Edge70

Hello, I have a Cobalt 272 with a Merc 496 HO Engine and Bravo 3 drive. At the end of last season, the service shop recommended that I replace the gimble bearing, rear shift cable, water hose and bellows (note, year of boat is 2008 and it has only 160 hours on the engine). In addition, they did the impeller and full drive inspection. Today was the first day in the water for the boat since this maintenance last year and the boat is giving a long solid beep and the engine temp is getting hot when it's running around 3200 rpm for a few minutes In addition, the first time I took the boat up on plane it felt like it was pulsing or surging which I've never felt before. The temp will come up in about 5 mins or less and then it will error out. I can run it slightly above idle and the engine cools back down allowing me to limp back to the dock. Something definitely doesn't seem right after this service. Any thoughts? Thank you in advance.

AllDodge

iTrader: (1)

If your belt is in place and not loose, take it back to the shop, they didn't do something correct.

underpsi68

Do you still have the stock brass sea water pump housing? They score on the ends and the impeller doesn't get good suction?

Edge70

The belt appears to be installed properly and isn't loose. It seems to be an issue that's more prevalent once the boat gets up on plane. I'll contact the service shop tomorrow. Thx.

Edge70

The invoice from the shop shows says "MerCruiser 496 Mag Impeller Change - brass seawater pump design" so I'm thinking they did not change the impeller housing but just the impeller. From everything I'm reading, it seems like the impeller is the likely cause of the problem. I had a 2 beep error last summer for a similar condition and it ended up being a faulty block PSI sensor. They changed it and the boat worked great. I'll ask them about them about this pump housing. Thanks.

BUP

iTrader: (9)

your location and are you willing to give out the name of the shop ? I have a lot to say especially changing an impeller at the end of the season ? why --- see your impeller is what 10 months old or very close to a year old currently -- Bad advice on their part. I bet their reply would be they could not run your engine cause the impeller was going out for lay up / storage. Wrong

BTW I do this for a living and know whats best for the boat owner plus having my interest in the boat owners best interest for service needs so they come back and realize I am on their side.

Edge70

Thanks BUP, that makes total sense. I'm in Canada and have the Cobalt serviced in the thousand islands area of Lake Ontario. Note, the dealer is pretty reputable but what you've said makes a lot of sense. Especially given the winters we have up here for the boats to sit in. I'm not certain it's the impeller but it's certainly learning towards it. It's not easy to get at that impeller on that engine either or I'd check it out as I have a spare one. I think I'll let them deal with it as it's the new impeller they installed has about 10 mins of use on it's life.

BUP

iTrader: (9)

one could watch water pressure on the scan running thru out all rpms on the water that's a telltail sign of water flow good or bad.

I am not saying its your impeller - I am saying you started your season out with an almost one year old impeller that is wasting money as they need to changed in 2 years or less depending on conditions. .ie water conditions or if the impeller just sat in one spot for a long periods of time. Kind of like putting new tires on your heavy truck and it does not move for one year. flat spots on the tires. Same with the impeller not moving forms a (set) blades folded over that do not bounce back.

GEN VII water pump impeller housing life span in clean to semi clean water is about 125 to 225 hours because they become deeply scared. Dirty water 50 to 125 hours and that's for the impeller housing. Backside and front side deep wear rings internally that form. This causes cavitation as the impeller is spinning. Decrease water flow thru out..

Anyways more info --- I would look into the heat exchanger for blockage and its end cap sealing round gaskets. The end cap gaskets are another problem for restricting water flow. Just throwing out some problem areas. I have a lot more but since its going back to the shop they should be able to handle it. .

Running problems engine side prob old gas and possible condensation in the fuel would be a good guess. I would change all fuel filters in the GEN 3 cool fuel as well. Thats another set of items, one should change out every first start of boating season not the end of the season

lakematdude

In this instance the higher probable cause to consider inspecting first would be that your new intake water hose may now have a kink/twist in it from improper installation. If one gets in a hurry while preforming this job, this tends to happen.
Bravo 3 High Speed Overheat Page: 1 - iboats Boating Forums 10442408

Edge70

Thanks for the suggestion, I'm thinking this is something that you need to have the drive off to verify. Correct?