Raw water temperature monitoring. Do You have one? Do you need one?

[David Hall]

this is only one system on the boat, and granted it's maybe the most important single system there are others I have neglected and need to put my attention on, mostly corrosion showing on fittings and electrical connections, the head is not working, window seals and rubber shields are all dried up and cracking.  It never ends.  Gotta go after them one at a time and keep after them,  I'm trailered now and kept in dry storage in an RV lot.  For 14 years this boat sat in the harbor 24/7 except during maintenance, but it was never out of the water for more than a week or two at any time.  Now I can get things right and they will stay that way much longer.  A good quality cover will help me to keep it clean and cut down on the UV damage. 
But next on the list, is FISH.

[David Hall]

Me and Rob had all we could stand from all the insanity in the world today so we decided that we would replace the trim tab actuator next week, fix the head one of these days, or maybe not.  regardless we needed to get on the water its been far to long, the new turbocharger, wet elbow and air cooler were in, oil and filter changed and a full coolant change, we launched Saturday around 0830 from Moss and headed out the jaws.  wind was up and sheep were everywhere, the angry sea fighting itself with winds from the north and the west whipping around making the sea like a big washing machine, could have picked a better day for certain but this was the day we had.  boat was running great so decided to push into the wind and bring the Long Hall up on plane and open the throttle a bit. everything fine at 2500 RPM and around 13MPH, engine temperature was steady around 60C.  could have rode around all day at that speed at least it seemed like it.  pushed it up to 3000 RPM, you could hear the turbocharger whistling, then the engine temp started to creep up to 70 then 80 then 90 and alarms went off, backed off the throttle and temp began to fall, within 15 minutes it was back to normal, so we ran straight out into the wind shut down to idle and let the wind and sea push us back towards the jaws while we drift fished the bottom hoping for a halibut or a lost salmon.  we did this over and over again until we couldn't keep our feet, the sea had had enough of us for one day and encouraged us to leave, so we did.  Back home, scratching my head while running through possible causes for this condition, starting this morning with removing the thermostat and testing it, if nothing is found there Im pulling the new air cooler I installed, I bought it off ebay last year and it looked to be in excellent condition and freshly serviced from all outward appearances but I did not open it up and confirm the cooling core passages were clean and clear of debris and did not pressure test it before installing it.
seems sometimes the more I do to prevent problems the more the problems do to prevent me.  I believe this issue goes back to the same overheat issue I was chasing last year when I determined that the coolant cap was damaged and did not maintain proper system pressure.  Now I believe it may have been a contributing factor but it was not the source of the problem. 
But first I have to see if I can repair the microwave in the kitchen, Heating water for coffee yesterday it quit working just went blank, I will replace the fuse, if that fixes it I will be happy, if not, then the house gets a new one.

[gstours]

Thanks Dave,, baots can b a pain in thewallet.   Sounds like a story from my past.  Constantly working on the boat,  my good wife thinks I love the boat more than her!   My Volvo duo prop was gas and carburetor issues, and ignition,   All bad are saltwater,  sitting is also bad.
   Both were bad enough and then heat exchanger and hoses.  I finally got rid of it.
      Now with an outboard I just put in ⛽️.   Waay less maintenance and easier to find parts.
When it's broke just send it to a shop.   Butt it still costs money 💰.
   I'm hoping that you're almost there and get your use out of it.   

[David Hall]

took me less than 30 minutes to replace the microwave fuse, clean everything up and get it back into service this morning.  Indeed I can relate, my wife is convinced I love the boat more than her, and shes okay with that? Hmmmm? yeah right, but that's what she says anyway.  she knows I spend more money on it than anything else and shes learned never to ask just how much I spent.  She really doesn't want to know for any reason other than to see how much I should spend on her,  When I bought the boat in August 2008, for Her, on our 35th anniversary she didn't complain? although I have come to realize in the past 12 years that shes owned her boat that she really doesn't like it, she never goes on it and never works on it?  I do everything I can to keep it in great shape for her but still shes just not into it.  she did go out on it often with me when the kids still lived at home, no wait? that was the other boat, I sold it 6 years after buying her the new boat,  since the kids have all moved on married and have families of their own she likes having the house to herself and I have become very fond of her boat so things have a way of working themselves out over the Long Hall.  who knew?

[boon]

If you've overheated the motor previously and it has strange hard-to-find overheating issues I would be doing a TK test to make sure the head gasket is still good.

[David Hall]

If you've overheated the motor previously and it has strange hard-to-find overheating issues I would be doing a TK test to make sure the head gasket is still good.

  I have not done  a TK test but sure wouldn't hurt. That is a good idea I think I will order one of those kits up and have it on hand just in case what I did yesterday doesn't improve the condition. I have done a system pressure test and it holds 13psi for 30 minutes with no detectable loss of pressure.  Although it has gotten hotter than normal I have managed to keep it at or below 200 degrees f and when it has touched 185-190 I throttle down quickly to idle and it cooled down to normal range in minutes. 
  I am hoping I found the culprit. I pulled the thermostat and tested it several times along with a brand new one in hot water.  The first time I tested the old one it did not open until over 200 F.  I repeated the test several times using both an infrared and analog thermometers. every time I repeated the test the opening temperature dropped a bit but after 5 tests it was still not opening at all until 185 f.  spec says 158-162 and fully opened at 175.  these are also three way T stats, they have two springs and two valves, the inner one normally open allows bypass fresh water to circulate within the closed cooling system, allowing the engine to heat up to normal operating temperature 160-190 per owners manual, mine normally runs right around 165-180f no matter what the engine load is. the primary valve opens between 158-162 and closes the bypass valve forcing hot system coolant through the heat exchangers.  I believe my old T stat was stuck closed and it took near boiling water to open it so I replaced it with a fresh OEM spec one and refilled the coolant system.  Im going to make another sea trial with it and see how it performs.  I am hopeful I haven't caused any long term internal damage.

[gstours]

Dave, I hope you are going to be good with the new t stat.  I've had similar issues with these in automobiles. It's usually the simplest thing and inexpensive to fix on your boat or car, track tor, etc.
   Hopefully nothing got cooked and also failed.   Best of luck.   🤑

[boon]

If you've overheated the motor previously and it has strange hard-to-find overheating issues I would be doing a TK test to make sure the head gasket is still good.

  I have not done  a TK test but sure wouldn't hurt. That is a good idea I think I will order one of those kits up and have it on hand just in case what I did yesterday doesn't improve the condition. I have done a system pressure test and it holds 13psi for 30 minutes with no detectable loss of pressure.  Although it has gotten hotter than normal I have managed to keep it at or below 200 degrees f and when it has touched 185-190 I throttle down quickly to idle and it cooled down to normal range in minutes. 
  I am hoping I found the culprit. I pulled the thermostat and tested it several times along with a brand new one in hot water.  The first time I tested the old one it did not open until over 200 F.  I repeated the test several times using both an infrared and analog thermometers. every time I repeated the test the opening temperature dropped a bit but after 5 tests it was still not opening at all until 185 f.  spec says 158-162 and fully opened at 175.  these are also three way T stats, they have two springs and two valves, the inner one normally open allows bypass fresh water to circulate within the closed cooling system, allowing the engine to heat up to normal operating temperature 160-190 per owners manual, mine normally runs right around 165-180f no matter what the engine load is. the primary valve opens between 158-162 and closes the bypass valve forcing hot system coolant through the heat exchangers.  I believe my old T stat was stuck closed and it took near boiling water to open it so I replaced it with a fresh OEM spec one and refilled the coolant system.  Im going to make another sea trial with it and see how it performs.  I am hopeful I haven't caused any long term internal damage.

As long as you always caught it a little bit of heat in the motor isn't a terrible thing. My automotive mechanic actually recommends periodically getting things a little over normal operating temperature, it helps prevent things seizing up. Sounds very much like you have a wonky thermostat, hopefully the issue is resolved.

[conchydong]

Chasing heat issues can be a pain. Hope you get it figured out.

Scott

[David Hall]

It's the waiting a week to get off work and also waiting a week to have decent sea conditions to get some sea time just to find out how it's going to run.  We got mixed seas and strong steady winds with gusts and wind waves, it's not going to be any fun out on big blue for the next five days.  I guess I replace the head pump assembly and maybe my new trim tab actuator will show up and I can take the bungee chord and bailing wire off the tab.  Took me only a few hours to drain the coolant, test and replace the TStat filter the coolant and refill the system, did a run test off garden hose and earmuffs but without any load this engine just will not heat up, so no way I can make the thermostat open up gotta have a load on the engine.

[David Hall]

Been awhile since I posted my results.  It was NOT the Tstat, engine continued to have temp spike at 2800 RPM .  I have since found the culprit and it was an odd one which I have never seen nor heard of but in a nutshell heres what I found.  the raw seawater circulating pump impeller was spun.  the inner brass splined shaft that is driven off the engine pump gear had come loose from the rubber part of the impeller.  it was still tight enough to operate the pump at seeds up to 2500RPM, above that the rubber stopped turning, the pump stopped pumping and the shaft just spun like crazy, and of course the temperatures went up.  So what caused it?  one thought is this.  In an effort to "save Money" I opted to purchase several aftermarket impellers which are advertised as direct OEM replacements, made right here in the USA and carrys a 5yr warranty against defects.  Turns out this $16 impeller saved me $34 over the cost of a Johnson OEM impeller.  So after replacing the cheap one with the real thing, my boat is back and running like a thoroughbred.  Its awesome how fast it revs and the new turbo kicks in I can cruise across the sea in 4-6' swells doing 22knts all day long and the temp guage never moves out of the safe zone.  I may do a help video on the dangers of aftermarket impellers soon since I wasnt able to find anything there myself while trying to diagnose the problem it might help others down the road.
  So now that the boat is running strong I am back to doing abit of upgrades.  todays peoject is installing Flir M232 thermal imaging camera

[oldmanjoe]

   The water pump impeller probably got hot also when the sea cock was closed and broke the bond between brass and rubber .

[Gobi King]

David,

I have learned the hard way to buy OEM parts when it comes to engine and other mechanical.

I have had the same costly experience of aftermarket parts failing.

To save $$$, I buy OEM parts from high volume obscure suppliers who discount them deeply.

I am glad you got it figured out.

oldmanjoe, Can we figure out what is the tamp range that part is designed to work in?

[oldmanjoe]

  I think you can find that information on the spec sheet for the make and model of the impeller.

[David Hall]

Ive never seen a spec sheet with the impeller kits and i have tried looking it up online but so far nothing.  whatever the safe temp is you can be sure its well above safe engine operating temp.