How long after start up should raw water begin to exit exhaust

[boeing1]

might check belt tension , as stated above, also check the water elbow on your exhaust manifold being clogged, have found several clogged on Yanmar engines, remove hose at elbow, start engine if you get water flow everything to that point is good.

[ebs001]

Originally Posted by bratzcpa

I've had a similar and ongoing problem getting adequate cooling water for my 3gm30 Yanmar.

Similar issue . . . not much water (hence, taking a long time to start exiting outside). I changed pump vanes, tightened water pump belt, then CHANGED water pump belt, etc. Monkeyed around but never quite solved the problem.

What finally worked for me was to work through the system one thing at a time. You can open the hoses and work through it step by step:

1. loosen and remove the water hose at the "input" to the water pump. It should free flow water (because it's lower than the water line). This verifies that the seacock isn't closed and the strainer isn't plugged.
2. put this back together and loosen/remove the hose where it goes INTO the heat exchanger. Put the hose end in a bucket and start the engine. There should be a LOT of water flow. This will verify that the pump is indeed pumping outside sea water.
3. Turnoff the engine, put this back together and more forward in the system. Loosen/remove the hose at the back of the heat exchanger. Again start the engine and verify good water flow (this is kinda messy).
4. From the back of the heat exchanger, my hose then goes up to a high loop/Vacuum breaker, and then comes back to the mixing elbow. So pull the hose off of the mixing elbow, start engine and verify good water flow.
5. If still good there, then the only other possibility is a blockage in the mixing elbow or muffler.

I had been fighting mine for a long long time. frequent but minor overheating.


I found partial blockage inside the heat exchanger pipes. EASY EASY to solve once I was identifying the actual CAUSE of the diminished water flow.


Good luck!


~markb

I agree you have a blockage and as stated above you will need to isolate the blockage. The only thing I would suggest you do differently than Mark suggests I would start in the middle at say the discharge of the heat exchanger. The usual suspect is at the mixing "Y" usually the incoming water hose.

[Parrothedd]

A little trick I learned from a mechanic a long time ago....shut the seacock and open the top to your sea strainer, squirt in some liquid detergent, then replace the top, open the seacock and start the engine. You should see soap suds in the exhaust within seconds, depending on the size of your water pump, hoses, etc. If I didn't see soap suds within a minute, something is wrong.

[SimonV]

A G65 Sherwood pump attached to a 4.108 @2000revs moves about 5 US g/h.

[FamilyVan]

Mine can be a bit slower to start spitting water. A couple of minutes some times. I find goofing the throttle speeds things up. I have a Perkins 4.108.

My engine is down low but the way the cooling system works is up through the sea cockpit, then up about 8" above my engine into my seafreeze system, then down to my raw water pump and then up and out the exhaust.

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[jkishel]

Originally Posted by SimonV

A G65 Sherwood pump attached to a 4.108 @2000revs moves about 5 US g/h.

Nope, 10 gallons per minute at 2000 rpm at 10 psi.

[Phennessey]

Thanks to everyone for all the great advice. Even though the impeller looked fine I replaced it and ran the motor a little longer and at higher revs and that did the trick. What a great resource this forum is I really appreciate everyone's responces.

[TomLewis]

Check your freeze plugs. Mine blew out and I noticed no water out the back. Noted water spitting out from where the plug was. I shut it down, got a large socket, extension and hammer. Popped the plug back in and working like a champ for over a year.

[fjwiley1]

Most will just change out the impeller but not consider having a good cleaning of heat exchanger. Local radiator shop can do a great job and reveal any issues with internal deteriation. You'll need to inspect/change the anode at some point also. Good luck..

Life is Good if you Keepa Smilin...😊

[SimonV]

Originally Posted by jkishel

Nope, 10 gallons per minute at 2000 rpm at 10 psi.

yup, should have been M not H taken from Sherwood flow graph.

[s/v Beth]

When I got my brand new Beta, I ran the impeller till it crashed (4 years later) after a haul out. No engine damage ( it started heating up, I just turned it off and sailed back) But I got smart. I got one of those quick impeller change kits, and a run dry impeller. This year's haul out, went back into the water, no water kick. Check the thru hull, the strainer, then the impeller (less than a minute with the new change kit) all have water.
It took 20 minutes to fill my pipe! But engine stayed cool and everything great. Got to love technology.

[SkiprJohn]

Originally Posted by Phennessey

Thanks to everyone for all the great advice. Even though the impeller looked fine I replaced it and ran the motor a little longer and at higher revs and that did the trick. What a great resource this forum is I really appreciate everyone's responces.

Good to hear!

[capn_mark]

Originally Posted by Phennessey

Thanks to everyone for all the great advice. Even though the impeller looked fine I replaced it and ran the motor a little longer and at higher revs and that did the trick. What a great resource this forum is I really appreciate everyone's responces.

Great news! Now on to the next thing to fix...


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[Ziggy]

Originally Posted by Phennessey

Thanks to everyone for all the great advice. Even though the impeller looked fine I replaced it and ran the motor a little longer and at higher revs and that did the trick. What a great resource this forum is I really appreciate everyone's responces.

That's consistent with my guess that it was caused by a lack of prime. Yanmar used to include a bit of silicone grease with their impellers, but apparently that was too costly...

[transmitterdan]

Some winterization checklists say to remove the impeller after winterizing the boat. Is it possible the impeller needs to be reinstalled? At the least removing the cover plate to check the impeller doesn't have broken vanes seems like a good idea.