Be Wary (Maybe) of Stay Cool Pumps Impellers

[a64pilot]

My exhaust note changed, I noticed waterflow was way down, but temp gauge was still right under 180.
Well I started with the intake screen of course, then moved onto the intake thru hull itself, cause the impeller was nearly new.
Well when I took the impeller out I found this, it has I’d guess maybe 50 hours on it, maybe a little more, but less than 100.

[sailorboy1]

did it stay cool :-)

[Mike OReilly]

Wow, that’s the worst I’ve seen. And of course the real PITA is finding all the pieces.

Pretty impressive that it still cooled though. We now know you like to sail, not motor .

[a64pilot]

It stayed right under 180f, I installed a temp gauge, normal temp is just a little lower maybe 170 ish or so.
I think that is cracking temp for the thermostat and 180 full open.
So yes it had enough water to keep cool, but it was loud and had little water flow.
The pieces is what has me irritated, it means of course that I’m going into the heat ex soon, work I didn’t want to do of course.
I have a strainer I was going to install in the line after the pump, I guess I should do that now.

[Jim Cate]

Don't know about that particular brand of impeller, but we had a normal Jabsco impeller fall apart in a similar fashion a couple of years ago. When we purchased it (from a chandler we had not used before) it had not been in a blister pack as usual, and was dusty. Seemed to feel normally flexible, etc, and it was the only one for miles around so we put it in.

I suspect that it had been years old, sitting on the shelf, and I was not astute enough to realize that most rubber products age, even not in use.

Won't make that mistake again!

Jim

[daletournier]

Originally Posted by a64pilot

It stayed right under 180f, I installed a temp gauge, normal temp is just a little lower maybe 170 ish or so.
I think that is cracking temp for the thermostat and 180 full open.
So yes it had enough water to keep cool, but it was loud and had little water flow.
The pieces is what has me irritated, it means of course that I’m going into the heat ex soon, work I didn’t want to do of course.
I have a strainer I was going to install in the line after the pump, I guess I should do that now.

When I purchased my boat the po assured me it had a super duper impellor that didn't need changing!

On investigation 5 vanes were missing.

I understand your pain in tracking them down and to be honest I haven't done it yet. Getting the oil cooler off is a bitch, and temperature seems fine as water flow , it's on my to do list.

One thing I absolutely hate about my boat is the postion of the raw water pump (what were they thinking) and the lack of access I have to it. Not sure I could do it at sea.... Grrrrrrrr.

I change it earlier than nessacary.

[a64pilot]

Thankfully mine is easy to access. I plan on installing a strainer after the pump, of course that means a longer hose, but I have some silicone hose for the job just haven’t done it yet.
Never had a reason until now, now I do.

[GordMay]

Jabsco Impeller Trouble Shooting (symptom - cause - remedy)
➥ https://www.jamestowndistributors.co...t.do?docId=745

Eg (1 of 6):
Symptoms: End faces hard and either polished or cracked. Some or all blades missing.
Cause: Dry running, lack of water in pump. Temporary suction blockage. Leaking suction pipework.
Remedy: Do not run pump for more than 20 seconds without liquid. Install a liquid sensor / temperature alarm. Check suction pipework, strainers, and skin fittings for blockages & leakages.

[a64pilot]

Thanks Gord. I guess a temporary blockage was possible, but not dry run.
It’s under the waterline and therefore always full of water, but a plastic bag etc., well is possible.

[gonesail]

plastic bag could've been there long enough to cause damage then dropped off?

[a64pilot]

Originally Posted by gonesail

plastic bag could've been there long enough to cause damage then dropped off?

It’s about the only way I could have gotten a temporary blockage that I can think of.
Assumption is blockage has to be almost complete, but then self clearing, cause I didn’t do anything to clear it.

[thinwater]

Originally Posted by a64pilot

My exhaust note changed, I noticed waterflow was way down, but temp gauge was still right under 180.
Well I started with the intake screen of course, then moved onto the intake thru hull itself, cause the impeller was nearly new.
Well when I took the impeller out I found this, it has I’d guess maybe 50 hours on it, maybe a little more, but less than 100.
Attachment 182877

Had the engine been winterized? If so, what agent? Was the vane material specified?

[sailorboy1]

Originally Posted by thinwater

Had the engine been winterized? If so, what agent? Was the vane material specified?

he's south, I doubt it has been winterized with that "safe" pink glycol that likes to destroy rubber stuff

[BobHorn]

Had one like that on our last boat. Pumped water just fine until we had the boat hauled and the water drained out. Without the blades it would not prime.

[Frankly]

Wouldn't worry about the blades traveling far in the system. On the Yanmar GM series the heat exchanger sea water passages are small tubes (40 caliber) and the end caps/ gaskets are configured for a three pass cooling flow. Pull the fwd cap, remove the blades and a little other crap, clean the tubes with a pistol cleaning brush, shaft extension, and a battery powered drill. Don't need another filter just the primary and an external scoop if you motor in grassy waters.


You left town just in time. Your old slip ain't looking so good as of October 10th.


Frank