impeller didn't self prime - a little paranoid now!

[sheral]

so we start up our new tug and discover there is no water exiting with the exhaust. (yes the seacock was open 🙂) i had to fill the strainer with water to get it to prime.

anyone else experienced this?

think i am going to pull out the impeller just to be safe and put in a new one...

 

[knotflying]

After the boat has been out of the water and the sea strainer is empty I open the seacock and then loosen the strainer lid to let water in. I never had an issue, but I figured it is a good way to prevent an airlock and have as much water in the system as possible before starting.

 

[sheral]

After the boat has been out of the water and the sea strainer is empty I open the seacock and then loosen the strainer lid to let water in. I never had an issue, but I figured it is a good way to prevent an airlock and have as much water in the system as possible before starting.

Likely a very good idea. 🙂

FWIW, today I rowed out to the boat and checked the impeller. It was all there, but the vanes were severely cracked where they meet the hub of the impeller. So out it came and in went a new Volvo-Penta impeller. Good news is that all of the impeller was there and I didn't have to go hunting for any pieces. Also, it was super easy access and only took maybe 20 minutes to have the new one in.

I wouldn't have thought that the impeller would be damaged as badly as it was. So if you have ever run an impeller dry even for a few minutes, it's worth checking it. Mine was still expelling lots of water with the exhaust so unless you physically check it, you may be 'cruising' for trouble.

 

[LAKERtoo]

.. would the Speed Seal Life set have saved the impeller ? if it was a very short time running dry ? Rob

 

[LAKERtoo]

.. this has got me thinking .. why is there not a strainer between the impellor driven water and the heat exchanger ? Rob

 

[sheral]

I have been seeing lots of 'shortfalls' with things, but I guess it has everything to do with price points.

Anyway, I do have a Speed Seal kit on the way. Even though it only took a short period of time to replace the impeller, not having the little screws to deal with, no paper gaskets, and a higher level of protection, it will be a welcome addition.

 

[SGIDAVE]

.. this has got me thinking .. why is there not a strainer between the impellor driven water and the heat exchanger ? Rob

Do you have Yanmar or Volvo power? If Yanmar, the factory installed strainer is STB side of engine slightly aft of oil filter mounted low.

Looks like this:

If you have a newer tug with Volvo then it likely has a different style strainer.

The factory installs a raw water strainer between the sea cock in the hull where the water enters the system and the raw water pump. The raw water pump needs to be protected from 'junk' so that's where the strainer should be located. If your boat lacks this item, maybe it has been removed by a previous owner?

Keep on straining,

dave

 

[seashanti]

I have a new 2015 Cutwater 28 and called to order a Speed Seal Life kit for my Volvo Penta D4 260 and was told that they didn't have a kit for it. So I was surprised that they did have one for your Volvo. By the way I added the Speed Seal Life kits for my Hino diesels on a previous boat and was very happy with them. Having the capability for the impellers to run dry for 10 minutes or so without damaging the impeller allows one to shut down the engine when the temperature increases before the impeller self destructs.

Mike

 

[SGIDAVE]

If you want to KNOW if your impeller/raw water pump is "pumping" then get one of these

It is an Aqualarm cooling water FLOW sensor. Our 21ECs need the 1/2-3/4" size as sold in kit form from Defender (and other venders) here
http://www.defender.com/product.jsp?pat ... &id=744093
You will also need to buy (2) male 3/4" mpt to 3/4" hose barb adapters to go with this kit. I've got one and it works as advertised. The units are sized according to the ID of your raw water supply hose.

ANY raw water impeller type pump can FAIL TO PUMP or STOP PUMPING for a variety of reasons...from small engines like our 21ECs to the 6+ cylinder big diesels...so KNOWING there is flow helps a lot by letting you take action (shut down engine) and troubleshoot the "failure to pump" situation BEFORE the impeller self-destructs. In many cases you will be 10-15 minutes 'down the road' when your overtemp alarm sounds...by then you may be in an area that shutting down the engine will endanger YOU/your passengers and/or PROPERTY (your boat or others' boats). Yikes. Knowing EARLY you have problem is always better.

The Speed SEal LIfe is a great product too especially for us 21EC owners who can EASILY access our raw water pumps 🙂

Fair winds and cool exhaust,

dave

 

[LAKERtoo]

.. my 3ym has the strainer between the seacock and the water pump, but my musing was in regards to another between the water pump and the heat exchanger .. if impellors destruct that frequently, I wondered why there wasn't another strainer to catch chunks ... Rob

 

[sheral]

.. my 3ym has the strainer between the seacock and the water pump, but my musing was in regards to another between the water pump and the heat exchanger .. if impellors destruct that frequently, I wondered why there wasn't another strainer to catch chunks ... Rob

that would make way too much sense 😉 . i had these awful visions of trying to find pieces of rubber in the heat exchanger or who knows where.