They might’ve started adding them in the 302/322 series, as that was after O’Day changed hands. I was referring to the earlier models, and specifically know that was the case for our ‘85 28.
Water Does not Come out the Exhaust
- Thread starter priopel
- Start date
Previous boat didn't have one, 1 yr in on the new to me boat, never found ANYTHING in the strainer...Northern Lake Michigan
EDIT: Pulled the strainer for winter haul-out (@Tally Ho ) and found a two small leafs
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We are blessed to sail in the clean, salt-free water of Lake Michigan!Previous boat didn't have one, 1 yr in on the new to me boat, never found ANYTHING in the strainer...Northern Lake Michigan
Now, only if global warming would heat us up enough that we didn’t have to haul out for 6 months
Gteg
My Volvo Penta MD 7A engine is raw water cooled. I a new to boat ownership and am awed but all that you guys know. Yes, the engine was running when I tried that test of disconnecting the hose from the thermostat, lowering it getting water to run then putting it back on. When this hose is detached, I can feel a bit of back pressure from the exhaust so thought that getting the water flowing without having to overcome that back pressure might get it working and it did. But I don't want to do that every time so maybe there is some problem with the pump or impeller.
The new impeller that I installed was purchased from the local Volvo Penta dealer and matched the old one. It is a tight fit and the vanes have to be bent quite a bit to get the impeller into the pump housing. If I knew for sure that this is the problem, I might buy a new pump with impeller installed.
The new impeller that I installed was purchased from the local Volvo Penta dealer and matched the old one. It is a tight fit and the vanes have to be bent quite a bit to get the impeller into the pump housing. If I knew for sure that this is the problem, I might buy a new pump with impeller installed.
It does sound like some kind of pump or impeller problem to me. The pump should be able to generate a decent amount of pressure, definitely enough that you shouldn’t need to lower the end of the output to get the water flowing.
Take the cover off of the water pump and check the impeller vanes. Are they perfectly flush with the pump housing or do they protrude slightly? On our Onan, with the correct impeller, the vanes protruded slightly. The blue impeller that I mentioned in my earlier post did not. The very thin gasket made up some of the difference between the vanes and the cover. If there is any amount of space between the vanes and the cover, it could be enough to prevent a good prime, which happened with our Onan. Also, be sure to test the shaft seal. I did my test by plugging one of pump ports and blowing hard into the other. No leaky.
@priopel it is the width that is important. Per @Terry Cox, check protrusion, or measure width (B). Also check condition of the cover, any grooves indicate wear. if water is getting around the sides it doesn't pump.
Thank you for the diagram of the impeller. Now, if I just knew the recommended measurements I would know something.
The collective wisdom here suggests that the problem may be with insufficient output from the water pump. Asked my Volvo Penta dealer about this and they said that they have no test for the water pump. Undaunted, I removed the thermostat housing, connected a clear poly tube to the water supply line with the other end in a bucket. I ran the engine at idle for one minute and it produced one gallon of water. The water supply line supplies water at two points, one to the manifold and this one at the thermostat. A gallon a minute might be adequate. But where is it going? Maybe the flow is sufficient when draining into a bucket but the pressure is not enough to overcome the back pressure from the exhaust.
The collective wisdom here suggests that the problem may be with insufficient output from the water pump. Asked my Volvo Penta dealer about this and they said that they have no test for the water pump. Undaunted, I removed the thermostat housing, connected a clear poly tube to the water supply line with the other end in a bucket. I ran the engine at idle for one minute and it produced one gallon of water. The water supply line supplies water at two points, one to the manifold and this one at the thermostat. A gallon a minute might be adequate. But where is it going? Maybe the flow is sufficient when draining into a bucket but the pressure is not enough to overcome the back pressure from the exhaust.
Critical is that all your hose clamps are truly tight all the way up and down the line, especially the one on the pump intake. If that is sucking any air, the pump will now draw right.
Scott, I think you are right. I finally got some good advice from the local Volvo Penta dealer and was told that the output I got was too low. They want $705 for a new pump but I am opting for a rebuild kit for $167. I let you all know the result. Hopefully this will finally do it.
Wow! That seems incredibly high. I replaced the raw water and the freshwater pump on my Yanmar for substantially less, I believe (I don't recall the price). Mine were even working. I had no real reason to replace other than they were 20 years old and I was replacing just about everything I pulled out in a general overhaul.
I've heard that Volvo Penta parts were high-priced but that's just ridiculous! Good luck with the re-build! I took apart a pump on my earlier engine and realized I wasn't getting it back together ... too sensitive replacing those seals for my inexperience!
Thank you all for your patience with this lengthy thread. I have been working on this for just over a year and have gotten nowhere.
I bought a water pump "wear kit" to overhaul the water pump, completed the repair and installed the newly rebuilt pump today. No change. In the attached photo, the part of the pump that I removed are in the top row. The second row show the parts from the repair kit that correspond and the bottom of the photo shows the extra parts in the kit that I could not use. The mangled washer in the top row was fine but hard to get out hence it is mangled. So basically, I paid $178 for a washer that I didn't need. Volvo Penta was very sure that this repair kit would solve the problem.
I am about ready to donate my engine for use as an anchor for a day mark.
I bought a water pump "wear kit" to overhaul the water pump, completed the repair and installed the newly rebuilt pump today. No change. In the attached photo, the part of the pump that I removed are in the top row. The second row show the parts from the repair kit that correspond and the bottom of the photo shows the extra parts in the kit that I could not use. The mangled washer in the top row was fine but hard to get out hence it is mangled. So basically, I paid $178 for a washer that I didn't need. Volvo Penta was very sure that this repair kit would solve the problem.
I am about ready to donate my engine for use as an anchor for a day mark.
Wow. Just out of curiosity, have you tried connecting the hose that leaves the raw water pump to a temporary connection to city water to make sure that the system will flow water if it is delivered to it? If it does, what about getting a 12v electric water supply pump and let it do the job. You could just remove the impeller from the raw water pump to decommission it.
Just be careful to not back water up into the cylinders via the exhaust with either of those approaches.
I did try connecting a length of poly tubing to the output of the pump with the other end of the tubing in a bucket. I got about a gallon after running the engine at idle for a minute. This should be enough flow but there is not enough pressure to overcome the backpressure from the exhaust. I like your idea of a 12v pump. The connections along the water supply line are of a ridiculous design and I can't see a way to insert anything there. However, I did put in a flushing T in the line from the thermostat to the exhaust as a way to prime the system. Maybe I could attach a pump there.
Make sure you heed Davidasail's advice. If you force water through the system, the engine must be running to prevent water from entering an exhaust valve.
WOW! What great advice. Thank you.
I am pursuing Hayden's advice and looking into a 12v pump. I figure that I will connect it to the water supply from the seacock, bypass the installed pump and connect it to the water supply tube that normally is supplied by the pump. In looking into it today, I see that I need a pump that is good for continuous duty and have spotted the following:
Seaflo 42 Series 12V Diaphragm Water Pump | Cabela's (cabelas.com)
and thinking about advice previously given in this thread, asked that firm about a filter and was shown one available here:
Seaflo Diaphragm Pump Inline Filter/Strainer | Bass Pro Shops
As far as I have thought it through so far, I don't see any problems and am optimistic about this approach. I will find a 12v source that is only hot when the engine is running.
I am pursuing Hayden's advice and looking into a 12v pump. I figure that I will connect it to the water supply from the seacock, bypass the installed pump and connect it to the water supply tube that normally is supplied by the pump. In looking into it today, I see that I need a pump that is good for continuous duty and have spotted the following:
Seaflo 42 Series 12V Diaphragm Water Pump | Cabela's (cabelas.com)
and thinking about advice previously given in this thread, asked that firm about a filter and was shown one available here:
Seaflo Diaphragm Pump Inline Filter/Strainer | Bass Pro Shops
As far as I have thought it through so far, I don't see any problems and am optimistic about this approach. I will find a 12v source that is only hot when the engine is running.