Volvo 2003 engine raw water problem

[Captain36feet]

I have a volvo 2003 engine. I have no raw water circulating.

I have changed the impeller. Still no joy. Sea cocks are open of course.

Raw water comes from sea **** to strainer. I have confirmed water is flowing to here freely and the sea **** is not blocked, nor the strainer. The intake line goes around the back of the engine under the transmission and around to the impeller at front of engine. I am not sure why it goes to a fixed pipe near the transmission. Is it cooling something there?

I've taken the pipe off after the impeller. There is no water or even air pressure coming out. So the problem must be before here and not after

I have confirmed the impeller is spinning.

So I have a few thoughts
1. a blockage after the strainer and before the impeller or
2. impeller pump gasket is not sealing properly letting air in
3. The fixed pipe under the transmission has something to do with it.
4. The new impeller is faulty

Would love some thoughts on what others have had when no raw water is circulating to the impeller or know about the volvo 2003 set up for the raw water.

[Faster]

Seems like you've taken a good methodical approach so far.... can you blow through the (disconnected) hose/pipe between the strainer and the RW pump?

[Captain36feet]

I tried that too. Tried blowing and water did not budge. Even rigged up a hand water pump after the strainer to try to pump water to the impeller under pressure.

That gives me an idea, I 'll try to rig up something the other way and try to backflush the line from the impeller to the strainer if there is a blockage.

I might also rig up a temporary line, bypassing what I can to confirm if there is a blockage.

Easier said then done though, some hoses are really difficult to get to, and hard to undo.

[39512]

Try marking one of the impeller vanes to make sure the pump is spinning. The drive shafts on pumps have failed before.

[r.furborough]

39512 has a good point, not common, but it can happen. Also check the hoses from the strainer to the pump, they can look good externally but can de-laminate internally and block water flow. Also from your description of the hose run, you probably have a transmission cooler in circuit, these are also prone to blockages.

To trouble-shoot, Initially check impeller for rotation, then by-pass the transmission cooler, finally replace hoses.

[Captain36feet]

Good suggestions. I'll try out them out. Will let you know.

The hoses are proving difficult to remove. I'll try a hair dryer to heat them. As usual, awkward to get to.

[sailingdog]

Really hot water works well to soften hoses... a bit messier than the hair dryer but often works when the hair dryer fails.

Originally Posted by Captain36feet

Good suggestions. I'll try out them out. Will let you know.

The hoses are proving difficult to remove. I'll try a hair dryer to heat them. As usual, awkward to get to.

[jrd22]

If the hot water doesn't work buy a heat gun. I keep one on the boat all the time just for hoses. Makes life easier.
Has the boat been out of the water, or did this just start when an impeller failed?

[Captain36feet]

OK. I had success with removing hoses with the aid of the hair dryer. It really worked quite well.

I was able to narrowed the problem down now.

I was able to connect a hose directly from the strainer to the pump, bypassing the rest of the hose. Impeller spewed out water nicely.

I was also able to put tubes down the hoses from the strainer to the transmission - all clear.

Also checked the hose from the transmission to the pump - all clear.
So the blockage is definitely where the water goes through the transmission.
I narrowed the blockage to a space of 6 inches. The pipe runs at the back of the transmission near the shaft coupling low down. I've tried backflushing and forwardflushing under pressure - nothing at all. It feels like a total jam.

I might have to remove this from the transmission if it is possible.

Originally Posted by jrd22

Makes life easier.
Has the boat been out of the water, or did this just start when an impeller failed?

The boat has been out of the water for a short time for an antifoul, and stern gland packing. The shaft had to be uncoupled to get to the packing as there was little room from the half coupling to the gland.

The impeller has now proven to be fine (with the old and new one)

I wonder if there is some type of valve in the this transmission cooling, or a barnacle has somehow got in here (unlikely) or part deliinated hose as suggested.

I'll have a chat to the local volvo mechanic to see if it is easy and uncomplicated to remove this transmission cooling pipes


Thanks for all the help. It has been good to talk it through


Any other suggestions?

[SanderO]

You might look for exploded diagrams of this engine online and download them to see how things fit together back there since you've isolated the blockage to the transmission area. Can you remove the tubes or hoses there, I know there is tube on one side at least, and push a snake or prob in there and see what gives? Have you tried to blow air or water through the tranny section? from both directions?

If it is something lodged in there see if you can get some sort of high pressure air and pump from the down stream side and it might dislodge whatever is stuck in there.