Yanmar 1GM1) water pump/exhaust - nothing coming out!

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PWR

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Yanmar 1GM10 Engine overheat alarm started after 4 or 5 minutes running. No water exhausting from the stern.

Stopped all. Checked salt water trap, clear. Took off impeller cover, impeller looks fine. Ran engine for 5 seconds with impeller cover off, impeller is is turning. Warm water was coming out of impeller at that time, not a big volume of it though.

I can see water coming up the pipe from from the seacock to the base of the impeller. The water exhaust pipe from the top of engine is cold, no warm water is getting to it.

This was the first time the engine was started since an unrelated repair earlier this week.

Two questions. 1. Does it sound like something that requires opening the engine to check? 2. Did I do something bad in a previous life that is coming to haunt me through my boat?
 
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same happened to me - the inside of my exhaust was old/delaminating and covering the slit in the side of the exhaust manifold through which cooling water entered exhaust. Either cut off end of rubber exhaust and refit making sure inside does not "scuff" over water outlet or fit new rubber exhaust.

PWR said:
Yanmar 1GM10 Engine overheat alarm started after 4 or 5 minutes running. No water exhausting from the stern.

Stopped all. Checked salt water trap, clear. Took off impeller cover, impeller looks fine. Ran engine for 5 seconds with impeller cover off, impeller is is turning. Warm water was coming out of impeller at that time, not a big volume of it though.

I can see water coming up the pipe from from the seacock to the base of the impeller. The water exhaust pipe from the top of engine is cold, no warm water is getting to it.

This was the first time the engine was started since an unrelated repair earlier this week.

Two questions. 1. Does it sound like something that requires opening the engine to check? 2. Did I do something bad in a previous life that is coming to haunt me through my boat?
Click to expand...
 
chrisedwards said:
same happened to me - the inside of my exhaust was old/delaminating and covering the slit in the side of the exhaust manifold through which cooling water entered exhaust. Either cut off end of rubber exhaust and refit making sure inside does not "scuff" over water outlet or fit new rubber exhaust.
Click to expand...

Great, ta. Where did the water that came in before the alarm sounded go, just circulating in the cooling system?
 
and would it be sensible to take off the exhaust at the engine end (it is jubilee clipped on) to see if, when clear, that water is exiting from the engine to the exhaust pipe?
 
Double check the impeller. The centre could have become unbonded from the rubber, so would give the impression of turning when the cover is off.

The water comes out of the top of the pump and into a T shaped fitting which goes into the block one way and then out through the thermostat, or up that little vertical bypass hose until the thermostat opens. Both the inlet to the block and the bypass bung up easily with salt deposits. When you start the engine from cold you should get water out of the bypass hose even if the pipe to the block is blocked up. If you do not then the pump is not working - needs a few revs to get it going. Possible culprit apart from the impeller, is air getting in, for example if you have a loose hoseclamp or the top of the water strainer is not sealing properly.

Also worth checking that the exhaust manifold and injection point are not corroded. Remove from the engine and inspect visually plus turning upside down, blocking the injection hole and filling with water. None should get through the inner tube.

Hope this helps.
 
Tranona said:
Double check the impeller. The centre could have become unbonded from the rubber, so would give the impression of turning when the cover is off.

The water comes out of the top of the pump and into a T shaped fitting which goes into the block one way and then out through the thermostat, or up that little vertical bypass hose until the thermostat opens. Both the inlet to the block and the bypass bung up easily with salt deposits. When you start the engine from cold you should get water out of the bypass hose even if the pipe to the block is blocked up. If you do not then the pump is not working - needs a few revs to get it going. Possible culprit apart from the impeller, is air getting in, for example if you have a loose hoseclamp or the top of the water strainer is not sealing properly.

Also worth checking that the exhaust manifold and injection point are not corroded. Remove from the engine and inspect visually plus turning upside down, blocking the injection hole and filling with water. None should get through the inner tube.

Hope this helps.
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ta for those, will check and report back ...
 
Had similar problem. The water pipes from the impeller housing onwards had scaled up. Removed pipes, hit hard on deck to remove scale and refitted.
 
If you removed the plate from the water pump and warm water trickled out, then that is coming back from the cylinder block. If your pump is working the pipe from the pump to the block will be full of cold water as it won't have yet entered the cylinder block. However, just do as others have suggested. I would remove the water pipe from the exhaust elbow first, start the engine and see if water is coming out of the end of the pipe. That should clear up any probs with the engine itself.

Also, I would suggest you replace the thermostat. I removed my old one this spring, and found it to be corroded and jammed in the open position. Yours could be jammed closed, and therefore not all the water is going into the block. This may not account for no water in the exhaust, but for a few pounds and 10 minutes work, it's worth doing in any case.

Geoff
 
thanks all for those suggestions. Matter of interest, what's the best way to loosen out those hoses, as I don't have enough 12v power to run a hair dryer, and don't have an inverter, is there any other trick to loosen off tight rubber hoses without tearing them?
 
They should come undone OK. Never had a problem with my 1GM. The bypass might need a bit of persuasion as it is a bit short and could be stiff with salt inside.
 
step by step investigation

Went out to try to prise off hoses by hand, not successful. Ran engine very briefly, looking closely, I see the water feed coming up into the impeller has air bubbles in it. Next step is therefore to open both the raw water strainer and impeller cover and check/replace gaskets in case of air leak, as Tranona suggested.

After replacing gaskets and changing impeller (if needed), is there a requirement to prime the pump with water, and, if so, how? Thanks for your help again.
 
1GM10

I prime mine by filling the raw water strainer. I had a similar problem in that water came out the exhaust in small spurts up to about 2000 rpm - higher than that almost nothing. I changed the impeller which improved it a bit - the one I took out had the vanes pointing the wrong way! I then started looking at the hoses. Replaced Kingston cock to strainer and strainer to pump - no difference. Replaced the right angled hose from pump to block which completely cured the problem. It had delaminated at both ends and the squelchy rubber bits were partly blocking the flow. The right angled hose I used for the replacement was a heater hose off a Ford Falcon - much cheaper than the Yanmar part! Sorry don't know what the UK equivalent would be
Sailorbaz
 
PWR said:
Went out to try to prise off hoses by hand, not successful. Ran engine very briefly, looking closely, I see the water feed coming up into the impeller has air bubbles in it. Next step is therefore to open both the raw water strainer and impeller cover and check/replace gaskets in case of air leak, as Tranona suggested.

After replacing gaskets and changing impeller (if needed), is there a requirement to prime the pump with water, and, if so, how? Thanks for your help again.
Click to expand...

Sounds like air is getting in - been there! If you have a Vetus type strainer above the waterline then it could be the Oring in the lid or a crack in the lid. My problem (same symptoms as yours) was a stripped thread on the clip holding the inlet hose on. Seemed to be tight but enough to let air in - so double check all the hose clips. The inlet to the pump is also awkward and if that is loose it leaks and seawater drips onto the oil pipe. The pump cover has a paper gasket, but the best for that job is to replace the cover with a Speedseal which uses an Oring to seal and is much easier to remove and replace.

Normally there is enough suction in the pump to prime the system, although you have to rev a bit to get it going. The alternative is to close the seacock, fill the water strainer, start the engine and then open the seacock. However if air is getting in it will probably dry up again.
 
Don't get drawn into panicking if the impeller vanes are "pointing the wrong way". When a single cylinger engine stops, it often bounces back from compression about 90 deg, which is enough to flip the vanes over as the impeller goes into reverse. They will flip back again as the engine starts again.

Rob.
 
I am in a similar predicament. Was doing my Engine check dockside (once a week). No water coming out the exhaust. Pulled the impeller plate, looked good, put in silicone grease as a just in case. Reassembled. Nothing. Not pulling water up through the strainer into the water pump. Checked the seacock. Not blocked. Replaced the hoses (tighter fitting). Still nothing. I am dock side, so i took a garden hose and with light pressure, fed it in. No water coming out so, it's stopped at the impeller (guessing). Ran the engine. It primed and ran. Removed the hose, reattached the innerhull. Nothing. I am guessing I am not getting enough suction. I know the water flows when the line is pressurized from city water. Replace the impeller? Thoughts. Thanks for any input.
 
Is the strainer sealing properly? Any air leak will reduce the suction, maybe try some silicon grease on the strainer seal.
 
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