Seems kinda counterintuitive to invest money in a nice FMIC to only have hot coolant going through your TB or intake...

 

i bypassed the coolant lines to my throttle body 20 years ago, if you live in extreme cold areas you would probably want to keep them

 

Removing the coolant/anti-freeze lines from the throttle body is a modification lots of people do, and supposedly it increases horsepower. I'll keep mine stock so I don't have to worry about driving in below freezing temperatures. The throttle body can get stuck when it's freezing if there is no antifreeze going near it-I think is what the problem is with the modification.

 

Depends where you live. Temps around me hardly get below 60

 

Is the coolant only going to the TB? I thought also the intake but maybe I was wrong.

 

There are coolant passages in the IACV for the same reason. If you live in a warm area, you can cap off the loop that goes from the crossover pipe to the TB and IACV and back.

 

Perfect, thanks for that diagram.

I don't think so but I want to ask this question...I've read reports of this causing searching idle and stuff. How true is this?

 

This one is from the back of the block near the heater hose, and goes to the side of the intake manifold. D16Z6

The bottom left port is where the coolant line goes from the first picture, where there is corrosion. The top clogged hole is where the coolant line from the throttle body goes back into the the intake manifold, then into the cylinder head. D16Z6

 

Don't think I have the same problem.

 

Bypass the TB and cap it (TB ports) off. Loop the coolant lines FOR the TB together. Keep the IM coolant as it should be, just get a thermal gasket. *Some* thermal gaskets are a tad thick so you might need longer studs. I got a Sikky thermal and it BARELY leaves anough thread for me to get a bite on with the nut. When torqued down, they are flush (stud and nut), so, not worried about hold.. Anywho.. TB coolant bypass is the norm..

 

I think I already have a Hondata gasket for it. I have a Skunk2 intake on the way and I'm up in the air about a Alpha 70mm throttle body or not.

But anyways, why would you want hot coolant going through the intake manifold?! That to me is just crazy...

 

As others have said, it's just for cold climates. I'm in the South East, and we get down into teens in the winter. I've still deleted all my "small" coolant hoses. Nothing going to TB, IACV, or FITV (I deleted the FITV). I do not have any idle or throttle sticking issues related to this at any time in the year.

The 5/8" loop hose that goes from the IM to the thermostat housing is to allow coolant to bypass the radiator portion of the circuit before the thermostat opens, but still allows the thermostat to see the warming coolant so it knows when to open. I'm guessing at what the Honda engineers were thinking, but I don't think it was run through the IM / IM gasket to intentionally heat up the manifold - it was just a convenient place for getting coolant from the head back to the water pipe. The small 1/4" or 5/16" coolant lines that go to the IACV, TB, and FITV are definitely there to heat those components up.

 

So what you guys are saying is the IM cannot be bypassed?

 

You may be able to run a custom IM gasket with no water port to block off the head, or have the head welded up, then use the heater hose port under the distributor to route coolant to the thermostat housing. Just brainstorming - never actually seen this done.

 

Simply run a hose from the water pipe nipple (above oil filter) to the nipple on the intake and you will bypass the IACV and throttle body. If you have surging/weird idle problems then most likely you have a vacuum leak or bad tune. Obviously you probably don't want to do this if you live in colder climates. IACV doesn't rely on coolant temp and will function normally if it's clean,working,good gasket,and wired correctly.