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Old Jul 15, 2011 | 10:26 PM
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Default DIY thermostat delete

I did this and the car has been running a lot cooler. I'm logging coolant peak temps of 184 degree F in nearly 100 degree weather and before it would peak 202+. I also have a full coolant bypass so that also contributes to the lower temps.


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Old Jul 15, 2011 | 10:47 PM
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I thought about doing this before.

Is the coolant temp gauge stable?
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Old Jul 16, 2011 | 05:59 AM
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Not saying that what you did is bad or doesn't work, but on some engines it can actually be risky. Basically the water flows too fast through the radiator and doesn't allow proper cooling. Engines CAN actually run hotter that way. A nismo stat would be a safer choice. I know my vq40 runs a max of about 181F with it.
However that aside, they do cost $100+ dollars. And since you are monitoring your temps and the stat delete appears to be doing well on your engine, I guess on the vq35 the flow isn't too bad and it still allows good cooling. Good job guy.
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Old Jul 16, 2011 | 06:04 AM
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This was a trick on the mustangs years ago. Way back on the 5.0s. I can't remember what the deal was and why it was a bad idea.

I guess as long as you monitor the temp it should be ok.

Does this affect long cruises or stop and go?
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Old Jul 16, 2011 | 06:15 AM
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You can drive like that for a while. As long as you dont need your heater.
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Old Jul 16, 2011 | 06:28 AM
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How did you block off the engine block exit for the thermostat? Any ses codes? More pics please
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Old Jul 16, 2011 | 06:43 AM
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Originally Posted by ImWeeZzel
How did you block off the engine block exit for the thermostat? Any ses codes? More pics please
He just remove the springs so therefore the coolant keeps flowing through the thermostat. This way the engine never need to take time to warm up and such.
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Old Jul 16, 2011 | 07:41 AM
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Originally Posted by Itzcashew
You can drive like that for a while. As long as you dont need your heater.
I have full heat as before. Before this I had a long warm up period in the winter with the full coolant bypass and now it's going to take longer. But I'm not bothered by it. I can let the car idle a bit before driving in the winter. I do that anyway.
Originally Posted by ImWeeZzel
How did you block off the engine block exit for the thermostat? Any ses codes? More pics please
Not sure about your question but I am using an HR/VHR thermostat housing with a full coolant bypass.
Originally Posted by midz350
I thought about doing this before.

Is the coolant temp gauge stable?
I'm logging the temp through an OBD scanner.

Originally Posted by rdrfronty
Not saying that what you did is bad or doesn't work, but on some engines it can actually be risky. Basically the water flows too fast through the radiator and doesn't allow proper cooling. Engines CAN actually run hotter that way. A nismo stat would be a safer choice. I know my vq40 runs a max of about 181F with it.
However that aside, they do cost $100+ dollars. And since you are monitoring your temps and the stat delete appears to be doing well on your engine, I guess on the vq35 the flow isn't too bad and it still allows good cooling. Good job guy.
I can see that happening with radiators that don't have enough cooling fins and channels for the water to be delayed and cooled, or cars that have higher idle speed causing the water to move fast before it can cool, or cars that don't have a temp sensor to detect the water temp and turn on the fans. I would definitely happen in very old cars where the radiators had a straight through design. I also did this on a 94 Ford Econoline straight 6 motor and you can visually see in the radiator neck the water moving through the radiator at a fast pace but it did not overheat and also ran cooler. The temp gauge was a lot lower after warming up.
Originally Posted by gidiup
This was a trick on the mustangs years ago. Way back on the 5.0s. I can't remember what the deal was and why it was a bad idea.

I guess as long as you monitor the temp it should be ok.

Does this affect long cruises or stop and go?
I noticed that the temp gets lower the faster the car moves. Say 60mph with light throttle I see dip into to the low 170s. NA with a bigger radiator and stronger fans, I'm expecting to hit 160s.

Last edited by Andrei; Jul 16, 2011 at 08:07 AM.
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Old Jul 16, 2011 | 08:07 AM
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Unless it's a racecar or the car overheats their's no reason to remove the thermostat.
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Old Jul 16, 2011 | 08:30 AM
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I can see it extending motor service life and it's good for anyone driving harder than normal. I can see it being beneficial for a car that is FI also.
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Old Jul 16, 2011 | 09:10 AM
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Originally Posted by Andrei
I can see it extending motor service life and it's good for anyone driving harder than normal. I can see it being beneficial for a car that is FI also.
You do understand the principle of a thermostat right? It's not "good" or nor will it extend the engine life.
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Old Jul 16, 2011 | 12:42 PM
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Originally Posted by Flo-ridaZ33
You do understand the principle of a thermostat right? It's not "good" or nor will it extend the engine life.
A thermostat reduces cold start emissions by bringing a motor up to operating temperature faster by staying closed before the operating temperature is reached. And it also means you get heat faster out of the AC.

The fact that I am seeing lower coolant temp is very good in my point of view.
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Old Jul 16, 2011 | 01:30 PM
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I forgot that our thermostat and housing is a one piece part, doh'.

Now I see what you did there...
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Old Jul 16, 2011 | 01:33 PM
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Originally Posted by Andrei
A thermostat reduces cold start emissions by bringing a motor up to operating temperature faster by staying closed before the operating temperature is reached. And it also means you get heat faster out of the AC.

The fact that I am seeing lower coolant temp is very good in my point of view.
why is lower coolant temp better in your opinion?
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Old Jul 16, 2011 | 05:45 PM
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Originally Posted by Andrei
A thermostat reduces cold start emissions by bringing a motor up to operating temperature faster by staying closed before the operating temperature is reached. And it also means you get heat faster out of the AC.

The fact that I am seeing lower coolant temp is very good in my point of view.
You have more engine wear on start up than any other time in a engine's life cycle... running cool is relative. The longer it takes the engine to achieve the temperature it requires the more wear your inducing on the engine, some engines start developing sludge at this state of the engine's life cycle(if not changed often). The A/C system has nothing to do with the cars cooling system but Heating does. It's pretty obvious that if your not racing the vehicle or can't afford a thermostat b/c your is bad... their's no reason to replace the thermostat.
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Old Jul 17, 2011 | 06:59 AM
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I'm still baffled by doing this. The stock opens between 170 - 180. If you run the coolant full time you won't give the coolant a chance to cool off in the radiator.

Why don't you just get an Nismo stat? They open at 150ish.

Still not sure if this is a really good idea. The engine needs to get to a certain temp so parts can expand and operate normal.

I hope not but I see a piston issue in the future.
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Old Jul 17, 2011 | 01:34 PM
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Originally Posted by gidiup
I'm still baffled by doing this. The stock opens between 170 - 180. If you run the coolant full time you won't give the coolant a chance to cool off in the radiator.

Why don't you just get an Nismo stat? They open at 150ish.

Still not sure if this is a really good idea. The engine needs to get to a certain temp so parts can expand and operate normal.

I hope not but I see a piston issue in the future.
I would swear that the Nismo T stat is 180 to 190
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Old Jul 17, 2011 | 07:58 PM
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Originally Posted by Flo-ridaZ33
You have more engine wear on start up than any other time in a engine's life cycle... running cool is relative. The longer it takes the engine to achieve the temperature it requires the more wear your inducing on the engine, some engines start developing sludge at this state of the engine's life cycle(if not changed often). The A/C system has nothing to do with the cars cooling system but Heating does. It's pretty obvious that if your not racing the vehicle or can't afford a thermostat b/c your is bad... their's no reason to replace the thermostat.
I don't see that happening once oil flows. Yes it's true that on a cold start oil settles and the valve train and cylinder sleeves/piston rings get heavy wear as the motor cranks but once the motor starts and oil flows over moving parts I think it's perfectly fine.
Originally Posted by gidiup
I'm still baffled by doing this. The stock opens between 170 - 180. If you run the coolant full time you won't give the coolant a chance to cool off in the radiator.

Why don't you just get an Nismo stat? They open at 150ish.

Still not sure if this is a really good idea. The engine needs to get to a certain temp so parts can expand and operate normal.

I hope not but I see a piston issue in the future.
Apparently mine cools just fine idling and moving. I logged the temp.

Last edited by Andrei; Jul 17, 2011 at 08:03 PM.
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Old Jul 18, 2011 | 04:43 AM
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Originally Posted by terrasmak
I would swear that the Nismo T stat is 180 to 190
154.6 vs 169.5 (stock)
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Old Jul 19, 2011 | 12:15 PM
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Anyone know what temperature the coolant is actually supposed to be at? I'm guessing the engineers didn't just pull a number out of their *** and say that is what we should set the thermostat at.
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