Re: 1977 Eska 7.5
Your impeller does a lot more than cool the leg, it actually cools the bottom half of the cylinder and the lower main bearing and sinks heat from the whole bottom side of the engine through the mounting plate design.
One of the nuance's of the Tecumseh based Eska is that they made subtle but important changes to the engine design over the years one of which was to the 640 series of blocks (which you have) to cool the bottom of the cylinder by casting in a water jacket, previous models such as the 639, IE the 7hp series block had no such casting and water cooling was directed to the main bearing and circulated through the heat sink to remove heat from around the exaust port but never touched the cylinder. Running your engine with out water cooling will in short order ruin the lower crank seal, main bearing and cause the piston to scuff and melt away on its bottom side.
You can get the impeller here ay Iboats using this sierra no. 18-3054 or ebay and most any merc dealer, you can use a needle bearing of the correct size for a new key or you can buy impeller and key pin from a ebay seller.
Be careful when first using the external tank male fitting on the little outboard, it needs to be flushed with gas because all of the junk and rust ends up there when there not used.
Also heres a lesson I learned from Eskaman2008 of ebay fame and one of our Yahoo group members, make sure you put your remote tank at the level it will be in your boat when you test run from a remote tank or you will get a lean condition and poor to no idle, also consider your fuel line length and diameter as the little Eska bladder pump is weak and will have a hard time pulling the fuel. I recommend a new bladder and keep a spare handy.
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