Nissan 370Z: Eliminating hot coolant heater hoses on both throttle bodies

VQ37VHR-K28

Disclaimer:

The DYI (Do it yourself ) below is only to share what I have been doing for the 370Z and Infiniti G37 cars. If you are lacked of automotive knowledge or experience, please DO NOT perform this task yourself.
I shall assume NO responsibilities, whatsoever, for any consequential damage to you and/or your vehicle in this case.
The 370Z in general, depending on what you do to it, is NOT a simple vehicle to work on. If one thing goes wrong, many more can follow since the car has very tight tolerance and very low margin for error. So, take care and be very careful.

This is a DYI for eliminating the throttles heater hoses for the VQ37VHR motor for your 370Z and Infiniti G37. I recommend removing these hoses ONLY for the folks that are living in the geographical region where the ambient temperature does not come below 30F (-2C). Otherwise, leave them on in order to prevent
possible throttles icing during freezing temperatures.
For the enthusiasts that live in the tropical regions, this heated throttle motors and chambers design not only clogs the engine compartment with hoses, but will DEFINITELY reduce engine performance dues to hot air temperature, especially for supercharged and turbocharged folks. By eliminating these hoses,
the system will NOT activate a CEL because this heat elimination occurs after the air temp sensors, and nothing is being monitor after that. Cooler air will DEFINITELY helps engine performance and prevents knocking.

So here are the basic steps:

First : Disconnect your battery before starting anything. One mistake could cost you the IPDM controller, which can be throat cutting expensive

Please refer to the factory cooling hoses diagram below and study this picture very carefully. I will be referring the 4 throttle coolant hoses by their respective numbers.

LEFT SIDE = DRIVER
RIGHT SIDE = PASSENGER


Pictures below show the original factory set up for the left and right throttles. Here you have burning hot coolant running through both the throttles and heating up the intake air considerably. The hood temp of the VQ37VHR is very high to begin
with due to the wonderful VVEL design and unfortunately, a very flimsy thin cooling radiator.

For the LEFT throttle, the hoses are #15 and #16. For the RIGHT throttle, the hoses are #6 and #7.



For both the LEFT and RIGHT side throttles:

Remove hoses #15 and #16, #6 and #7 from the both throttles' end.



For the LEFT side throttle:

1) COMPLETELY remove hose #15 out of the car. Discard this hose.
2) Connect hose #16 to the metal coolant pipe shown below.
3)) Plug both the throttle nipple openings with high quality rubber plugs.
4) BE SURE that hose #16 does not rub against anything. If it does, you have to put rubber sleeve on the hose.
5) Done for this side.


For the RIGHT side throttle:

1) COMPLETELY remove hose #7 out of the car. Discard this hose.
2) Now you only have hose #6 as shown below.



3) Cut this hose #6 around the place shown below, just between the 2 sleeves



4) After the cut, this is how hose #6 looks like



5) Custom fabricate a preformed hose, around 4 inch long as shown below. Also, custom make a sleeve around 2 inch long to go over the hose . Use a barb fitting and install on one side of the hose as shown:



6) Connect the other side of the barb fitting of this hose to the cut end of hose #6 shown above



7) Connect the the loose end of the custom hose ( Marked X ) to the metal pipe ( Marked X ) as shown in the photo below.



8) Finally, the hose #6 should look like this. BE SURE to adjust the sleeve to where the hose rubs against the harness below.
9) Put high quality rubber plugs on the throttle nipple openings.



9) You are TOTALLY done.

10) Start up the car and check for leak.
11) Drive the car, hard and fast..... and check for leak again.
12) Periodically inspect to be sure that there is absolutely no leak !!!
13) Have fun with cooler air intake....

You engine compartment will be less clogged from now on. It will be easier to get to your spark plugs and coils. Most importantly, you shall have colder intake air for sure.

JDMz

Which ones are the supply hoses to the return hoses. The reason why I ask is because I'm thinking of doing this mod with a 2 way solenoid valve so you can bypass or have normal config. thanks

2004YZFR1

Nice detailed write up! I did the same type of job to my old CBR 600F3 race bike. It helps.

__________________
K & N Filters | HPS silicone air intakes| Fast Intentions CBE with 18" resonators |

vjarnot

I'm no expert, but the hoses that remain must be the supply hoses, don't you think? Looks like he's just short-circuiting the supply to the return.

VQ37VHR-K28

It makes no difference which is the return or the supply hose in this case because : All I did was disconnecting the throttle connections completely and route the input hose to the output hose ( or other way around ). So this is in no way a disruption to the coolant flowing paths. Let me know if you ahve any more questions.

VQ37VHR-K28

Thank you very much

VQ37VHR-K28

Thank you very much

carlitos_370z

the thread is old but im thinking on do it!!!

JARblue

I took the opportunity very recently when I removed my throttle bodies for cleaning. I made it a lot simpler though and did not reconnect the hard line at the back of the engine. I took hose #6 and disconnected it from the passenger side TB, rotated it around, and connected it to where he reconnects hose #16 on the driver side. The FSM identifies this as E: Heater Pipe, where hose #5 was originally connected (cut off in the diagram). No extra parts required, except 2 extra plugs for the hard line behind the engine.

__________________

conquistador

Doesn't the TB get heat soaked anyway? After 15-20 minutes of driving EVERYTHING is heat soaked...

DEpointfive0

This write up is better than the others

__________________
Do YOU want to know what/where I got my username from?

JARblue

This is the one that should be stickied. My only comment is I prefer forum hosted pics (either attached to post or linked from an album) for DIYs because links to 3rd party hosting are not guaranteed to still be active years down the road

__________________

JARblue

Also an update on my Z. I noticed the rotated hose I used was rubbing a little bit. So I used some hi-temp felt gasket I had lying around as a protective barrier for the hose.

__________________

Smashley

Anyone monitoring their intake temps close enough to notice a difference after doing this?

RN SHARK

So I'm sitting here, doing this modification and was wondering if I'm introducing a bunch of air into the coolant system. Do I have to bleed the system after this??

__________________
___________
'09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare
'14 SRT Grand Cherokee; '08 TL Type-S