No Raw-Water Flow for Yanmar 3HM - HELP!!!

[sailscallny]

Got 2 on board butt no help as of yet
Still working on 172lb Great Dane boarding ediquite
Kinda like Marmaduke, likes the sailing part not the boarding part

 

[Davidasailor26]

Start by checking the sea water impeller, and any filters that may be in that side of the system. You should have a reasonable flow of water out the exhaust whenever the engine is running. If the impeller looks ok, then check for any blockages either in tenge through hull or heat exchanger.

 

[sailscallny]

Check my posts
I'm new to this forum stuff

Is the pump after the strainer
Strainer said out to pump

No water
New bolts on pump
Maybe exchanger is clogged and blew pump?
Dont know how old pump is but bolts are new

 

[Davidasailor26]

I don't know the configuration of your boat but usually the strainer is before the sea water pump. The typical order is seacock -> strainer -> pump -> heat exchanger -> exhaust elbow -> exhaust. There are a few places where problems can occur, and ways to troubleshoot each. First in line (although probably not most common) is a blockage in the seacock. To check that you can disconnect the hose before the pump, quickly open the seacock, and check for good water flow. Next would be broken vanes in the impeller. After more than a couple break off water flow will be noticeably reduced. Then if the vanes or any other debris get stuck in the heat exchanger they will also reduce the flow. Finally, it's possible for the exhaust elbow to get clogged, but usually that would lead to loss of power and unusual smoke rather than reduced water flow.

 

[twalker H260]

Maybe start a new post with your info. This post dates from 2014.

 

[sailscallny]

Maybe start a new post with your info. This post dates from 2014.

Thanks
Did got help

Thanks new at this forum stuff

 

[SG]

Aside from the advice above....

You have the manual? http://j30.us/files/yanmar-manual.pdf

You need to be careful with impeller. See the illustration below. You have to set the blades correctly with that pump. If you don't do that, the pump isn't a pump.

After you have checked the impeller, I'd take the hose off the DISCHARGE SIDE OF THE PUMP. Crank the engine, but DON'T START IT. I'd like to know if there is water being pumped out by the pump. If there is, then I'd reconnect the hose to the pump.

I'd then go to the discharge side of the engine water. Disconnect the hose. Crank the engine (but don't start it.) You should see water coming being pumped-out. There are cases where hose collapses INSIDE between the engine and the muffler. You wouldn't see that from the outside because because the hoses are double walled. (THAT's a long-shot).

IF you see water in "force" coming out the back of the engine, then you have narrowed down the problem.

 

[sailscallny]

TThanks so much

Could not find Manuel anywhere!

I will pull closed system cover and check the impeller again
Looks new , not sure in regards to diagram

Now I can check model #

Ogff to walk the dog
Aussie and Great Dane. A feat gettting them off and on the first day with the dogs
(Need a David for the dogs!

 

[SG]

Click on the link in my post above for the manual for three Yanmars. You can find others on the web.

There should be a plate on the engine with the numbers.

 

[sailscallny]

Service guy said he could not find it but II' look now that youu gave me the Manuel
Thanks

 

[sailscallny]

What a bitch to get to the late
I have a

2QH-20M Yanmar

How do I find that manuel

 

[SG]

My original post was for Greybeard.

 

[Davidasailor26]

Assuming you mean the model is 2qm20, there's a manual at http://www.melody-in-blues.org/downloads/QM-QMOperationManual_3.pdf.

Are you sure you don't have the fresh and seawater pumps confused? It's the seawater (open loop) side that you should be checking to see the condition of the rubber impeller. That's the one that would affect amount of water in the exhaust.

 

[sailscallny]

What does the "H" at the end mean
Is there any difference