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1968 OMC Overheating; no thermostat,

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Restored

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I have a 1968 OMC, the engine runs fine for about 15 minutes and the overheats. I've replaced the water pump, checked the thermostat to find there isn't between the upper and lower housing. Is there an alternate way to cool this engine since I can't get a upper or lower housing anymore? Appreciate any help on this one. Spent way to many hours troubleshooting this problem already. Thanks
 
I have a 1968 Evinrude, 155 HP V6 Engine, Sportsman Model. I have replaced the water pump, checked to make sure I'm getting flow through the system, but after about 10-15 minutes under load it begins to overheat. It get so hot it produces high pressure steam and keeps burning through my exhaust hoses on one side. I took apart the thermostat housing and found there was no longer a thermostat between the upper and lower chamber. Is there an alternate repair to replacing the thermostat and housing, because the housing won't come apart to re-intstall a thermostat and the housings are no longer available on the market. Any help is appreciated.
 
Restored said:
I have replaced the water pump,
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you mean the impeller in the outdrive? or the circulation pump?

those housings pop up on eBay occasionally...
I'm just searching some old posts.... pretty sure some clever marineengine.com posters determined at one time, that the lower housing was just the same on Jeep and Kaiser, Buick used on the car version of that engine..upper of course is marine specific
 
Thanks, that info is helpful, I know I was able to come up with a NAPA part number from one of the threads to get a replacement water pump, but I didn't know about the lower thermostat housing auto use on the Jeep and Kaiser. I might be able to find a complete unit on eBay or at least begin to look for a replacement part number for the lower housing. I can a replacement thermostat at marinengine.com. Let me know if you find the posts with additional info. Big Thanks.
 
If your leg waterpump isn't working, pumping that is, you are in strife.

Is there a tell-tale spray of water coming out of the leg pivot point on the Starboard side?

Bruce.
 
My spurt goes out the the Starboard Side, and as far as I am award, the Ball Gears are dry. The spurt holes are on both outsides of the housing at the hinge.

I have seen tin covers for over the Ball Gears for sale, but there was none on my unit when I purchased it. And not mentioned in the Workshop Manual.

Bruce.
 
Restored said:
I have a 1968 Evinrude, 155 HP V6 Engine, Sportsman Model. I have replaced the water pump, checked to make sure I'm getting flow through the system, but after about 10-15 minutes under load it begins to overheat. It get so hot it produces high pressure steam and keeps burning through my exhaust hoses on one side. I took apart the thermostat housing and found there was no longer a thermostat between the upper and lower chamber. Is there an alternate repair to replacing the thermostat and housing, because the housing won't come apart to re-intstall a thermostat and the housings are no longer available on the market. Any help is appreciated.
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It seems you've got the same engine as I do. I have a spare Thermostat Housing. You can still buy Thermostats for this engine. 165 degrees is what is stamped on mine.

These housings do have a 5/8ths sized passage on one side. This keeps some water flowing all the time. 2 years ago, a chunk of rust broke off from somewhere, and jammed my thermostat closed. the engine got so hot, it was burning the paint on the engine. Thank god for cast iron heads, and block !!! I had to have 2 buddies continuosly pouring water on the engine on the way back in, hobbling along at a bit above idle. Any more than that, and the engine was getting really hot. When I took the Thermostat out, the rust chunk was still there.
 
I cant figure out what Tassie Devil is talking about. The Ball Gears on my Boat are submerged most of the time. NO dryness at all.

I think I own the oldest OMC Drive on this Website.
 
My Ball Gears are sitting above the waterline when stationary, and when under way, (planing) the water is streaming back from the bottom of the transom and the Ball Gears are well away from the water.

Next time I am out, I will take some pictures, but for the life of me, I can't see how the water can get up that high to wet them.

Bruce.
 
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