Distorted/leaking thermostat covers

[fleetwin]

Well, I haven’t had too much trouble with this style cover, although it is hard to clean because of the protrusion. Usually the one gasket and some OMC gasket sealer is all that is needed. I suppose if someone over tightens the screws, the ears might get pulled down. You could put a straight edge on the head to be sure that surface isn’t out of whack. Flattening out the head surface is no big deal. Dan raises a good point about the cap though, messing with that surface too much will cause the thermostat seal to get distorted/crushed too much.
One final test might be to loosely bolt the cap to the head (no thermostat or gasket), distorted/warped areas should be pretty obvious.

[johnyrude200]

quote t2stroke:

Removing material around the outside surface only will make the casting dig into the thermostat and warp it at the screws. Just something else to think about when you are dealing with this irritating part.

Dan in TN

On top of that, the reason why I didn’t respond to ‘doubling up gaskets’ is for the same reason you cited…is only a band-aid to the situation instead of a solid long-term solution.

I don’t remove thermostats because I’ve learned, the way you and the veteran techs did 30 years ago, running a motor without a thermostat is simply a band-aid for a weak impeller or faulty cooling system. I have observed in the last 50-60 motors I’ve serviced that basically 60-70% of motors I acquire either are like this or simply have faulty cooling systems. It’s to the point where I think I may raise my resale prices across the board by $30 to account for a new thermostat and impeller (I don’t count my troubleshooting time as part of this figure) and explain this on my sales page.

When you say material around the outside surface, are you saying lapping that t-stat cover is a futile cause? This seems to happen at least 80% of the time when I remove a cover after seeing a motor run too cold, or overheat, despite seeing plenty of water being expelled at the blubber hole or telltale, or just chasing down the cooling system problem (thanks again Frank R. & GARY, for sharing the trick about the impeller housing pin hole which can basically shut off all water to the rest of the motor…can anybody say INVALUABLE and NOWHERE in any manual I’ve ever read).

Now just wait until I become a PIA for all the 80’s through 2004 25/35hp motors I am diving into currently….

Thanks again for all your help folks…as I said last week, have a local FD asking me for a 18hp evinrude, which I guarantee you will look and run like a showroom motor once I’m through with it to insure reliability when trying to save drowning victims….wouldn’t be possible without the devotion of you retired mechanics and service reps to the AOMCI and the forums.

[phil-b]

quote johnyrude200:

(thanks again Frank R. & GARY, for sharing the trick about the impeller housing pin hole which can basically shut off all water to the rest of the motor…can anybody say INVALUABLE and NOWHERE in any manual I’ve ever read).

I’m not going to argue that it’s obscure knowledge, but the "pinholes" are pointed out in Evinrude service bulletins M-214 and M-66, reprinted on pages 80 and 82, respectively of "Cheap Outboards" by Max Wawrzyniak.

Someone collected and scanned a WHOLE LOT of service bulletins, but reading them all, and REMEMBERING what you read is another matter!

[johnyrude200]

hey Phil, great callsign pic, those mid 60’s 18hp motors just go and go and go, and are sooooo smooth at all ranges!

[chinewalker]

On occasion, I have installed the cover WITHOUT a gasket and gently tapped the top of the cover with a rubber mallet to return it to shape. The metal-on-metal will prevent the cover from cracking. Aluminum can be bent a little bit if it is supported during the process. I have also straightened skegs in a similar fashion, with a ball peen hammer and a sledge. The sledge rests against the convex side of the skeg, with the ball peen hammer tapping on the concave side until the skeg is straightened. Same can be done with most aluminum castings. The key is to support the back side so that the casting doesn’t just flex and break. Many moderate taps will work better than a few heavy blows.

[Author]

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