frost and Ice damage

[jack daniels marine]

1997 DT40

Hi folks.
I bought my first ever boat just last summer. The boat is used only in sea water however my mooring place is about half a mile up a river so the engine gets a good flush with fresh water after every use.
The temperature here has been about 0 - 40deg F ( 5 to -15 C )
I have not sprayed preservation spray in the motor for the winter, Instead I have just started the motor with an oil rich mixture every week or so ( 50:1 oil injection + 50:1 premix in the tank ) just to coat the internal surfaces.

4 weeks back the motor would not start, I assumed the battery was flat so I charged it overnight and the following day the starter only just managed to crank 2 rotations very slowly, the motor jumped into life despite the exceptionally slow starter motor speed. After a couple of minutes I shut it off when I noticed very little water coming out the tell tale hole.

Now 2 weeks later, I used the pull start to "feel" just how much resistance was in the motor , it was too much for me to pull start so I used the el. start and it fired straight away. No water at all out the tell tale hole, just exhaust gas, never seen that before. After using a cleaner wire up the tell tale some dribble began.

So , I'm just wondering now:
what actually happens to the water pump in freezing conditions with the motor tilted back?
should the water pump house drain fully when the motor is tilted back completely out of the water?
Can the rubber impeller freeze onto the rotating surfaces regardless?
If it is frozen, can the the impellor shed rubber peices that block the cooling passages?
Can the impellor drive shaft be damaged by cranking a motor with a frozen water pump?
Is it safe to blow compressed air, 10 bar/ 140psi, up the tell tale hole?

any experiences welcome.

 

[99yam40]

Re: frost and Ice damage

I would pull it out of water to store during winter and check the water pump to see if there is damage.

With motor tilted up it will trap water in housing and if it freezes and it can damage the housing

 

[jack daniels marine]

Re: frost and Ice damage

I was hoping to use the boat during the winter too.
After each use, would it help to tilt the motor up while the engine is running to perhaps pump out all the water from the water pump house?

Or even use the starter motor without the dead mans key in place?

I have purchased a water pump kit but I dont want the pump to get damaged each time I start it.

 

[99yam40]

Re: frost and Ice damage

Why not leave the motor down in the water?
Is the water turning to ice around the boat? if not it will keep motor from freezing

It may not be the pump freezing and getting damaged, you need to check

Water trapped in lower unit housing, not necessarily the water pump is what needs to drain out to keep metal casting from cracking when it freezes

 

[jack daniels marine]

Re: frost and Ice damage

I saw a nature program on TV recently, Russian eskimos hunting at sea in northern siberia. They were out in sub zero temps. with what looked like late 90's yamaha 40hp 2 strokes, though they were quiet.

The river Im moored in does not freeze, though any water in the boat itself freezes.
I tilt the motor up because I assumed that it would drain fully.

I guess I'll just have to investigate more in the summer when I change the pump kit. Test what actually drains and see if the pump house is actually empty or retains some water.

There are holes each side of the shaft housing, beside the water pump house that drain when the motor is tilted back.

Maybe I can just pump in a cup or so of wiper fluid or similar in the tell tale tube after each use, it may find its way to the pump house and may protect to about -20C / -5F.

 

[99yam40]

Re: frost and Ice damage

I saw a nature program on TV recently, Russian eskimos hunting at sea in northern siberia. They were out in sub zero temps. with what looked like late 90's yamaha 40hp 2 strokes, though they were quiet.

What does this have to do with draining your motor?

motor needs to be tilted down to drain properly put boat back on trailer after use and put back in water when you want to use it

 

[jack daniels marine]

Re: frost and Ice damage

I have no trailer, and no where practicle to park the boat if it was out of the water, that's why the boat is in the river all year.

The eskimos' outboards seemed to function ok in conditions more severe than here where I live.
Ill try leaving the motor down in the water.
Thanks for the tip.

 

[99yam40]

Re: frost and Ice damage

Sounds like you need a boat lift so the whole boat can be up out of water with motor down and drained properly while not in use
If the water temp is low enough water will freeze trapped inside motor with no movement, if the movement of the river water is the only thing keeping river from freezing over

 

[Capt Ken]

Re: frost and Ice damage

The suction hole on the pump is in its lower rear area and exit at the top. So tilted up, it will hold water in its front half. You also hold water in the exhaust behind the prop when tilted. If that freezes hard, you will crack the gear housing. You froze the pump and destroyed the impeller.

 

[jack daniels marine]

Re: frost and Ice damage



with the motor tilted up:
should water drain out , right down to the water inlets, the plastic grills in this photo?
what are the two holes near just over the cavitation plate near the oil flush port? water drains out here too.

 

[99yam40]

Re: frost and Ice damage

Majority of the water will drain out of the leg, but you still end up with some water in places you do not want to freeze by tilting the motor up

tilted up, it will hold water in its front half. You also hold water in the exhaust behind the prop when tilted. If that freezes hard, you will crack the gear housing.

 

[jack daniels marine]

Re: frost and Ice damage

I spoke to an elderly mechanic at the local boat repair shop today and was told the following:

In this particular motor, water will remain down by the prop shaft but not enough to crack the housing.
Water in the gear house is a different story, I should have changed that before winter I guess.
After motor stop, leave the motor down for a couple of minutes to let the powerhead drain.
After use, tilt the motor up, then crank it a few turns to empty the water pump house.

Leaving the motor down may ehance galvanic corrosion between the dissimilar metals.
With the motor tilted up, the water pump may freeze, melt this prior to starting by lowering the motor down into the water for about 5-10 min.
If the water pump tell tale is frozen, run the motor a couple of minutes then stop it and let the heat help melt the ice.

 

[jack daniels marine]

Re: frost and Ice damage

PROBLEM SOLVED:

the water pump has been replaced. The old impeller was complete with no pieces missing.
A chunk had cracked out of the inner diameter such that the driveshaft had no contact with the impeller or key at all.
the key that was lying loose in the pump housing was smaller, with less engagement, than the new genuine suzuki key.

The impeller had probably been frozen onto the wear plate when the motor was started during winter.