Thermostat - lowering temp - beneficial or bad for ECU

[huyduchoang]

My NSX take a bit long to warm up on cold days... so I'm going to replace the thermostat and in the meantime replace the coolant on my next oil change.

My question is... if I get a thermostat 10 degrees lower will I actually benefit from having a cooler running car. Or will the ECU run in loop causing a lost in gas mileage and lessen performance. I know nothing about the ECU or themostat - i read about people lowering the thermostat for better performance and cooling... (a flaw in the design of the NSX?) but if that was the case I think honda engineerers would be fired.

Is everyone running at the middle mark on the temp guage?
my car is running right on the middle at norm temp.

 

[gheba_nsx]

I think it would be of no benefit at all (maybe the opposite ) or it would have been done by Honda already (since it is a cheap and obvious thingt). Making you want to go lower of another 10 degree... and so on until you hit the absolut zero temperature!

 

[Larry Bastanza]

huyduchoang,

I agree with Gheba, not recommended to change the thermostat temp. Could you describe what "a bit long to warm up" is??

HTH,
LarryB

 

[nsxtasy]

Not recommended. Just get a stock thermostat if you need to replace it.

What's funny is that this was just asked, and answered, in yesterday's Chicago Tribune:

Q. If you remove your thermostat in the summer, will the engine run cooler or hotter? I was told that it would run hotter. Also by putting a thermostat in that is 10 or 20 degrees higher than called for in the winter, will you do any damage to the motor or heating system?

B.O., Chicago

A. Don't touch that thermostat. Installing a colder one in the summer can make the engine run cooler, but the emission control system will be screwed up. It relies on the correct engine temperature to work properly. You won't get any more heat or get it any faster by installing a hotter 'stat in the winter. Don't mess with it.

 

[huyduchoang]

I'll stick with the acura oem thermostat. thanks for the suggestions. The warm up may take 5 minutes... actually i'm not sure but it takes much longer then my acura 3.2TL. I might as well replace the thing as a precaution since I am due for a coolant change anyways.

honda now sells premix bottles of anti-freeze and its the same price. so instead of buying just one bottle I have to get two bottles. what a scam.

 

[nsxtasy]

honda now sells premix bottles of anti-freeze and its the same price. so instead of buying just one bottle I have to get two bottles. what a scam.

Not necessarily. The service director at the biggest servicer of NSXs in the Midwest has noted that they are getting much, MUCH better results using the premix bottles of anti-freeze, because Honda is controlling the quality of the water that is mixed with the coolant for the pre-mix. They had been encountering serious problems with owners who had been mixing the previous coolant with tap water, due to the poor water quality in the area. So the pre-mix turns out to be much better for the car. I can't speak for the pricing, though.

 

[huyduchoang]

Oh I see! So its good news! Great!

 

[saxonsaxon]

Bad water for coolant

If the water is so bad than what the hell do you guys make your tea with??????

 

[huyduchoang]

i used distilled bottle water to mix with my coolant... tea either boiled or microwave the water from the h20 cooler

 

[Gerry Johnson]

Just to let you know, the cooler a motor runs the faster it will wear. A motor running at 210 degrees will wear less and make more power than a motor running at 170.

 

[gheba_nsx]

Gerry,
good input!

This is something I did not take into account when answering huyduchoang above in the thread. It is also possible that Honda did put into equation "wear vs power" and also they did not go for the best thermostat setting from the beginning since there was no absolute best option... all depended on what you wanted to achieve (wear, power ?).

 

[Supercar]

How long

So how long does it exactly take for ur NSX to warm up every morning? (In the summer for u, coz I am in a hot country). My NSX seem to take the longest time to warm up compared to my other cars. I need to know if I need to change my thermostat as well.

Thanx in advance

 

[gheba_nsx]

My NSX takes 10-15 minutes to warm up properly, depending on the external temperature and the driving during the warm-up phase. You should not watch the water temperature to decide if the NSX is warm enough but the oil pressure.

A quick way however (experimental, noticed over several times) is to wait that the water temperature reaches the correct value (needele in the middle) and wait other 4 minutes.

This works on my car, YMMV.

 

[Supercar]

Well I guess that is just about right. 10-15 mins of the water temp needle to reach mid value. I'm just curious how my other car, with a bigger engine (BMW 735li) takes a little shorter time to warm up.

Thanx Gheba

 

[hlweyl]

I've been trying to pay attention to how fast my NSX warms up. My car is garage kept so it does stay about 15 degrees warmer than the outside temp.

I also have concerns that the car is taking too long to warm up. 15 minutes into my drive today (about 35 degrees F) and the water needle was still on the lowest hash mark!!! About 25 minutes into the drive the needle was in the middle but if I turn the heat on the needle drops again.

Is this doing damage to the engine? I always heard that warming the car up in the driveway is not always recommended, I usually only sit for a minute before I start my commute. Should I let the car warm up more before I leave???

 

[gheba_nsx]

Strange! My car is warm after about 15 minutes without leaving it idle before driving,. I switch it on and drive right away...

Now I am wondering if my car is strange but I am on my third NSX and the behaviour is common on all three.

Here it is 40-50 F at the moment...

 

[huyduchoang]

Yes in fact my car does take a very long time to warm up fully. Its about 40 degrees and takes at least 10 minutes of actual driving to get upto normal operating temp.

I usually let it idle for a few minutes - I don't exceed 2000-2500 rpms until its fully warmed up just to prevent any excessive wear on the engine.

 

[Autophile]

This may be obvious, but it should be noted here that the reason why the NSX takes so long to heat up is it has a larger reservoir of water than most cars of similar engine size. The engine is behind the passenger cockpit, yet the radiator is in the front of the car. There is a lot of water in the coolant lines connecting the two. The extra hose/pipe length provides both more material to heat, and more surface area to cool the water along the way.

Actually, nevermind.... if the thermostat is working properly, then it doesn't matter how much water is behind it for the engine to heat up quickly.

 

[huyduchoang]

nevermind... hehe - maybe i'll get one of those oil heat dipsticks - wonder how they work and how benefitical they are.

 

[ak]

I also have concerns that the car is taking too long to warm up. 15 minutes into my drive today (about 35 degrees F) and the water needle was still on the lowest hash mark!!! About 25 minutes into the drive the needle was in the middle but if I turn the heat on the needle drops again.

Is this doing damage to the engine? I always heard that warming the car up in the driveway is not always recommended, I usually only sit for a minute before I start my commute. Should I let the car warm up more before I leave???

If you look at page 58 of the 91 service manual, it shows that in addition to the coolent in the engine, it also has to warm up the coolent going to the heater core and the expansion tank in order for the thermostat to pop open.(however not radiator) I think 10-15 min warm up is normal for NSX...I have not heard of anyone's NSX warming up much faster.

Hlweyl, I'm not sure if what your car is doing is normal. My theory is that, if you turn on the heat before the thermostat pops open, then it's like adding a small radiator in the cooling system and it's possilbe that it cools down the coolent temp. Does this happen even when the car has been warm for a while? If yes, then the thermostat is stuck open possibly?

 

[canuck]

honda now sells premix bottles of anti-freeze and its the same price. so instead of buying just one bottle I have to get two bottles. what a scam. [/B][/QUOTE]

It is not a scam. It is also a newer "long-life" formula. It has 3-4 times the serviceable life span of the older coolant. This means it is actually cheaper in the long run.

 

[hlweyl]

Does this happen even when the car has been warm for a while? If yes, then the thermostat is stuck open possibly?

Yes, once the car is warmed up, i.e. needle about half way in the temp gauge, if I turn the heat on full blast the temp gauge goes down to about the quarter mark.

I guess it is possible that the thermostat is stuck, but I always thought that if a thermostat failed, they fail in the "shut" position. I could be wrong though.

It seems common that the NSX just takes longer to warm up. I guess it could be the design of the engine/radiator/ air ducts that keeps the car running cooler. This is my first winter with the NSX so i'm not sure what is normal. The owners manual doesn't mention anything about running too cool.

I assume that the temp gauge only monitors the temp of the coolant, even if it runs cold that doesn't mean that the oil isn't still doing the job.... I hope!

 

[ak]

Yes, once the car is warmed up, i.e. needle about half way in the temp gauge, if I turn the heat on full blast the temp gauge goes down to about the quarter mark.

Well I did this test on my car and the needle never went down after I turned on the heat full blast. It was about 30-35F when I did it.

 

[hlweyl]

I'm starting to wonder if I have the proper thermostat installed, or if there is a thermostat at all in there???

 

[ak]

I'm starting to wonder if I have the proper thermostat installed, or if there is a thermostat at all in there???

I"m not sure. Have you gotten it replaced recently?