Somebody Explain this to me Re: T-Stats Question

[boscoe99]

The thermostat "frame" appears to be copper or brass. What if that was covered in some sort of nitrile coating. Alodine and zinc chromate primer help. Would that prevent the battery effect by reducing the chance for conduction?

Later models have a separate thermostat housing made from a plastic type of material.

I was thinking of a large diameter hose that could run to a port on that housing. On the engine side of the thermostat. So flush water would flush backwards from the top and down instead of from the bottom and up. Half inch ID at least.

The current flush hose is too small and too long IMO to really be effective. Water being introduced into the base of the block is being lost out below while at the same time it is trying to fill and flush the block.

On the other hand, I dare guess that the vast majority either don't flush or don't need to flush (fresh water users) so maybe Yamaha things "why bother improving the system"?

[HMBJack]

it's a saltwater engine. There has to be a way to do it.

Perhaps adding what I'd call a "flush valve".
Such a valve could be sandwiched (bolted on) in between the T-stat and T-stat bore.
There seems to be enough room under the hood for this.
Then, have some kind of lever that protrudes through the base of the cowling.
Pull down, and the T-stat flush valve opens to allow water to pass.
Push up, and the flush valve closes.

[pstephens46]

What could the design engineers have done to facilitate greater water flow through the thermostats housing area to prevent or mitigate the build up of crap?

The thermostat "frame" appears to be copper or brass. What if that was covered in some sort of nitrile coating. Would that prevent the battery effect by reducing the chance for conduction?

[TownsendsFJR1300]

I have fantasized about drilling the thermo housing and pressing in a hose barb

- as from some exhaust covers -

then "tee" those into the flush hose.

That'd work!!

Do that and you likely wouldn't even have to run the engine, flush port ONLY..

I'm not sure if the LU would get a good rinse NOT running, but plumbing into the rest of the system is great!

[fairdeal]

What could the design engineers have done to facilitate greater water flow through the thermostats housing area to prevent or mitigate the build up of crap?

I have fantasized about drilling the thermo housing and pressing in a hose barb

- as from some exhaust covers -

then "tee" those into the flush hose.

[boscoe99]

What could the design engineers have done to facilitate greater water flow through the thermostats housing area to prevent or mitigate the build up of crap?

[pstephens46]

FWIW, I run my motor with two hoses. F150TXRD. 65 degree tap water. I have noticed the exhaust water "pulses" between warm and cold while idling. The T stat will open momentarily and then cool down and close. Hard to imagine the F250 doesn't heat up enough to open either t stat at all.

Even still, I have found enough of a "salt bridge" from time to time to cause some pitting in the bore.

[HMBJack]

Yes, I will certainly switch from always flushing engine OFF on garden hose fitting to flushing with muffs and engine ON now.

I suppose even though the T-stats remain closed, jamming 90-100 degree fresh water up there with the water pump pressure can only help.

I will report back on the results of this mid year after I reach 100 hours or so.

Thanks.


Lastly and FWIW, I looked at my maintenance log, and the salt in the photo up above in my first post was after 14 months and 270 hours of use flushing only with the powerhead garden hose fitting.

[panasonic]

Try just the muffs, don't turn the water on full blast, let the water pump do the work... as if the boat is tied up at the dock idling waiting to go. As Yam stated above bump the idle speed up a bit as well. I think that will work.

[HMBJack]

Boscoe - You're a great resource to us. Thank you for what you do on behalf of all of us who use this site for help with our Yamahas. I, for one, greatly appreciate what you and your colleagues do for us here.

As to flushing - I cannot use a flush bucket or bag since my 33' boat is stored in a slip up high on a floating hoist (called a Hydro Hoist). I wish I could since the flush water would certainly get HOT and likely open up the T-stats.

Page 48 of my 2006 Owners Manual says "inspection/replacement" of the thermostat every 200 hours or 1 year. I see it has changed to every 100 hours now. Given the lousy flush system, this now becomes all the more important.
As stated, I truly don't believe many 3.3L V6 Owners actually pull their thermostats. Why? Because it's kinda hard relative to flushing which is easy but mostly a pointless act. Flushing looks good and makes you feel good but it's a waste of time.
You can use all the Salt Away and fresh water you want but those T-Stats will lock shut before you can say "Turn on the hose".

So instead of flushing, your time is better served pulling your T-stats as often as you can (at least annually) to keep your bores from accumulating salt. Yes, it's a bit of a pain to pull them without dropping a bolt or stripping the threads in the block. But I think it is worth doing. And doing often. And buy a few extra T-Stat housing bolts. Because you're sure to drop one or two along the way.

[oldmako69]

For a bunch of supposedly very smart guys, whoever the guys were that designed, and then signed off on this cooling system weren't using their noodles. Too much Sapporo and sake perhaps?

I'm watching this thread because one of my engines already shows evidence of salt rot in the T-Stat bore, even though it only has 200 hours. So I'm guessing that my other one is on the road to hell as well. What a load of salty crap.

These engines appear to have not one, but at least three Achilles heels. Good thing they're so inexpensive.

[99yam40]

I would try kicking the RPM up to 1000-1200 while flushing to see if that would put enough heat to open the stats

[boscoe99]

Panasonic - Good point. I might try flushing it on the muffs alone. I however am not confident it will reach 160 degrees but perhaps.

Boscoe - What percent of Owners of the 3.3L V6 four strokes pull their T-stats every year? Or every 5 years for that matter? I am in the very salty brine of ocean off San Francisco. Because of the pathetic design of the flush system in these engines, I agree with you that an annual clean out of the bores is necessary. Kind of like having to remove the fenders of your car to do an oil change. I know you can't throw mud at Yamaha here but I also know you know what a crappy design this is. And the flush, flush, flush message from Yamaha is a joke.

The final take away here is:

Whether you flush on muffs or the garden hose fitting - Don't think for a minute that flushing actually removes salt in your corrosion prone T-stat bores. The salt stays there and accumulates after every trip in the dead end street of your T-stat bore.

This is a Yamaha dealer site. Separate from Yamaha the engine maker. They let us do pretty much here whatever we want to do. There are some strange filters that prevent us from typing the word goold (without the extra o) but that is about it.

We can and do throw mud at Yamaha here. I am one of their most vocal critics when it comes to their data. It stinks. All of it. I have long advocated for different designs in certain areas but Yamaha does not care what their consumers want. Give me a real electrical generation system for one. A belt driven alternator if you will.

As poor as the flushing system might be, what else can Yamaha say but to flush, flush, flush. Better to flush and maybe do a small bit of good than to not flush at all.

Now as a solution to your problem have you thought of using a horse trough filled with water into with the lower unit can be lowered? Or a flush bag? I have used same and can confirm that the water in the trough will get hot. I suspect hot enough such that the thermostats are fully opening.

Pretty good, not bad, I can't complain. Because actually, all them engine brand designs are just about the same.

[fairdeal]

2. Can a small hole be drilled into the face of the T-Stat cover to allow more water to pass through? Like a small hole drilled in the center of the blue mark in the photo above.

I actually tried that. Must have some record of the result; I don't recall but doubt it made much difference.

[HMBJack]

Panasonic - Good point. I might try flushing it on the muffs alone. I however am not confident it will reach 160 degrees but perhaps.

Boscoe - What percent of Owners of the 3.3L V6 four strokes pull their T-stats every year? Or every 5 years for that matter? I am in the very salty brine of ocean off San Francisco. Because of the pathetic design of the flush system in these engines, I agree with you that an annual clean out of the bores is necessary. Kind of like having to remove the fenders of your car to do an oil change. I know you can't throw mud at Yamaha here but I also know you know what a crappy design this is. And the flush, flush, flush message from Yamaha is a joke.

The final take away here is:

Whether you flush on muffs or the garden hose fitting - Don't think for a minute that flushing actually removes salt in your corrosion prone T-stat bores. The salt stays there and accumulates after every trip in the dead end street of your T-stat bore.