I just purchased my 86 CAT 30 two months ago, and in motoring out in to Galveston Bay I was maintaing 2300 RPM, not knowing the max cruising RPM and all was fine, except I was being overtaken by all the other motoring sailors. Knot log not working so don't know my speed. Next weekend out again, I tried 2900 RPM, ran much faster, but engine got hot setting off the alarm horn. The engine noise was so loud motoring at that RPM I didn't notice the alarm horn until throttling back to put the canvas up. I let the engine idle 10 minutes and then shut it down, got to about 240 F degs. Am I running too fast, I don't know which prop I have, but the water temp down here is around 88 F degs. I have not had the boat hauled yet as I bought it from a friend so I haven't inspected scoops, props, etc, I am just wondering what the approx safe cruising RPM is for the CAT 30 (ie, passagemaking) on the 25HP Universal?? Any and all feedback appreciated. Mark Magee Kemah TX USA CAT 30 (To Be Named!)
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cat 30 overheat
mark, i have a 85 cat 30 with univ.25. i motor at 2600 rpm at 160 degrees.i also am in kemah.s/v freda.kemah harbor marina try flushing your system,check and or change the impeller.also check the exhaust system this could also be causing you problems
mark, i have a 85 cat 30 with univ.25. i motor at 2600 rpm at 160 degrees.i also am in kemah.s/v freda.kemah harbor marina try flushing your system,check and or change the impeller.also check the exhaust system this could also be causing you problems
TO CORRECT OVERHEATING
I have an M25 Universal engine in my 36 Catalina.I can run all day @ 2500 RPMs without the overheating problem.(I keep the valve in back of the engine open).They make a larger heat exchanger that isn't too difficult to install. The cost is $300. It will enable you to go a little faster (1/2 knott maybe) without overheating.I am thinking of getting one but I hate to motor at all---- so I have not done it yet.With the larger exchanger you can get more RPMs without as much heat....Good luck!
I have an M25 Universal engine in my 36 Catalina.I can run all day @ 2500 RPMs without the overheating problem.(I keep the valve in back of the engine open).They make a larger heat exchanger that isn't too difficult to install. The cost is $300. It will enable you to go a little faster (1/2 knott maybe) without overheating.I am thinking of getting one but I hate to motor at all---- so I have not done it yet.With the larger exchanger you can get more RPMs without as much heat....Good luck!
Check your impeller & strainer
You're probably overheating cuz you either have a bad impeller (as mentioned previously) or your strainer is clogged with that Galveston Bay gunk!
As far as RPMs are concerned, you shouldn't be overheating from running it "too" fast. My guy Rob had an 87 C30 w/an XP25 (?) Universal & it wouldn't go over 2200 RPM (that was max - cruising was 1800) cuz it had a huge prop. In flat water, we'd get 7 knots easy! I'm guessing you have a smaller prop cuz you're getting higher RPMs and going slower than the other boats. I'd look into changing up to a bigger prop when you do haul out if speed is a big issue. LaDonna
You're probably overheating cuz you either have a bad impeller (as mentioned previously) or your strainer is clogged with that Galveston Bay gunk!
As far as RPMs are concerned, you shouldn't be overheating from running it "too" fast. My guy Rob had an 87 C30 w/an XP25 (?) Universal & it wouldn't go over 2200 RPM (that was max - cruising was 1800) cuz it had a huge prop. In flat water, we'd get 7 knots easy! I'm guessing you have a smaller prop cuz you're getting higher RPMs and going slower than the other boats. I'd look into changing up to a bigger prop when you do haul out if speed is a big issue. LaDonna25 HP or Model 25 Universal?
I had a model 25 Universal (21hp) on my 1985 C36 and overheating was a constant problem when at higher RPMs. In speaking with several other owners with the same engine, the problem really is a undersized heat exchanger. I replaced impellers, cleaned the heat exchanger, left the valve on the exchanger all the way open, and nothing worked! If you plan on keeping the boat for a while I would spend the money for the larger heat exchanger. you never know when you will need full power, and the last thing you want is overheating when you do!! MPJ
I had a model 25 Universal (21hp) on my 1985 C36 and overheating was a constant problem when at higher RPMs. In speaking with several other owners with the same engine, the problem really is a undersized heat exchanger. I replaced impellers, cleaned the heat exchanger, left the valve on the exchanger all the way open, and nothing worked! If you plan on keeping the boat for a while I would spend the money for the larger heat exchanger. you never know when you will need full power, and the last thing you want is overheating when you do!! MPJ
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