift]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

Thanks for posting your repair procedure with pictures.

 

[saltyfries]

Re: Newbie tune-up '69 Merc 75 (7.5 HP)

Here is a closer look at the underside of the water pump. That irregularly shaped stuff around the perimeter of the bearing is hard. Almost like maybe the housing melted at some point? Can someone give me some advice on this? Should I just replace the pump base? At around $50, I'm not much in the mood for that.