Abin 25 - AD21 Impeller

[Plum76]

Morning all,

A question for the group. I munched up my impeller yesterday after lunch, heading back to our mooring. I had a spare from the PO aboard, so I put it in just to get back, and it seemed to run a reasonable temp for the few minutes I needed it.

Here's my issue. My secondary impeller for the bilge pump part of the casing is not installed, as that part of the pump isn't being used, and neither is the 8mm (?) separation plate/spacer between the two pump chambers. So now that I get a good look at things, I can't see what's keeping my cooling water impeller from walking out of it's housing and being ineffective. Second to that, it seems that with a second open casing connected to the one impeller, I'm not really pumping effectively.

My plan is to order the replacement parts (perhaps a whole assembly for the pump) and reinstall the separation plate/spacer and then an impeller bushing without the impeller fins in the unused bilge section. In the meantime, I'm hoping to install a second impeller for the bilge pump and a spacer between the two to keep everything seated correctly, so I can keep using the boat in the interim.

Anybody see any issues or concerns with this plan? What are other folks doing that are not using the bilge impeller in their setup?

Thanks.

Jason

[DesertAlbin736]

dkirsop is your go to guy for AD21 issues.

[dkirsop]

Hi. My set up is slightly different than yours as my engine is fresh water cooled so I do not have the bilge pump configuration however, the pump is pretty much the same with either option. Your bilge pump is my coolant recirculation pump. At some point the pump was modified by Albin to allow for the placement of two seals between the sea water and coolant side of things so there are two separate shaft lengths and two different spacers. If you do not have the original spacer then you will have to remove and determine the length of your shaft to know which spacer to order.

The shaft is fixed in position and will not wander so you do not have to worry about movement in the chamber without the impeller. Nothing is going to move around. You do need the spacer for your sea water pump to work properly as it is the backing plate for the impeller. You also need the o-rings that complete the seal between the chambers. You should also install a new shaft seal in the spacer.

At 8mm it sounds like you have the old style spacer and shaft as mine is around 12mm thick.

[Plum76]

My boat is also freshwater cooled, so I have the two-impeller shaft, designed to be both the cooling impeller and the bilge impeller, separates by my missing spacer which is also the pump volute seal, and perhaps an intermediate shaft support?

My shaft won’t wander, but without the disc seal in between the two chambers, there doesn’t appear to be anything keeping the impeller from wandering on the shaft.

I can install spacers to keep everything located correctly, but without the disc to separate the chambers, I effectively have a single impeller in a chamber sized for two, plus a thick spacer, thinking way inefficient.

I’m assembling an order for the parts i need, and just planning on running a. ‘Dummy’ impeller on the unused bilge side, just to maintain all my shaft spacings. My biggest issue is I’m not quite sure what I’m missing, will be reviewing the exploded diagram on the boat tomorrow for comparison, as well as taking some measurements to confirm dimensions..

[dkirsop]

Ok, here is where boating on the Great Lakes is different from salt water boating. My cooling system has a closed coolant loop (fresh water) that keeps the engine coolant separate from the sea water loop (salt water). The pump impeller closest to the engine circulates the engine coolant, the next pump impeller circulates the sea water through the heat exchanger and discharges at the exhaust elbow. Two seals, hence the thicker disc, are installed between the impellers to prevent mixing of the two liquids. The longer shaft and thicker disc were implemented to accommodate the additional shaft seal. There is no "bilge pump option" for my motor configuration.

Good to hear you have the exploded drawing. Make sure it is the correct drawing for your engine configuration. I do have copies in pdf format if you need a different one.

[Plum76]

Ah, I see. My nearest impeller is drawing from the thru-hull intake, direct from the lake, second (outboard) impeller is unused.

Am I correct to understand that if I don’t require a closed cooling system that I may not need the block off plate between the two chambers? I was worried about efficiency without the block off plate installed, with just the impeller and a large pump chamber.

Thanks for feedback..

Jason

[dkirsop]

I can't answer your question with certainty. After looking at the two drawings it became clear that our pumps have significant differences. However, I do have 40 years of experience with large pumps and pumping systems and I can say that without the plate your pump efficiency must be significantly impaired. The plate would prevent the internal re-circulation of water that is probably occurring within the impeller chamber now.

[Plum76]

I’m also of pumping background and I’m suspecting the same thing, no way it can be pumping what it’s supposed to with an open volute like that.

Will order some parts and see..

Thanks for the input.

Jason

[Plum76]

Alright, so I have it back together. In my hurry to make a repair to get back to the mooring, I overlooked my disc/spacer glued into my out boat housing with sealant. Upon further inspection post incident, I removed everything and gave it a good clean.

Not finding o-rings of the right thickness, I used basically o-ring string (make your own o-ring kit stuff) and have it reassembled. I used silicone grease on the impeller housing (the interim one was already tearing, I suspect from dry install) and new stainless hardware. Seems to be pumping water as well as before.

I did add a paper gasket between my case and cover, previous owner had coated with sealant, so i suspected flaws that would lead to drips, so a preventative measure. I used anti-seize on the stainless bolts, so they don’t gall into the case threads.

Thanks for guidance, now to see if I can sort the nuisance oil leak from my transmission..

Jason

[Plum76]

Test run tonight, seems to be running fine, if a tad bit warmer than before. Running 180f (~82c) at 1700 rpm.

Thermostat check is next, I suspect that I have a 75c thermostat, seeing recommendations that I should be running cooler (60c) thermostat to help keep lime deposits in the cooling jacket down.

Anybody find a domestic replacement thermostat for the AD21?

Thanks.

Jason

[Farlander]

Hi All!
I am working on removing the INNER impeller from the AD21 with fresh + raw water impeller setup.
The raw water impeller is easily accessible behind the cover.
The fresh water impeller however is behind the 8mm bronze disc plate.
There is a 'locking pin' that indexes the disc into the water pump housing.
Do I need to drill out the 'locking pin' before I can take the disc out?
How can I do this without destroying the pin or the disc?
Thanks in advance all!
Joe
1970 Ericson 35 Berkeley CA

[Plum76]

In my housing, I did not have a pin in place upon inspection, and the bronze disc did not seem to need it to stay in place. There was a small nook in the face of the bronze disk that I could use with a small pick to remove it for impeller servicing.

I would not anticipate that drilling would be required to perform such a routine part of impeller maintenance, as it should likely be checked at least yearly for condition? I have since parted with my boat, but getting in and out of checking my impeller became quite a quick and easy process with minimal fuss.

Plum

Hi All!
I am working on removing the INNER impeller from the AD21 with fresh + raw water impeller setup.
The raw water impeller is easily accessible behind the cover.
The fresh water impeller however is behind the 8mm bronze disc plate.
There is a 'locking pin' that indexes the disc into the water pump housing.
Do I need to drill out the 'locking pin' before I can take the disc out?
How can I do this without destroying the pin or the disc?
Thanks in advance all!
Joe
1970 Ericson 35 Berkeley CA

[dkirsop]

The bronze disc comes out without disturbing the pin. Remove the disc using a piece of hardwood and a hammer. Place the hardwood against the disc and tap the other end with the hammer. Do this at several locations around the perimeter. The disc is a friction fit and will gradually come out.

My disc is scribed with a forward facing arrow mark so I use the pin and mark to make sure it goes back in the same orientation that it came out. Not sure if this is essential but it doesn't hurt to be cautious.