Shameful Admission - Overheat due to closed thru-hull

[rmbrown]

First let me say that I religiously store my key on my strainer thru-hull.  I never take that key off without first opening it, and that's just what I did this weekend... but then I decided to clean the strainer out and I closed it again.  When I was ready to go, I fired it up, untied my lines, ignored my wife when she said something didn't sound quite right, and left the dock.  I got to the end of the dock, got the alarm, realized I was overheating but not the cause, spun around, put it back in the slip and shut it down.  That's about the moment I realized what I'd done so I opened it, fired it back up and watch the temp drop nicely.  After giving it a chance to cool and verify that operating temp was normal, I set out for my weekend with friends.

Now that I'm back in my slip again, I'm wondering what I might have damaged and what maintenance, preventative or otherwise, I should do to tell my poor engine I'm sorry.

I plan to change my oil and, because I'd already purchased a new raw water pump (OD to replace the sherwood) I plan to replace that rather than just the impeller that I may have damaged.

Any other recommendations? 

[KWKloeber]

I'm sorry Mike.  The boat is toast. What day do you want me to come take it off your hands?

Say you're sorry, toast her with some alcohol, and sleep well.  Just ck (obviously) coolant level.

[rmbrown]

Yah... coolant is a touch low.

[Noah]

Been there done that...  not to the extent of tripping the overheat alarm but a couple times just running with seacock closed until I noticed (my brain finally  "woke-up") to no water flow.  No damage. If it appears good now, with good temp and good water flow, you should be A-Ok! If you had a very old impeller I would advise inspecting it, but as you are replacing pump anyway, not necessary. Oil change not needed. Caveat: all this advice is from a non-mechanic.

[rmbrown]

Impeller replaced 6 weeks ago, but I swear it was running 5-10 degrees cooler on my recent trip than the current 180.  Maybe the impeller is worn and now generating as much flow.  Maybe (definitely) I'm just paranoid.

[mregan]

You need a 5 year old.  That was my daughter's "job" when we first got our boat.  Make sure there is water coming out the back of the boat, yell if there isn't.

[Steve Hansen]

Had a fouled strainer due to algae. "Something didn't sound right..." Temp went over 200. Chewed up impeller. no fragments in exchanger and all in all, no harm done only lesson learned. Pause and listen at startup. 

[KWKloeber]

Mike

You should be running 160-165 with the salt water thermostat. 180 with the freshwater That's +/- because gauges are about 10F +\- anyway. Consistently is key 

If higher then possibly the impeller shredded some and is blocking the Hx tubes.  Check the impeller when you pull the Sw pump and just pop the Hx caps for a look-see. If weeds got past the strainer that will block the tubes as well. Been there. Depending on when/if you serviced the Hx it might be time to "rod" it (just like a radiator) to ensure the tubes are free of scale.

[Ron Hill]

Mike : As you already know the water lubricates the water side of the raw water pump!!  Those items are toast. 
The other item you might want to watch is the nipple in the riser where the raw water mixes with the HOT exhaust gases (cracks in the weld). 
Also look at the riser inlet connection into the muffler - I found that the fiberglass inlet can be warped by the HOT gases!!

Always listen for the SPLUSH/SPLUSH!!

A few thoughts

[rmbrown]

Thanks for the words of wisdom... some of it hard won.

I'll go this weekend, pull the old impeller, which was new 6 weeks ago and go spelunking for any missing chunks.  HX rodded out last fall (and the difference in water flow was amazing) but if there are missing impeller bits, I'll open it up.

I'll check the riser nipple and inlet connection to the muffler, but hoping that the adventure was short lived enough that I'm OK there.

I've been running maybe 170 on the gauge (which matches pretty well with my IR thermometer when directed to the housing... now I'm closer to 180, so something changed.  Not sure what thermostat I'm running.  When I bought the boat three years ago, it was changed by a mechanic I hired to go over engine and do deferred maintenance.

Mike

[KWKloeber]

[edited]
Kubota Tstat- 15531-73014
Gasket - 16851-73270


If you have the inclination you can check the temp sender resistance at a few temps - gauge troubleshooting is on the wiki.

The TStat will have the temp (C) stamped on its flange and of course you can test when that opens.

But unless you know what the mechanic changed IIWMB I'd update them just because. Cheap insurance (unless you use Westerbeke parts) and one of the few times I say replace rather than troubleshoot.).
The AC shows a 1/8" sender with a bushing to 1/4". That's fubar, just use the 1/4" sender (Sierra or NAPA TS26611) and deep6 the bushing.

[Jim Hardesty]

I installed this
http://www.borelmfg.com/products_alarm.htm
The one I installed also has low fuel pressure ie plugged fuel filter.  Was easy to install.  Can't report if the alarm works for no raw water flow.  One screw up I haven't done...yet.  Borel claims only seconds without raw water flow till alarm sounds.
Jim

[scgunner]

    Mike,

      No worries, we could have a whole separate section on bonehead things we've all done on our boats. The good news is that Universal is an "Iron Horse", you could probably put it on the end of a cable and use it to demolish buildings. For various reasons, blown coolant hose, kelp clogged strainer, I've pegged the temp gauge needle probably 3 or 4 times with no ill effects. One of those times I was forced to, for reasons of safety, run the motor for 15 to 20 minutes. If you're concerned you could always perform a 100hr service for peace of mind.

[Roc]

Whenever I start the engine, I always focus on the "swoosh, swoosh" sound of the water exiting the thru-hull.  It's so automatic, it's like breathing!

[rmbrown]

Yep, me too... except that day.