67 60hp thermostat operation

[Lion hunter]

Can someone explain the theory of operation on a 1967 60hp thermostat.

1. How does the small thermostat operate?
2. Is there a bypass that allows water through before it opens?
3. Also, the brass nipple on the thermostat, I assume that this heats up and raises the valve above it. The nipple was loose and able to be pulled from the body. Is this correct?

This was the 1st time I ever tore in this type of thermostat. The top 2 pieces came off as one part so I set it aside to inspect the rest of the body. Needless to say it blew up while sitting there and I spent the next hour looking for the 2 springs. I had to enlist the help of my 4 yo and bribe with candy to get her to crawl around and find the last spring. Kind of handy that I had already found one to show her an example. I'm pretty confident that it is all together correctly now, but I am curious as to it's operation.

Other question: I replaced the impeller just because the motor is new to me. The old impellar didn't look like it had any wear what so ever. In fact there is a "rib" where it looks like the top and bottm halves are molded together. That rib on the old one is still present. When this occurs does anyone just keep it for a spare? I was thinking of pouring oil on it and sticking it in a ziploc bag. Most everyone I have ever replaced needed replaced so I'm wondering if it's worth the $25 to keep this one.

 

[Lion hunter]

Re: 67 60hp thermostat operation

After much searching I think I found the answers to my questions. The thermostat is a "vernatherm". Helps to know the correct nomenclature when searching.

The pin is supposed to loose and should pop-up at about 140 degrees. Does this sound correct? I am going to pull it back out and test tonight and see if it works.

I'm guessing that there is no bypass that lets a small amount of water through before it opens. Basing this on the fact that when I put a hose on the pick up tubes no water flowed out the exhuast.

 

[F_R]

Re: 67 60hp thermostat operation

After much searching I think I found the answers to my questions. The thermostat is a "vernatherm". Helps to know the correct nomenclature when searching.

The pin is supposed to loose and should pop-up at about 140 degrees. Does this sound correct? I am going to pull it back out and test tonight and see if it works.

I'm guessing that there is no bypass that lets a small amount of water through before it opens. Basing this on the fact that when I put a hose on the pick up tubes no water flowed out the exhuast.

OK, you asked and here it is:

When you start the motor and it is below operating temperature, the vernatherm is retracted and the plastic valve above it is closed. A small bypass groove in the flat side of the valve does allow a mist to be discharged. When the valve is closed, water pressure forces the other valve open, which is a return line to the water pump, through the second tube. At this time, it is in recirculation mode--the water keeps going around till it is warm enough to expand the vernatherm.

Once the vernatherm valve opens, water flows through it and is discharged, and fresh cool lake water replaces it. Now the cool water has to be warmed up and the vernatherm may put it back into recirculation mode. The point here is that the vernatherm is constantly sampling the coolant temperature and opening and closing as necessary to maintain proper temp. That is why the amount of water being discharged is not constant.

Yes, the pin is loose in the vernatherm.

 

[Lion hunter]

Re: 67 60hp thermostat operation

Thank you FR,
That is the exact answer I was looking for.

 

[Swivelhart]

Re: 67 60hp thermostat operation

I have the same motor except it's 1965. I assume all is the same when talking thermostat. My question is what part number is this thing. I am pulling my hair out trying to find a part number. I don't have a parts manual yet!