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Discussion Starter · #1 · (Edited)
Nismo 350Z Thermostat Swap Mod

Cost: $145
Time Needed: Less than 2hrs. Took me about 2hrs due to writing notes & taking Temps.

Materials:-Nismo 350Z Thermostat (P#21200-RSZ30).
-10mm Socket and Wrench
-Simple Pliars (large + small mouth)
-2 Gallons of Coolant (rated for our trucks, and probably not that much, but you can always return whats not opened)
-Small/Medium Sized bucket to catch whatever coolant you can
-a couple of wrags to wipe clean with, that coolant is slippery.


First off you’re going to need a 350Z Thermostat. I got mine from West Covina Nissan (the nismo shop) for around $125, it was also the cheapest price on the net after shipping, including eBay. You’ll also need 2 jugs of anti-freeze, I just used the 50/50 pre-mixed Prestone stuff that works in all makes/models ($20).





1. Make sure you do this w/ a cold engine!!! Start by letting the pressure off the cooling system, remove both coolant caps. Remove MAF Sensor Connector. Remove Intake. I normally take mine off directly from the TB (8mm socket), and I just lay it up over on the engine so I don’t have to disconnect a ton of stuff. Like this:




2. Now you need to locate the Thermostat. It’s hiding on the Driver-side nestled down under near the timing chain cover. It’s a pain to get to without taking off the fan+shroud. If you can do it without taking the shroud off, more power to you, I just cannot do it!



3. Before disconnecting the t-stat I went ahead and pulled off my fan+shroud. I did the fan first, its connected by 4- 10mm bolts on the Water Pump. Take them off w/ the Serpentine Belt still on and TIGHT. If not you will not get the fan nuts loose. Now you can take the shroud out, 2- 10mm bolts located @ the top of the radiator and actually bolt onto it. Undo those, and on the bottom side of the shroud, there are a few hoses that need to be un-clipped from the shroud, as well as the A/C Low Pressure Sensor (located on the passenger side, under the Upper Radiator Hose) and 2 little retaining posts that go into some rubber grommets on the bottom of the shroud(they just pull out). Before you try yanking out the Shroud you need to undo the UPPER Radiator hose FROM the Radiator so you can slip the shroud out easily. I just pushed the hose between my Radiator and an A/C line to keep it out of the way. After the hose is off both Fan & Shroud will need to be removed at the same time until there is enough room to pull the fan out. Its going to fight you every step of the way, but it WILL come out without breaking it.The reason for removing the shroud is simple, work room!











4. After I pulled off my fan+shroud I went ahead and popped off the Thermostat so I could drain the coolant. There are 3- 10mm bolts holding it in, and 2 hoses, one hose for the radiator and one for the heater. Be careful when you take off the thermostat + hoses, the heater line didn’t drain much if any but the lower radiator line kept running out no matter what. This is where I LEFT my stock thermostat connected to the radiator line so as to minimize more coolant coming out. This is where I used my small bucket to catch and re-use what coolant I could. I ended up re-using about 2/3rds of a gallon.



5. Before I put my Nismo 350Z Thermostat in, I connected the Heater hose (small hose) to the thermostat since its too much of a pain to try and get it on after the thermostat is in place. To get the Nismo 350Z T-Stat + Gasket in, I had to use 2 bolts inserted into the T-stat to make sure the gasket stayed in place on the t-stat and gently threaded the bolts in. After those two bolts are threaded in and hand tight I went ahead and installed the third bolt and tightened them all down. I then connected the Lower Radiator Hose and slid the clamp in place and double checked everything.





6. Now all you have to do is re-install the fan+shroud (don’t forget the lines that attach to the shroud), top off the radiator and possibly the coolant reservoir. I want to say I used a little more than a gallon. After you’ve filled/burped the system, replace the coolant caps. The one with the spring/pressure rated on goes on the “Overflow” tank, the one without a spring(its just a cap) goes on the radiator. After everything is done and tested I always double check the tightness of all my bolts just for security, as well as check my fluid levels and all the parts associated with the install.




All Temperatures Taken with A/C On MAX!

Initial Warmed Up temperature:
-Prior to Nismo T-stat.
-Old 350Z Thermostat (76.5*C=169.7*F)

Peak temperature on a non-heatsoaked engine:
-Prior to Nismo T-stat.
-Old 350Z Thermostat (76.5*C=169.7*F)




Initial Warmed Up Temperature Nismo T-Stat (54*C):
-Smaller Font for warm-up temp.
-170.x*F



Peak Temperature after Nismo T-Stat (54*C):
-Completed Multiple 13Xmph runs
-unable to obtain prior peak temperatures



After letting the truck idle in the driveway:
-A/C Still Max’d.
-taken about 10mins after 181*F Picture.

 

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Discussion Starter · #2 · (Edited)
First Impressions

First Impressions:

After my normal 80+/- Mi. round trip with an average speed of about 75mph and a few passes in the triple digits, I was only able to achieve a peak temperature of 183.2*F. Thats 14.4*F Less than my Old 350z Thermostat which was rated to operate @ 169*F. And 25.4*F COOLER than a STOCK FRONTIER thermostat! Thats grounds enough for me. Upon start-up there's nothing different, No Codes, No Issues, and the truck actually warms up Sooner. But as for the drive, the truck seems Normal as ever, but where as before after more than 20mins of driving the truck would act "Heat Soaked". Just upon the time I've spent at the track, I know for a fact heat soak has cost me 1-2/10th's of a second when Hot Lapping. That means you're Losing power due to running HOT. Well, It doesn't act heat soaked now!!! Whenever you lay the pedal down, it runs like the engine has had time to cool down between runs. Some of you Racers might know what I mean.

Although I'd deem this a "Track-Worthy" mod, some of you Northern guys may not want to consider this due to how it might effect the heater output and how the truck operates in cold weather, but for South Texas (Im 2-3hrs From Mexico south...) Its DAMN worth it! . Of course whenever "Winter" hits here, I'll report back.


Mind you, my STOCK thermostat was rated for 82*C=179.6*F. So, if a Nismo TStat rated @ 154*F Operates @ 183*F, that means the Actual temperature of the truck is running About 29*F HOTTER than what the thermostat is rated for. So a STOCK Frontier's thermostat would be operating @ about 208.6*F, which explains WHY I was seeing peak temp's well into the 210*F+ range.


For the time & $$$ Invested, I'd do it again without hesitation. So if you race, or just want something to aid in building power, this IS a mod for you.
 

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Good writeup, Colton. And nice test data too. I might also go the Nismo stat as soon as I can come up with the spare dough. I have the Zstat that I think just droped me about 5 deg. or so. Another 10+ deg cooler would be nice, especially for our hot texas summers and for track visits. It just pisses me off that Nismo charges us $125 for something that shouldn't cost over $25. But I will still probably bite the bullit this summer & get one too.
 

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So I see the WRP IMS in there, the PS and Crank pullies but no Throttle body spacer? What gives?
 

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Discussion Starter · #5 ·
Good writeup, Colton. And nice test data too. I might also go the Nismo stat as soon as I can come up with the spare dough. I have the Zstat that I think just droped me about 5 deg. or so. Another 10+ deg cooler would be nice, especially for our hot texas summers and for track visits. It just pisses me off that Nismo charges us $125 for something that shouldn't cost over $25. But I will still probably bite the bullit this summer & get one too.
I Agree 100%. Its outrageously overpriced, but think who the REAL market is for them, 350Z Owners. The group who can pretty much afford to do what they want as they want. So they're priced accordingly. If you look through the data, 197.6*F was a peak on regular 350Z Tstat....which is supposed to operate @ 169*F. Now my truck is running a fairly consisten 170*F Cruising, and 180*F driving it as hard as you can. Thats pretty darn good to me. Of course you could modify as stock one.....but to me thats like taking a stab in the dark. Its basially hit or miss as to how it can/wil operate. which is why i took this route, but hey, used ones can be scored on Nissan 2009 370z Coupe and 2003 - 2008 350z Coupe Research, Reviews, Specs, Photos, Prices, Forums, and more for around $90, but lemme tell you, THEY GO FAST!!

So I see the WRP IMS in there, the PS and Crank pullies but no Throttle body spacer? What gives?
All of which are operating Perfectly! Except for the TB Spacer, I took it off bc my stock intake tube was just giving me FITS each time I had to take it off. So, I took the WRP TBS off and tossed it in the tool box until I have plans for him later. If not, hell its shiny, and looks cool :)
 

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All of which are operating Perfectly! Except for the TB Spacer, I took it off bc my stock intake tube was just giving me FITS each time I had to take it off. So, I took the WRP TBS off and tossed it in the tool box until I have plans for him later. If not, hell its shiny, and looks cool :)
I changed my plugs yesterday. Popped off the manifold and the IMS and TB spacer are still doing great. Plugs were in good shape but i was getting a little hesitation and rough idle (after 65K) like you reported in the spark plug thread. Engine is running smooth now.
I'm curious of your results with such a low temp thermostat. Conventional thinking would say it is much too cold, I would never use one but I can live vicariously through ol' Shiney right? :laugh:
 

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Discussion Starter · #7 ·
I changed my plugs yesterday. Popped off the manifold and the IMS and TB spacer are still doing great. Plugs were in good shape but i was getting a little hesitation and rough idle (after 65K) like you reported in the spark plug thread. Engine is running smooth now.
I'm curious of your results with such a low temp thermostat. Conventional thinking would say it is much too cold, I would never use one but I can live vicariously through ol' Shiney right? :laugh:

as long as you're sending me random a$$ pictures via message, SURE! lmfao.

So you had the hesitation/rough idle too? I thought that was just me from driving the thing too hard. its interesting to see you report that after replacing plugs it went away. Its also nice to hear about your WRP Products, even though Im sure mine are doing A+. There are still plenty of people happily running them and cutting some nice times!

Whats keeping you from running the Nismo Thermostat? I ran the heater last night on full blast just for the hell of it, it was still pretty scorching hot for me. But, the truck runs a fairly consisten 170-180*F. Which is perfect for a performance oriented vehicle. DARREN GETTT ONNEEE ! lol.
 

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With your program, can you see at what temp your truck goes into closed loop? Most vehicles are right around 160F.
 

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Discussion Starter · #9 ·
With your program, can you see at what temp your truck goes into closed loop? Most vehicles are right around 160F.
Im sure I could, but the truck gets up to temp so fast down here that I didnt even bother looking. Of course, the truck cant really get down to 160*F since the thermostat wont allow it. Under the initial warm-up though the lowest temp it was registering was 170*F which is shown in my pix
 

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as long as you're sending me random a$$ pictures via message, SURE! lmfao.

So you had the hesitation/rough idle too? I thought that was just me from driving the thing too hard. its interesting to see you report that after replacing plugs it went away. Its also nice to hear about your WRP Products, even though Im sure mine are doing A+. There are still plenty of people happily running them and cutting some nice times!

Whats keeping you from running the Nismo Thermostat? I ran the heater last night on full blast just for the hell of it, it was still pretty scorching hot for me. But, the truck runs a fairly consisten 170-180*F. Which is perfect for a performance oriented vehicle. DARREN GETTT ONNEEE ! lol.
The hesitation and rough idle were very light. Most wouldn't notice it. I did though. No thermostat for me man. I have no problems with heat, even here in Sac with triple digits its only for part of the year.
 

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This is so sweet, nice write-up.
 

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Im sure I could, but the truck gets up to temp so fast down here that I didnt even bother looking. Of course, the truck cant really get down to 160*F since the thermostat wont allow it. Under the initial warm-up though the lowest temp it was registering was 170*F which is shown in my pix
Not in your neck of the woods in wont and probably not where I am either, but those where temps stay in the teens-below 0F in the winter it will.
Yea, sure the engine temp stays at that temp but when the thermo opens it is letting out the 170-190 and that cools well below the the thermostat rating in the radiator, so when it gets let back into the engine the ECU goes nuts.

This is also great for those of us who have auto trans, cooler = longer life, espically when towing, crawling in the summer heat.
I just need to know for sure when the system goes closed loop for the winter.
 

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great write up man though my truck never seems to get about 190* while driving 40+ on open roads. Well worth while mod for those of you down south. But i do know what you mean about heat soak and I'm working on a fix for that my self.
 

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Discussion Starter · #14 ·
The hesitation and rough idle were very light. Most wouldn't notice it. I did though. No thermostat for me man. I have no problems with heat, even here in Sac with triple digits its only for part of the year.
It's normal for us to see triple digits for more than half of the year, and its not that the truck has a problem with heat or anything. I mean it cools just fine... but I want a little bit of an edge :D Not to mention Im always Driving... LOL.

This is so sweet, nice write-up.
Thank you sir

Not in your neck of the woods in wont and probably not where I am either, but those where temps stay in the teens-below 0F in the winter it will.
Yea, sure the engine temp stays at that temp but when the thermo opens it is letting out the 170-190 and that cools well below the the thermostat rating in the radiator, so when it gets let back into the engine the ECU goes nuts.

This is also great for those of us who have auto trans, cooler = longer life, espically when towing, crawling in the summer heat.
I just need to know for sure when the system goes closed loop for the winter.
Looks like you've got some calling around to do. If you're in Jersey, I'd just recommend using a Z Thermostat. That way you wouldn't have to worry about closed loop or anything.



great write up man though my truck never seems to get about 190* while driving 40+ on open roads. Well worth while mod for those of you down south. But i do know what you mean about heat soak and I'm working on a fix for that my self.
All of you guys who are reporting running lower temps are Lucky! Its got to be a geographical issue. I was barely running high 190's with a 76.5*C ZStat. Of course another way for you Northerners to get around that is an EFan with a temp controller that just turns the fans on when needed. Im actually not to far from doing that :)

Hey Drew, stick that in your easy mods thread! haha.


Thanks guys!
 

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All of you guys who are reporting running lower temps are Lucky! Its got to be a geographical issue. I was barely running high 190's with a 76.5*C ZStat. Of course another way for you Northerners to get around that is an EFan with a temp controller that just turns the fans on when needed. Im actually not to far from doing that :)

Hey Drew, stick that in your easy mods thread! haha.


Thanks guys!
I know man E-fans are also on my list. I would throw this in there but doesn't fit the sub $100 part for that.
 

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Discussion Starter · #16 · (Edited)
I know man E-fans are also on my list. I would throw this in there but doesn't fit the sub $100 part for that.
Well thats lame. Fine, Cut out the cost of coolant and it just about fits!!!!!!




More test data.... RPerry03, see if this helps you.

Before Even Starting The Truck:


After driving approximately 1mi (easy driving):


Idling in the drive-through line getting BREAKFAST!:


Headed Home, Cruise Control set to 85mph'ish:




Had one triple digit jaunt and still only saw a peak of about 175*F. Thats how I wanted her to run all along. Im FINALLY getting somewhere!





My conclusion:

Do this Mod IF:
You live in "warmer" parts of your region.
You're building for max power output.
You don't use the heater too often.


DONT do this Mod IF:
You live in a cold climate
You rely upon the heater





Other than the few drawbacks, its a decent mod but steep in price for such "gains" if any. I did it for one reason, Cooler engine temps. Its given me that FOR SURE.

Enjoy!
 

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hmmm interesting waiting for a winter to come and see what happens
ya need to drive in a colder area to see if it throws any codes. where i live it get downs to 25s maybe a few weeks out of the year and teens maybe once or twice a year but always warms up above 40 almost everyday so i dont think it will be that big a deal just waiting for more info before dropping the cash.

but would be great for me i drive alot when it about 95 in the summer and i am hitting it pretty hard to try to make it to work

lol been a long day i bet i just wrote alot of gibberish if so i will edit it
 

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^^ For you, the regular z Tstat should work. I am currently running it since the price is so much cheaper then the Nismo version.
 

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didn't know the superchips had all the cool stuff but i tested it on a 1hr dr it ran at about 192 engine temp with an intake air temp about 85 it was 75 outside and when i shut off the truck i came back in about 15 mins and it was at 210. great writeup just gonna wait through winter and see what happens
 

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Discussion Starter · #20 ·
we'll see what happens this winter. I doubt I'll see a problem as where I'm currently living 40*F is RARE. lmao. So you northern folks might be out of luck for winter testing. Farthest north I'll make it this year is Hondo, Tx for my annual hunting trips. Time to put it all to use!
 
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