Pressure reg and cooling questions '01 150 OX66

[5X]

Hey folks,

I did a search before posting and think I found my problem to be one of two things.

History: Just bought boat. Had cooling issues. Dealer replaced everything (pump housing, impeller, thermostats, sensors, pressure reg. spring. It has run well for two weeks of almost daily use. Today, the temp alarm went off twice at speed. I instantly look back and no pee stream. Once at idle all returns to normal. Starting it and stopping it several times brought the pee stream back. I made a couple of runs at speed and all seems well.

So... I read two posts talking about what happens if you get sand or pebbles in the system; they hang out in the pressure reg valve and cause troubles.

In one of those posts it was mentioned that a certain hull design can starve the intakes in a turn.

Well, I have both conditions. I live on a river with Gulf access. It's tidal with shifting sand bars everywhere. I was *****ing the night before and scrubbed up on one, basically blasting reverse to get me away. I was trimmed up, but the mud did stir. So it could be the sand in the valve.

BUUUTTTTT, I have a 20ft Century with deep channels in the hull design which do inject a lot of air into the water on each side of the lower unit. And both times it went off I was in long sweeping turns. (yes I was trimmed properly).

So a couple of questions. Either way I've had the motor turning at high rpms when either the intakes sucked air, or the pressure valve shut down.

Given that water had just been flowing (verses starting the motor of the trailer after it's been sitting a month), how much of this starved condition does it take to wipe out an impeller and/or pump housing?

And is there a way to toughen up the system for us river rats? We can't always come and go on the high tide!

And any step by step for getting to and cleaning sand out of a pressure regulator valve would be appreciated.

Thanks so much,

Steve

[boats.net]

If the alarm signals and no water seen at tell tale usually means no water getting to engine. Mudrunning can plug up water intake screens on lower unit and even damage water pump. When you put in reverse it is pushing the mud back towards water pump.

[Ken]

Steve,
Sounds like you are just losing water to the pump in the turns. If you are, the prop should also be ventilating (sucking air) and would be obvious from the increase in motor rpm. You might try slowing down in the turns to see if that helps, or try trimming down a little.
The best indicator of water pump performance is the water pressure gauge - you might consider installing one.
The pressure control valve (aka pressure relief valve, poppit valve) is locate near the bottom of the exhaust plate. Take a look at the diagram of your motor in the online catalog (above). The pcv is located under the metal dome that has a water hose going to it. You might have to slide the CDI over to get to it.
If debris clogs up the pcv and it sticks open, then cooling water will pre-maturely dump out the relief holes at the top of the upper casing, and this can lead to overheat condition. There should not be very much water coming out the relief holes under normal operation. The pcv is designed to open at pressures over 20 psi. You can remove the pcv and inspect for debris - also, check the spring to make sure it is not broken. And check the pcv seat to make sure it is smooth.
As far as how long you can run a pump dry before any damage occurs, I can only guess. Under the conditions you are talking about, maybe no more than 30 seconds. By then, the thermo switches should have closed and the alarm sounded.
Good luck [img]smile.gif[/img] ,
Ken K

[5X]

Thanks to both of you. I like the idea of adding a water pressure gauge. Where should I locate the sensor? Is there a particular line or port off the engine which is best suited?

Thanks in advance!

Steve

[5X]

[Ken]

Steve,
You want to mount the pressure fitting to the lowest bank of cylinders - if it's like my V-4, it will be the port side. There is a threaded plug (14mm hex) on top of the cylinder bank on both sides. The starboard side is where you would mount a temp gauge sensor - that's where I have mine.
I need to add a water pressure gauge, and it's on my list of things to do.
Check with boats.net (sponsor of this forum) for the gauge kit - good folks, and great prices.
Good luck [img]smile.gif[/img] ,
Ken K

[pb]

Ken,

I like the idea of those gauges and will look into installing them on my 115 4 stroke. Do you, or anybody, know where the necessary ports are on these blocks. On your temp. gauge.......is it electrical or mechanical??

[5X]

Okee Dokie,

I ended up at marinesupplyusa.com. If I zigged wrong, point me. But there I found order numbers for Teleflex Gauges. OB water press 0-30 #17697 or 0-15psi gauge, #757641. The only temp gauge kit I saw was order #79188. Are these the gauge kits you are talking about Ken (or boats.net, of course)?

any thoughts about the 15 vs. 30 choice?

**Edit**

And now I see that B.Net offers Yamaha gauges as well.

6Y5-83590-00-00
PRO SERIES WATER TEMP GAUGE (requires sender)/ 688-83591-00-00
WATER TEMP SENDER

and

6Y5-83660-10-00
PRO SERIES WATER PRESSURE GAUGE (requires sender) / 688-83667-00-00
WATER PRESSURE SENDER

Is there an install ease advantage by going with the factory accessories?

Thanks again,

Steve

[Ken]

pb,
Don't know about your 115 four stroke - take a look at the diagram for your motor in the online catalog (above). Should be two plugs in the water jacket somewhere - one for water temp and one for water pressure. The temp gauge sensors are electrical - technically, the sensor is a thermistor which is a resistor that varies with temperature. The console gauge is calibrated to read the temp range of the sensor. There is just one signal wire from the sensor to the console gauge - and battery ground is the other.
The pressure gauge has pneumatic tubing that goes back to the fitting on the motor and measures water pressure directly. And you have to be careful routing that tubing so that it does not kink on you.


Steve,
If you can afford it, go with the Yamaha gauge kits. My Teleflex temp gauge works fine, but I had to buy an adaptor (metric vs standard thread) for the sensor to fit into the threaded hole in the top of the water jacket.
Then I discovered that the top of the sensor hit the inside of the cowling because there was no clearance [img]tongue.gif[/img] . So I had to cut out a relief hole in the inside of the cowling. If you go with Yamaha, there should be no clearance problems.
Since the pressure control valve is designed to open at around 20 psi, I would go with the 0-30 range rather than the 0-15 psi. With the Yamaha gauges specifically for your motor, the range will be correct.

Ken K [img]smile.gif[/img]

[Hamfisted]

PB, as far as I know there's only one available plug hole to stick either a temp sensor or a water pressure fitting into on the F115. It's to the left of the oil filter, just below the pressure relief valve cover. Its a 14mm bolt/plug you remove and replace with the sensor or fitting, your choice. But I'm pretty sure there's only that one spot. I would recommend the Yamaha gauges because the fitting and everything else is metric, just like the motor, and it'll somewhat match your Yamaha gauges and illumination wiring.


The V4s and V6 motors all have two 14mm holes available, one at the top of each cylinder bank.


PB,
The F115 thermostat starts to open at 122 degrees (F) and should be fully open at 140 degrees (F).


Mike

[pb]

Thank you Mike and Ken for all of the information. By any chance would either of you know the "normal" ranges for the water temperature and water pressure?? Thanks again for all of your help!

[boats.net]

I sent a Email to PB and 5X for the water pressure sender location chart. If you use the Teleflex or any gauge besides Yamaha gauges you will need MAR-WPRES-AD-TR adapter to connect water pressure tubing to engine block.

[Ken]

pb,
Normal operating temp for your F115 is going to be what the thermostat is set for. On my C115, it is approx 135 degrees f. I can watch my temp gauge and see it rise to 135 and stop there - that tells me the thermostats have opened (I believe you have only one for the F115 since it is an inline four cylinder block). The thermostat will try to regulate at the temp that is stamped on it - of course, water pressure and intake water temp will play a role also - but if all components of the cooling system are working properly, then the operating temp will hold pretty steady, give or take, say, five degrees.
You might want to get a Yamaha shop manual for your motor - it will have the exact temp for the thermostat. Yamaha may be running their four strokes a little hotter than the two - dunno.
Normal water pressure for my C115 (I'm gonna guess at this since I do not have a pressure gauge - yet) would be around 8 pounds at idle and up to 20 pounds WOT. Of course, this assumes no stuck (open) pressure control valve and a good water pump impeller. For your F115, should be pretty close to this - again you need that shop manual (or maybe a forum member with an F115 and pressure gauge can help).
Good luck [img]smile.gif[/img] ,
Ken K