300XS won't warm up. Poppet valve open? Or stats?

[Sleek Jr]

Have a 300XS that will idle in the water all day at 80-90 degrees, indicated on SmartCraft gauge.

In dash gauge goes to compressor sensor, reads about the same.

Also, I noticed that when on the hose (out of the water), that water pours out of four holes, two half-round
holes in the front (one on each side) where the lower unit meets the mid section, and two round holes facing
strait down, in the mid section, just below the cavitation plate. I never noticed that when running other times.
Is that normal?

The water from the rear holes feels warm, but the front two feel cold.

I noticed on a water flow chart, that the water from the poppet valve seems to exit down a certain hole in the mid,
could that be an indicator hole to tell you that the poppet is stuck open?

Also, the notes on the flow chart page say that "If the poppet valve is stuck open, then the motor will never warm up
at idle or low RPM".

How can i tell if the problem is a stuck open poppet valve, or thermostat?

When I'm running at speed, it may get up to 120 on the smart craft. The flow chart says the stats are 143 degrees, and it
has never warmed to that temp.

Also, when I use an infrared thermometer to measure temps, I'm finding the temp sensor area on the right bank is about 105
and the left bank is about 85, so I'm thinking the Smart Craft gauge is displaying the left right bank?

How can i tell if the problem is a stuck open poppet valve, or thermostat?

[XstreamVking]

The t-stats are always getting clogged up with crap that won't allow them to close and get the motor up to temp. Pull the stats and I bet you have wood or some pcs of trash in them. I put them in a pot of hot water and watch them open and usually some debris comes out of them. Clean while open. New gaskets may be needed ,and while your at it clean the inlet screen on the lower port side of the motor that cools the compressor. Follow the hose from the compressor to the fitting un screw and clean. Most smartcraft gauges will run 127-135. They take an average of the 3 senders and show that. Pull the poppet and clean it if you want. With all this you should be good to go. You will have to pull air hose going into the fuel rail star side top, by removing shiny flat clamp that holds down the hose fitting. Two allen head screws.

[Sleek Jr]

Thanks Xstream, the following was very useful for my understanding how the display works: "They take an average of the 3 senders and show that."

Also, you were right, the thermostats were stuck open with sand, little gravel, and debris. I fixed it.

Then, I went out again, and pulled slowly up to a beach and parked to go for a hike with kids. Then, after backing out and leaving, after at speed, I noticed my seperate gauge
which is dedicated to compressor temp only was climbing too high again. Checked the pee hole, and no water. Plugged AGAIN with sand. Cleaned it out with a tie wire from a loaf of bread,
and ok again.

Question is: 1. If there is a strainer before the compressor, HOW in the world is debris big enough to clog the pee hole, getting through it?
2. If it the screen in large enough, by design, to let that much dirt through it, then what it the point of having it there at all?
3. Why would Merc do this, when it is so EASY to simply put a 5/16 filter in the line, which would be easy to get to, easy to replace or clean,
and hold 30 times the dirt that would clog the pee hole and overheat the compressor??

There's plenty of room for a filter both before, and after the compressor. This seems like a pretty stupid thing for Mercury to do to an otherwise
finely designed motor, especially considering the consequences.

Oh, one last thing: I pulled the flush plug while running the motor on the garden hose, into the sportmaster lower unit, and nothing came out.
Shouldn't water be coming out of the flush port with the motor running? Water was spraying strongly out of the telltale hole, but nothing
from the flush port. Seems odd to me.

Thanks again!

Sleek

[XstreamVking]

The screen is really for grass and bigger stuff. I have used a small drill bit and CAREFULLY enlarged the pee hole some. Flush has a check valve, so no water...Clean that screen as it may be nearly clogged....But still letting water pass. Weed whacker string works well for clearing the pee hole also. Stay outta the dirt with a low water pickup lower!

[Sleek Jr]

I see. I haven't seen the screen, so assuming it must be pretty coarse (large holes) to let through big enough dirt to clog the pee hole within seconds or minutes.

Do you see any problem with installing an inline filter either before or after the compressor? At least that would keep the telltale from getting plugged up and allow
one to finish their vacation or trip to the lake without worrying about overheating.

If enough dirt got in to cause further attention, like sticking the stats open, you would know it by the motor not warming up, but at least that would not be dangerous
or cause and alarm and have to idle home, like overheating the compressor.

Also..about keeping it out of the dirt... this is my first sportmaster lower, so man are you right. Very sensitive to this, even the slightest little bit, and for sure it's going to clog the pee hole.

Strange thing is, prior to this year, I have spent multiple times camping for days with the boat beached, and had to idle through and back up through plants, and it never caused a problem, including
backing up with significant power to get the boat unstuck when lake water level dropped overnight, blending up all kinds of mud and sand, and it never stuck the pee hole once until now, it seems it
does it immediately.

Funny thing is, Mercury claims their cooling system in the only motor out there that does NOT get glogged running through heavy grass. Check this out:

https://www.youtube.com/watch?v=RVGynkjiuNs

By the way, there was also vegetation stuck in my stats, and pee hole, not just sand.

Reading another forum, they said the torquemaster also has bottom (nose cone) water inlets? Is that true?

Thanks for all your answers and help.

[XstreamVking]

All the newer 3.0's have bullet p/u's. I charter with my boats and have to be fairly careful not to get in to the dirt. Follow the cooling hose from the compressor to the screen fitting in the lower block. Takes a minute to clean when u get used to doing it. The other filter idea is ok but not really needed imo. You have crud coming loose from the strainer or the pee hose before the tell tale outlet. Pull the fitting for the tell tale and clean the hose. Start out with everything clean and it will be good to go for a while.

[Sleek Jr]

All the newer 3.0's have bullet p/u's. I charter with my boats and have to be fairly careful not to get in to the dirt. Follow the cooling hose from the compressor to the screen fitting in the lower block. Takes a minute to clean when u get used to doing it. The other filter idea is ok but not really needed imo. You have crud coming loose from the strainer or the pee hose before the tell tale outlet. Pull the fitting for the tell tale and clean the hose. Start out with everything clean and it will be good to go for a while.

Thanks again. I agree, but don't see the point in the inconvenience and distraction from the fun of an outing, to remove the cowl, remove the pee hose, and clean it and the orifice out.

We all agree that a plugged pee hole overheats the compressor, and I assume that is not good for it, even if you shut it down and clean the pee hose and hole out every time.

I just measured the pee hole and it's 3/32, or .094". That's an area of .007 square inches. The smallest inline strainer I found (VacMotion.com) has 3.95 square inches of filter area, and with
the coarsest "20 mesh" screen, it has 52% of open area, around 2.0 square inches, or almost 300 times the flow capacity of the pee hole. The holes in the screen are .036 so it will filter particles
out that are around 1/3 the size of the pee hole so no way it will ever get clogged again, and it should hold almost 300 times the particles that it would take to clog the pee hole.

So, it seems the party line is "it ain't no big deal to clean out the pee hole every time it gets clogged"... but I would say, "Is it really diligent and a good idea to allow your compressor to overheat
and your alarm to tell you after the fact, time after time? And do you really enjoy cleaning out your line? And does every boat owner know that when he loses water to the pee hole and overheats
his compressor, that it's simply a clogged pee hole, and does not require a cancellation of their outing and a trip back to the shop? Does every boat owner even have the skills or know he can
clean this out again? And do we really enjoy having to do it multiple times, because sometimes the first time you clean it, just allows the flow to bring more loose debris and clog it again?"

Etc. etc. etc.

I don't see any pros to not having the inline screen added before the pee hole, and I don't see any "cons" to having it there.

Thanks again, hopefully we can all learn from each other and continue to improve our boating experiences.

[XstreamVking]

There has been talk for years about the x-tra filter idea. If you think it is a better way, then by all means try it. I never said don't do it.....By the way, I just got home from running a low tide flats charter. Ran my opti in some knarly crap and had no problem. I only clean it periodically and have no problems. I am looking fwd to seeing what you come up with. Might be a better way, indeed.

[Sleek Jr]

Thanks Vking, I'm working on it now. I know what you mean, I ran mine before also in some murky, muddy, or sandy stuff, and never had a problem. Then I barely get close to bottom, and this happens. Twice. Second time out had to clean out the pee hole three times that day.

Oh well... I was thinking about the check valve in the flush port. If there is one, why do many of us (including myself), report sand and debris sitting behind the plug, when we pull it? In fact, another guy on here said he
got a "handfull of sand" falling out of the port when he removed the plug.

Just wondering how that happens, trying to gain a more complete understanding of these motors. Thanks.

[XstreamVking]

The check valve leaks a little and when the motor drains it lets sand go to the areas that are lowest. Never seen but a small amount of sand there. I would def. open up the tell tale nozzle some if it is a place where crap blocks up the works. I have on mine.....

[Sleek Jr]

Thanks again. Your experience has helped me a lot. I'm about to take my strainer out and check it. The stats were plugged again, just cleaned them. Got a new strainer just in case mine is damaged, and the thought
occurred to me: The strainer holes on the new strainer are around 1/8 " square or 4/32" . The telltale hole is about 3/32". If we enlarge the telltale hole slightly bigger than the strainer holes, then any particles
small enough to get through the strainer, would pass through the telltale hole. I'm thinking a little bigger than 1/8, or 9/64, even 5/32, would do the trick. Then you would not need any filter screen inline, or "flojet".

The only reason I'm concerned about not to do this, is if the telltale hole is a calibrated size designed to limit flow through the compressor. This I don't know but would like to find out.

It seems the volume of water the water pump is able to provide, is way more than enough to be able to supply a little extra though an enlarged telltale hole, so at this point I don't see that as a concern.

However, the compressor sees only cold water in and out, with nothing to control temperature. So I'm wondering if the compressor needs to "warm up" and it needs the flow restricted some? If so, that seems
a rather crude and imprecise way of trying to control temperature (seeing inlet water could vary from 33 degrees to 90 degrees, depending where you're boating).

If it doesn't matter if the compressor runs cold, and the water pump can still supply sufficient water pressure and volume to cool the motor, then it seems and enlarged hole is the easy way to stop the telltale from plugging.

The only other reason I could imagine Merc WANTING the hole to plug, is that may motivate the boater to take it to the shop to get serviced where a professional my also be diligent enough (if you're lucky) to check and see if the stats are now stuck open, or other problems.

A plugged telltale indicates particles have gone up as high as the compressor, and therefore also as high as the thermostats, and may have stuck them open, as it did in my case.

However, I would rather simply observe the temperature being too low and take action when we can, rather than have the compressor overheat from a plugged hole.

Better yet, maybe Merc should put a "low temp" alarm as well.

[XstreamVking]

They have a low temp alarm. Let your stats get stuck open and it will beep once every few mins. As far as the tell tale, I have enlarged all of the ones on my optis and have had no problems. I bet that the size was determined by the nozzle pc that was on the shelf. The compressor is bolted to the block, it will come up to temp just fine. Cleaning the path from the strainer to the tell tale going thru the compressor is a good idea too.