How Do I remove the Thermostat from the Housing, Ford 5.8

[KM7]

How do I remove the thermostat from the housing on a 91 Ford 5.8?

The shop manual only says, "The Thermostat is held in place with an O-Ring. Pry the O-ring out of its groove, then lift the thermostat out of its housing."
The inside of the housing is a bit rusted, and it is hard to see the O-ring. I don't want to damage anything trying to get it out.
I could just leave the thermostat in place as it seems to be working fine.
Any suggestions?

 

[kenny nunez]

Just dig out the “O”ring with a pick. The thermostat will then come out. If you know someone with a blast cabinet would help. Or with a sharp angled scribe to clean out the “O”ring groove.

 

[KM7]

Thank you. I found a video on YouTube that shows the O-ring being removed with a sharp pick. I should be able to get it out.

 

[Lou C]

Yep, pry it out with a pick. I like to test them in a pot of hot water with an old-fashioned radiator thermometer to make sure they open at the specified temp (160*F). OMC/Volvo thermostat housings and design are very simple compared to Merc. In fact the whole cooling system only has like 4-5 hoses and none of those plastic fittings that Merc is so fond of.

 

[KM7]

The thermostat seems to be working fine. With the housing off the engine. the spring is holding it closed. The engine warms up and then stays right near the middle of the range on the gage. The port elbow getting hot is a different issue. There is a separate post on that. Should I just leave it alone?

Never mind, I got the thermostat out. I will change it. It's an easy fix and cheap insurance.

 

[Lou C]

I change them as soon as the temps on the gauge are not normal (160-170 I feel is normal). Most often a piece of rust gets stuck in the stat and makes it run too cool.