Hello, thanks for your help in advance. I have used the forum to solve many problems but this is my first post. I have a 2006 Four Winns 348 Vista with dual 5.7 GXi-G motors with 320 hours on them. We have owned the boat for 3 years and never had a problem with the engines. The boat has been in fresh water in Lake Michigan in lower Wisconsin most of its life and we have had it in Lake Geneva the last 2 years. We are having 2 similar problems lately on different engines:
1. 2 weeks ago my starboard engine burst the coolant hose from the thermostat housing to the water circulator. I took the thermostat housing apart and found impellor chunks clogging the bypass hole. I have cleaned this out and the engine is back to normal except I am getting a whining noise in our water circulator. It seems to quiet down after 10 minutes at idle. I just wanted to check if the strain from the clog could have done damage to the water circulator and if I should replace it. The coolant hoses do not seem to have pressure on them since the clog was removed and the engine is running normal and has good temperature.
2. More urgent issue- About a week after the fist engine, I had a similar problem with the port engine. When I changed the thermostat on the first engine, I also did the 2nd engine (should have left it alone I guess). After I changed it and did a test drive to check it, the thermostat fell down. So we ran back to the marina and put the thermostat back in. I must have had some rust in the o-ring groove. I cleaned it out and the o ring held fine after that. The boat ran fine for 2 days (just normal drives or 30 minutes to an hour, nothing hard on the motors), then I started it up the next day and was motoring around the marina and blew the same coolant hose from the thermostat to the circulating pump. I have put it back together and can not find a clog. The hose is pressurized still and it seems that as soon as I would get up to 2-3K RPM it will blow. Seems like there is a clog. Also, I noticed that the starboard riser is much hotter. Here is what I have checked already:
a. taken the thermostat housing apart a few times and it is clean of impeller parts
b. I have taken all the hoses off from the raw water pump to the hoses going to the risers and cleaned them and made sure there were no clogs.
c. I have checked the raw water impeller and it looks good (replaced this March)
d. I have pulled the riser plug and it has good water coming out of it at idle
e. I have pulled the starboard riser and checked it for clogs. It looked really good and I did not see any blockage. I sprayed water through it with a water hose while it was off and it seemed to have good flow and the water came out. I also sprayed penetrating oil into the water jackets while it was off thinking that it might have blockage inside of it that I could loosen up. I was thinking that if water can get through it then it should not be blocked. But based on it getting hotter this seems like it would be the problem. Based on the appearance it does not look bad. Has anyone had one go bad inside that you cannot see the obvious problem. I am not sure if you can pressure test these.
f. I have detached the hose going to the starboard riser at idle and it has a good stream of water.
g. The water pump starts to whine after 30 second at idle. Seems like the pressure is causing this.
h. I have followed all the hoses at idle and they seem to be fine with flow. The large coolant hose is the only one under pressure.
i. I replaced the thermostat thinking maybe it was damaged when it fell down during the test drive.
j. I don't think the engine got too hot when the hose blew. It starts up fine and runs well. But I can tell the hose will burst with any load on it.
Thanks for your help. These issues are strange because they happened so close to each other. I am debating throwing parts at it and thinking it is either the riser or the circulating pump but wanted advice on if I am missing anything or something to check. It must be a clog causing the pressure but I can't find it. Here are pictures of the risers.
1. 2 weeks ago my starboard engine burst the coolant hose from the thermostat housing to the water circulator. I took the thermostat housing apart and found impellor chunks clogging the bypass hole. I have cleaned this out and the engine is back to normal except I am getting a whining noise in our water circulator. It seems to quiet down after 10 minutes at idle. I just wanted to check if the strain from the clog could have done damage to the water circulator and if I should replace it. The coolant hoses do not seem to have pressure on them since the clog was removed and the engine is running normal and has good temperature.
2. More urgent issue- About a week after the fist engine, I had a similar problem with the port engine. When I changed the thermostat on the first engine, I also did the 2nd engine (should have left it alone I guess). After I changed it and did a test drive to check it, the thermostat fell down. So we ran back to the marina and put the thermostat back in. I must have had some rust in the o-ring groove. I cleaned it out and the o ring held fine after that. The boat ran fine for 2 days (just normal drives or 30 minutes to an hour, nothing hard on the motors), then I started it up the next day and was motoring around the marina and blew the same coolant hose from the thermostat to the circulating pump. I have put it back together and can not find a clog. The hose is pressurized still and it seems that as soon as I would get up to 2-3K RPM it will blow. Seems like there is a clog. Also, I noticed that the starboard riser is much hotter. Here is what I have checked already:
a. taken the thermostat housing apart a few times and it is clean of impeller parts
b. I have taken all the hoses off from the raw water pump to the hoses going to the risers and cleaned them and made sure there were no clogs.
c. I have checked the raw water impeller and it looks good (replaced this March)
d. I have pulled the riser plug and it has good water coming out of it at idle
e. I have pulled the starboard riser and checked it for clogs. It looked really good and I did not see any blockage. I sprayed water through it with a water hose while it was off and it seemed to have good flow and the water came out. I also sprayed penetrating oil into the water jackets while it was off thinking that it might have blockage inside of it that I could loosen up. I was thinking that if water can get through it then it should not be blocked. But based on it getting hotter this seems like it would be the problem. Based on the appearance it does not look bad. Has anyone had one go bad inside that you cannot see the obvious problem. I am not sure if you can pressure test these.
f. I have detached the hose going to the starboard riser at idle and it has a good stream of water.
g. The water pump starts to whine after 30 second at idle. Seems like the pressure is causing this.
h. I have followed all the hoses at idle and they seem to be fine with flow. The large coolant hose is the only one under pressure.
i. I replaced the thermostat thinking maybe it was damaged when it fell down during the test drive.
j. I don't think the engine got too hot when the hose blew. It starts up fine and runs well. But I can tell the hose will burst with any load on it.
Thanks for your help. These issues are strange because they happened so close to each other. I am debating throwing parts at it and thinking it is either the riser or the circulating pump but wanted advice on if I am missing anything or something to check. It must be a clog causing the pressure but I can't find it. Here are pictures of the risers.
