M-25XP running hot + white smoke

[Stu Jackson]

I'll look into that.  The o-ring is working but the bowl and flange dont have any sort of recess to hold the oring.  The idea of a square rubber ring is likely to be the correct part.

Alex, have you considered taking the cover with you to a good local hardware store that has a selection of O rings?  Or is that where you got this one?

[Ron Hill]

Guys : The square "O" ring gasket is the correct part.  When I ordered the finer mesh screen I got a couple of new gaskets (less than $1 each) and keep them nimble with silicone spray.

A thought

[waughoo]

]

Alex, have you considered taking the cover with you to a good local hardware store that has a selection of O rings?  Or is that where you got this one?

I got a sherwood raw water strainer gasket (oring) at Fiaheries.  It was the correct diameter however it is round rather than square.

[Derek]

Problem Solved - posting this to help someone else who may find himself or herself in this situation.

Situation - white smoke coming from exhaust; engine running hot (~195*F).

Troubleshooting - this was a bear, I spent a lot of time chasing gremlins and second-guessing myself.  Ultimately, people on this forum proved to be immensely valuable and I couldn't have solved this without everyone's help.  The culprit is likely not enough raw water working through the system to cool the hot exhaust coming from the motor.  For the sake of this post, I'll layout the troubleshooting in logical order from the start of the raw water intake to the end of the exhaust system.

1.  Thru-hull:  If you have any barnacle growth inside the thru-hull, it will reduce the amount of raw water that your water pump can pull through the system.  To clear out the thru-hull, I closed the seacock; disconnected the hose; opened the seacock; and stuck a dowel rod in-and-out of the thru-hull to break away the debris.  I was scared that the thru-hull would allow an enormous amount of water inside the boat, but I was able the stem the tide with simply covering the thru-hull with my thumb until I inserted the dowel rod.  This was simple and I now don't fear messing with thru-hulls while the boat is in the water.

2.  Water strainer:  Make sure the strainer is clear of debris.  Mine was clear; yours might have an octopus inside it.

3.  Hose bends:  As the raw water hose leaves the strainer and makes its way to the water pump, it makes a 90-degree turn to enter the engine compartment.  My hose was old and and tired and as the water pump sucked water, it slightly collapsed the hose at the bend.  I fixed the problem by inserting an elbow at the point of the turn; you can choose a 90-degree or a 45-degree elbow to get the job done.

4.  Impeller:  Make sure your water pump impeller is in great shape.  If it's missing even one fin, it'll reduce the amount of water it can suck into the system.  Good practice is to replace the impeller every year for preventative maintenance.

5.  Thermostat:  This was a game-changer; if the thermostat fails, it won't open to allow the rest of the coolant loop to circulate throughout the system, causing the engine to run hot.  I replaced the thermostat with a $15 replacement and made a world of a difference.  I made sure to drill holes in the flange, as pointed out in multiple posts in this forum, to allow a little bit of coolant to flow even while the thermostat is closed.  I now carry several spares due to how effective this was.

6.  Coolant flush:  You have to read Ron and Stu's posts about how to flush the coolant and refill it in a way that bleeds all the air out of the system to prevent air-lock.  Air-lock will prevent your coolant from flowing and will cause your engine to run hot.  They've cracked the code and it's simple to use gravity as your friend to flush the system; it now takes me only 10-15 minuets to drain the coolant and then refill it with no air bubbles that can cause air-lock.

7.  Heat Exchanger (HE) size:  Make sure you've upgraded to the correct HE size so that it can handle the proper amount of water needed to cool the system.  The wiki has the latest info; I believe the upgraded size is 3", but someone here can correct me if I'm wrong.

8.  Heat Exchanger scaling:  Over time, minerals can build up inside the HE, reducing the amount of water flow.  You can take the HE to a radiator shop to have it boiled out, or give it a muriatic acid bath yourself (with a lot of safety care).  Admittedly, this would probably be the last thing I do; it was a bear to get the HE out and then give it a muriatic acid bath without killing myself and then reinstall it.  Mine turned out to be just fine after years and years of sailing in the Chesapeake Bay.

9.  Vented Loop:  I have a vented loop in between the HE and the combiner, where the raw water combines with the exhaust gas.  Minerals have a tendency to build up inside the rubber of the duckbill/joker valve, causing it not to seal correctly and allowing water to escape.  If your vented loop in leaking, check the hose connections and replace or clean out the duckbill valve.

10.  Water Exhaust:  Make sure all the hoses are properly sealed around the water exhaust.  If anything is leaking, it's reducing the water that should flow out with the exhaust.  I like multiple people's recommendations of putting a strip of leather underneath the hose clamps on the water exhaust; you can cause a lot of damage to the water exhaust by over-tightening the hose clamps. \

11.  Exhaust Riser:  If the metal pipe between the engine and the water exhaust (exhaust riser) is old and failing, exhaust will escape from cracks or corrosion in the pipe, which is a dangerous situation.  Evaluate if you need to replace the exhaust riser.  I like a lot of member's recommendations to mount a carbon monoxide detector underneath the bottom step on the companionway since CO is heavier than air and will sink to the bottom of the boat.

12.  Exhaust hose:  If the exhaust hose is old and tired, it could potentially be the cause of the white smoke due to the heat burning off debris or chemicals in the hose.  Check the hose for cracks and evaluate if it needs to be replaced.  This would not be the first thing I do; it'll take an entire afternoon to replace.  I like someone's post to also make sure there are no bird's nests inside the exhaust hose; I feel like once water starts flowing out the exhaust it'll solve that problem if it existed.

Take from this what you can and I'm sure I missed a lot.  I'd encourage anyone else to post other things of which they've experienced and solved.  My problem was a combination of multiple problems:  growth in the thru-hull; no hose elbow on the bend into the engine compartment; an impeller missing a piece of a fin; and a failed thermostat. 

I can't thank you all enough for all the support; this forum has saved my butt at least a hundred times.  Thank you, thank you, thank you.

And Merry Christmas!!

Derek
SV Tiki

[waughoo]

Derek,

Thanks for the write up.  I do believe water flow is key in the raw water loop.