I have a 1987 Yanmar 2GM20F. One of the impeller blades is missing! I have removed the hoses and the heat exchanger housing but cannot find the piece(s). I have not removed the heat exchanger but looked for the pieces in the tubes with no luck. What problem would you think I'll encounter? How far should I go to find them....how important is it to find them?
Impeller
- Thread starter Seashell
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If you have looked in the inlet hose and the outlet hose of the pump itself, and in the end of the heat exchanger fed from the pump and have not found any pieces, then the pieces must have been ground up small enough to pass through the heat exchanger and out of the engine.
I would not worry about it, but I would keep an eye on the engine temperature for a short while.
I would not worry about it, but I would keep an eye on the engine temperature for a short while.
Not important that ya find the part.. it is really important that you know that you have un-impeded flow. Almost the same problem.. I would have suspected that the blade would have been in the inlet side of the heat exchanger,covering a couple of tubes. If you are sure it is not there, then pull the outlet cover and check there .. if it is not in the outlet side cover then look thru each tube to see if it is in one of 'em.. or get a pistol cleaning kit and brush the interior of each tube .. something like a 30 caliber brass bore brush is fine.. The tubes are 5mm ID by 6mm OD.. There arre 24 of 'em; it is three pass on the tube side so the whole flow is in 8 tubes.. Flow goes front-to-back then turns in the back cover and flows back-to-front, then turns again in the front cover and flows front-to-back. If the blade is not in the heatex or the covers then check the two little elbows, one where it leaves the rear heatex cover and the other where the water enters the exhaust mixing elbow.. you need the water flow to cool the heat exchanger and exhaust. Happy hunting
I decided to change mine last spring while still on the hard. Got the old one out and found one of the blades missing, was lucky to find that one blade stuck in the upper part of the impeller housing, had to use a mirror and flashlight to see it. Good Luck!
I have the same engine/water pump/impeller. When I bought my boat in 2003, I was surprised to find two blades missing from the impeller when I inspected/surveyed the boat. I checked all the possible downstream places the missing parts could be -- and found none. I replaced the impeller and motored down the bay for 2 full days to get the boat home. I kept a close eye on the engine for signs of overheating. The engine ran perfectly -- and has done so ever since I bought the boat. I assume the missing impeller blades got through the cooling system and out the exhaust. If you cannot find your missing pieces and have checked all the "usual suspects," just keep eye on the overheat alarm and assume the pieces have departed for parts unknown. FYI, since I only put 50-60 hrs on the engine each season, I now replace the impeller every other year.
Thanks all for the responses. I found the mising piece sitting on the engine. I simply missed it the other night. It was hard enough to see Saturday in sunlight! It must have been in the hose, and came out in the flow of coolant when I removed it.
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