Another Moomba overheating...

[jsol_way]

Seems like this is a popular problem with these boats. I bought my 98' Moomba Kanga about 6 weeks ago. Had her on the water for 3 fun-filled weekends with no problems...then a squealing noise with overheating. Impeller was shredded so I replaced it and ran it another weekend. As I was pulling her off the water same noise so I trailered it. Dropped it in the water next week, started overheating, and raw water pump housing was leaking so I replaced that...ran for about a day this weekend, started making a squealing noise again and overheating. From the rest of the threads I'm guessing blockage? Is there any way the shredded impeller pieces can get into the actual heads or into the cooling jackets in the engine block? I'm about to schedule an appointment with the dealer unless anyone has any suggestions.

[Sled491]

At this point seems the problem may have compounded. There is no simple solution. Well there is simple just not easy. Your gonna need to flush the whole system and pull as much of the system as you can apart to relieve the blockage. If you do your own winterizing this should be straight forward.

[LSM]

Seems like this is a popular problem with these boats. I bought my 98' Moomba Kanga about 6 weeks ago. Had her on the water for 3 fun-filled weekends with no problems...then a squealing noise with overheating. Impeller was shredded so I replaced it and ran it another weekend. As I was pulling her off the water same noise so I trailered it. Dropped it in the water next week, started overheating, and raw water pump housing was leaking so I replaced that...ran for about a day this weekend, started making a squealing noise again and overheating. From the rest of the threads I'm guessing blockage? Is there any way the shredded impeller pieces can get into the actual heads or into the cooling jackets in the engine block? I'm about to schedule an appointment with the dealer unless anyone has any suggestions.

Over 10 years ago I had a Malibu Sunsetter with this problem. I allowed the impeller to fail to the point of completely shredding inside the raw water pump housing. The rubber pieces in mine were actually hung up in side the water jackets on the exhaust manifolds.

I removed the exhuast manifolds and took them to a machine shop where they used a bead blaster to blow (sand) through the water jackets to clean them out. I put a third impeller on it and she ran perfect for 5 or 6 more years until I sold it.

I new mine was plugged somewhere becuase I could see very little water (to no water) coming from the exhaust while the boat was running.

It would overheat to the point of melting my exhaust hoses coming off the manifolds. It was hot !!

Yours could be plugged elsewhere but that was my experience.....

[jsol_way]

Thanks for the advice gentlemen...I think I am going to fake-lake it in the driveway tomorrow to see if there is more water coming out of one exhaust port than the other. If they both look equal it would have to be blockage in the lines, or possibly a water pump or thermostat issue? I'm guessing at this point...hope I shut her down in time before any damage to the impeller was done; fingers crossed. I need to figure this out and be wakeboarding this 4th of July weekend...

[NH Moomba]

Did you check to see that the transmission cooler on the water intake hose isn't blocked with some weeds or debris?

[zegm]

NH Moomba has a point, I had this happen several times on an old MasterCraft!!!
That might explain why I ordered the see through water inlet filter with our 2008 LS, probably the second best option I ordered after the Z-Cargo bimini. Check this area first as it can fill with enough debris to almost completely stop the water flow!!!

I had shredded impellers in over 22 years of owning inboard ski boats but never had a blockage problem due to this debris and yes I have had to purchase that expensive exhaust hose too, however, this occurred on a Ford Windsor 351 block and not on a Chevy small block.

[jsol_way]

Allright, so I pulled all the line up to the tranny cooler, there was a little bit of debris but nothing that would cause serious blockage. Also pulled all the hose from the raw water pump up to the thermostat housing, and replaced the thermostat while I was at it...still no serious debris that would cause blockage. I also installed the high pressure fuel pump conversion kit which eliminated the water cooling canister set-up for the old fuel pump which was dumping fuel into the cooling system. Pulled the cover off the impeller, and it is shot like the other two; so I am back to scratching my head. I am wondering if the old water cooled fuel pump assembly that was dumping raw fuel into the cooling system may have tore up the impeller? I ran water through it and let it run for a while, and the temp never went over 175, and it appeared that both exhaust flaps were spitting an equal amount of water.* But, with the impeller destroyed; I can't really tell if it will cool itself down while on the lake. I guess the only option is to order a 4th impeller, run it and see what happens...no wakeboarding this weekend, damnitt.