Thermostat & relief valves? '81 70hp jonnson

[imported_beck]

Well replaced the water pump and have a few questions but will go to a local omc dealer as they would be too hard to describe here.

But since I did the water pump of course I wanted to go into the thermostat well and found it very corroded.

1. There were 2 relief valves, what are they for? I'm guessing if the ther. sticks perhaps they are a safety? And would pass water.

(I plan to replace relief valves, gromets, stat and gasket, and housing gasket) Anything else I should consider?

2. What is the best way to "clean" for lack of a better word, the water passages of an outboard? I know the best thing to do is to flush when you get home but after the fact the best way now? I've heard something about vinegar and water in a barrow. What exactly does this do?

Thanks for the info.

 

[CILO]

Re: Thermostat & relief valves? '81 70hp jonnson

with regards to the vineger, i'm guessing it would remove all the calcium deposits in the water passages, similar to running vineger through a coffee maker to get the calcium deposits out of it. my only concern with doing this would be its effects on any seals in the motor. perhaps someone else has more info on this

 

[Joe Reeves]

Re: Thermostat & relief valves? '81 70hp jonnson

Salt corrosion.... I use various tools to scrape it out as good as possible, then blow it out with pressurized air. You might also spray some CRC-666 in there as I've found that to fight corrosion quite well.

The relief valves.... As the rpms are increased, the engine requires more water than what can pass thru the thermostat(s). The water pressure gets to a point where it forces those valves open in order to supply that extra needed cooling water.

Note that even with those relief valves working properly with a top notch water pump, if the thermostat is jammed shut for some reason, the engine will still overheat.

 

[imported_beck]

Re: Thermostat & relief valves? '81 70hp jonnson

Joe,

Thanks for the info. I've heard some who say to just leave the t-stat out, but then I've heard then the engine doesn't get to the proper operating temp. Would it be good to possibly leave one or both of the relief valves out?

Kinda just thinking out loud.

 

[Joe Reeves]

Re: Thermostat & relief valves? '81 70hp jonnson

Do not leave anything out. Those components are there for a reason.

 

[imported_beck]

Re: Thermostat & relief valves? '81 70hp jonnson

10-4 Joe I read you loud and clear.

I ordered the service and parts manual today.

Thanks again for the info.

Ps: This site has help me alot both with my previous 48 spl and with this new to me old 70. Not to mention I can just sit and read for hours I think yall know what I mean.

Anyway just wanted to say THANK YOU to all who take the time to read and respond.