Mercruiser 305 V8 which upper thermostat gasket?

[Josephmcg]

Hello all, I have a 1982 Mercruiser 228, Chevy 305 5.0 V8, Alpha 1 Gen1. It used to have the log style exhaust manifolds where the riser is on the rear of the manifold. I have since upgrade to the later style, where the riser is in the center of the exhaust manifold, and the later style thermostat housing.

My question is the upper thermostat housing has 3 different types of gaskets available. I am not sure which of the 3 I need in my particular situation. One has a pin hole in it, one has a notch in it, and the last one has a block off. I do have the the thermostat housing that has the T-valve with a ball and spring on each side. Any help would be greatly appreciated. I will post pics if that will help, thanks-joey

 

[Josephmcg]

[No message]

 

[AShipShow]

If I recall correctly, it has to do something with either the temp thermostat your motor has or the type of cooling system... However, someone much smarter than me will be by to help you out

 

[Josephmcg]

The boat always had a 140 degree thermostat in it

 

[achris]

Can you lift the thermostat cover and show us the housing without the cover?

Chris........

 

[Josephmcg]

Sure, the forums are limiting me from posting, guess I cant post more then 5 posts per 24hrs

 

[Josephmcg]

Well I answered my own question by looking up the different cooling systems, the notched gasket is for closed cooling systems, and is the new style which superceded the pin hole gasket. And the block off gasket, which is the one I need, is for standard cooling design 1(raw water) systems... incase anyone would like to know