running without a t-stat

[wiscoboater]

Guys, I’m just kidding Scott about the Lark. He and I are good friends. We share a site at Tomahawk and attend meets together throughout the year. It’s just some fun ribbing between two friends, nothing more.

[opposedtwin]

Thanks everyone for your input! Typically parts are there for a reason and should be included. I will track one down and install it. The prospect of exhaust gases damaging the impeller, etc is not one I’m willing to chance.

Wannabe (Jeff): despite your summer of misadventure with the 135, you gotta admit that OMC motors have their place both in history and on the water. Easy boy, easy….

[opposedtwin]

Jeff, I hope we have a nice long autumn that lasts into November and we’re able to take that 135 out on the water sometime.

[opposedtwin]

Well…maybe I pulled it too soon. I tested the little bugger in some hot water on the stove and it appears to open and close. Still, if I couldn’t keep my hand on the housing, isn’t that too hot?

Does anyone happen to know at what temp these things are designed to open? To repeat, it’s a 1959 lark.

[frankr]

There should have been at least a mist of water coming out, even with the stat closed. That is necessary to keep the exhaust system cool. Saying there must have been some kind of problem with no mist and hot temps.

I seem to remember it opens at 140 degrees. Or something like that.

[wiscoboater]

Didn’t the thermostats have a couple little pin holes to allow some water through if they were stuck closed. If not the stat, maybe the flange it rests on? I remember reading about that when having trouble with an FD 20 running hot. Could those be clogged?

Scott, If you have a free weekend after Labor day I’d love to bring the boat out by you to try out your local lake. All the lakes in my area have 35MPH speed limits. Would love to get on your big lake and open her up.

[opposedtwin]

Jeff, that would be awesome! Mendota is big and about 8 blocks from my house. As far as I know, there’s no speed limit that would affect us. I boat here until early November. I think they normally take the last dock out just before thanks giving.

[opposedtwin]

quote FrankR:

There should have been at least a mist of water coming out, even with the stat closed. That is necessary to keep the exhaust system cool. Saying there must have been some kind of problem with no mist and hot temps.

I seem to remember it opens at 140 degrees. Or something like that.

Thanks frank, I’ll check it at 140 degrees. I remember it was misting at first but then that stopped and so that’s when I shut it down. I will re-install it, try it again and report back.

Jeff: I will check for those little holes. That may have been what it was.

[rudderless]

Opposedtwin..cant do pm’s yet…here is what I did for my adjustable water throttle deal on my ’76 9.9/15…

Pulled head and outer cover on head. Removed thermostat. Made aluminum washer with 1/4 hole in center to go where the thermo was. Beveled outer edge of washer to hold an o-ring tight when cover is installed. Temporarily assemble outer cover, washer and oring. Turn head over and look at thermo hole. Insert 1/4 drill bit through washer hole to mark back of outer cover. Drill tap hole and tap 1/4×20 in outer cover. Take 1/4×20 stainless slotted screw and thread it into inside of outer cover. By turning screw in and out it covers the hole to various openings. Use nut on outside to hold setting. There is not a lot of room so the screw will be short. If I were to do again I would use a 3/16 hole in washer. Use a slotted screw so one can’t turn off the water fully.

[wiscoboater]

Many times when these old motors are put away "wet" and forgotten for years the water trapped within can corrode and form calcium deposits within the water jacket. When fired up again years later the scale formed from the water, or just condensation from the water sitting for years can come loose in flakes…or layers, and wreak havoc in the small water passages. Spending many years working on classic cars, I have seen this many times. The hard calcified flakes can clog all but the biggest passages. It transcends to old outboard motors as well.
Don’t know if this is your issue but it is good food for thought.

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