2019 350 Sundancer 6.2 w Bravo 3s - Overheat: what to check

Shaps

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Nov 4, 2019
2,456
Long Island,NY
Boat Info
2010 Sundancer 500
2015 Brig Falcon 330T
Engines
Twin Cummins QSC550 w Zeus Pods
Asking for a friend, he has a new to him 2019 350 Sundancer 6.2 w Bravo 3s.
Took it out yesterday and about 15 min the port engine threw an overheat error code. He was able to limp back to his slip, with limited rpm on that motor (2400 rpm). He said the port motor was 175 and the stbd was below 170.

I'm going down tonight to help take a look but i asked him if he checked his strainers and he said his boat does not have strainers, that there are "holes in his drive that act as strainers".

I admit I am new to these drives, systems and am looking for any guidance at all.
I will be swapping sensors from one engine to the other to see if it follows the sensor.
Any and all help appreciated!
 
My last 2 boats had the 5.7s with Bravo IIIs. One was a 2001, one was a 2006. I do not know how a 2019 works, I have to assume the same.

There was a raw water pump on the motors that pulled water thru the outdrives, no main engines seacocks/strainers in the engine compartment. Almost sounds like a raw water impeller issue to me. Swapping the sensors is a good place to start though.
 
I forgot one time one of my 5.7s did this. Quickly overheated but would start and run ok up to 2000+- RPMs. Turned out to be the engine water pump. The engine was going into "limp" mode, or something like that I think they called it.
 
I forgot one time one of my 5.7s did this. Quickly overheated but would start and run ok up to 2000+- RPMs. Turned out to be the engine water pump. The engine was going into "limp" mode, or something like that I think they called it.


I think he called it "Guardian Mode"
Appreciate the tips!
Just seems like an odd setup.
My pods have pickups as part of the pods, but they feed a strainer...
 
I had twin 6.2's with Bravo IIIs on my Rinker. You are correct in that is guardian mode which limits RPM if a sensor goes off like oil pressure, temp, etc. Those water temperatures noted (170 and 175) would not set off the sensor and cause guardian mode. Not sure what the trigger temp is but is well above 170 I am sure. There are multiple possible scenarios. Most likely, the raw water pick up on the engines surpentine system (Bottom right each side) are worn out and not pulling enough raw water to cool (BTW does this boat have fresh water cooling?) as the empeller inside is worn out. Under this scenario, those temps recorded on the gauges are not properly reading then. The way to tell is to get a real time reader connected to each motor via the OBD dongle near the throttle body and direct read. You'll need a reader like a Rinda Techmate ($500 and well worth it for these reasons). ANother scenario is bravo-Itis. Without going into a ton of explanation, the water inlets/pickup (you mentioned as "holes in his drive that act as strainers") between them and through the transom (goes from I think like 3/4" to 5/8" through transom back to 1 inch) could be plugged for various reasons.

In leu of a techmate, get an infrared temp gun and start checking points on the engine (Risers, Oil filter housing, manifold, ect) and see what temps you get. Check this against the gauges to give some idea of accuracy. This is just a start of some things to eval.

BTW-the grill on the bravo III's inlets arent really strainers. Strainers are much more fine grill/filter type modules almost always installed in through hull water pick ups. Rinker, my former boat with the 6.2's didnt initially have strainers/through hull water pick ups for cooling. Due to overheat issues I had through hull pick ups added with strainers. I bet your OEM doesnt have through-hull picks either and simply uses the Bravo III's pickups.
 
I had twin 6.2's with Bravo IIIs on my Rinker. You are correct in that is guardian mode which limits RPM if a sensor goes off like oil pressure, temp, etc. Those water temperatures noted (170 and 175) would not set off the sensor and cause guardian mode. Not sure what the trigger temp is but is well above 170 I am sure. There are multiple possible scenarios. Most likely, the raw water pick up on the engines surpentine system (Bottom right each side) are worn out and not pulling enough raw water to cool (BTW does this boat have fresh water cooling?) as the empeller inside is worn out. Under this scenario, those temps recorded on the gauges are not properly reading then. The way to tell is to get a real time reader connected to each motor via the OBD dongle near the throttle body and direct read. You'll need a reader like a Rinda Techmate ($500 and well worth it for these reasons). ANother scenario is bravo-Itis. Without going into a ton of explanation, the water inlets/pickup (you mentioned as "holes in his drive that act as strainers") between them and through the transom (goes from I think like 3/4" to 5/8" through transom back to 1 inch) could be plugged for various reasons.

In leu of a techmate, get an infrared temp gun and start checking points on the engine (Risers, Oil filter housing, manifold, ect) and see what temps you get. Check this against the gauges to give some idea of accuracy. This is just a start of some things to eval.

BTW-the grill on the bravo III's inlets arent really strainers. Strainers are much more fine grill/filter type modules almost always installed in through hull water pick ups. Rinker, my former boat with the 6.2's didnt initially have strainers/through hull water pick ups for cooling. Due to overheat issues I had through hull pick ups added with strainers. I bet your OEM doesnt have through-hull picks either and simply uses the Bravo III's pickups.

Much appreciated. I didn't think 175 seemed too high.
Is there a way to check flow? is it possible the intake is partially clogged? Is there a way to push water through the pipe going through the transom?

Thanks very much! I'll ask him when/if impellers were done.

Edit:
I believe the boat has a closed cooling system.
So heat exchangers, etc
 
Perhaps you can disconnect the raw water hose at the back of the raw water pump and put an air compressor and/or garden hose on it to force air/water back thru the drive? Put a coat hanger/wire up thru the inlet at the drive?

I read where folks convert these to strainers/seacocks.
 
Perhaps you can disconnect the raw water hose at the back of the raw water pump and put an air compressor and/or garden hose on it to force air/water back thru the drive?
Thank you, that's kind of what i was hoping to do.
 
Perhaps you can disconnect the raw water hose at the back of the raw water pump and put an air compressor and/or garden hose on it to force air/water back thru the drive?
I would be very careful about this on that 350. I assume its moored year round. You can disconnect that raw water pump yes, but only an experienced mechanic should do this on a boat afloat. If its hauled out, yes, no problem.

Again, I believe, there are/is a sensor that also monitors water pressure? that can be accessed with a Scan tool (Rinda Techmate or the high order Mercruiser ones the marine techs have). its a 2019 boat and should have Vessel view capabilities through the ECM. Also, there are many threads here that detail now to troubleshoot overheat and trying to figure if its the outdrive thru-hull to raw water pump or the raw water impeller. Some use clear section of tubing to install inline to visually "see" the flow. Maybe you could pull of the outlet to the raw water pump at the heat exchanger and measure there, not sure. Again, wouldnt attempt this with a boat on the water, only on the hard connected to garden hose with muffs on the outdrive inlets.


And yes, it is possible the intake is semi plugged. Its not uncommon for zebra mussels and other marine growth to foul the coolant path in the outdrive of hoses. Again, inspection is best way to do that with the boat out of the water

Oh, and Raw water impellers should be changed annually or every other year depending on use. I replaced my the last time with Hardin Marine Stainless Steel housing with upgraded impellers. The Stainless is said to go up to 3 years between change outs due to polished internal surfaces and corrosion resistance. Here's what a stock impeller looks like after 3 years and here's a photo of the thru-hull I added on starboard side of my former Rinker with same setup. Note is also shows the sea strainer in line discussed above.
Starboard Thru Hull.jpg

Seawater Pump 3.JPG
 
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I would be very careful about this on that 350. I assume its moored year round. You can disconnect that raw water pump yes, but only an experienced mechanic should do this on a boat afloat. If its hauled out, yes, no problem.

Again, I believe, there are/is a sensor that also monitors water pressure? that can be accessed with a Scan tool (Rinda Techmate or the high order Mercruiser ones the marine techs have). its a 2019 boat and should have Vessel view capabilities through the ECM. Also, there are many threads here that detail now to troubleshoot overheat and trying to figure if its the outdrive thru-hull to raw water pump or the raw water impeller. Some use clear section of tubing to install inline to visually "see" the flow. Maybe you could pull of the outlet to the raw water pump at the heat exchanger and measure there, not sure. Again, wouldnt attempt this with a boat on the water, only on the hard connected to garden hose with muffs on the outdrive inlets.


And yes, it is possible the intake is semi plugged. Its not uncommon for zebra mussels and other marine growth to foul the coolant path in the outdrive of hoses. Again, inspection is best way to do that with the boat out of the water

Oh, and Raw water impellers should be changed annually or every other year depending on use. I replaced my the last time with Hardin Marine Stainless Steel housing with upgraded impellers. The Stainless is said to go up to 3 years between change outs due to polished internal surfaces and corrosion resistance. Here's what a stock impeller looks like after 3 years and here's a photo of the thru-hull I added on starboard side of my former Rinker with same setup. Note is also shows the sea strainer in line discussed above.
View attachment 124713

View attachment 124712

Thank you @89P270

This boat is new to my friend, literally has put maybe an hour on it. Was just launched and is in its slip. I asked about the impeller, his response was he didnt have any record of it being changed being a 2019. My response was same as yours... Think they're supposed to be replaced at the least every 2 years if not annually.
It's a learning process...
 
Sounds like a short haul is in your friends future to check the intake, and while out backflush from the raw water pump.
 
Double negative..........But I agree too. Keep us updated. I can provide a plethora of data on my thru-hull improvements to the cooling on this 6.2L MX set up if you need. Its expensive but worth it for piece of mind. Another consideration if you haul out - Bravo III's run hot to start, I had drive showers added to mine by previous owner and this keeps the upper drive cases cool when your on plane and the upper drives are above the water line. Cheap to add these. No cheap for the thru-hull adds.

Another thing for your friend to look into, Vesselview. Its a 2019 and if he doesnt have this from OEM, the boat would be set up for it. Its like a digital dash with connection to the ECM that reads all kinds of things that the analog gauges have no way of providing. Google around and get excited about it - Somewhat expensive to add to a twin set up but again, real time data reading while underway is fabulous feature. You can get an APP for it too.

And, because I cant help myself, another great add for this 6.2L MX set up-Get yourself a pair of Hill Marine 4x3 prop sets. I added these to the rinker (340 fiesta vee) and I picked up 8 seconds out of the hole to plane with only a 2 MPH top end speed loss. More efficient at cruise as well.
 
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Double negative..........But I agree too. Keep us updated. I can provide a plethora of data on my thru-hull improvements to the cooling on this 6.2L MX set up if you need. Its expensive but worth it for piece of mind. Another consideration if you haul out - Bravo III's run hot to start, I had drive showers added to mine by previous owner and this keeps the upper drive cases cool when your on plane and the upper drives are above the water line. Cheap to add these. No cheap for the thru-hull adds.

Another thing for your friend to look into, Vesselview. Its a 2019 and if he doesnt have this from OEM, the boat would be set up for it. Its like a digital dash with connection to the ECM that reads all kinds of things that the analog gauges have no way of providing. Google around and get excited about it - Somewhat expensive to add to a twin set up but again, real time data reading while underway is fabulous feature. You can get an APP for it too.

And, because I cant help myself, another great add for this 6.2L MX set up-Get yourself a pair of Hill Marine 4x3 prop sets. I added these to the rinker (340 fiesta vee) and I picked up 8 seconds out of the hole to plane with only a 2 MPH top end speed loss. More efficient at cruise as well.

Amazing info. Thank you.
Was down at his boat tonight. It looks like we are going to wind up doing a short haul and replacing the impellers. Next off season (can't believe we're talking about that) he is considering the through holes. Any information on those drive showers would be greatly appreciated. Thank you so much for all the guidance and assistance
 
Been where your friend is and these are the issues I found to help immediately. Definitely change out the impellors, be sure to use the NEW kits that include the back plates in case you have any scoring in the impellor housing. Also, observe your raw water PSI on your gauges. High numbers indicate blockage downstream from the pump, low numbers indicate starvation of water before the pump. The blockage to check first is in the heat exchangers. Bunch of little tubes in there that get plugged up from the above mentioned sea junk. Our was obviously blocked and we took them off and cleaned them with muriatic acid. Another way to do it is the take the raw water houses off and run a loop through it using Barnacle Buster. Will need to flush it (using the loop) for a good 15-20 minutes and recheck. You should be able to look through the heat exchanger from end to end with all tubes wide open. We also did a loop using the Barnacle buster going through the steering and oil coolers. The crude finds it way there as well and causes restriction. After this we added through hulls and strainers and put block offs from the B3 drives along with adding the drive showers as mentioned above. This addressed everything with the exception of the manifolds. It also cleaned our entire raw water system, renewed our impellors and we now knew the condition of the raw water system. Our raw water PSI came down to normal range, 1-3 at idle and around 17-20 at cruising speed - 3200 rpms. Temps consistently at 168-170 on our 496s. Also as mentioned above is bravoitis. This is easy to check (out of the water) by removing the connection at the transom where the hose comes from the drive. 2019 should have the rigid tube in the drive that is supposed to fix this from happening, but i have still seen it. We had it and that is what drove our decision to abort the drive pickups and add the thru hulls. Cleaning the heat exchangers was the first thing we did and that stopped our alarms. Also, the temps you are seeing on the gauge are the engine coolant temps, not the actual motor temps. Good luck..
 
Thank you @89P270, @Bill Curtis, @Korkie
This is HUGE info, truly appreciated
Sent him the drive shower info, great suggestion.
I don't think his drives should be susceptible to bravoitis, but anything is possible. New impellers are definitely coming.
He would like to get through this season and then do the new through hull/strainers/b3 block off in the off season.
Should be do-able on new impellors if all else in good shape. it's a 2019 with less than 120 hrs on it.
 
If not aware of their condition, have a couple anode kits on hand as well for the short haul. There should also be one on the inlet end of the exchanger. Possibly another service item that was missed.
 
Impellers changed and still had the high heat issue
Short hauled it...
IMG_20220428_155511.jpg


Problem solved
 
Same page...
I told him it looked like an elephants condom
 

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