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Discussion Starter #1
My flowkooler thermostat for my Cleveland has a stamp on it that says “this end toward radiator.” I just realized that I forgot to pay attention to that when I installed it and filled the cooling system.

Does it really make a difference which side is facing forward? I’d rather not have to drain any coolant to open it up if I don’t have to.

Thoughts?
 

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Oh, it does. The "bulb and spring" must face DOWN into the block and you also need to make sure you installed the "block off washer" first. The 335-series has a unique bypass system where the thermostat seals the bypass when it opens.

769934
 

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Discussion Starter #4
Thank you. I had it in properly. I was thinking that it had to be spun in a certain orientation with the stamping toward the radiator - which doesn’t quite make sense. I now realize that stamping is probably intended to make sure it is not installed upside down.
 

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Engine is stat specific
You need the correct one that has the extended hat

The RT139 fits and will work but does not have the extended hat.

Just Google correct 351C stat
 

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Thank you. I had it in properly. I was thinking that it had to be spun in a certain orientation with the stamping toward the radiator - which doesn’t quite make sense. I now realize that stamping is probably intended to make sure it is not installed upside down.
I misunderstood the original question.......
 
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