Somebody Explain this to me Re: T-Stats Question

[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.

[HMBJack]

Zeno - as to the temperature thing - here it is again (below). I will estimate the air and dockside hose water temps to be about 50 degrees I'd say.


Here is a little experiment I performed today with my boat up on a lift:
1. Connected FW hoses to a set of muffs as well as to the garden hose fitting at the base of the powerhead.
2. Started the engine and let it idle in neutral which is about 600 RPM's.
3. With a digital heat sensing gun, during every minute of run time, I measured the temp of the starboard side T-Stat housing (outer casing where the T-stat sits inside).
4. Temperature was 74 degrees before I started the engine then it rose to 88 after 2 minutes then ranged between 90 and 98 until I shut off the engine after 20 minutes.
5. I repeated the above 4 steps on the other engine and experienced similar results. Temp range was 91 to 109 over a 17 minute run time on muffs + garden hose fitting.

When I returned home, I took a set of identical T-Stats I had removed from my F250's and placed them in a bowl of water measured at 100 degrees per a digital mouth thermometer.

None of the T-stats opened at 100 degrees. I warmed the water up to 109, my highest reading while idling, and again, none opened up - not even partially. They of course all opened when exposed to boiling water (~212).

This all makes sense since the T-stats for an F250 is set to open at 158 degrees.

[zenoahphobic]

I am the Original Poster and I do not think this is the dumbest thread.

I tested my engine at idle and found the thermostat cover ranged from 90 degrees to a high of 109 over a 17-20 minute test.

The T-stat on my engine doesn't open until it hits 158. So, I can only conclude the T-stat remains closed while flushing on muffs.
Panasonic (?) took the time to measure the water that the bleeders pass and found it was only a 1/2 gallon over 10 minutes.

My point is flushing - no matter how you do it - does NOT really flush the T-stat bores which are up high on the V6 four strokes) 3.3L).

I flush all the time and the photo I posted is after 270 hours. I'm telling you the t-stats remain closed and those pathetic bleeders are just that - pathetic.

If you think you're really flushing salt out of your T-stat bores while at idle, don't take my word for it.
Get your 10mm socket out and pull your t-stats and tell me what you think then.

Might be time to refocus on the temperature thing.
How did you take the thermostat temperature, couldnt find how on rereading thread?
My concern is that this doesn't represent the coolant temperature, or more poignantly the actual temperature of the thermostat "bulb".
There is a lot of engine mass to heat up, and conversely a lot of surface area to dissipate heat. At idle the heat energy produced is little and as a percentage compared to the engine running at full load, a lot more of this heat goes out with the exhaust.
Now the critical thing here is the ambient temperature and the water temperature. Conceivably, at low enough temperature , the heat produced balances the "natural heat" dissipation of the engine and the water (just sitting somewhere up the block) without the need to actually have much circulation at all.
So the pertinent questions are how cold is the air and water?
The thermostats may actually be open, or the load must be increased and/or the motor run for a longer time. No other reasons possible.

[HMBJack]

I am the Original Poster and I do not think this is the dumbest thread.

I tested my engine at idle and found the thermostat cover ranged from 90 degrees to a high of 109 over a 17-20 minute test.

The T-stat on my engine doesn't open until it hits 158. So, I can only conclude the T-stat remains closed while flushing on muffs.
FairDeal took the time to measure the water that the bleeders pass and found it was only a 1/2 gallon over 10 minutes.

My point is flushing - no matter how you do it - does NOT really flush the T-stat bores which are up high on the V6 four strokes) 3.3L).

I flush all the time and the photo I posted is after 270 hours. I'm telling you the t-stats remain closed and those pathetic bleeders are just that - pathetic.

If you think you're really flushing salt out of your T-stat bores while at idle, don't take my word for it.
Get your 10mm socket out and pull your t-stats and tell me what you think then.

[pstephens46]

So what I am getting from this whole discussion is the following. If you have said engine on the boat sitting in the water tied to the wharf, start the engine and let idle for say half an hour that the thermostats will never open? Is this correct? The engine at idle, with just the WP supplying water as per normal, will not produce enough heat to open the stats?
Yes, No, maybe so?

I believe the OP ran his "test" with muffs etc. I recall the stats begin to open at a temp of 140 fully open at 158. I am not looking at the particular engine data at moment. Betting they were opening somewhat if not 100%. If the stats didn't open at all in 20 mins what do you think would be the outcome?

[panasonic]

So what I am getting from this whole discussion is the following. If you have said engine on the boat sitting in the water tied to the wharf, start the engine and let idle for say half an hour that the thermostats will never open? Is this correct? The engine at idle, with just the WP supplying water as per normal, will not produce enough heat to open the stats?
Yes, No, maybe so?

[pstephens46]

thankfully we don't have any "battery" or "charger" threads here.

those are guaranteed to bring out the apex of cluelessness

other than the "which boat/engine is better" posts (I assume - since I decline to look at them)

Can't resist the urge to pile on regarding The Whole Turd. My personal favorite was the lower unit thread regarding pressure testing. 4-5 of the regulars stating they ALWAYS vacuum test as well. Not a damn one of them would respond as to whatever standard would be used to run this test. One of the fellers over there said vacuum testing is "just good physics". As opposed to bad physics? Yam engineers employ bad physics apparently.....

[pstephens46]

I think the OP might be mistaken in saying his thermostats do not open while running on muffs. Like I said before, the stat on my motor will open and close on muffs/flush port. Water runs warm for about 20 seconds and then cold. Hard to believe his never open.

[99yam40]

I would think it does not shove as much water into the motor as the water pump would.
Maybe that would let the motor warm up enough to get the stats to open.
just my thoughts

[fairdeal]

We long to reach for the levels of dumbness displayed on TOS.

thankfully we don't have any "battery" or "charger" threads here.

those are guaranteed to bring out the apex of cluelessness

other than the "which boat/engine is better" posts (I assume - since I decline to look at them)