8V71N water pump identification/replacing the impeller.

[RJM]

I am getting an overheating issue at higher throttle and the former owner's mechanic suggested that I start with replacing the impeller. My water pump appears to be a Jabsco 6980-3100 as best as I can tell. The cover has no identification on it but by matching up picture I have come up with this. Would this be correct? It has a 5 bolt cover and inlet/exit are at 90 facing up from the body. Also, this is my first go-round so any tips/suggestions are welcome! [h=1][/h]

 

[Captain Ralph]

Just need the height of the impeller. Set it on end (splines vertical).
2.5" impeller, Jabsco pump 2570, impeller PN 17935-0001.
3.5" impeller, Jabsco pump 6980, impeller PN 17936-0001.

 

[SEVEN]

Should be Jabsco 17936-0001 and the gasket is 816-0000

 

[RJM]

Rummaging around in the boxes of stuff that the P.O. left I found a torn up impeller with 17936-0001 on it. A safe bet, I am going to assume that this was a replaced impeller for one of the engines. Looking back at old posts I didn't see anything about draining the water out. Remember, this is my first go at this. Is there much water inside and what is the best way to drain it? I am also going to clean the raw water filter at the same time. I know, newbie questions... and yes, first step-close the seacock. Thanks in advance..

 

[RichardM]

Rummaging around in the boxes of stuff that the P.O. left I found a torn up impeller with 17936-0001 on it. A safe bet, I am going to assume that this was a replaced impeller for one of the engines. Looking back at old posts I didn't see anything about draining the water out. Remember, this is my first go at this. Is there much water inside and what is the best way to drain it? I am also going to clean the raw water filter at the same time. I know, newbie questions... and yes, first step-close the seacock. Thanks in advance..

There won't be a lot of water. Maybe a pint or so but yeah, close the seacock... It's sometimes hard to remove them. Especially if it's been there for a while. It's not stuck on the shaft. In most cases, it's the vanes that took the shape of the cam and it prevents it from coming out easily. Usually, 2 flat screw drivers will do the trick. If it doesn't want to come out or access is limited (like on my boat), it helps to have the proper impeller puller, it won't necessarily get it out just by itself but it will put tension on the impeller while you pry it out with the screw drivers. It keeps it from going back in when you release the pressure to reposition your screw drivers. I use glycerine as lube (most pharmacy has it) but it won't do miracles to get it out. More to put the new one in. Be careful not to damage the edge of the pump body with your screw drivers. If you do, just use a file and fine sand paper to fix it. Also, to put the new one back in, it helps to put a 2 or 3 ty-raps around the vane to compress them. You cut them has the impeller is going in. Oh and never mind the direction of the vanes, they will flip on the right side on the first revolution... Just my experience... Good luck ;-)

 

[SEVEN]

One thing I would add to Richard’s comments above, put the new impeller in really hot water for about 10 minutes. It makes it really pliable and easy to bend the vein’s when you put the wire ties around it.

 

[RJM]

Thanks for the suggestions. On the mechanic's advice i also ordered an impeller puller. Seems like a worthy tool investment given that these things need replacement. Also, like the zip-tie idea-a cheap alternative to the compressor tool that I saw. And yes, thanks for the hot water tip!

 

[dottieshusband]

I used to use liner clamps to compress the blades, but the last few time, I just simply rotated the impeller while pushing and was able to get the splines engaged. I have a puller, and do occasionally have to use it, but the 2 big flat blade screwdriver works well almost every time.

 

[bostonhatteras]

I am getting an overheating issue at higher throttle and the former owner's mechanic suggested that I start with replacing the impeller. My water pump appears to be a Jabsco 6980-3100 as best as I can tell. The cover has no identification on it but by matching up picture I have come up with this. Would this be correct? It has a 5 bolt cover and inlet/exit are at 90 facing up from the body. Also, this is my first go-round so any tips/suggestions are welcome! [h=1][/h]

You are correctly identifying the pump. Attached is a picture of an original pump cover from that model pump. Quite a bit of info imprinted on it. Do yourself a favor and use Globe impellers model #1213. you'll be very happy with Globe impellers. While you're at it, buy some GREEN Grease and grease the pump splines generously, Green Grease is the brand name and its also the color of the grease. Its highly waterproof grease. If your boat has the old style, and indestructible, wilcox crittendon tapered cone seacocks this green grease is an excellent and probably the absolute best grease to maintain them with.

 

[spartonboat1]

Thanks for the suggestions. On the mechanic's advice i also ordered an impeller puller. Seems like a worthy tool investment given that these things need replacement. Also, like the zip-tie idea-a cheap alternative to the compressor tool that I saw. And yes, thanks for the hot water tip!

Compared to the "old" impeller design, the "new" impellers have a greater number of vanes, which are much more flexible and and are far easier to compress by hand. The vanes in the old ones were very thick and stiff. You often had to compress them with a hose clamp to reduce their diameter for loading to the impeller cavity.

 

[Captain Ralph]

Depco Pump explained to me; the more vanes, the less water gets moved.
Also advised us to stay with the stock impellers on the Jabsco engine pumps.

Globe Impellers vanes are soft and fly at higher rpm causing less water thru the engine.
Glob impellers have their places, not in a main engine.

Northern Lights has changed their raw pump vendor. Still uses the same impeller.
Still, warranties are denied with out this stock impeller in use.

From the business side, liabilities at risk not using stock parts.

When in doubt, stay stock.

There was one place we found where the Globe impeller worked great. On a slow turning, hydraulically driven, oil cooling pump. Seemed the pump never turns fast enough to spin out set rubber impeller vanes that sit and take a set. This was on a later Hatt with hydraulic everything.
During a conversation with Paul Hall (then with Hatteras) he confirmed that the Globe impellers were recommend here because they did work better at lower rpm and dock queen equipment.

 

[Captain Ralph]

I have tried ring compressors, hose clamps and cable tie wraps.
I never could get these to work with out a loud song of bad naval words.

We learned to grease the inside of the pump body and shaft. Wash hands, with NO grease on hands and NO grease on impeller (greatly improves your grip), insert impeller with a twist to find the impeller center on the shaft, continue to twist until the shaft splines catch. Now pushing with the palm of your hands, push towards the body cam and in. Usually glides rite in.

On those long impellers (Cats) or pumps not reachable with both arms, Ive used the handle of a mallet or short block of wood to help push (light tapping) the impeller the rest of the way in.

 

[SEVEN]

I soaked mine in hot water for 5 minutes. I use 4 zip tie. Squeeze them down tight. Grease the opening, insert until just before the first zip tie hits the wall. Snip it off with wire ties, push in to it hits the second zip tie snippet off and so on. Works like a breeze.

 

[rwaldrop13]

I have tried ring compressors, hose clamps and cable tie wraps.
I never could get these to work with out a loud song of bad naval words.

We learned to grease the inside of the pump body and shaft. Wash hands, with NO grease on hands and NO grease on impeller (greatly improves your grip), insert impeller with a twist to find the impeller center on the shaft, continue to twist until the shaft splines catch. Now pushing with the palm of your hands, push towards the body cam and in. Usually glides rite in.

On those long impellers (Cats) or pumps not reachable with both arms, Ive used the handle of a mallet or short block of wood to help push (light tapping) the impeller the rest of the way in.

Adding to Capt Ralph, I found an oil filter wrench works to compress the vanes and will slide towards you as you ease the impeller into the housing. I haven't done it on mains yet but it worked like a charm on the genny. I can't find the video but there is an Onan generator servicing video demonstrating the technique.