Delete Thermostat

[BKennedy]

I had my Explorer overheat on a summer drive up the grapevine (long mountain grade on I-5 north of Los Angeles). I didn't notice the stuck open thermostat until I changed it a few months later. Changed it just because I was addressing the overheating issue by replacing most of the cooling system.

I have a backhoe that's stored at a friend's ranch in Arizona. I encourage him to use it as much as he likes, because I know that vehicles fall apart faster by not being used than by being used.

 

[BrooklynBay]

It's a good idea to check your fan clutch. Excessive slippage could cause overheating.

 

[Justin J]

CLOSE to Radiator (top door)/ OPEN to bypass (bottom door)

OPEN to radiator/ CLOSE to bypass



The bottom smaller plate is the door to bypass.

 

[Justin J]

This STRONG /BIG spring will make the thermostat stay in CLOSED (to radiator) position in cold temperature, based on my engineering knowledge. This should be the most failure state: stuck closed, aka, fail to open! As once wax leaks, it can’t push the PIN/PISTON out any more.

When coolant Temperature drops gradually, the spring SHOULD push the PIN back in, most of the time if not always!

This spring is so strong that it will also contribute to premature failure! It has nothing to do with the whole cooling system PSI IMHO, which is controlled by the radiator cap instead.

 

[Justin J]

Thermostats are IN NO WAY DESIGNED TO FAIL IN THE "OPEN POSITION". In fact, there is ONLY ONE COMPANY called "Fail Safe Thermostats" which figured out HOW to have a thermostat fail in it's open condition and that company has a patent on their design. No other manufacturer in the world can legally sell copies of the Fail Safe Thermostat design.

Totally agree!

 

[Justin J]

The PIN works as a piston, when wax in the cylinder is heated, it explands, forcing the PIN to extrude!

Surprisingly, my bad one is made of stainless steel and copper/brass!

 

[caymanbluelongranger]

Have any of you TRIED deleting the thermostat from 4.0 SOHC? aka, run the engine without a thermostat. Did it throw a code? Thanks!

Based on my understanding so far, thermostat is an optional equipment that breaks often.

The thermostat is NOT OPTIONAL on either an OHV or SOHC engine

 

[Justin J]

Thank you all! The discussion is very good and we all learn from each other!

 

[caymanbluelongranger]

Sure.

The big spring on it keeps it closed by default,and when the wax (or other thermo expansion material) has leaked, so it will stay closed. No surprise! In contrary, it would be very odd for it to stuck open!

Virtually every thermostat failure I have experienced has been stuck open and most quality thermostats have a failsafe mode where the thermostat WILL fail open. I have NEVER, on any of MY vehicles, had an overheat problem from a failed thermostat. Failed water-pump? yes - both on a slant six and a Mondeo/Mystique 2.5. From failed radiators, and collapsed radiator hoses and failed fan viscous drives, and failed electric fans and missing fan shrouds - and that's over 55 years of driving. In about half that period of time wrenching for a living I can likely count every failed thermostat overheating problem on the fingers of one hand - definitely on two and most of those would have been on vehicles that had sat for a long period of time and the thermostat seized shut from sitting.

 

[BrooklynBay]

How does the thermostat in a car's cooling system work?

How does the thermostat in a car's cooling system work? I had to test my thermostat today and was amazed as I watched it!

auto.howstuffworks.com

 

[Mbrooks420]

Lol.....how old are you, kid. And what's your vehicle repair knowledge consist of..... Serious questions......Thermostats are IN NO WAY DESIGNED TO FAIL IN THE "OPEN POSITION". In fact, there is ONLY ONE COMPANY called "Fail Safe Thermostats" which figured out HOW to have a thermostat fail in it's open condition and that company has a patent on their design. No other manufacturer in the world can legally sell copies of the Fail Safe Thermostat design.

Funny how you say you replaced at least 3 thermostats which were stuck open......congrats.......for every three thermostats that I replaced which were stuck open, I've replaced at least 2,000 which were stuck in the closed position.

I’ve never replaced a stuck closed thermostat. I’ve replaced several stuck open. Apparently I’m extremely lucky.

My repair knowledge comes from growing up poor, driving junk, and never taking any vehicles to garages for anything other than inspections. In that time I’ve driven over a half million miles in only a few vehicles.

 

[Josh P]

I’ve never replaced a stuck closed thermostat. I’ve replaced several stuck open. Apparently I’m extremely lucky.

My repair knowledge comes from growing up poor, driving junk, and never taking any vehicles to garages for anything other than inspections. In that time I’ve driven over a half million miles in only a few vehicles.

Reading between the lines, especially the last one and the paragraphs too, you have over 1 million miles driving experience.

 

[Mbrooks420]

Reading between the lines, especially the last one and the paragraphs too, you have over 1 million miles driving experience.

That’s combined vehicle mileage, not half a million per vehicle. I’m sure I’m under the million mile mark, but probably not by a ton. I used to drive a ton in rental vehicles, and I’ve never driven less than 25,000 miles in a year in my own personal cars.

 

[Lee's Automotive]

That’s combined vehicle mileage, not half a million per vehicle. I’m sure I’m under the million mile mark, but probably not by a ton. I used to drive a ton in rental vehicles, and I’ve never driven less than 25,000 miles in a year.

Dang that's a lot of miles I average 10-15k a year

 

[BKennedy]

I'm going to lock this thread. Everyone has an opinion, thanks, thermostats fail open or closed. We don't need to argue this point anymore. That's all folks....