Diesel: water not coming out the exhaust?

[Jacana]

Maybe airlock.Take off the hose that goes to the mixing elbow,start your engine and suck the hose ,usually only takes a couple of seconds then when the water starts to flow put hose back on elbow and tighten clamp.You can leave the engine running as only takes a couple of seconds to refit.

[Elie]

I once had that problem in the spring launch. I was bafled until I discovered that the strainer-filter cover was not tight and leaked air. Easy to fix!

[keepondancin]

By any chance is the cover plate worn? You may not be getting the full effectiness of the impeller if the plate is worn once there is back pressure from having to pump water through the cooling/exhaust system.

[baycruiser]

Originally Posted by montenido

This may sound silly, but have you tried reversing the hoses to the water pump? My last sailboat had a raw water pump that was easy to replace backwards, giving the same symptoms.


Cheers, Bill

I also had this problem as the pump could be rotated a full 180 easily and then the hoses were on the rite way

[Island Time O25]

I few years back I was motoring an hour or two with engine running hotter than ideal. But not hot enough to have to shut it off. Then all of a sudden no water was coming out (turned out my mixing elbow became plugged up with salt and minerals). The cause was that what water was able to escape the plugged up bend was being quickly evaporated, resulting in steam and not water coming out of the end of the exhaust and much salt and minerals settling inside the elbow.

As I attempted to flush out the elbow (as per advice of my marine pro buddy - his usual advice is to look for easy solutions first) I realized that the elbow was on its last legs and would croak if not now soon thereafter. After much huffing and puffing and with much needed help from my buddy we got the old elbow off, installed the new one and the issue was resolved. BTW the water pump was not too long prior replaced by the PO as per advice of my surveyor so that was not an issue.

[AgPilot]

I had the same issue.....I did the same checks as you......it ended up being a salt build-up in the mixing elbow just before the thermostat. I removed the build-up, hooked up the hose, and it worked perfect.

[CHM]

Just de scaled my entire raw water system and found both crud at the thru hull and air locks to be issues, especially if you have hoses going to a hot water heater.

[Island Time O25]

Originally Posted by AgPilot

I had the same issue.....I did the same checks as you......it ended up being a salt build-up in the mixing elbow just before the thermostat. I removed the build-up, hooked up the hose, and it worked perfect.

I would've kept the cleaned up elbow but my marine pro buddy insisted that since it looked original, on a 30+ year old boat, I should replace it. And given the fact that we did all that work removing it it would be a shame to have it crumble in the middle of the ocean in the next season or two. The new one was $150 so it did not make sense to take a risk with the old one. My buddy said if we had the leisure of time (this happened in the middle of the Summer) he would have manufactured one himself out of the parts available in any plumbing section for under $20-30 but Universal dealer is 2 min drive from my mooring so that made my decision even easier.

On another boat, 2QM Yanmar which I was installing in place of a croaked Universal 5411, the mixing elbow was actually and not just figuratively crumbling in my hands. Since Yanmar dealer wanted an arm and a leg for it I got one online for $130. The only caution I was told by my buddy is to keep on eye on it since it was ss.

Since these experiences with the elbows I de-mineralize these engines at the end of every season by adding calcrid or some such to the bucket right before winterizing the system. I don't do much motoring during the season otherwise I'd repeat the procedure at least once or twice while in the water.

PS Anyone knows if a carbon elbow is possible/advisable?

[bratzcpa]

I had some trouble similar to this on a Yanmar 3GM30. Replaced the pump, but still had cooling issues. Eventually, I just worked through the system backwards to identify where the problem was.

for example, pull off the hose where it leaves the water pump and start the engine. IS there good water flow? Ok good, then put it back on, then move forward to the next spot and take off the other end of the hose where it enters the heat exchanger. Good flow still there? Great, then move to the other end of the heat exchanger. Good flow there? Great, then, etc. etc etc.

It could be blockage in a strange place (for example, where the hoses go forward to the galley water heater, etc. ).

Eventually, you'll find a place where it suddenly quits. THEN, you isolated the problem.

Also, in response to some other suggestions on here, it only takes a few seconds (surely less than a minute) to fill up the system. So if you're not seeing water exit the boat in that amount of time, there's a problem in the system somewhere.

The good news is that it's all just simple plumbing. NOT rocket science. Find the blockage through logical testing - don't just jump into the middle of the system.

~markb

[Jason Flare]

The instructions with the impeller, (I just replaced,) said that water should appear out the exhaust within 30 seconds. In my case water was quick.

[J Clark H356]

Make sure the impeller cover is on good and 0 ring in slot and sealed. I've changed a lot of impellers and last fall when I changed my generator impeller, started up and didn't have flow. I assumed something in the line. I brought my compressor the next week and blew out the line. Installed the cover and still had no flow. My o ring had slipped out of the inset and was causing an air leak due to a bad seal. Once I realized the problem, new o ring and some Teflon grease and I was good to go. Never happened before and I have changed a lot of impellers on the generator and the 3GM30F. May be something that simple.

[ranger58sb]

Sometimes a new impeller, or an impeller that's been sitting unused for a while, will fail to spin on start-up as if it's just stuck in the pump bore. Sometimes a quick RPM bump to the "throttle" will break it free...

-Chris

[Terra Nova]

Impellers are keyed to the pump shaft.

[ranger58sb]

Originally Posted by Terra Nova

Impellers are keyed to the pump shaft.

Yeah, I don't see how a keyed impeller can fail to spin in a gear-driven water pump... But ask me how I know...

Actually, that's the way the "problem" was described to me by our diesel tech. The symptom was "no water."

The fix, goosing the engine briefly, whatever the actual cause... caused water to flow.

-Chris

[Tetepare]

It could be as simple as the muffler being flooded. I know it doesn't make sense (well, it will to somebody, but to me sounds counter intuitive) but it happened to me. Drain muffler and try again.