Delete Thermostat

[Justin J]

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.

 

[Lee's Automotive]

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.

If you want your engine to run right and have cabin heat youll need a thermostat and yes it will throw a code and can also cause it to run rich all the time aka open loop operation which will eventually destroy the catalytic converters

 

[J_C]

No, it does not break often, and is not very expensive to replace if you DIY.

 

[Justin J]

If you want your engine to run right and have cabin heat youll need a thermostat and yes it will throw a code and can also cause it to run rich all the time aka open loop operation which will eventually destroy the catalytic converters

Could you elaborate it a little more? I don’t understand why it will cause engine to run rich.

My so-far understanding is, the thermostat diverts coolant flow. When temperature is low, it closes the door to radiator but limits it to the bypass hose only; when temperature has reached, it closes the bypass and opens the door to radiator hoses. When the thermostat is deleted, coolant will go into BOTH hoses at the same time, isn’t it better for the engine cooling (except it warms up a little slower but I don’t care).

Thanks!

 

[Justin J]

No, it does not break often, and is not very expensive to replace if you DIY.

I just tested mine in boiling water and it’s broken (stuck closed). Seems this has been for quite a while, without any symptoms of overheating on the gauge on the dashboard. Wired.

 

[Justin J]

No, it does not break often, and is not very expensive to replace if you DIY.

My Honda mower has a similar device for choking. Thermo Wax choking: https://a.co/d/15yhTPf

I have deleted it and it is much simpler and saves $. The wax thing breaks/leaks in 2-3 years with light uses.

I think the car thermostat is essentially of the same principle.

 

[Mbrooks420]

Just replace it with a quality one. Very odd for it to stick closed.

The motor is meant to run at a specific temp. Keep the thermostat.

 

[Justin J]

Just replace it with a quality one. Very odd for it to stick closed.

The motor is meant to run at a specific temp. Keep the thermostat.

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!

 

[Josh P]

I'm curious what you do with all the extra parts when you are done working on your car? The thermostat is needed cause the pcm monitors the coolant temp. On cold startups, the pcm will cause the engine run rich to quickly get the coolant above 160 degrees. Without a thermostat the coolant temp will never reach operating range.

 

[Justin J]

I'm curious what you do with all the extra parts when you are done working on your car? The thermostat is needed cause the pcm monitors the coolant temp. On cold startups, the pcm will cause the engine run rich to quickly get the coolant above 160 degrees. Without a thermostat the coolant temp will never reach operating range.

Thanks! This clears my mind!

For the old parts, if I’m interested in how they work and how they are designed, I cut them open or disamble them.

Since you asked this, do you know why the thermostat manufacturer puts SUCH A STRONG SPRING on it? In my view, it’s not needed; instead, it contributes to early failure, aka, planned obsolescence!

 

[Blackhawkxx]

Get a genuine Ford thermostat that is the right temp for your car. Some aftermarket ones aren't so great.

 

[Josh P]

Thanks! This clears my mind!

For the old parts, if I’m interested in how they work and how they are designed, I cut them open or disamble them.

Since you asked this, do you know why the thermostat manufacturer puts SUCH A STRONG SPRING on it? In my view, it’s not needed; instead, it contributes to early failure, aka, planned obsolescence!

How often are you changing the thermostat? I don't know what the spring rate is (psi) on the thermostat.

 

[Justin J]

How often are you changing the thermostat? I don't know what the spring rate is (psi) on the thermostat.

This is the 2nd time, about 15K miles since the last replacement.

I just noticed the old one was not Motorcraft. I’ll DIY this time, with an OEM one in a new aluminum housing.

 

[Josh P]

This is the 2nd time, about 15K miles since the last replacement.

I just noticed the old one was not Motorcraft. I’ll DIY this time, with an OEM one in a new aluminum housing.

I've had good luck with the OEM parts, aftermarket stuff seems to be hit or miss.

 

[Rcflyer330]

The spring is there to return the thermostat valve to the closed position. Just as an added data point I am on my 4th motorcraft thermostat in my 2010 v6 with 176k miles and as of now two thermostats have stuck open and one was sticking closed. This last time I replaced the housing to Simmons aluminum one due to the original plastic housing finally leaking after 174k miles and two thermostat changes. the Simmons housing it very well made and would definitely recommend it but when you receive it before you cut the zip ties holding the upper housing on the lower housing inspect it for any damage and that the top an bottom housing are sitting correctly.

 

[BKennedy]

I've never heard of a thermostat sticking closed. If it's closed, its no longer allowing coolant to flow through the engine. It would seem like it would overheat in seconds. I've only had one fail and it was open, so it still allowed coolant to flow through the system. Some have a catch on them so if the engine overheats, the thermostat gets stuck open. In any case, they are inexpensive, easy to change, and a very important part of the cooling system.

 

[Lee's Automotive]

Could you elaborate it a little more? I don’t understand why it will cause engine to run rich.

My so-far understanding is, the thermostat diverts coolant flow. When temperature is low, it closes the door to radiator but limits it to the bypass hose only; when temperature has reached, it closes the bypass and opens the door to radiator hoses. When the thermostat is deleted, coolant will go into BOTH hoses at the same time, isn’t it better for the engine cooling (except it warms up a little slower but I don’t care).

Thanks!

So when the engine reaches operating temp it goes in to whats known as closed loop which basically tells the computer that the engine is at operating temp and it can now inject less fuel but when you do a cold start in the morning the vehicle is in open loop which tells the computer to inject more fuel until the engine has reached operating temp and once it has warmed up to operating temp it goes back in to closed loop thus injecting less fuel but if you have no thermostat the engine will run cool all the time and you will stay in open loop which means more fuel (rich condition) and eventually you can damage the catalytic converters

 

[Justin J]

Thank you all!

So when the engine reaches operating temp it goes in to whats known as closed loop which basically tells the computer that the engine is at operating temp and it can now inject less fuel but when you do a cold start in the morning the vehicle is in open loop which tells the computer to inject more fuel until the engine has reached operating temp and once it has warmed up to operating temp it goes back in to closed loop thus injecting less fuel but if you have no thermostat the engine will run cool all the time and you will stay in open loop which means more fuel (rich condition) and eventually you can damage the catalytic converters

Thank you! This is good info!

 

[Lee's Automotive]

Thank you all!

Thank you! This is good info!

Your Welcome

 

[Justin J]

I've never heard of a thermostat sticking closed. If it's closed, its no longer allowing coolant to flow through the engine. It would seem like it would overheat in seconds. I've only had one fail and it was open, so it still allowed coolant to flow through the system. Some have a catch on them so if the engine overheats, the thermostat gets stuck open. In any case, they are inexpensive, easy to change, and a very important part of the cooling system.

View attachment 436867

The thermostat for the engine in the discussion is operating slightly differently (than the pictures show), if you look at a physical one. No Matter how they are designed, a basic principle is it only opens the door to radiator when it’s HOT enough to EXPAND/EXTRUDE !