"Custom" thermostat?

[mitch184]

So still working thru this motor...….. came across this. Seems the previous owner drilled and tapped a hole in the thermostat housing ran a housing from the nipple to the tell tale. Any idea why? Some "performance" upgrade? The flush kit hose from the exhaust cover is just pinched off since the flush kit is missing as well.

[robert graham]

Maybe did this to check water flow at/through thermostat..

[TownsendsFJR1300]

If not using muffs, (even if so), you may want to put the factory flush parts back on.

If he had a hose connector connected to his "modification", I'd guess it'd be to fresh water flush around the thermostat.

I have no idea what he was attempting to do. Show water is making it to the top of the powerhead?

[zenoahphobic]

Probably usefull for all of the above.
I like the idea that you can reverse flush through that fitting, albeit slow through the only small hole in the thermostat as the thermostat will be closed with cold water.

[BQUICK]

I've run a hose between t-stat housings so water can cross over up top as well as lower crossover which often ends up clogged. Greatly aided cooling on older motor with semi clogged system.

[99yam40]

I've run a hose between t-stat housings so water can cross over up top as well as lower crossover which often ends up clogged. Greatly aided cooling on older motor with semi clogged system.

I was trying to remember who on here ran a hose like that not too long ago.
And though maybe you had sold the motor to the OP

[TownsendsFJR1300]

Probably usefull for all of the above.
I like the idea that you can reverse flush through that fitting, albeit slow through the only small hole in the thermostat as the thermostat will be closed with cold water.

That hose might be 1/4" ID tops.... I don't know how, (I guess with lots of trouble), you'd hook up a garden hose to that fitting.

Actually, on the other side of the thermostat (in the block) is where the bad corrosion occurs. Even with "this set up", when using the factory flush(not even installed), water is still AWAY from the block (wrong side of the thermostat)

With that said and the way it's hooked up, seems to be a homemade tell tale (as the factory set up is clogged/ not working).


**I like the idea posted sometime ago about opening up the thermostat vent hole a tad to allow fresh water to get in that area prone to corrosion (with the thermostat closed).
Obviously not too big to make the thermostat useless....

[mitch184]

So it sounds like it’s not a bandaid fix something else then? Would rather not have to buy a new thermostat housing but want it correct. It’s not bypassing the thermostat or reducing the cooling I take it.

Where does the normal tell tale come from on these then?

[boscoe99]

So it sounds like it’s not a bandaid fix something else then? Would rather not have to buy a new thermostat housing but want it correct. It’s not bypassing the thermostat or reducing the cooling I take it.

Where does the normal tell tale come from on these then?

What model motor?

[mitch184]

90tlrd ... 2005

[boscoe99]

My best guess re the tell tale hose and nipple.

[boscoe99]

So still working thru this motor...….. came across this. Seems the previous owner drilled and tapped a hole in the thermostat housing ran a housing from the nipple to the tell tale. Any idea why? Some "performance" upgrade? The flush kit hose from the exhaust cover is just pinched off since the flush kit is missing as well.

The flush kit seems to be an option. Might not have been installed on your motor.

[mitch184]

So sounds like it may have been done to mitigate potential cooling issues and it's fine to leave as is? I really don't need a flush kit as this is a freshwater motor.

[TownsendsFJR1300]

[QUOTE=mitch184;n213484]So sounds like it may have been done to mitigate potential cooling issues and it's fine to leave as is? QUOTE]

Does sound like it. As you don't need the flush kit, I would find out how the engine tell tale SHOULD BE SET UP and correct it accordingly.

You can simply cap off that fitting but Yamaha didn't design that cover for a tell tail hose..

It can very well be hiding an issue (clogged hose, WP, ??). You'll only know once the engine hoses are set back up correctly...


*I'd be curious if there's even a thermostat under the cover. I'd definitly pull the cover (or hose) and see if there's one there.
You REALLY SHOULD have a thermostat installed...

[robert graham]

If you decide to remove this fitting and tube, just plug the fitting hole with JB Weld.....who knows how much$$$ Yamaha gets for that thermostat cover?