Convert The 2 Zz Coolant Ports To An Fittings on a Lotus Exige

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Any truly competitive or enthusiastic driven car needs to consider the fact constant maintenance will be performed. Whether this is wear and tear or the never ending 'upgrading' access to engine bay components should be easy and fast.

This brief guide outlines a method to convert the cylinder head ports to standard -6AN fittings for easy removal and compatibility. This same procedure can be followed for other coolant ports of different sizes with the correct sized hard line to AN adapter.

Remove coolant hard line bead

The Dremel with a metal cutting wheel is preferred as it makes dust instead of metal shavings like a hacksaw. Under no circumstances do you want metal bits getting into the block or coolant lines.

Alternative methods exist, go with what you're comfortable with. An Oscillating tool with a very fine tooth metal blade may work as well.


Disconnect existing coolant lines from the hard lines to convert.

  1. Use pliers to release the OEM tension clamp on the coolant hose.
  2. Remove the coolant hose from the engine block hard line.

You should see the hard line exposed similar to the picture (ignore the white tape, more on that next)

While all manufactures create their fittings with the same Internal Diameter (ID) and threading, the length and style of the exterior of the fitting changes from brand to brand. Some brands, especially cheaper ones, have a much longer fitting some of which will not work on the limited length 2ZZ coolant hard lines.

The Vibrant fitting linked above work well and are in use on my car.


Verify your chosen tube to AN fitting will fit.

  1. Take the AN fitting and eyeball on the outside where the olive seats inside of it.
  2. Hold the fitting up to the hard line and ensure you will have enough working room to slide the fitting and olive on the hard line BEHIND THE BEAD.

In the next steps you will cut the hard line shorter to remove the bead. It is critical you assume the hard line stops at the bead when verifying the fitting fits. If you're confused read the rest of the steps before continuing as the next procedure is not reversible.


Prep for cutting the hard line.

This is an optional step.

Find a way to plug the hard line just past the bead in the line. This will help confine any metal dust / shavings for easy removal.

  • Rolling a 2" piece of foam mounting tape lengthwise and inserting works well. Just don't insert more than 1/2" inch to ensure you can get it back out.
  • Alternatively, foam ear plugs or cotton balls will work as well. Just push them in past the bead and ensure you have a way to pull them back out for removal.
  • If using a dremel or similar that doesn't create shavings just cutting and using a shopvac to suck the line out works.

Remove the bead in the hard line.

This is required to slip the olive onto the hard line, without this step you can't proceed.

  1. Setup a Dremel with a metal cutting wheel.
  2. Proceed to cut off the hard line just behind the bead. CUT AS CLOSE AS POSSIBLE TO THE BEAD!
  3. If anything was inserted to plug the line, remove that now.
  4. Debur the hard line to ensure it is smooth and free from jagged edges. Grinding stones on the Dremel work well.

You should have something similar to the picture below.

Installing the AN tube adapter


Install the AN Fitting

  1. Test fit the olive will slide onto the hard line with your hand (no tools).
  2. Continue deburing / shaping the hard line until the olive will slip on. It's designed to be a tight fit so expect resistance, but it should easily slide on.
  3. Slide the AN Fitting on then the olive and push both as far back towards the block as possible.
  4. Thread in the other half of the AN fitting
  5. Use two 6AN Aluminum wrenches or standard wrenches with the box ends wrapped in duct tape to protect the anodized finish on the fitting. Tighten the fitting together until you can't thread the end in further.

Remember these fittings are made of Aluminum (it's soft) and the olive is brass (also soft). It doesn't take a lot of muscle / torq to install these properly.

Do not use cheater bars, wrenches bigger than 8", or power tools to tighten the fittings

Image 8379 from Convert the 2ZZ coolant ports to AN Fittings on a Lotus Exige

The picture above is a completed installation on one of the coolant ports with the other ready to be installed.

Congratulations you now have standard AN fittings on your coolant lines.

You may have noticed the hard line was 5/16" and the end on the coolant tank is 3/8". Replacing that OEM coolant line is a nightmare with two different sized ends. With this mod you can use standard 6AN (3/8") hose with AN ends (hose ends or barb adapters) to replace it.

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