Cooling system improvement

[2dogsnight]

motor temperature gets up to140-155 degrees....my oil pressure goes from 50 down to 30 at 1200rpm and speed 5-6 mpg. Looking into a way to get some more air / water, giving some extra cooling capabilities to my old motor.
The ideas are:
- install an air intake pipe from the front of the windshield to the motor box
- make windows that can be opened
- look into getting improved water pump - what is the model of my water pump??!
- ....any more ideas??

My new alternator is working great!! Very thankful to everyone for your help!!

[Surcouf]

140-150F and 30 psi are (very) good values... why would you want to go lower? It may hurt your "mileage".

Great boat by the way

[2dogsnight]

because I feel that the motor is so hot that the heat will melt all wires and hoses. Most the time I have the lid off the motor box, trying to get the heat out of there. I must add that this is my first year using the boat everyday for short runs. Finally managed to install the hour counter and have recorded 3.5 hours on it so far.
So basically I am learning the motor and the boat. With 25HP motor this boat should be going up to 17mph, and I had her going at that speed. But when motor gets to 150's she will not go that fast. Could be because of tidal currents or.......? I don't see any smoke coming out of exhaust, so the motor is strong. So I'm trying to make sure that all systems are working correctly.

[joe_db]

The boat starts at 17 knots and then slows down?

140-150 degree temperature and 30 PSI oil pressure are well within the norms of this engine.

[JOHN COOKSON]

Venting the area around the engine will help dissipate the heat that is generated.
The running temperature of the engine is determined by the engin's (correctly working) cooling system not the ambinate temperature.
Maybe the packing is a bit tight or the exhaust system is not up to the job or ?. This is not meant to be diagnostic - I'm just guessing here........


ex TRUE GRIT

[2dogsnight]

Starting at 5mph and rarely go faster. Tonight will do some testing.
Exhaust is fine I believe, but shaft packing is tight, maybe too tight. I will loosen the nut some more.....just installed new packing a month ago......not getting any drip yet! The nut temperature started at around 140 deg, after few nut adjustments is down to 110........but still no drip!!!! .....

[edwardc]

The nut and shaft should be 10-20 degrees F above the ambient water temp. Keep loosening.

[2dogsnight]

Will do Edward!
Have a hope that with this Forum help I will have my motor fine tuned and running like a clock!
I have been drooling over Sam Devlin's trawler designs (20 to 25 feet), but truly my little Fontana is plenty a boat for me........ just want it to have reliable motor.

[sastanley]

Does anyone know if the Moyer flange pump would fit on an early model? 2dogs, it definitely pumps more water..Also an Oberdorfer 202m7 should pump more water too..You could also run the bilge blower and see if it helps with engine box temps.

[JOHN COOKSON]

The new packing is settling in. You will need to continue to adjust the packing nut until it is "broken in" all the way.
I used to approach packing by adjusting the nut until I get the drip rate I like* then if the packing gland is not at or slightly above the water temperature I know is time to repack.
*one drop every 10-15 seconds for me
I once had a gutsy mechanic help me once. We started the engine and ran it up to ~1500 RPM in gear and he adjusted the drip rate while the shaft was turning! his fingers not mine.

ex TRUE GRIT

[2dogsnight]

Thank you for the ideas coming in!!
John - I hate the idea of water coming in to the boat for any reason. I would have to come up with a way to contain the drip......when I'll get it One thing I didn't do was to clean and lubricate the shaft before installing new packing. Newbie!
Shawn - I was looking into a bilge blower already. Feels like should help.
When I was working on motor, Moyer guys told me to leave the pump alone if is working. So it still does work I have the same questions as you are posting here regarding the water pump. Wander if the impeller needs changing or is it a metal one..??! I mean water is going trough the motor fine, but would be good to have more

[JOHN COOKSON]

John - I hate the idea of water coming in to the boat for any reason. I would have to come up with a way to contain the drip......when I'll get it One thing I didn't do was to clean and lubricate the shaft before installing new packing. Newbie!.
Wander if the impeller needs changing or is it a metal one..??! I mean water is going trough the motor fine, but would be good to have more

If by chance the shaft is scored where the packing contacts it the packing will never be right.

Water is going through the engine or around the engine via the bypass? By removing the thermostat and putting a valve on the bypass you will be sure all the water is going through the engine.
The impeller is rubber.
If you want a good summary test of the water pump and strainer attach a hose to the pump output, start the engine, and rev it up briefly. The water output should be like a garden hose.

ex TRUE GRIT

[2dogsnight]

If by chance the shaft is scored where the packing contacts it the packing will never be right.

Water is going through the engine or around the engine via the bypass? By removing the thermostat and putting a valve on the bypass you will be sure all the water is going through the engine.

ex TRUE GRIT

well, the last packing material had a graphite in it and shaft had black residue on it, which I didn't remove/cleaned.

no idea where the bypass is - will be looking for that. I believe my motor does not have a thermostat. I had this thing in pieces during rebuild. Then again it was few years back and my memory is not what it used to be.

Went out on the boat, turned back one turn ( 1/3 at the time), no drip. Temperature still 110 /140
Speed test didn't work the way I hoped. Motor was very happy at 1000 rpm, 6.5mph....full throttle produced max speed of 8.2 mph.
Something is not right

[sastanley]

2 dogs...looks like a grease cup on that bracket forward of the packing.
For testing, you need to be willing to experiment, but don't too many things at once.

One test may be to set the packing way loose and let some water in to see if it makes any difference (I doubt it) and different throttle settings. The next thing I would check is things like timing. If the water temp is OK, then getting the heat out of the engine box are two different problems.

We just need to focus on your goals and knock them out one at a time.

[2dogsnight]

thank you Shawn,
I read Moyer Atomic 4 book I have, looking for answers, also learning about shaft packing.

Cooling system in my motor does not have a thermostat or coolant bypass.

Tomorrow I will take the packing nut out ( at low tide, sitting on tide land), will clean the shaft from graphite, use some light coat of grease on shaft before installing new packing. Packing nut temp. should be 30 - 40 deg over the cooling water temp, so no more than 100 deg. Packing nut should be hand tight to start. Interestingly no need to have water dripping out of packing nut as long as nut temperature is not more then 30-40 deg more than water

Will make small adjustment to oil pressure with spring loaded relief valve. According to the book oil pressure should be 40psi........oil pressure is slowly getting lower from 50psi down to 30, will go back to 40 with higher throttle, but after few minutes will go back down

I don't suspect that the timing is not right, as I have the boat going 17mph a week ago

.....starting thinking about getting an outboard again ......