Bravo 1 Water Pump/Running On Muffs Question

[jserr68594]

I was running my new-to-me boat for the first time this season on the hose. It has a 2006 350 MAG MPI engine and a Bravo 1 out drive.

I first duck taped the lower water inlet closed. I then put my muffs on the engine and turned the water on. I started the boat. I let the engine run for a minute or two and had very little to no water coming out of the exhaust.

The former owner just had the impeller replaced last season and had no issues with the boat. I took it out today and ran it for a few hours with no issues. After reading online, I was afraid I could have damaged the impeller.

On the bravo drives on a cold engine, does it take a bit for the water to come out the exhaust? Could I have caused any damage? Should I have any concerns?

Thanks for your input in advance!!

 

[Fun Times]

Re: Bravo 1 Water Pump/Running On Muffs Question

With this cooling system, while on the mercruiser flushing device (muffs) it is best to take the engine RPM up to 1300 upon startup and leave it there until ready to shut it down to help get/keep the water flowing correctly.

 

[jserr68594]

Re: Bravo 1 Water Pump/Running On Muffs Question

With this cooling system, it is best to take the engine RPM up to 1300 upon startup and leave it there until ready to shut it down to help get/keep the water flowing correctly.

Thank you. Do you think I did any damage?

 

[Fun Times]

Re: Bravo 1 Water Pump/Running On Muffs Question

Thank you. Do you think I did any damage?

Unfortunately it's hard to tell with out looking at the impeller. I've seen it go both ways on the bravo's. Bravo impellers can be sensitive with not getting adequate water flow from the drive to the impeller housing due to a potential air pocket. From what i have found in the past that works well for me is to lower the drive down, then go back up, then back down, then hook up the muffs and tape up the low water pick up, turn on water, engine, go to 1300, then back down to idle and check water flow. Also carefully check impeller housing for heat or cool, you want it to be cool.

 

[jserr68594]

Re: Bravo 1 Water Pump/Running On Muffs Question

Do you think running the motor from a cold start for a couple minutes would overheat the engine? Thanks for your help.

 

[MarkSee]

Re: Bravo 1 Water Pump/Running On Muffs Question

I let the engine run for a minute or two and had very little to no water coming out of the exhaust.
I took it out today and ran it for a few hours with no issues.
On the bravo drives on a cold engine, does it take a bit for the water to come out the exhaust? Could I have caused any damage? Should I have any concerns?

I have a Bravo 3 and have found that if the engine had not been run in awhile it can take a good 10 seconds for water to appear out the exhaust. The PO kept the boat in a slip so he had the below kit installed where it could flush fresh water through it.
Photo(s) - Mercury Quicksilver 898235A01 FLUSH KIT-MCM - MarineEngine.com

Even though I keep the boat on a trailer now I do "pre-fill" the water systems using this device if the boat has not been run in a few weeks. Probably overkill but since I have the garden hose out anyway and the system is already installed I figure I'll use it and be sure water is already present.

I'm sure Merc. designed the Bravo water pumps knowing it will take several seconds to get water flowing out the exhaust so it must not be a big deal. But what bothers me about your statement is where you say "very little to no water". Even the times I did not "pre-fill" the system and it took the 10 seconds to see water coming out the exhaust I always saw a pretty steady low flow of water even at idle which would increase if I raised the rpm up to about 1100; never saw 'no water'.

The fact that you used the boat for a few hours with no temperature issues is a good sign but get a helper and do as FT suggests and see what it looks like. Here's the flushing procedure when running on a hose if you don't have it.

Mark

 

[tpenfield]

Re: Bravo 1 Water Pump/Running On Muffs Question

I first duck taped the lower water inlet closed. I then put my muffs on the engine and turned the water on. I started the boat. I let the engine run for a minute or two and had very little to no water coming out of the exhaust.

On the bravo drives on a cold engine, does it take a bit for the water to come out the exhaust? Could I have caused any damage? Should I have any concerns?

Thanks for your input in advance!!

Tell us about the duct tape . . . what's it for and why is it going over the water inlet holes ??? You put the muffs on the outdrive?

 

[lrdchaos]

Re: Bravo 1 Water Pump/Running On Muffs Question

If it is like my bravo the lower unit has low water intake holes on the front of the drive. You duct tape the front intake holes the put your muffs on like normal.

 

[dubs283]

Re: Bravo 1 Water Pump/Running On Muffs Question

Tell us about the duct tape . . . what's it for and why is it going over the water inlet holes ??? You put the muffs on the outdrive?

some bravo drives have lower water pick-ups located in the front of the bullet/nose cone in addition to the inlets on the side of the gearcase

you have to cove them with something, usually duct tape, otherwise the water supplied by the muffs will run out the lower pick-up

the volvo AQ series or "white drives" also have a lower pick-up in that area that needs to be covered when running on muffs

 

[MarkSee]

Re: Bravo 1 Water Pump/Running On Muffs Question

Tell us about the duct tape . . . what's it for and why is it going over the water inlet holes ??? You put the muffs on the outdrive?

There actually is a Merc. item you can purchase that covers both the lower and "normal" water inlet locations for running on a hose; duct tape is the lower cost alternative.

Mark

 

[Fun Times]

Re: Bravo 1 Water Pump/Running On Muffs Question

Do you think running the motor from a cold start for a couple minutes would overheat the engine? Thanks for your help.

Going by your description of the event, The engine is going to be fine, you would have known if the engine overheated due to you would/should have heard the warning horn by 196 degrees.

It's the rubber impeller that your playing the las vegas odds with. If the rubber impeller started to overheat due to No, lack of water, air pocket even at a low RPM, then the odds are you may have weakened the rubber's sensitive integrity.

Try re-running the engine the correct way keeping an eye on the water flow and carefully feeling the temperature of the impeller housing at 1300 then at idle speed (600-540 rpm), if you still have very little to no water coming out of the exhaust then it's definitely time for a new impeller. If you have good water flow, then the odds are in your favor but always keep the tools and a new impeller on board the boat and a way to block the inside diameter of a 1 1/4 inch intake water hose to prevent water from filling the bilge area while changing out an impeller while on the water.

Sorry i can't be more specific with accurate information, it's hard to tell not being there for the full event.

Do bear in mind that most preventive maintenance type people installs a new impeller every year regardless of anything.

Good luck.

 

[jserr68594]

Re: Bravo 1 Water Pump/Running On Muffs Question

Thanks for the help guys. I am going to replace it to be safe!

 

[jserr68594]

Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage?

Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage?

I was running my 350 Mag MPI/Bravo combo off of the hose the other day and the impeller was not circulating water well due to improper procedures (I did not rev the engine to 1300 RPMs to get the water flowing). It was spitting a little water however. I took the boat out afterwards and it ran fine as well.

Last season it was backfilled with antifreeze and well so the block did have coolant in it. I ran it for about 1-2 minutes before I shut it down. I am just curious if from a cold start would I have any concerns of overheating? Do I need to check the exhaust flappers or change the engine oil? Any other concerns besides the impeller? I may just be being paranoid....

Thanks for your input!

 

[26aftcab454]

Re: Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage

Re: Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage

your impeller probably disintegrated into a few hundred pieces that are now lodged in your coolant passages that are not removable and will lead to engine overheating .....
I would remove the impeller and inspect for missing pieces. If it is intact you dodged a bullett.

 

[jserr68594]

Re: Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage

Re: Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage

I took the boat out for 3 hrs after the fact and it ran fine with no overheating!

 

[tazrig]

Re: Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage

Re: Ran motor (350 MAG MPI) for a couple of minutes w/o water. Any chance of damage

I'm not sure exactly what you're saying. Did you run it off of the hose meaning it was hooked up to water or it was off of the hose completely and not hooked up to any water? If it was hooked up to water than you are probably O.K. If not, although the bravo impeller is pretty beefy you no doubt (at the very least) damaged or greatly shortened it's life expectancy by running it dry. I would strongly recommend you pull the impeller and at the very least inspect it. If it was run dry my guess is it now needs to be replaced and is probably on its last legs due to being run dry for 1-2 minutes. Either way, while you have it out of the water take it out and inspect it. An ounce of prevention is worth a pound of cure. Even though you got 3 hours of trouble free use from it, it doesn't mean it may not disintegrate on your 4th hour of use.

 

[Don S]

Re: Bravo 1 Water Pump/Running On Muffs Question

I just merged your two threads together. Please don't start two threads on the same subject. If you want further clarification about running it, then just ask in the original thread. Then ALL the information on the subject is available.