Volvo D2 55F Cooling System

[spiv]

Hello cruisers friends,

I have 2 Volvo D2-55F on my cat, they are 5yo and run 1,500h.
I notice that one of them was blowing white smoke (vapour??), I checked the impeller and two blades were missing so I replaced it.

There is still only a little water coming out of the exhaust and the small water jet, less than the other engine.

I checked the water intake and it is clean.

I wander where the two missing impeller blades are..... somewhere in the heat exchanger i guess, how do I find them?

[DougR]

Most likely, but not necessarily, the two impeller blades are located on the input side of the heat exchanger tube bundle.

You should remove the hose between the sea water pump and the heat exchanger inlet, and start by checking the outlet of the pump for any blade fragments which might be wedged there. Then check that nothing is jammed in the hose itself. Next, see if you can see or feel any blade fragments pressed against the tube ends in the heat exchanger bundle. Most likely you will have to remove the end cap on the rear of the heat exchanger to remove any fragments of impeller.

This should turn up most of the pieces of impeller, but unlikely as it seems, I have also seen pieces of impeller that have traveled into the hose feeding water into the pump and become lodged there. It's a good idea to check in that direction as well.

DougR

[rwidman]

Originally Posted by DougR

Most likely, but not necessarily, the two impeller blades are located on the input side of the heat exchanger tube bundle.

You should remove the hose between the sea water pump and the heat exchanger inlet, and start by checking the outlet of the pump for any blade fragments which might be wedged there. Then check that nothing is jammed in the hose itself. Next, see if you can see or feel any blade fragments pressed against the tube ends in the heat exchanger bundle. Most likely you will have to remove the end cap on the rear of the heat exchanger to remove any fragments of impeller.

This should turn up most of the pieces of impeller, but unlikely as it seems, I have also seen pieces of impeller that have traveled into the hose feeding water into the pump and become lodged there. It's a good idea to check in that direction as well.

DougR

That pretty well covers it. Save the pieces and try to determine if you recovered all the pieces.

Have you been changing the impellers as scheduled maintenance? Look in your owners manual but every two years is what's usually recommended.

[spiv]

Originally Posted by DougR

Most likely, but not necessarily, the two impeller blades are located on the input side of the heat exchanger tube bundle.

You should remove the hose between the sea water pump and the heat exchanger inlet, and start by checking the outlet of the pump for any blade fragments which might be wedged there. Then check that nothing is jammed in the hose itself. Next, see if you can see or feel any blade fragments pressed against the tube ends in the heat exchanger bundle. Most likely you will have to remove the end cap on the rear of the heat exchanger to remove any fragments of impeller.

This should turn up most of the pieces of impeller, but unlikely as it seems, I have also seen pieces of impeller that have traveled into the hose feeding water into the pump and become lodged there. It's a good idea to check in that direction as well.

DougR

OK, removed hoses, no impeller pieces.
Stuck my finger in the heat exchange cover: nothing. This cover is impossible to remove as I cannot get the hex spanner to one of the bolts, I can hardly touch it with my finger, stupid design

I pushed an electrical 'snake' into the hoses and it was clear, except could not get into the intake seackoc because of a bend in the hose.
Closed the seackoc and removed the hose, opened the seackoc and water just tricled in from the saildrive, even though the saildrive intake is clean.
I pushed a wire in the hole, dislodged something and water gushed in.

Reassembled the lot and the water flows from the exhaust and the small hole even at idle.
No more white smoke!!
I am on anchor and not run the engine under load, but I expect to be all fixed.

As for the impeller blades.... I wish them luck wherever they are...
I am going to install a small s/s strainer just after the raw water pump, so in the future any bits of impeller will be caught there. I did the same already in my generator last year.

BTW, I replace my impellers yearly and keep the old ones for emergency use.

[DougR]

Glad to hear that you have resolved the issue. I hope the "something" that you dislodged was able to flow out with the incoming rush of water. If there were no impeller pieces to be found, hopefully they were small enough that they made it thru the heat exchanger and hence overboard.

In the past when VP delivered a new saildrive, the interior passages of the drive were coated with antifouling paint. This paint however doesn't last forever and the interior passages should be repainted periodically with antifouling paint. How to do this? When the boat is hauled for a bottom job you should take a 3/8" or 10 mm wooden dowel rod and use the rod to clean the water passage, coming up from the water feed hole which is found on the bottom front of the saildrive leg. Pieces of shell and other debris can be dislodged from the inside of the lower leg in this manner. Then remove the seacock from the upper half of the drive inside the boat and clean as much as you can from there. Then flush out with a water hose or air pressure from the top. Let it dry for a day or so if you use water. Next tape over the water inlet slots on the front of the leg, and also tape the hole in the bottom of the leg. Pour non-copper based antifouling paint into the water cavity from the top until it's full, then remove the tape on the bottom of the drive and catch the paint as it drains out of the leg. Reassemble the seacock, giving as much time to dry as you can. This will go a long way toward keeping the interior of the water passage clean.

DougR

[spiv]

Thank you Doug,
that is good advice, will do at next houlout.