Bravo 3 Cooling water pressure question

[2xsl_1998]

Hey guys, I have a question about the cooling water system on my boat with a Bravo 3 outdrive.

My boat has the 350 Mag MPI engine. Last fall I moved to a saltwater location, and I had the local Sea Ray dealer install a flushing kit on it to allow flushing the boat in my lift. While it was in the shop we also had the sea water pump serviced, impeller changed, etc.

The boat has only 80 hours on it now, and has only had maybe 10 hours put on it since the impeller change. I have thoroughly flushed it each time it has been used.

So my question is, what is the normal pressure that the cooling system should put out? I never really paid much attention to that and yesterday when we were about to go for a ride I started getting low water pressure alarms. This was before I even got underway, and we had used the boat a few days before with no issues.

I didn't take the boat out because of the alarm. I went back down this morning and ran it a while both on and off the hose flush, and it looks like the boat at idle is only producing about 0.2-0.5 psi. It dips down sometimes to set off the alarm and it won't clear.

I'm guessing that something isn't right with the sea water pump. I know the suction isn't plugged because I get good water flow out of the lower unit with the hose on.

Any thoughts or suggestions? I'm guessing that I will have to have the impeller replaced again.

 

[SeaJay62]

if it has the old style inlet water hose thru the transom it may be getting 'bravoitis' restriction

 

[Espos4]

I get right around 1 psi when I run it on the muffs on the trailer.

Are you running the fresh water flush while the outdrive is completely out of the water?
If so, i believe that the instruction say to close off the transom inlet when using the flush while out of the water.

 

[2xsl_1998]

Thanks for the replies guys. This boat is a 2012 model that has pretty low hours. I read a little about the "bravoitis", but I'd have a hard time believing it could happen that quickly. Could be though.

I always have the outdrive submerged when running the engine, even if the flush is being used. I leave the flush going a few minutes after killing the engine also.

I have a set of muffs, but they are still packed away from our move. Maybe I will go buy another set and take the kayak out and hook them up to see how it does. With the boat being in a lift it is really hard to get to the outdrive.

I did run the boat on muffs at our previous house every time we used it. I just never paid attention to the water pressure. I do know that it never got low enough to sound an alarm.

I never got any instructions with my flushing kit, but I don't think mine has a way to close off the transom inlet. It just has a quick connect type fitting on top of the engine. There is a piece that goes on the hose and that locks into the fitting on the engine.

 

[paulswagelock]

After a new impeller, water pump and bravoitis fix, I got 3 at idle, 12 at 3000 rpm, and 16-18 at WOT.

 

[scoflaw]

The brass water pump was just poorly designed out of the box. Sometimes putting a new impeller in a scored pump body makes things worst. The smartcraft threshold for setting off the alarm is another issue as well. I assume your boat doesn't overheat ?

 

[2xsl_1998]

Thanks again for the info. paulswagelock, approx how many hours were on the boat that had the "bravoitis"?

scoflaw, I haven't let it run long enough to overheat. It just started doing this as I was about to depart yesterday. I quickly put the boat back in the lift and hooked it up on a flush hose setup for my testing. FWIW, I think that it would overheat because the temperature was definitely climbing. I never let it get above 175 deg though.

 

[Espos4]

It could also be a faulty water pressure sensor. They are pretty easy to replace once you crawl over the top of the motor to reach it.

 

[2xsl_1998]

Thanks Espos4. Any idea where that sensor is?

 

[Espos4]

It’s on the power steering cooler, on the rear of the motor.

 

[Espos4]

#17 in the photo is the cooler.
The water pressure sensor screws into the starboard side of the cooler. The sensor itself isn’t pictured here, just the p/s cooler.
FYI, this info is for my 2007 240 SD with 350 MAG.
I assume yours is similar.

 

[paulswagelock]

Thanks again for the info. paulswagelock, approx how many hours were on the boat that had the "bravoitis"?

scoflaw, I haven't let it run long enough to overheat. It just started doing this as I was about to depart yesterday. I quickly put the boat back in the lift and hooked it up on a flush hose setup for my testing. FWIW, I think that it would overheat because the temperature was definitely climbing. I never let it get above 175 deg though.

Boat was 8 years old with 200 hours.

 

[2xsl_1998]

Thanks again for all the great information guys! The way the engine cover is made on our boat there is a lift out portion right above where that pressure sensor and cooler should be. I'll try to take a look at it this evening when I get home. Sure would be nice if that ends of being the issue.

 

[2xsl_1998]

Well I managed to find the pressure switch and take it out. Really nothing visibly wrong with it. Didn't see to have any debris in the port and the tap on the cooler was clear.

I put it back in and ran the boat again with pretty much the same results. Very low indicated pressure at idle and it swings quite a bit between 0 and about 0.9 psi. Eventually it sets off the SmartCraft alarm and it limits the rpm. If I hook up the flush hose the pressure goes to about 2.5 psi and is much more stable.

So now I'm wondering if I should just replace the switch? It was a little aggravating to get out, but it looks like a new one is about $130 or so. That would certainly be cheaper than sending it to a dealer.

I may try to put it on muffs tomorrow as well. I didn't have time to do that today.

 

[Espos4]

Also, If you haven't checked the water hose at the transom inlet, that would be my next recommendation. Even with the low hours, it could be restricted.
Do this with the boat on the lift. Removing the water neck at the transom will sink the boat if its in the water. There is a quick connect to remove the thick walled hose that goes to the raw water pump, and 2 bolts that are pretty tough to access to remove the water neck.
I checked mine this year, I can sill insert the tool to remove the original insert, so I didn't change to the new water hose design.

 

[Espos4]

Heres the kit with the redesigned hose. There are 2 water necks included, one for the quick connect design and one for the “push on” hose design.

 

[Lazy Daze]

You mentioned you just recently (a few months ago) moved to a salt water location. It's EXTREMELY unlikely that you have Bravoitis as that takes quite a few years to "possibly" happen.

I'm leaning towards thinking you either have a faulty sensor or the raw water pump housing is scored (as mentioned above). You can do a raw water pump test by measuring the flow coming into the t-stat housing. Must be done in the water. Look to get about 7.5qts in 15 seconds at 1,000RPM. Do it multiple times.

 

[2xsl_1998]

You mentioned you just recently (a few months ago) moved to a salt water location. It's EXTREMELY unlikely that you have Bravoitis as that takes quite a few years to "possibly" happen.

I'm leaning towards thinking you either have a faulty sensor or the raw water pump housing is scored (as mentioned above). You can do a raw water pump test by measuring the flow coming into the t-stat housing. Must be done in the water. Look to get about 7.5qts in 15 seconds at 1,000RPM. Do it multiple times.

So how do I do this test? Is it as simple as taking the hose loose and aiming it at a bucket? LOL

Probably makes sense to try this before changing the sensor.

 

[Espos4]

Another thing to consider, when the impeller was changed, were there any pieces missing?
If so, was the cooling system inspected to locate the missing pieces of the impeller?

 

[paulswagelock]

I put it back in and ran the boat again with pretty much the same results. Very low indicated pressure at idle and it swings quite a bit between 0 and about 0.9 psi. Eventually it sets off the SmartCraft alarm and it limits the rpm. If I hook up the flush hose the pressure goes to about 2.5 psi and is much more stable.

Here is the clue. I have seen B3 drives where the plastic insert has collapsed, almost looked like it melted, on boats with the flush port. Not salt water related. It was described to me that running too long on the flush port without cold water coming in through the drive allows the temps to get too hot and make the plastic insert collapse, restricting the water. The one boat I have personally seen this on was an 8.1 Merc with factory flush connection. The telling clue was the water pressure went to 2.5 from near zero if run from the flush port (bypassing the inlet tube and restriction). That said, the same symptom could occur if the water pump was faulty (impeller or housing scored) since the water is pressurized using the flush port giving it a boost.