NA Supra: Coolant Bypass Mod

**Kirk** · 10-29-2007, 01:58 PM

Thanks to kbprice:

There have been a few questions on how and why to do the coolant bypass mod so I figured I would post up my explanation of how I did mine.

There are a couple of ways to do it but here is how I did it.
Remove throttle body like you are changing the spark plugs. Disconnect the TB coolant lines from the TB. Drain radiator. Remove the coolant lines that attach to front and rear of block that supply TB. Cap the rear coolant tube with a 5/16 vacuum cap and secure with a small hose clamp. Remove the front supply pipe from the block. THis is held on with 1 12mm bolt and 2 12mm nuts. Once this is off you can either use another 5/16 vacuum cap and hose clamp or what I did was remove the supply tube and tap it with an 1/8 Pipe Tap Fitting. I then put in a plug with some pipe dope around it then reinstalled back onto the block. Replaced TB and and refilled coolant and was good to go.
The other nice thing about this is it cuts down on the time it takes to change your plugs because you don't have to mess with the coolant lines any more.

If you are planning on using vacuum caps make sure they are heavy duty. I had one rip after about 6 months and spray coolant all over the place. One thing I added was a small rubber expansion plug in the rear pipe in addition to the vacuum cap.