Somebody Explain this to me Re: T-Stats Question

[rodbolt17]

this has got to be the dumbest thread I ever posted on.
when you use the onboard flush the water has two paths.
up and out or back through the pump housing.
unlike the closed cooling system in your truck, this system must bypass a certain amount of water.
your at a dead idle trying to use cold water that is NOT recycled and your doing it on 200+pounds of an incredibly good heat sink.
you will most likely NEVER get the block past 150*F on a flusher.
simply aint gonna happen.
yam and merc never went on a joint venture with a 250.
back in the day when jonnyrudes went to an opening t-stst on the cross flows we had overtemp issues when first started.
cause the T-stat would not bypass water.
that discussion is why I got banned from another site.
it is called maintenance, why not simply do it?

[boscoe99]

I am curious how you came up with this.

here when the rivers run hard and fresh there is salt layer on the bottom of the river with the fresh running over it

He is in Australia. Where his up is our down.

[99yam40]

Salt laden water rises above fresh water. So the theory of it depositing this way has some merit.

I am curious how you came up with this.

here when the rivers run hard and fresh there is salt layer on the bottom of the river with the fresh running over it

[HMBJack]

Yes indeed Zeno.

You make some excellent points - none of which I can disagree with.

Still, you can't deny the salt build up in the "as is" system after my 1 year and 270 hours. And I flush routinely.

I'm so passionate about this because this is the 2nd time I'm seeing this salt build up in the bores (starboard side mainly).
I saw it a couple years ago when I first pulled my T-stats and was horrified. This 2nd time is simply more of the same.

My modified T-stats (4) are installed on my twin F250's. I have another set handy in case I observe any - and I mean any - operating issues. Only takes an hour to swap them out with my 10mm.

I will report back in July or August and share my results. I'm happy to be the guinea pig!

Personally - if there was a really good design in FW flushing for these engines, I think they could last for 20,000 hours.

In the end, I hope this thread is helpful to all who read it. I got a lot out of it and hopefully so did you.

[pstephens46]

Although some water has passed in this thread (pun intended), I still have a few points to make.

I'm not overly convinced that the thermostats don't open. The infrared reading is more the outside cover temperature than the inside water temperature. The lower the temperature or the closer we get to ambient outside temperature, the closer to actual "block" temperature it becomes, and not the temperature of the water somewhere behind.

The water flow past the thermostats with engine running on muffs hasn't been measured.

So there are only assumptions not verified.

Salt laden water rises above fresh water. So the theory of it depositing this way has some merit. It wouldn't keep caking up harder and harder, as mentioned earlier, it will cyclically mostly redissolve at every full warm use of the engine.

However that aside the OP is looking for a better flush. In this regard I'm all for some form of a bypass attachment/tube. This drilling of holes in thermostat want produce enough flow without seriously compromising their function. You might as well put in a lower opening temperature thermostat to be more effective. You will need to search for such that have more satisfying opening "curves". The OPs location may warrant such modifications.

I'm very disposed to proven modification solutions to all sorts of design failings, but sadly very little experimentation or mods exist for outboards generally.

A reasonable man, this Zeno.

[zenoahphobic]

Although some water has passed in this thread (pun intended), I still have a few points to make.

I'm not overly convinced that the thermostats don't open. The infrared reading is more the outside cover temperature than the inside water temperature. The lower the temperature or the closer we get to ambient outside temperature, the closer to actual "block" temperature it becomes, and not the temperature of the water somewhere behind.

The water flow past the thermostats with engine running on muffs hasn't been measured.

So there are only assumptions not verified.

Salt laden water rises above fresh water. So the theory of it depositing this way has some merit. It wouldn't keep caking up harder and harder, as mentioned earlier, it will cyclically mostly redissolve at every full warm use of the engine.

However that aside the OP is looking for a better flush. In this regard I'm all for some form of a bypass attachment/tube. This drilling of holes in thermostat want produce enough flow without seriously compromising their function. You might as well put in a lower opening temperature thermostat to be more effective. You will need to search for such that have more satisfying opening "curves". The OPs location may warrant such modifications.

I'm very disposed to proven modification solutions to all sorts of design failings, but sadly very little experimentation or mods exist for outboards generally.

[pstephens46]

I think someone with a V-6 3.3 liter needs to post some videos of water flow, both flushing and with engine running out of both open bores. Just sayn....

[boscoe99]

I would think salt +water would be heavier than plain water(higher S.G.) and the water drains out of the bottom of the block/motor, so I do not think the water would push stuff up to the top of block

from what I have seen the 2 sides run at different temps even the way they came from factory.

do these motors have temp sensors you can read with the proper software?
Is it motor temp or water temp they read?

The thermosensor that comes with the motor measures upper block temperature. That is the temperature seen on YDIS.

Yamaha makes a water temperature meter that will indicate water temperature at the sender mounting point. Mounting point varies from model to model.

Teleflex makes a temperature gauge that will measure the temperature of the block wherever the sender is placed.

[99yam40]

I would think salt +water would be heavier than plain water(higher S.G.) and the water drains out of the bottom of the block/motor, so I do not think the water would push stuff up to the top of block

from what I have seen the 2 sides run at different temps even the way they came from factory.

do these motors have temp sensors you can read with the proper software?
Is it motor temp or water temp they read?

[HMBJack]

And - Thinking about this some more - I have a theory WHY the salt accumulates more in the Starboard side T-Stat bore Vs. the Port side.

Salt might be accumulating on the Starboard side bore because, since it is HIGHER than the port side bore, as flush water fills the block, like a drain, all salt in the block will naturally flow to THAT side. It is the LAST place that the water goes. And, since the T-stat is closed, it reaches a dead end.

This may particularly apply when flushing on muffs engine on. The water pressure surely will push water and particles in the block to the highest point.

If this is kind of true, then I may only need to put the modified T-stat on the Starboard side only. It will serve as a drain when idling on muffs.

[HMBJack]

Thanks Boscoe.

To your point, I have already coated the T-stat bores with oil based paint (at least a coat every time I inspect them).

After several inspections, for my two engines, the powerhead's starboard side T-stat bores had much more salt build up than the port side bores.
I thought about only putting the modified T-stat on the starboard side only but was thinking the temperature differential in the block (right side/left side) might be problematic.

Your thoughts? I really don't see any harm in using the modified T-stats. It's not a fuel system - just a cooling system.

I have yet to do the install but I'm thinking to install all 4 of these soon. Want to see other remarks before I do.

I commercial fish so 100 hours goes on in like 3 or 4 months so I can report back on results then.
I am optimistic these modified stats with the weep holes will work nicely.

[boscoe99]

Regarding inspection intervals, here is what Mercury Marine has to say with respect to their version of the F225 (same system as the F200/F250) when it comes to the thermostats. They also say that corrosion control anodes should be inspected more often when the motor is used in salt water. The thermostat cover has to be removed to inspect the anode. The thermostat and thermostat cavity can be inspected at the same time.

This reminds me of the adage about "an ounce of prevention is worth a pound of cure". Or something like that.

[boscoe99]

By the way, the F250 uses "a stupidly simple heat exchanging cooling system".

[boscoe99]

We await your feed back.

Why not modify just one thermostat instead of both. On the side that seems to be the most problematic.

Flush as you have always been doing. Then inspect both thermostats in six months time to see if the modified one is the same as, worse than or better than, the unmodified one. If there is no difference then the only real thing to do is to step up the maintenance interval and inspect/clean/replace the thermostats more frequently than suggested by Yamaha. Actually, develop your own specific maintenance interval that will protect your motor based on the conditions that it is operating in.

If it were me, just me only, I would treat the inside of the thermostat bore to prevent any "battery effect" between the copper thermostat components and the aluminium bore. As opposed to painting the copper parts. Like what fairdeal has shown us in some photos he has posted. Not only will it reduce any "battery effect" it will simply better protect the aluminium thermostat bore from damage being caused by any other reasons.

Maybe fairwinds will come along and tell us if what he did seems to be working.

[HMBJack]

Townsends,

I know my T-stats are working properly because as the water cooled down in the cereal bowl, the T-stats very slowly started to close.

So I started this thread, dumb or not, seeking why the darn T-stats don't open while running on the muffs.
It makes perfect sense that the V6 3.3L just doesn't generate enough heat at idle. I'm seeing between 90 and 109 degrees at idle.
And this was after 17 & 20 minutes respectively on two F250's running on muffs + flush attachment.
I choose not to be rev'ing up my engine above 1,000 rpm's while flushing and I can't flush in a big bucket or bag where the water would become hot.

So given my question of "Somebody Explain This to me" and given the responses here on this site, I now conclude that the T-stats really don't open at idle and the 3 bleeders basically don't help since FairDeal measured the leak rate on them to be only a 1/2 gallon of flush water in 10 minutes. That rate of flow is pathetic. Flushing is a waste of time.

So, with my other set of T-stats (see photo), I have two improvements:

1. Drilled weep holes to help the bleeders do their job, and
2. Applied two coats of oil based paint to the copper frames of the T-stats to minimize the "battery effect" of different metals (Copper Vs. the Aluminum bore).

No, I don't think I'm smarter than the Yamaha Engineers. But I will say I'm very unimpressed with their flush system and no one on this site can explain it all to me. These engines simply DON'T flush water while on muffs or the flush attachment. Period.

Yes, with my weep holes, my engines will take a minute or two longer to get to operating temperature (the weep holes aren't THAT big btw). But to me, this is a very fair trade off.

These T-stats will certainly pass flush water now and therefore keep my T-stat bores cleaner than if the weep holes weren't there.