Motor died. Two mysteries. Is it the snap ring on the impeller?

[ernst]

1. Gaskets should always be installed on clean mating surfaces
2. Gaskets should never be reused
3. Generally speaking, gaskets do not require additional sealant
4. Grinding down the flange of a new MMI 502 flange pump - ugh! You may have little choice because you're combining components from different manufacturers but still, ugh! I realize it's too late now but a threaded stud in the accessory drive hole with a hex nut to fasten the pump and bracketing could have solved the misfit.

Hm, thinking about it: I hope the new gasket arrived in the mail (I am still on a business trip) and now I wonder if I should install the pump with threaded studs, instead of the bolts. It is too late to undo my grinder job on the pump but it seems like a better solution overall. For instance, I expect it will make the installation process a little easier. I don't anticipate any problems but it appeals to me to just slide the pump with gasket on the studs and be done with it.

Does that make sense? If it does, do I need to order studs somewhere, or can I just cut off pieces of suitable length from a threaded rod? I may even have one (stainless) lieing around, have to check when I get home.

And I suppose the studs need to be installed just with a drop of oil on them, right?

Thanks for your advice.

[ndutton]

Be sure you don't thread the studs too far into the accessory drive. There are moving gears in there and you don't want to engage them. Rather than oil you might consider Loctite.

[roadnsky]

Be sure you don't thread the studs too far into the accessory drive. There are moving gears in there and you don't want to engage them.

To enhance Neil's warning about threading the studs too far, here are a couple of pics.
In the lower right, near the gear, you can see the backside of the lower pump bolt.
The last pic gives you an idea of the thickness of the threaded area for the stud/bolt.

[ernst]

Be sure you don't thread the studs too far into the accessory drive. There are moving gears in there and you don't want to engage them. Rather than oil you might consider Loctite.

Thank you, Neil and Jerry. Something else I hadn't thought about!

[ernst]

Thank you, Neil and Jerry. Something else I hadn't thought about!

Situation update: Yesterday I took out the pump again. Of course that included removal of the alternator bracket, which means moving downthe alternator. As expected, there was old gasket material on the flange. After I cleaned that up and installed the new gasket (requiring a trip to the hardware store since the lockwasher on one of the bolts was donated to the bilge), the oil leak is gone.

Whether my whole problem is solved is not clear. Before I started the above-mentioned work, I noticed that the bilge under the motor was again filled with about a half gallon of what looked to be at least partially coolant (no, I did not taste it, I have my limits!). I had not put in a diaper this time, precisely because I wanted to see if I might have a leak somewhere. Nevertheless, I did the multi-stage refilling of the block and heat exchanger, I am getting pretty good at that , and increased the controlling temperature slowly to 180deg, as prescribed. All went well but when I checked again today, to my surprise the overflow/expansion container was completely empty even though I had filled it to the brim yesterday (by mistake). I was expecting that the motor would have ejected some coolant when it cooled off, leading to an overflow of the expansion container but it looks like the motor sucked in its whole contents! No idea what that means.

Unfortunately, when I was done I had to winterize the boat for the season. We will have a cold snap this week, with 36 hours below freezing (down to the teens). I have things set up so that winterizing is not a big deal so I could presumably go for a last sail next weekend but I am really busy at work so most likely this is the end of my season.

I guess I won't know if this is the end of my saga or not until some time next April.

Again, thanks A LOT for all the advice and hand-holding. I will for sure keep y'all updated once I emerge out of hibernation!

[ernst]

Situation update: Yesterday I took out the pump again. Of course that included removal of the alternator bracket, which means moving downthe alternator. As expected, there was old gasket material on the flange. After I cleaned that up and installed the new gasket (requiring a trip to the hardware store since the lockwasher on one of the bolts was donated to the bilge), the oil leak is gone.

Whether my whole problem is solved is not clear. Before I started the above-mentioned work, I noticed that the bilge under the motor was again filled with about a half gallon of what looked to be at least partially coolant (no, I did not taste it, I have my limits!). I had not put in a diaper this time, precisely because I wanted to see if I might have a leak somewhere. Nevertheless, I did the multi-stage refilling of the block and heat exchanger, I am getting pretty good at that , and increased the controlling temperature slowly to 180deg, as prescribed. All went well but when I checked again today, to my surprise the overflow/expansion container was completely empty even though I had filled it to the brim yesterday (by mistake). I was expecting that the motor would have ejected some coolant when it cooled off, leading to an overflow of the expansion container but it looks like the motor sucked in its whole contents! No idea what that means.

Unfortunately, when I was done I had to winterize the boat for the season. We will have a cold snap this week, with 36 hours below freezing (down to the teens). I have things set up so that winterizing is not a big deal so I could presumably go for a last sail next weekend but I am really busy at work so most likely this is the end of my season.

I guess I won't know if this is the end of my saga or not until some time next April.

Again, thanks A LOT for all the advice and hand-holding. I will for sure keep y'all updated once I emerge out of hibernation!

Many moons later (Covid related): I believe the mystery is solved! The resolution of the saga is posted at the end of a seemingly unrelated thread, on painting the motor: https://www.moyermarineforum.com/for...t=11215&page=2

Cliff notes version: There was a slow leak at a completely unsuspected location. It was discovered by SASTANLEY on this forum when I proudly showed my 'after' pictures of the paint job, and he pointed out that in one picture there were some drops visible on the top of the block. Sure enough, that was it! I am extremely grateful for his eagle eyes, I would have NEVER suspected this cause!

So of course I am very happy that this saga has come to an end, with a good solution. And I have learned a lot! The only possible negative is that I may have junked a perfectly good coolant pump. Well, it is still there, I guess I should order the snap ring (one of the things that I learned is that this is needed!) and keep it as a spare.

Again: Muchas gracias for all the great input!