My engine was overheating before I even got out of the marina yesterday (immediately returned to slip). Having read many articles about replacing impellers every couple of years, I have put it off for 3 years as I knew those articles didn't apply to me!!!(ha) I checked the thru-hull and hose to the pump and they are clear. I then removed the smaller output hose to the engine, and started it. It does pump some water, but in my opinion an inadequate amount, so I assume it is the impeller. Does this sound logical? Could it be the impeller but still be pumping, or would it quit entirely? I don't have any experience with this and only have moderate mechanical skills. Any suggestions will be appreciated. Keith
RENAULT - RC8D Diesel, Overheating. Impeller?
- Thread starter Keith6660
- Start date
- Status
All at once? or gradual failure?
Hi Keith, I'm not sure how you're estimating an "adequate amount" of water flow. My 2 cents worth is that if it has failed gradually, then the impeller is a likely candidate. Getting the plate off the pump is a bit of a hassle, but you're going to have to do it sooner or later, so now's the time. If the impeller looks good and it's still overheating (as mine did) or if the overheating has come on suddenly, then I'd recommend pulling the line where water exits into the exhaust and checking the water flow there. Remember that there's a by-pass, so water flow here doesnt' gaurantee that the water is going thru the engine. So... I recommend blocking off the bypass and backflushing the engine with one of those little pressure nozzles that fit on the end of a garden hose. You should hear water flowing back thru the pump. Move the belt a bit back and forward to make sure the opening isn't covered. If you get a lot of resistance at first and then hear a big "whoosh", then you know something was stuck in there somewhere and has been purged. Best of luck with it. Tom Milke
Hi Keith, I'm not sure how you're estimating an "adequate amount" of water flow. My 2 cents worth is that if it has failed gradually, then the impeller is a likely candidate. Getting the plate off the pump is a bit of a hassle, but you're going to have to do it sooner or later, so now's the time. If the impeller looks good and it's still overheating (as mine did) or if the overheating has come on suddenly, then I'd recommend pulling the line where water exits into the exhaust and checking the water flow there. Remember that there's a by-pass, so water flow here doesnt' gaurantee that the water is going thru the engine. So... I recommend blocking off the bypass and backflushing the engine with one of those little pressure nozzles that fit on the end of a garden hose. You should hear water flowing back thru the pump. Move the belt a bit back and forward to make sure the opening isn't covered. If you get a lot of resistance at first and then hear a big "whoosh", then you know something was stuck in there somewhere and has been purged. Best of luck with it. Tom Milke
Thanks Tom
Thanks Tom, I picked up an adapter for the garden hose and plan to go out tomorrow and check your theory. I'll let you know what I find out.
Thanks Tom, I picked up an adapter for the garden hose and plan to go out tomorrow and check your theory. I'll let you know what I find out.
Tom, you are the MAN!
Tom, Finally got out to the boat this evening with my new garden hose adaptor and followed your instructions. I didn't hear any 'whoosh' but I kept the water running for 2-3 minutes to make certain I got a good flush. Then I started it and let it run for 15-20 minutes, and the last 5 minutes at around 1200rpm, the needle didn't even come off the peg!!!! I think I'm fixed!!! Thank you very much for the suggestion. I am going ahead and ordering an impeller though and will replace it for pre-emptive reasons. The only source I'm aware of for the impeller is Mermaid Northeast Engines. Do you have any other suggestions? THANKS AGAIN!!! Keith
Tom, Finally got out to the boat this evening with my new garden hose adaptor and followed your instructions. I didn't hear any 'whoosh' but I kept the water running for 2-3 minutes to make certain I got a good flush. Then I started it and let it run for 15-20 minutes, and the last 5 minutes at around 1200rpm, the needle didn't even come off the peg!!!! I think I'm fixed!!! Thank you very much for the suggestion. I am going ahead and ordering an impeller though and will replace it for pre-emptive reasons. The only source I'm aware of for the impeller is Mermaid Northeast Engines. Do you have any other suggestions? THANKS AGAIN!!! Keith
- Status