Bilge blower replacement 90 310 sundancer

[mr300z87]

I am in the process of replacing 1 of the 2 blowers in our new to us 1990 Sea Ray 310 sundancer. Both were working but 1 makes a horrible screeching when turned on. Before removal I ran them and noticed that 1 draws air out of the bilge and the other (the one I'm replacing) draws fresh outside air in. Is this correct? The out blower has a tube going down low in the bilge (tube needs to be replaced also) as I would expect. The in blower had no tubing after it in the direction of air flow. It looks like there may have one been a tube also going low into the bilge. With safety be very important I want to put this back the way it should be.


Note the blowers are not easy to get at but with the exhaust off at the moment now is the time to get this back to the way it needs to be.

Any advice is greatly appreciated


Mike

 

[hughespat57]

All power blowers in a gas boat should exhaust. The attached ducts should be as low in the bilge as practical.

There should be two inlet duct that are mounted higher.

 

[mr300z87]

FYI I Found this on Boat US web site. Mine is this way.
"The best plan is usually to have two blowers, one to blow air out and the other to suck outside air into the engine space. However great care must be taken that the outside air intake is free of CO and other fumes."

 

[FINAL DRAW]

I am in the process of replacing 1 of the 2 blowers in our new to us 1990 Sea Ray 310 sundancer. Both were working but 1 makes a horrible screeching when turned on. Before removal I ran them and noticed that 1 draws air out of the bilge and the other (the one I'm replacing) draws fresh outside air in. Is this correct? The out blower has a tube going down low in the bilge (tube needs to be replaced also) as I would expect. The in blower had no tubing after it in the direction of air flow. It looks like there may have one been a tube also going low into the bilge. With safety be very important I want to put this back the way it should be.


Note the blowers are not easy to get at but with the exhaust off at the moment now is the time to get this back to the way it needs to be.

Any advice is greatly appreciated


Mike

 

[ErikE]

While completely different boats, I would have to verify, but am 99% certain both my blowers blow out...sucking in fresh air from the vents.

On your boat, are there fresh air vents into the compartment? I have to think so. Only reason to have one blower to suck in would be lack of other incoming vents.

 

[FINAL DRAW]

I’ve replaced both of ours. On ours, both exhaust air out starboard vents and intake hoses rout low in bilge, one on each side. I would replace both. I always thought mine were noisy mounted solid to floor member. What I did was use a piece of heavy rubber mounted to boat and then mount blower to hang from that. So much quieter. We run blowers continuously to also keep engine room cooler. The rubber is very flexible, like inner tube but about 1/4 in thick. You probably won’t encounter anything that I haven’t in our 26 years with this boat! Lol,’Ask away

 

[Nater Potater]

'92 300; both blowers draw air out of the bilge.

 

[hughespat57]

FYI I Found this on Boat US web site. Mine is this way.
"The best plan is usually to have two blowers, one to blow air out and the other to suck outside air into the engine space. However great care must be taken that the outside air intake is free of CO and other fumes."

I would love to have the link to that
BoatUS articles are not an authority
And why would I care if my engine room sucked in a little CO? No one lives in the ER.

 

[ttmott]

On a gasoline engine powered boat, the blowers draw the fumes from low in the bilge and vent them out of the boat. Fresh air replaces the gasses removed from the engine room low areas through the engine room vents. Gasoline fumes are heavier than air and will collect low in the bilge; the specific reason there are hoses to those low areas from the suction side of the blowers. All blowers in these boats need to draw the fumes out. Consider if you should blow air into those low-lying areas through those hoses and disperse low oxygen gasoline fumes into a potential stoichiometric mixture then really creating a huge hazard.
Regarding blowers the OEM ones are not continuous duty rated and will self-destruct if ran all of the time, but I believe it is wise to operate the blowers whenever the boat is not moving (sans put away for the day). Replacing the blowers? Consider continuous duty squirrel cage blowers like the Jabsco ones here - https://www.hodgesmarine.com/jab357...html?msclkid=da1a5328b46d11ec8eec03c47948ca3c
Plus they are very quiet....
I think one of the first things I have done on my boats is replace the cheesy blowers with the Jabsco fans.

A diesel powered boat is an entirely different requirement and the two cannot be compared other than SR uses the same crappy blowers.

 

[mr300z87]

First let me say I am not trying to start an argument here. I posted what I found because it seemed strange, which was 1 in 1 out both from starboard vents. Not much tubing left after the blowers. The consensus here and on another forum is that the should both suck air out. I just want to put it back together right to keep us safe. No explosions please.

My plan is to install the new blower sucking air out. I will the plumb both blowers with new 4" tubing to what looks like the original location, low just in front of each engine. I just do not see any landing spot for the incoming vent tube from the port side vents. Will dig a little deeper tomorrow.

Final Draw, do you have any photos of how yours are set up?

Have a great night

 

[FINAL DRAW]

I’ll get photo tomorrow. Both intake hoses draw from down low in back near rudder posts each side if I remember correctly

 

[B BARKER]

The bilge blowers were the first thing I did when I got my boat, it had some in line cheap-o's and I got some similar to the Jabsco's in post 9..Now you can turn them on and walk by the vents on the dock and feel the air coming out, if there were some gas fumes you could smell it right off..If my boat is running those blowers are running all the time they have lasted 8 years so far, best 400 dollars I spent as far as I'm concerned !! Both of mine are blowing out as one vent on side is intake and one is exhaust...B.B.

 

[FINAL DRAW]

Hoses are each side, separate blowers fastened to top of stringer behind engine. Blowers are mounted on rubber hangers. Best photos I could get.

 

[mr300z87]

Thanks so much for the photos Final Draw!! Here are pics of what I did yesterday and it looks just like yours. Unfortunately I could not find any black hose locally so I had to use white.

Each tube goes to a blower drawing out. In the next photo you can see the screw hole circled where the holding strap was. I have it temporarily tied to the steering strut bar. BTW the exhaust is still disconnected only to ease access.

The 2 incoming tubes going to the port side vents are right above the port muffler. Should they extended further in or lower? I do not see any signs as to where they might have gone

 

[FINAL DRAW]

I think that is where my port side intake hoses terminate. Don’t think I’ve ever noticed though. Now on to next project! Lol. It never ends. How are the bilge pumps now that you can access them?

 

[mr300z87]

With the exhaust tube out of the way the bilge pumps were relatively easy to access. It turns out they connect to the single start battery bank for the port engine as is the memory for the stereo? So with all batteries connected the main pump works both with the switch and the float. Here is the wierd one! All wires to the high water pump were cut? I was told the pump was running continuously last year before we purchased the boat, rather than replace/repair ( (remember access issue) someone cut the wires. Why all 3?? the high water pump is float actuated only. I did some testing with a meter and test leads, to my amazement it worked. However since the high water pump will run with battery switch off I spiced in a little extra length of wire with plugs on temporarily so I can keep it disconnected until launch and connected to shore power. Once convinced there is no issue with the pump or float I'll permanently splice the wires. BTW the extra length of wire is just for ease of access with exhaust tubes installed. I am making good progress.

Our last boat was a 90 250 Sundancer that was a super storm Sandy victim. I not only replaced the 7.4L engine and outdrive but went through every system making sure everything worked and she was safe for our family and friends. I will do the same with this one.