Volvo Penta AQ131A Cooling System

[AnAugustSunLeo]

I recently purchased a 1986 Bayliner Capri in immaculate condition. I have replaced all fluids in motor and outdrive. I pulled the cover off the impeller housing to check the condition of the impeller. It was a little eaten up but not broken yet. I will replace anyways. The copper suction and discharge lines attached to the impeller housing is where I ran into a problem. The copper lines themselves are in great condition. The half diamond shaped flanges are rusted through. Is there a way to replace those flanges without replacing the copper tubing. Is there a way to replace copper tubing with reinforced rubber hose. If so how?

[dennis461]

Great question.. hope someone has done this before. Seems like we should be able to make a hose adapter for this. Mine are in good shape now...but later I could find myself in the same boat. :-) where is the half diamond? pump or pipe?

[AnAugustSunLeo]

They are on the copper pipes. The copper piping is flared. The flare is where the rubber gaskets seat, and they prevent half diamond flange from sliding off pipe.

[RicardoMarine]

I believe that the two half clamps can be replaced with this style, and that you'd have to leave the originals on the tubes.

This one is on e-Bay right now.

[boatdoc55]

Rick, I think the OP is speaking of the two thin tin pieces that your picture holds down. I've seen plenty rusted ones but have never had to come up with a better mousetrap. The clamp in the pic wouldn't work proper to seal the copper lines without the tin piece. It does look like a diamond shape as the OP say's.

[RicardoMarine]

Gary, I think you are correct. Both must be used.

[dennis461]

We should not need both. Mine are so thin, they cannot possibly add any value. I have the s-shaped holder on top of the thin original parts. The key to getting this system to seal is flat, perpendicular tubing flanges and perfect alignment so the square-profile rubbers sit flat in/on the pump housing. My boat leaked all the time when I first bought it. I finally made some small bends to correct previous owner/mechanic manhandling these copper tubes. I also used a hammer and mandrel to beat the flanges flat. In the picture above, the rubber seal is installed on the flange.

[AnAugustSunLeo]

Thanks guys for the info. I just can't justify paying $544.79 plus shipping for two copper pipes, because the two flanges on the pipes I have are bad! Those flanges probably cost a couple bucks. I Beleive there should be a conversion kit , which would replace the copper pipe with reinforced rubber hose. Most of the newer volvo engines I have seen have rubber suction and discharge lines on the raw water system.

[AnAugustSunLeo]

Would I remove the impeller and/or the strainer to flush the raw water system with water hose? Where do I connect to flush backwards?

[dennis461]

Flushing with a hose could be tricky. If the engine is not running, you could force water into the exhaust ports. The impeller has a small bypass, so water would slowly pass around it, but taking it out is not hard. The tubes stay in place. I have a spare pump, maybe this winter I'll try and Gerry rig some adapters for the pump. You figure out how to do the heat exchanger end!

[RicardoMarine]

Most of the newer volvo engines I have seen have rubber suction and discharge lines on the raw water system.

Different animals..... the later Volvo Penta 4 bangers are the GM 3.0L engines.

[AnAugustSunLeo]

Ricardo, I'm new to all of this. This is my first boat. I understand the newer motors are different. I was curious if there were any interchangeable parts as far as the raw water pump is concerned. Since I've joined this forum, I've read probably close to a hundred threads in regard to this motor trying to educate myself. Through doing so I've discovered your a Volvo guru.

[AnAugustSunLeo]

I wonder if this is a possibility. It seems like it could be. I wish I had an old raw water pump to try this on. Maybe I'll buy a new one and try it on the one I have.

[crankbait]

i like your line of thinking on this solution. the cooling system, ( at least on my aq120) is only 4 psi at the radiator cap.with those threaded in, in my opinion, the o rings are way more likely to fail before your setup would. when mine gets degrades to that point.....that is exactly what i will be doing.

[AnAugustSunLeo]

When I hook the water muffs to the outdrive and start the motor, the raw water strainer doesn't fill with water. Im not sure if it is supposed to or not. When I fill the strainer with water, it will exhaust out, but thats it.

[dennis461]

http://www.volvopentastore.com/Cooli...n_id.033970843
Oh yea fab some up and save 150 bones.

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you need help with math, the piping is part 6 and 7 282+266 = 548 and change

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/. to OP the filter tube fills up when engine starts and idles, the muffs alone won't do it.

[AnAugustSunLeo]

I understand the engine has to be running. With the engine running and the water muffs on, the raw water strainer doesn't fill with water, and I wasn't sure if it was supposed to or not.

[JimS88]

You may have a leak in the outdrive where the hose runs from the intermediate unit through the transom shield. If air leaks in it will prevent water from drawing into the pump, and then to the strainer.

[RicardoMarine]

I`m wondering if you can just tap some pipe threads in the ports and just screw in barbed nipple adaptors.
like this

If you were to switch over from the copper tubes to hose, the suction hose must be collapse proof.


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[crankbait]

when running with the cap on, my strainer is full to the top. when the cap is removed while running, the water level, drops to the bottom of the strainer. when I place the cap back on while it is running, the water comes back up to the top of the strainer.

[AnAugustSunLeo]

So how do you know if the strainer is full to the top? Can you hear it? Is there a certain amount of water I should see coming from exhaust? I'm new to all of this so sorry for the ignorance. I disconnected the hose that connects the outdrive to the motor and put the water hose there and the motor didn't overheat. It was around 180 at idle.

[crankbait]

after the motor is running at temp,i remove the strainer cover cap quickly, and you will see the water level drop to the bottom of the strainer. if you do this too slow, the water will already will be at the bottom.it sounds like everything is just fine.

[RicardoMarine]

So how do you know if the strainer is full to the top? Can you hear it? Is there a certain amount of water I should see coming from exhaust? I'm new to all of this so sorry for the ignorance. I disconnected the hose that connects the outdrive to the motor and put the water hose there and the motor didn't overheat. It was around 180 at idle.

Here's my two cents.

Check the cap gasket that's over the strainer, and make sure that it seals correctly, and don't worry about the water level in strainer for now.

When we trouble shoot a cooling issue, we should look at the entire system, and not focus mainly on a thermostat or pump impeller right off the bat..... although these are suspects.

Start at the drive area where the sea water first enters.
On your drive, there is an O-ring seal at the lower most end of the pivot tube where the tube joins the lower unit housing.
This is not an easy O-ring to access, but it needs to be in good condition.

At the upper end of the pivot tube, is a pivot tube bushing, and a water neck fitting.
The water neck fittings are prone to corrosion issues.

The fix is a new water neck fitting and the special beaded gasket underneath it..... bead facing downwards.
If you have not replaced the water neck fitting, it's time to do so.

However, if the upper pivot tube bushing is worn, the play between the pivot tube and suspension fork will prevent the new beaded gasket from holding for any duration.
The fix, is a new bushing and a new water neck fitting.
This is also not an easy bushing to replace, as it involves drive dis assembly.

Next will be the S hose and it's connection to the water neck and the chrome water tube.

Next will be the main suction hose and it's connecting points at the interior side.

Your sea water pump is engine mounted. Anything upstream of this, is on the suction side of the system.
A tiny air breach will absolutely kill suction.

The sea water pump will offer two thrust surfaces for the impeller.... one deep within the body, and the other will the cover surface.
These surfaces must be free from gouges or groves.

The impeller must be resilient, in that the vanes still have elasticity to them as to flex correctly and create the pumping action.
Impellers that remain in the pump body during winter, do not fair well.
You'll know by inspecting it if this should be replaced or not.

From the sea water pump to the Heat Exchanger, is on the pressure side of the system.
If you have a breach here, it will show itself in the form of a visible water leak.

On the pressure side, you'll see a visible water leak.
A breach on the suction side is more tricky to find.
Some will use shaving cream. The suction breach will pull the shaving in and it will disappear at the breached area.

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[AnAugustSunLeo]

Im sure the suction lines inside the boat are good. I ordered the water neck a few days ago, because it was very corroded and the gasket underneath looked rotted. I haven't received it yet. The o ring you speak of, is it part # 18-7184-9. I'll go ahead and order that and the bushing asap. I appreciate all of the info you have provided me with. I try to figure things out by reading other threads and looking at schematics, but that only gets me so far.

[dennis461]

mine overflows with bucket or "muffs". But my muff setup is a bit creative. I use duct tape to cover the finned intake on front of leg. Then I put a plastic pipe nipple-garden hose adapter in the small hole on bottom of leg. Here is a thread I ran during my raw water intake science project.http://forums.iboats.com/volvo-penta...pm-520119.html

[RicardoMarine]

mine overflows with bucket or "muffs". But my muff setup is a bit creative. I use duct tape to cover the finned intake on front of leg. Then I put a plastic pipe nipple-garden hose adapter in the small hole on bottom of leg. Here is a thread I ran during my raw water intake science project. http://forums.iboats.com/volvo-penta...pm-520119.html

Dennis, you may want to consider that when checking a cooling system, or running an engine on a garden hose supply, we want to create a scenario that most resembles an "in-the-water" like condition.

If you have taped off the OEM pick-up area, and if you are forcing garden hose water into the system via the small hole (of which is actually a self draining hole), you may be circumventing an otherwise suction breach that you'll now never learn about.

When I test an AQ series system, I want the sea water pump to pull suction from the lower unit housing.
If I have a suction breach, I'll find it and I'll correct it.

Just a thought.

This idea works as well, but IMO is not necessary.
If you were to use the correct garden hose muffs, and were to plug the drain hole, you won't have any issues.




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