Only issue I have with this is capping the ports. The system I'd guess needs to flow in a circular direction. By not connecting C to E makes me uneasy. To do this very easy just take the passenger side front hose that connects to C in the back of the motor and flip it around to attach to E on the drivers side. Then remove all the other hoses. This way coolant still flows as designed and no more heat to the TB's. I've done this on every car I've owned. Before the TB is about 200 degrees hot like the coolant. After they are damn near ambient temp. Only way to test is drive down the road, quickly pull over and touch the TB's before and after. Touching them after sitting wont do anything since the TB's will heat up from engine bay heat soak.

FYI I lived in Ohio my hole life and never had a freezing issue.

Here's the hose from C that used to go to the front passenger side port. Flip it around and attach to E. pretty sure nissan did this on purpose cause the hose is a perfect fit with perfect bends!!

FYI guys who capped their system. In my experience the rubber/silicon caps from autozone or alike are extreme junk. Pull one off your car after being on there for so long and let me know how the dry rot looks. They crack and break extremely easy.

http://i39.photobucket.com/albums/e1...ps8b470afb.jpg

http://i39.photobucket.com/albums/e1...ps1e1838ce.jpg

So when switching to the M370 manifold you actually disconnect the TB coolant lines anyway, yes?

I just took the Allen bolts off and left the tb's connected....shortcut!

True that's a good call. I'm just surprised the install instructions don't even mention it and they call for disconnecting the TBs

FWIW, I do currently run a bypass hose like synolimit mentions. I used a length of blue silicon 5/16" hose (from Z1 I think). I did that because I never found a cap solution I was happy with (they would tend to leak over time; there's just no good way to secure a rubber cap against that kind of heat+pressure). But I really don't think there's a flow reason to do so. The tiny amount of flow that goes through the TB lines is insignificant in the big picture, and parallels two other much larger bypasses (the true bypass and the heater core bypass).

I am guessing the reason for the coolant through the throttle bodies is kinda like carb heat on a small piston aircraft. Prevents icing in the throttle and rough running or stalling. I would say do it, you're not in an airplane and I live in Texas so it won't get too cold here.

Quick question:

What size diameter would the metal bypass tube need to be to fit inside the throttle body coolant supply hose?

I believe the rubber tubes for the throttle bypass flow are 8mm (aka 5/16") inner diameter roughly.

Perfect and thank you. Going to make up a couple bypass tubes this evening.

i was running a pair of U shaped pipes to bypass the throttle bodies while keeping the hoses as-is to aid reversibility. I wasn't satisfied with the messy hoses and the heat radiating off them onto nearby components such as hard brake lines, throttle bodies etc. I went as far as strapping them to the strut bar.

This weekend i decided to get rid of the contraptions completely. The only part i couldn't remove was the hard line behind the intake manifold as it was welded to the vacuum line beneath. I used 5/16 fuel hose with 8mm stainless bolts jammed and clamped in one end.

Since i had already removed the coolant hoses from the throttle bodies, i did not have to remove any intake components.

The hardest and most painful part was actually the hose connecting the metal pipe on the left of the engine (the one which is almost beneath the intake pipe). It probably would've been less painful if i removed the intake pipes in the way but mine are double wrapped so that was going to be a last resort option.

For the hose connecting at the rear of the engine, there's actually heaps of room compared to other areas of the engine bay. Enough room to get a regular pair of pliers down to release the ring clip. Any stubborn hoses - simply jimmy up with a flat blade screwdriver to encourage it a bit then work it off by hand. I suggest lube-ing the plug/plugged hoses before fitting as the one was the most stubborn to push on.

At first it looks daunting because you can't actually see it from either side but don't be afraid to put your knees up on the radiator core support and pull yourself up using the strut bar. You'll be working in an arse-up position on your fours - or if you like, it's a perfect time to call your other half to help ;)

Put a cushion or gym mat on the core support and also on the intake manifold as you'll be resting your elbow there (remove the decorative covers). Much much easier.

On a side note, my heater started working properly after i did this. Maybe there was trapped air in my U pipes because i mounted them so high.

Happy modding :)

I am cleaning throttle bodies on a couple of Z cars this weekend. While I'm removing the TBs, I figured I'd go head and do this hose delete on my Z. Definitely straightforward, but I'm going to ask for one clarification regarding the bypass hose.

The bypass hose should go from the Heater Pipe (E) located below the driver side TB to the Water Outlet (C) located at the rear of the engine, correct? And my understanding of Synolimit's post is I can leave the hose connected to the Water Outlet (C), disconnect it from the passenger side TB, rotate it around the engine, and connect it to the Heater Pipe (E).

Yes, that all sounds correct. Don't forget to blow out whatever lines remain (or just the TBs and the metal pipe along the rear that end up with open ends, if you're removing the other now-useless rubber hoses) with compressed air or something. Some like to cap them off to keep out dust and bugs as well. The water outlet connection at the rear (C) is hard to see sometimes, but it's in the center of the backside of the engine, and it's a small nipple facing straight upwards.

Thank you, sir :tiphat:

The TBs are coming off completely for cleaning, so those will be easy to blow out. I'll figure out something for the hard line at the rear - I've got a really small can of air that will probably work just fine once I remove the intakes and engine cover. Also, I'm going to pick up some small rubber stoppers that I am hoping will work well to plug all the open lines

They look like the really small ones here:

Could you put a stop-**** (jokes ensue) inline so that you could open it up during winter and close during summer? It would obviously have to be heat and corrosion resistant.