Went for a sail yesterday, 2nd of the season. Motor overheated within 10 minutes of leaving slip. Did some trouble shooting on the water and after being towed back into the slip. After my last step I started the motor and it had good water flow. Never found a definitive reason. Here are the trouble shooting steps I took:
1. Motored out into the channel leading from my slip to the bay much more slowly than usual (3 knots vs 5 knots) due to traffic.
2. Just as I entered the bay overheat alarm sounded. A quick look over the stern and I saw no water going out of the exhaust. Total run time of 10-15 minutes.
3. Shutdown motor, unfurled the jib and sailed away.
4. Opened the intake water strainer. Water was good coming out top of strainer. Strainer was clean.
5. Changed impeller on Oberdorpher water pump. (I change the impeller every spring. Never had one with broken vanes.)
6. Started engine. No water flow.
7. Removed hose from strainer outlet. Good water flow. Reinstalled hose.
8. Opened impeller cover. Good water flow out of water pump. Reinstalled cover.
9. Removed anode from bottom of 3" heat exchanger. Started engine. Good water flow out of HX. Reinstalled anode. (HX was removed refurbed by radiator shop in 2018)
10. Tow boat arrived and took me to slip.
11. Started motor and observed flapper on exhaust outlet to ensure gasses were being expelled. They were. Didn't let the motor run long enough for water flow to start.
12. Removed outlet hose of siphon break which is between HX and water injection port on exhaust manifold. Good water flow and pressure into bucket.
13. Used zip tie to check water injection port for blockage. No blockage. Clear into hump hose on water lift muffler.
14. While I was at the siphon break, removed duck bill and flushed with clean water. Reinstalled.
15. Started motor. This time had a good water flow.
I ran the motor for 6 hours today. Water temp was steady at 165 deg temp.
The only other thing of note is the exhaust flapper sometimes sticks open sometimes. We had a NEstr over the weekend. Maybe some water got pumped into the muffler? (I'll be fixing that flapper on Thursday.
Could a stuck siphon break valve cause a hydrolock?
Do raw water systems suffer from hydrolock?
Appreciate any input on what might have caused the water flow failure and allowed the flow to return to normal without the obvious findings. (blockage at inlet thru hull, strainer, HX, failed impeller, etc.
1. Motored out into the channel leading from my slip to the bay much more slowly than usual (3 knots vs 5 knots) due to traffic.
2. Just as I entered the bay overheat alarm sounded. A quick look over the stern and I saw no water going out of the exhaust. Total run time of 10-15 minutes.
3. Shutdown motor, unfurled the jib and sailed away.
4. Opened the intake water strainer. Water was good coming out top of strainer. Strainer was clean.
5. Changed impeller on Oberdorpher water pump. (I change the impeller every spring. Never had one with broken vanes.)
6. Started engine. No water flow.
7. Removed hose from strainer outlet. Good water flow. Reinstalled hose.
8. Opened impeller cover. Good water flow out of water pump. Reinstalled cover.
9. Removed anode from bottom of 3" heat exchanger. Started engine. Good water flow out of HX. Reinstalled anode. (HX was removed refurbed by radiator shop in 2018)
10. Tow boat arrived and took me to slip.
11. Started motor and observed flapper on exhaust outlet to ensure gasses were being expelled. They were. Didn't let the motor run long enough for water flow to start.
12. Removed outlet hose of siphon break which is between HX and water injection port on exhaust manifold. Good water flow and pressure into bucket.
13. Used zip tie to check water injection port for blockage. No blockage. Clear into hump hose on water lift muffler.
14. While I was at the siphon break, removed duck bill and flushed with clean water. Reinstalled.
15. Started motor. This time had a good water flow.
I ran the motor for 6 hours today. Water temp was steady at 165 deg temp.
The only other thing of note is the exhaust flapper sometimes sticks open sometimes. We had a NEstr over the weekend. Maybe some water got pumped into the muffler? (I'll be fixing that flapper on Thursday.
Could a stuck siphon break valve cause a hydrolock?
Do raw water systems suffer from hydrolock?
Appreciate any input on what might have caused the water flow failure and allowed the flow to return to normal without the obvious findings. (blockage at inlet thru hull, strainer, HX, failed impeller, etc.