sometimes cooling water does not come out from engine

[eranb2]

yanmar 2gm20
hoses replaced.
without strainer.
I take the hose before the pump and push air , water goes out.

everything is ok , but sometimes water not come out.

what can this be?

 

[steve28]

The only things it can be is either a bag over the intake, the pump belt slipping or the impeller has come away from the drive dog. you will have to take the impeller out to see if this is the case.

 

[richardabeattie]

The forum is going to love "The only thing it can be ... "!

 

[colvic987]

you will have to check the following:

First check you don't have a blockage in the inlet seacock/scoop on the outside of hull. If ok then check and clean the seacock strainer.

If you have not yet checked the impeller then check it is not broken or old, change it for a new one if possible..

check the hoses clips are tight and not letting in air, and the impeller cover is on properly with the appropriate gasket and not letting in air...


I had the same sort of problem when i fitted a new impeller and i changed a hose which was not sealing properly which allowed air to be sucked into the system stopping the impeller sucking enough water into the system and enough pressure to push it out to the exhaust..

 

[fluffc]

If you have a water trap, you will find sometimes that it will come out in stops and starts, with a few seconds in between, and not a continuous stream. This is normal.

 

[neil_s]

My Bukh engine suffers from this too. Sometimes the cooling water will flow OK when you start up, sometimes not. I found that the pump impeller needs to be changed. The old one might look perfectly OK but If you put in a new one, water flow becomes reliable. By trial and error, I find I need a new impeller every 2 years, no matter how few hours the engine does.

Best of luck!

Neil

 

[Anonymous]

Everything that colvic said plus check that the impellor housing plate is not badly worn. If it is, you can usually turn it round the other way - just scrape of paint or stickers, clean and polish. And be sure the gasket is the correct one. Impellors are VERY tricky and problems can be hard to trace.

 

[FAITIRA]

same as the other chaps, i had a minute air leak going up the rhone a few years back, created a similar prob. cure as per Lemain.

 

[jax]

If you have a water fillter check the O ring seal. If that is worn or the cap is loose air will be sucked in instead of water.

 

[dickh]

Agree with jax - I had this problem after clearing weed from my see-thro water filter - pump wouldn't suck water. Eventually had to well grease the 'O' ring on the lid with Vaseline and then make a wooden tol to just give the lid an extra tweek and this solved all the problems. But I now have to use the 'tool' to undo the lid and have to be carefull I don't wring off the whole filter off the bulkhead!

 

[Topcat47]

I had huge marine polyps growing from my inlet that were blocking the hole. Enough to set off the high temp alarm. I scrubbed them off with a stiff brush. That'll learn me to leave bronze fittings un-antifouled.

 

[srp]

Not sure about the 2gm, but on the 1gm10 its worth checking the rubber hoses from the pump outlet up to the thermostat, and from the thermostat to the head - I saw one last week with these two hoses almost completely blocked with some sort of chalky salty crud. 2 minutes with a bit of wire made all the difference.

 

[FAITIRA]

Thanks jax, it was a few years ago, it proved to be an unbelievably tiny air leak on the face plate of the Jabsco pump. I had to remake the gasket several times, as lemain says, these pumps can be very tempremental.

 

[jjgmullins]

Check the "T" fitting where the water goes from the impeller to the block and from there to the thermostat. The "T" fitting gets clogged with algae and debris that becomes a carbon and salt powder plug. Simply use a phillips screw driver or rod the internal diameter and push it in the "T" from the top, then push it in the fitting "pointing screwdriver end towards the block" and gently shove the carbon plug into the block. This should clear the fitting blockage and then flush the system to remove the carbon from inside the engine block (head). If you don't want the plug to go inside the engine, you can use lady's crochet hooks (start small and work up in size) and push it through the plug, then pull out as much debris as possible until you are using a large size crochet hook and have cleared the T fitting of debris.

This can be avoided each season by opening the fitting (remove the two hoses from the fitting) before winterizing and scrubbing out the "T" fitting with a nylon brush that has a flexible twisted wire middle (the type like people use to clean small test tubes in a chemical laboratory).

Hope this clears it up for you.

J