Bonehead Move: No Cooling Water . . . Now What ?

[gardnsailor]

So last Saturday night the plan was to head out with the seabreeze to enjoy the sunset and moonrise and take in the cool of the day, such as it is in SW Florida. Clearly I need to breakout the checklist I compiled when I first bought SweetPea because it was only after letting the engine warmup, casting off lines, and backing out of the slip that I looked back to discover a dry exhaust. It dawned on me immediately that I'd failed to open the raw water intake. That was the first mistake.
I immediately jumped from the helm down to open the seacock, my second mistake, perhaps. Dashing back up to the helm, I observed us still moving astern toward the trawler docked across the canal. Somehow I managed (I hope) to avoid further disaster and put the boat back into the slip, verified that cooling water was now being circulated, and let the engine run for a few minutes to cool down. The hot engine alarm did not sound. In hindsight, I'm now wondering if I should have left the seacock closed in the event that the impeller had disintegrated and, thus, preventing the remains from being pumped into the engine. Total running time PRIOR to the water being turned on was approximately 10-12 minutes.
Opinions? Was turning on the water a second mistake? How bad will it be?
I'll go to the boat tomorrow and check out the pump and impeller hoping that the rubber is all in the pump and not in the cooling system and report back.

[Astrid]

Well, good thing is you will probably not make that mistake again in the near future. It does not hurt to have a check list for the engine at the helm station.

[Bash]

It would probably be a good idea to change the impeller at this point.

Otherwise, I'm thinking that an engine idling for ten minutes is unlikely to get all that hot. My engine never seems to want to warm up until I engage the transmission.

[Cheechako]

Most of mine wouldnt have lasted 10 mins. I would check it....

[Tripod]

Been there, done that, and haven't done it since I made a checklist. Does your engine have a screen on the output side of the pump? Mine does and that's where I found all of my impeller vanes. Thank you Perkins.

[malbert73]

I now have an inspection port in my engine room cover, with a hook on the inside. When I close down the boat, I open the cover and close the seacock, hanging the key inside next to the seacock. I can't tell you how many times I have tried to find the key to start the engine before I remember- oh, right- open the seacock first!

[Me-and-Boo]

First thing I think of is whether or not there was any residual liquid in the system. That would have reduced the hot period. The other is whether is if the water stream that went in turned to steam. Steam expands and causes internal problems in the heads and block.
I don't think your running time would have been long enough to overheat your engine. If you were at idle of a notch up from that you did not have your engine under load either.

However

Get an engine oil analysis kit; follow the directions; now change your oil and filter.

If you burned bearings or rings the test will let you know that.

When you run your engine the next time listen for odd noise (doubt you will hear anything), and look for anything. You should not have anything show up. White steam is bad, and what I would expect if you popped out a gasket or cracked a head. If you see black you have a very big decision ahead of you; rebuild or replace.

But, the optimistic thinking is you did not do damage to the engine - just your nerves.

[Ziggy]

In addition to changing the impeller, if you have a plastic waterlift (like Vetus), you should inspect it for any signs of heat damage.

[Loquat]

Why do you close the engine water seacock? I never do, is that bad?

[roverhi]

Something crawled into my intake and died. Noticed I was having problems when the boat interior filled with steam. Shut the engine down and tried to figure out what was going on. Couldn't see anything obvious so filled the heat exchanger and the overflow bottle with coolant/water mix and started to power the mile or so to the slip. After a short time at 2500 rpm, boat filled with steam again. Shut the engine down and inspected, the water only slightly down in the over flow tank. Started it back up and ran at idle for the 20 minutes or so back to the slip without any further signs of overheating. Engine has run for two hundred hours since then with one 30 hour plus straight stint. Doubt that you've done any damage to anything in the engine including the raw water pump impellor. As long as their is water in the freshwater side, running them doesn't seem to generate enough heat to cause problems. Actually maybe I should qualify and say it doesn't seem to bother a Yanmar 3gm30f.


Assumed it was the coolant elbow in the exhaust so dismantled the exhaust system but couldn't get the the elbow off the riser from the engine. Callled a diesel mechanic who had the acetylene torch, humongous winch and pipe wrench to get the elbow off. He sent me after a couple of gaskets we'd need. While I was gone, he went through the system and discovered the blocked intake. The only other problem was the impellor was missing a couple of vanes. Found one in the heat exchanger, the other must have passed through to the exhaust before the water inlet plugged. Good idea to change the impellor but would be willing to bet the one you'v got is still good.

[Blue Stocking]

In my neck of the woods, Sargassum weed berries are likely to be more of a problem blocking the H/E tubes. I put a Vetus 150 strainer on the line between Raw water outlet and heat exch. inlet. Surprising what you can catch. Once had Blue fry in the basket.

[roverhi]

It's a good idea to close the water intake. If the intake is closed, the engine can't back flood if water syphons into the muffler. On my last boat, always turned off the inlet seacock. Forgot it once and it cost me an engine rebuild.

[sww914]

If you have a heat exchanger and a freshwater system, your engine is fine but you do need to replace your impeller as you've said before you run it more. I just installed my engine and my boat's 100 yards from any water and I've run the engine several times for 5-10 minutes with the impeller out and no raw water circulating. It takes 10 minutes for it to reach 170 degrees at idle.
What you've done is akin to idling your car with no fan installed and no airflow through the radiator. The radiator still has water moving through it as did your engine keeping the temperatures under control. The fact that your temperature alarm stayed quiet tells the whole story.

[Talbot]

Originally Posted by sww914

If you have a heat exchanger and a freshwater system, your engine is fine but you do need to replace your impeller as you've said before you run it more. I just installed my engine and my boat's 100 yards from any water and I've run the engine several times for 5-10 minutes with the impeller out and no raw water circulating. It takes 10 minutes for it to reach 170 degrees at idle.
What you've done is akin to idling your car with no fan installed and no airflow through the radiator. The radiator still has water moving through it as did your engine keeping the temperatures under control. The fact that your temperature alarm stayed quiet tells the whole story.

This depends whether your engine is fresh or salt water cooled!

There are more expensive impellors available that will allow the pump to run dry for a while without damage.

[Wand]

I'd also bet your impeller is okay, but it's easy to check.

Re the seacock, closing them all when you leave the boat is prudent. Plenty don't and most get away with it, but it's an unnecessary risk imho.

Leaving the key on the seacock is a good reminder. The clever previous owner of my steely wired the seacock so ignition wasn't possible without the seacock being open. Now that's foolproof.