5.7 thermostat confusion

[fstalfire]

Hi all.......I have a 1990 bayliner 2651 with a mercruiser 5.7. the thermostat housing has the check balls in it, it's all corroded and needs to be replaced but i'm reading that this design has been replaced because of design flaws but there are so many different ones i find on the net that I'm not sure what i need...any clarification would be much appreciated.

 

[Failproof]

Re: 5.7 thermostat confusion

Does your housing have any part numbers on it? Superceded numbers will follow original part numbers when you look it up. That should get you closer.

 

[Bondo]

Re: 5.7 thermostat confusion

Hi all.......I have a 1990 bayliner 2651 with a mercruiser 5.7. the thermostat housing has the check balls in it, it's all corroded and needs to be replaced but i'm reading that this design has been replaced because of design flaws but there are so many different ones i find on the net that I'm not sure what i need...any clarification would be much appreciated.

Ayuh,.... The T-stat housing has to match the drive's water pump, 'n the exhaust manifolds used....

You have an Alpha 1 drive, which uses the check-balls....

In '91, the Gen.II came out with the different water pump...

Replace what you've got, with another copy of what you've got...

 

[Brentathon]

Re: 5.7 thermostat confusion

There was a single cast iron t-stat design, that followed an earlier design that used a brass Tee. I believe the single cast iron design is no longer available, and you will likely find that it has been replaced by the original (brass Tee) design.
I like the brass Tee one better, anyway, as the brass seats do not corrode much where the plastic balls seal.
All this info should be available from Mercruiser (parts lists).