1983 85HP: Thermostat orientation- which way is correct?

[Benz Mondi]

This is a pic of my thermo as it lay when I removed it after a slight beaching (the cause for my prior overheating thread). I had not previously touched the thermo since I bought the boat in 2010. (I've since replaced the thermo, dropped the lower unit, flushed out the motor with a garden hose from the thermo port and replaced the whole impeller set, including the housing- though it still looked great). I was watching some vids on youtube about OB maintenance when I noticed that the "stem" end of the thermostats I had viewed were placed toward the center of the engine in the flow of the water. In my pic, the stem end is located away from the center of the engine and in the thermostat housing cover. Which way is it supposed to be? Thanx.

 

[Jiggz]

Re: 1983 85HP: Thermostat orientation- which way is correct?

As far as your model is concerned, yes it is oriented correctly. Depending on the model some do have an opposite orientation.

 

[Frank Acampora]

Re: 1983 85HP: Thermostat orientation- which way is correct?

Chrysler and early Force thermostats always puzzled me. They are installed backward from what would be considered correct. Typically the thermostat is inserted so the plug and spring is toward the block--the hot water. Chrysler and early force installed the opposite way. Your thermostat is in correctly, with the spring inside the cover. In fact, the hole in the head is not large enough to place the thermostat in opposite.

 

[jerryjerry05]

Re: 1983 85HP: Thermostat orientation- which way is correct?

They should only go in one way???
Spring OUT!
If you look at the parts diagrams they will show the correct orientation.

 

[Benz Mondi]

Re: 1983 85HP: Thermostat orientation- which way is correct?

Though I wrote earlier that I had "replaced the thermo", I had actually only purchased one and had not installed it because I thought I could rejuvenate the old one with a dip in CLR remover. Then I went to re-install the old one and found that it could only go in with the spring outwards. I've now installed the new one which is rated for 130 degrees. My old one I believe was rated for 110, per some of the threads I had read here, though I couldn't find any markings. It never opened even up to 155 degrees. I ran it today continuously for about 15 minutes on the muffs. I then used an infra-red temp gun and didn't find any spot on the engine over 125 degrees. Does that seem optimal? Should I have stayed with 110 degrees? thanx.

 

[jerryjerry05]

Re: 1983 85HP: Thermostat orientation- which way is correct?

The same thermo was used in the 1979 through 1991.130d
It should have a number engraved on the end.

 

[Jiggz]

Re: 1983 85HP: Thermostat orientation- which way is correct?

I believe you are running optimally at 125 degrees considering it is way more inside the block. But as long as the t-stat is validated to be opening you should be OK. How do you know it is opening, the engine heat sensor or buzzer do not sound off while running the engine. With a non-working t-stat the buzzer can sound off (even on muffs) as soon as less than 3 minutes of idling.

 

[Benz Mondi]

Re: 1983 85HP: Thermostat orientation- which way is correct?

I believe you are running optimally at 125 degrees considering it is way more inside the block. But as long as the t-stat is validated to be opening you should be OK. How do you know it is opening, the engine heat sensor or buzzer do not sound off while running the engine. With a non-working t-stat the buzzer can sound off (even on muffs) as soon as less than 3 minutes of idling.

I boiled the new and old t-stats on the stove and noted the water temp when it opened or didn't open at all in the case of the old one. thanx.

 

[Jiggz]

Re: 1983 85HP: Thermostat orientation- which way is correct?

From the look of the old one I would have not expect it to operate within parameters anymore considering the scale build up shown.