Thermostat O-Ring - HELP?! Where does it go?

[Matt-Max]

Hi all,

I know it's a daft question, but I have changed my thermostat and ordered new seals and o ring to go with it, but I'm agonising over where to place the smaller o-ring. When I took it apart I thought there was no o-ring present (which would have explained the gentle weeping from the seal) but looking closer there seems to be a groove halfway up the inserted section which may have the old o-ring in it.

DO I a) dig out the soft rubber in the groove half way up the housing shaft and put it in there , or B) fit the orange all the way up to the top so it compresses at the rim.

I've scoured the posts, the internet and the exploded diagrams, but am none the wiser. Anyone done this who knows the correct answer?

 

[MaxMidnight]

My best guess would be for where the drain cock elbow goes into the t.stat housing?

 

[Matt-Max]

Ignore above post - I went for optiona) on the assumption the last person in there wouldn't have been stupid enough not to have one.

I'm really p*ssed off with the replacement seal 11H-12412 though. It creates a lousy fit and rolls up, the cut out makes it unstable and you can't slide the housing cover back in with it in there. If you fit it neatly to the top of the thermostat, you can't get the thermostat fully home.

 

[02GF74]

Does the Haynes Manual not cover all the seals and o-rings?

 

[Matt-Max]

Does the Haynes Manual not cover all the seals and o-rings?
View attachment 73071

If I had a Haynes manual that would really help. Time to get buying! The seal here is a complete round, the one supplied has a nasty cut out notch leaving a really weak and insecure fit. With a massive bite out of the rubber it twists and threatens to lose its ability to actually be a seal.

I will pop up some images in a bit, but I'm going to use the old one. I really don't like this and it doesn't match the parts diagram or the Haynes pics. Thanks for those, really helpful - I've just ordered a copy!

 

[Fire-medic]

This may help, now or in the future.

http://vmoa.net/VMX12-Service-Manual01.pdf

 

[Matt-Max]

Thanks @Fire-medic

Here are some images to illustrate my frustrations.
1. Different thickness and weak spot on replacement


2. Different internal diameter, new one much tighter.


3. Old one fits flush to outer edge of thermostat.


4. New one is proud all round


5. Nice fit on old, seats no bother.

6. New one is tight, needs stretching and starts to curl slightly at cut out.

 

[Matt-Max]

Have a look at the two rubbers under light pressure as they would be in the housing.

Original full rubber, nice and flush, flat to all surfaces..

And the supposed replacement under light load, curling up and becoming misshapen.

Don't know about you, but thats a no for me!

 

[Fire-medic]

I didn't see the earlier posting, just going-off the pics on this page, did you get the gasket from Yamaha? Do you still have the part # bag in-which it came? You can use the website parts reverse-look-up to see what you have-there. It certainly doesn't appear to be seating properly.

https://www.ronayers.com/oemparts/c/yamaha_motorcycle/parts

 

[Matt-Max]

@Fire-medic I ordered from Fowlers in Bristol UK. The parts were all Yamaha OEM and the number on the package matched those on the diagram and even those you can find elsewhere online. Bizarre isn't it.

 

[Tony.H]

Is that the original OE thermostat it looks a bit different to the one in my 1988 . The cut out in the rubber gaskets lines up with the vale shown at 6 oclock position in the picture

 

[Matt-Max]

@Tony.H Thanks for the image - that would certainly explain that, I have however bought an OEM replacement which didn't have the same valve as yours. The one which came out didn't either, so I'm not sure when they changed or whatever, but it's all back in now and watertight.