Throttle Body Coolant Bypass Mod

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Throttle Body Coolant Bypass Mod

Postby MrEs » Sun Jul 22, 2007 7:51 pm

Background:
On MOST cars, hot radiator coolant flows through the throttle body, this is SUPPOSEDLY for colder climates where there is a possibility that the air fuel mixture is frozen. The THEORY of the coolant is to keep the throttle body/intake manifold hot enough to prevent this freezing from happening.

NOW, I don't know the PROs/CONs of this modification but I did it just to see it for myself. And the TMIC WAS cooler on touch but i'm still nto sure if there are any negative effects so I CANT RECOMMEND THIS MOD, DO IT AT YOUR OWN RISK


Purpose:
When throttle body gets heated it in turn heats the TMIC. With this mod i found that using the scientific method of 'touching with my fingers' my TMIC was significantly cooler after a spirited squirt. After hard driving it is also possible to put my finger on the throttle body and upper portion of the intake manifold without getting burnt. This all generated heat for the TMIC as well...


What you need:
To perform the mod you will need to purchase the following "Compressor hose repair kit" which cost me $8 from Bunnings:

Image
From this pack you will need two of the clamps and the bottom part.


Process:
Let me start by saying that I wasn't going to make a DIY out of this so I haven’t got pictures from every step but I’ll give it my best shot...

It is a good idea to perform this mod when the car is cold as there will be less coolant in the upper hoses of the engine and nothing will be hot! Also put some cardboard underneath the car as you will loose a small amount of coolant...

Firstly you'll need to take off your TMIC. Undo the 4 bolts mark by red; I believe they are all 12mm...
Image
This unbolts the TMIC from the car and also undoes the BOV which makes this MUCH easier...

Now we have to loosen the TMIC intake and outlet, so loosen the clamps shown once again in red...
Image

Image

Pull off the hoses marked in YELLOW (from the bits marked in RED)
Image

Image

Now is the tricky part, the TMIC is unbolted and only held on by the "Y" pipe end to the turbo and the "Short Fat" intake hose bit... I found it easiest to take off the fat bit and then pull/twist the whole TMIC to the right and up. Took a bit of elbow grease and twisting...

Once the TMIC is off you can easily see the throttle body. The following two pics are stolen from rexnet and are not of my car, i forgot to take pics :oops: . The pics show piping for a FMIC but we can ignore all that and just concentrate on the marked components...

Image

Image

Now let me explain what is going on here, in the stock factory set-up #1 is connected to #2 and #3 is connected to #4.
The hot coolant comes from #4 and runs into the throttle-body via #3, then is comes out of #1 and goes back into the engine at #2. What we are trying to do is eliminate the point where is enters and exits the throttle-body. So we need to take the hose (NOT PICTURED) from #4 and join it with the hose (NOT PICUTURED) from #2.

Pull the hose end out of point #3, a few drops of coolant may come out here try not to spill too much.... Now grab that barb pieces that came in the pack we bought from Bunnings and put it on the end of the hose and clamp it down!

Now pull the hose of at point #1 quickly, a little more coolant might leak out this time. Now put that hose end into the other end of that barb that we put into the hose that we took off of #3 and clamp it down. I left the points #1 and #3 open with no capping or anything, i cant see any problems with this.
Now it should look similar to this...
Image
Next time i have my TMIC off I'll take proper pictures (probably wont happen until i do a TMIC upgrade :P )


Now you have to put the TMIC back on. This seemed tricky at the start and then it all just fill into place. I put the "Short Fat" intake hose bit back on the throttle-body and clamped it down. Then I grabbed the tmic and lined it up with the Intake hose and the "Y" piece end. I was then trying to get the ""Y" piece end in first and was getting nowhere; but when i tried to get the intake hose in I found that the both just went in at the same time nice and easily! Now follow the steps you used to undo the TMIC in reverse order and hey presto!
Last edited by MrEs on Sun Jul 22, 2007 9:45 pm, edited 1 time in total.
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Postby nfenech » Sun Jul 22, 2007 8:19 pm

Nice write up.
But the question is, is it worth it? Does it make a difference?
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Postby MrEs » Sun Jul 22, 2007 8:32 pm

For $8 and an hours of playing with the car why not :wink:
And yes i can notice a difference in temperature BY TOUCH!
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Postby deafwish » Sun Jul 22, 2007 9:01 pm

Good job, Denis! :thumbs:
Keen to see how this goes, over time!
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Postby MrEs » Sun Jul 22, 2007 9:10 pm

no problems :wink:
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Postby blackrex » Sun Jul 22, 2007 9:26 pm

I did the same mod on my MY98, but I had two datalogged temp sensors before and after the TB when I did it. Prior to the mod, I would have pre TB temps around the 30 degree mark, and post TB around the 70 degree mark. After doing the mod, the temps stayed the same pre and post. I did consider trying to hook the aircon coolant to run through the TB pipes as well, but ended up CBF'ing that idea.
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Postby MrEs » Tue Jul 24, 2007 10:41 pm

yea I've seen data showing about a 20 degree drop in temperature :thumbs:
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Re: Throttle Body Coolant Bypass Mod

Postby dimi » Sun Aug 23, 2009 7:20 pm

Hows all the cars going that have this mod done? I'm pretty set on doing it after reading about it.

Also, how would you go about hooking up the aircon coolant to run through the TB pipes? And would that just be overdoing it? Would the con of doing that be hot aircon?

Would also be good checking this out from rexnet, top idea! http://www.rexnet.com.au/forum/index.ph ... 9690&st=10
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Re: Throttle Body Coolant Bypass Mod

Postby MrEs » Fri Dec 04, 2009 12:19 pm

all thumbs up from me :thumbs:

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Re: Throttle Body Coolant Bypass Mod

Postby closed deck » Tue May 04, 2010 8:29 am

You may not be aware that part of the reason we have the water flowing through the throttle body is to prevent the throttle body icing up.When this happens the throttle freezes in the open position and its very "exciting".Nothing like passing a truck at 120 kph in the dead of night and having the throttle stick open, switching the motor off and trying to pull over into the dirt with said truck now bearing down on you thinking your trying to be smart pulling out in front then slowing down.
On a more positive note it can certainly liven up another wise boring trip.
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Re: Throttle Body Coolant Bypass Mod

Postby deafwish » Mon Mar 14, 2011 5:26 pm

Finally did this after not hearing of any ill-effects.
My car rarely travels at night and/ or in the country.
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Re: Throttle Body Coolant Bypass Mod

Postby Callahan » Tue Mar 15, 2011 9:26 pm

... and your humble opinion please Daz ... hmmm
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Re: Throttle Body Coolant Bypass Mod

Postby deafwish » Tue Mar 15, 2011 10:10 pm

My throttle body is SIGNIFICANTLY cooler after a drive as opposed to skin melting hot.
My coolant lines looked nothing like the images up the top - but still easy to do with the 10mm brass hose joiner. Lost about 20ml of coolant, too! :smart:
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Re: Throttle Body Coolant Bypass Mod

Postby funwin » Tue May 10, 2011 12:33 am

Did this mod on my 99 the other day when i had the cooler of. On the older ones you dont need any parts at all, just a pair of pliers. As it has one hose going in one side then coming out the other side of the throttle body and returning to right next to where the first hose is. So i just unplugged the 'out' hose, threw it in a cars part box and then took the 'in' hose of the throttle body and plugged it into where the 'out' hose returned to the cooling system. A 1 minute mod.... if you already have the cooler off
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Re: Throttle Body Coolant Bypass Mod

Postby Swav » Tue May 10, 2011 7:19 am

did the same last week and yeah i feel the car runs better especially in these colder mornings. same as you nick a lot eaisier to do on the gc8
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Re: Throttle Body Coolant Bypass Mod

Postby subi06NA » Sun Jun 03, 2012 7:40 pm

With regards to icing over? What conditions would you need to be in? it is possible to take my car to the snow this year?

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Re: Throttle Body Coolant Bypass Mod

Postby 14WRC » Sun Jun 28, 2015 6:09 pm

Quote from my text
intake and fuel delivery mechanism receives air at 104 degrees Fahrenheit or about forty degrees Celsius, regardless of outside air temperature. Maintenance of this temperature assists vaporization of the fuel, particularly when the engine is cold.

Vaporization is also assisted by heating the intake manifold, normally by circulating hot liquid coolant through passages in the manifold.

If a manifold is too cold, fuel condenses on its inner surfaces, which will create a lean mixture, and may cause incomplete combustion. Carbon monoxide and hydrocarbon emissions are highest from a cold engine."
Last edited by 14WRC on Mon Jun 29, 2015 6:29 pm, edited 1 time in total.

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Re: Throttle Body Coolant Bypass Mod

Postby Lupin » Sun Jun 28, 2015 6:14 pm

How old is your text book?
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Re: Throttle Body Coolant Bypass Mod

Postby 14WRC » Mon Jun 29, 2015 6:21 pm

Its current the main purpose is emissions but they claim if the inside of the manifold is to cold condensation forms on it.
But its all a trade off i guess cooler air opposed to incomplete burn who cares about the emissions lol

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Re: Throttle Body Coolant Bypass Mod

Postby matto20v » Thu Nov 26, 2015 9:12 pm

And who cares if the engine runs lean...... right?
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