Ran engine with raw water intake closed

[henry.blanchette]

My first post on this forum is an admission of an embarrassing mistake. I was trouble shooting a fuel line issue and closed the raw water intake as I was doing this. I got the engine running again and got distracted but only ran it for a couple minutes before shutting it down. The next day I started the engine up with a feeling like I was forgetting something but couldn't remember what.

5-10 minutes later I realized what I had done when it sounded alittle odd, I checked the thermostat (maxed out) and the engine was billowing some type of combination of smoke / steam. I shut it down, opened the raw water intake paused for a few minutes and then thought maybe it would be good to run the engine with the intake open to maybe more effectively cool it. I did that for a few minutes, but unsure of what might have been damaged decided to just leave the engine compartment open and wait.

Hours later I started it up and it seemed to run fine, but quickly started to overheat and I shut it down.

I am hoping that someone here may be able to offer some insight into what are the most likely things I damaged and where to start my damage control process. Thank you!

Henry

[joe_db]

The most likely problem is you damaged the rubber impellor, the water pump does not want to run dry.

[alcodiesel]

Henry- forgot something? You're in the right place! There are a lot of us old farts lurking in this forum. But the suggestions or advise I have found to be excellent.
Welcome to the forum.
Here's to hoping you caused no permanent damage.
My guess vote is: no

[joe_db]

FYI - whenever I have the intake shut off, I pull the wire out of the coil

[TimBSmith]

Please see my thread from earlier in July.overheated,my raw water intake was blocked.

There is a lot of great trouble shooting advice in the thread.

https://www.moyermarineforum.com/forums/showthread.php?t=12244

Carefully segment and trouble shoot your cooling system. You can do this work on your own slowly and carefully. All the help you need is here; as long as you don't cut diagnostic corners you will find answers.

You know the root cause was at RWC feed.

What do you have in place between the through hull and the water pump? Strainer? Flushing T? Check those segments for blockage and damage.

Water pump. Others already commented. Check your impeller. Look for any missing blades, impeller pieces. Any missing pieces? Work to locate them downstream. Get water pump functioning.

Move to the hose then injector at the water jacket. Then bypass valve if you have it. You may need to check all common blockage points. The water jacket injection, the bypass, the thermostat (which needs inspection and testing).

See my thread for other cooling fluid choke points outside of block and manifold cooling ports. Start with the bigger diameter blockage points then go to the smaller diameter blockage points.

Evaluate water flow behind water jacket, through block, and manifold. One step at a time. Aside from material or mechanical failure we know that poor coolant flow is what causes overheating.

Confirm pump function.

Make sure you did not crack anything.
Confirm compression.
Confirm manifold pressure.
Confirm block pressure.
Confirm exhaust pressure.
Spot check temperatures using IR handheld FLIR etc.

I learned first hand that these mighty motors can take some temperature abuse. Not repeated abuse but acute episodes of short duration are tolerated better than I imagined.

Most importantly, take your time. Good luck. You got this.

[sastanley]

Henry..welcome..let's hope when you open the water pump housing, all the bits and pieces of the impeller are still there. Worst case scenario is some broke off during the overheating event and ended up in other areas of the cooling system. Best case scenario is you burned it up and the impeller is fried, but intact.
Hopefully, no permanent damage to the motor, but fixing the raw water pump impeller is 1st priority and we go from there.

We've all done it..hopefully, only once.

[Dave Neptune]

What Shawn said plus this. Once you have the pump working fire up the engine and let it warmup and while running look for water leaks around the head and manifold. If you find no leaks there and she runs smooth your OK. However if it runs rough take a good look at the plugs for moisture and/or do a compression check to see if the head gasket leaking between the cylinders. If you find an issue the head gasket will need replacing, not a bad job depending on access.

Dave Neptune

[henry.blanchette]

Thank you

Wow, thank you all, this has been super helpful. I will start with the impeller and go from there. and I'll be sure to disconnect the coil next time I closed the raw water intake, I do not want to do this again!

Henry

[TimBSmith]

Another trick I learned here for raw water intake awareness / reminder...

I hang my ignition key on the through hull when shutting down and then take it off when starting, which reminds me to open the through hull after she starts up. I start up in closed position, then open, to protect from over cranking flooding issues. There was a great checklist I marked here on the forum that I will go back and find for start-up and shut-down. Update when you can...fair winds.

[BVLew]

Thanks -- you asked MY embarrassing question!

My first post on this forum is an admission of an embarrassing mistake.

Hah! I logged on today because I did precisely the same thing and was hoping to find the kind of excellent advice you've already generated from the experts on this forum. (Actually, mine was even more embarrassing : I just forgot to open the RWI, plain and simple.) Thanks for asking the question and thanks to everyone who answered!

[BVLew]

Am I doing this right?

OK, so after reading a bunch of related threads, today I removed the Moyer backing plate, which appears to have gone on an Oberdorfer 202M pump (haven't confirmed that). Was able to pull impeller out with simple tug with pliers, came out with the shaft. Several vanes missing, so that's at least part of the problem.

As near as I can tell, there's no snap ring (I know PO replaced impeller every year or two, and he had boat for 25 years). But I can't get impeller off the shaft. So I'm currently soaking with PB Blaster and will try the "knock out shaft with wooden dowel" method -- if that doesn't work, will CAREFULLY cut off impeller with hacksaw.

As I reassemble after I replace impeller, I'm confused about whether I NEED to use a gasket (for 202M or cut from dollar bill/brown paper bag), or whether just cleaning the backing plate and using O-ring will be enough? (PO did have a gasket there.) I've ordered new O-ring and gasket from MM, but they can be spares if I can re-use the current O-ring and don't need a gasket.

I've also seen some references to lightly lubing the impeller before putting the backing plate on. Is Blaster White Lithium Grease OK to use? Or is this really not necessary?

(And, yes, after I get all this done, I'll check downstream for bits of impeller or other blockages. I'm on inland freshwater lake, where 44-year-old Catalina 30 has always been sailed.)

Thanks.

[joe_db]

You need to find all the missing pieces of the impeller. They are someplace!

[TimBSmith]

O Ring on backing plate is all that is needed...

If the backing plate is flat and the O Ring properly seated there is no need for an additional gasket made from anything.

I read through the Moyer Flange Install document when I researched replacing my O Ring.

I have recently replaced the O Ring gasket on the backing plate.

I cleaned it(backing plate) up gently and on advise here used marine grease in the O Ring slot to hold the O Ring in place during plate tightening.

Using some lubricant on the impeller is a good idea just to be sure you don't run it dry.

I tightened using an "X" shaped pattern to be sure to have best chance at flat mounting.

The backing plate does not leak.

Best with finding your missing blades. Hope they are nearby right at the entrance to the water jacket injector.

All best.

[BVLew]

Success!

Final update:

So, I was wrong. There WAS a snap-ring. Tried a screwdriver. Didn't work. Bought the $5 Harbor Freight snap ring tool. Didn't work. Tried the screwdriver again, and it worked. New impeller back on shaft, pushed in the snap-ring with screwdriver, all looked good.

Yesterday, back at the boat, disconnected water-lines at water-pump and thermostat ends. Used the regular dock hose with a standard twist-down-to-thin-fast-stream brass nozzle to spray through the hose, flushed out a few pieces of old impeller blades.

Also used an old wire coat-hanger to probe the 90-degree turn from water pump to hose outlet -- I think I found a piece in there, too.

I put it all back together. Used Vasoline/petroleum jelly to hold the O-ring in place (at recommendation of local marine store, which was out of small tubes of marine grease). Sprayed white lithium grease on the impeller vanes before closing everything up, tightened the knobs in cross-pattern.

CHECKED TO BE SURE RAW WATER INPUT WAS OPEN! Fired 'er up. Checked spitter on the transom, looked OK. Stayed in neutral. At idle for 10 minutes, 140 degrees. At 4000 rpm for 10 minutes, 160 degrees. Back to idle for 10 minutes, dropped to 140 degrees. Said that was enough for the day.

Today, went out for a lovely 2 hour sail. Engine worked entirely normally going in and out of marina, temperature ran 140 in idle, about 150 when I motored at full throttle (which when I'm in gear tops out at 1800-1900 rpm) for 30 minutes after wind died.

Success!

Thanks to everyone in this thread and others who helped this engine-naive guy through it!