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1978 Evinrude 70HP (70873C) Thermostat

A

Avi8orKS

New member
Good Morning,

I am replacing my thermostat as preventative maintenance on my 70HP Evinrude. Old one tested ok (original), however, I wanted to check the passages to see how bad they were. They turned out normal. My question is - in both my Factory Manual and Clymer Manual, I am having a hard time determining the proper torque for the bolts. Also - I do not have access to the OMC/Evinrude gasket sealant. What is best used in place of this? Thanks in advance!
 
Thank you Racerone! That is the thread diameter not the head size correct? The head size is a 3/8" socket. Sorry - I am new to working on these motors. Would you recommend a gasket sealer? I appreciate it!
 
Hopefully you are replacing the grommets on the poppit valves.-----A very thin smear of Permatex Aviation sealer is used.-----Yes I know what the head size is on these bolts !
 
Thanks! I am indeed replacing the grommets. The poppet valves look to be in ok condition. The newer style has a seal on the poppet that seats against the gasket whereas my originals have a beveled edge. Would it be worth the upgrade? My engine looks pretty good inside for the age - I figured if it has worked for this long, just the grommets would work but I value your opinion!
 
racerone said:
Hopefully you are replacing the grommets on the poppit valves.-----A very thin smear of Permatex Aviation sealer is used.-----Yes I know what the head size is on these bolts !
Click to expand...
@racerone - do I need any thread sealant or gasket sealer on the bolts? I noticed some appear to go through the head and others terminate outside?
 
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