Flexible EGR Tube Reroute

The EGR tube carries hot exhaust to the intake when the EGR valve is open. EGR reduces NOx emissions and engine temperature under specific conditions (low load). Some coolant reroutes are not compatible with the OEM EGR tube, and this was a workaround for that case. Eventually, my Miata got a standalone Megasquirt ECU and the EGR system was removed.

This project replaces the stock EGR tube with a flexible stainless steel line (for gas home appliances).

Stock EGR tube
Replacement gas line and fittings
Ends removed from stock EGR tube
Brass fittings were too wide to fit behind manifold, yellow plastic removed from gas line
Correct length replacement EGR tube

I used some exhaust sealant at the fittings just-in-case, but the 1/2″ compression fittings created a tight connection on the cut off ends of the old EGR pipe.

EGR connection to intake manifold
EGR connection to exhaust manifold

Carefully route the EGR so that it does not touch any plastic or rubber parts. Use high-temp thread lock on the exhaust side or the connection will rattle loose.

1/2 inch flexible gas line – 24 inches long$20
1/2 inch OD compression to 1/2 inch FIP brass fittings$15
1/2 inch FIP to 1/2 inch NPT union adapter$5
Exhaust sealant$6

Here’s a miataturbo.net forum post about the same project.

9 Comments on “Flexible EGR Tube Reroute”

    1. 1/2″ plumbing compression fittings from the hardware store, and a 1/2″ NPT to 1/2″ flare union adapter. Also, some high temp exhaust sealant to fill any gaps.

    1. I remember scrubbing it with a metal brush, but I don’t remember if I used brake clean or some other chemical to dissolve the coating. It would probably be fine to leave on too, from the BrassCraft website, “…the ProCoat coating is baked directly on the connector surface at high temperatures to provide a uniform coating over the entire length of the connector… corrosion resistant to most household chemicals, UV rays and salt.”

    1. No issues with heat. It’s a stainless steel line, without any plastic or rubber gaskets. The OEM EGR tube is just an uninsulated metal tube too, so there is nothing near it that can’t handle the temperature.

  1. A very big thank you! Spent hours trying to find a good enough guide or even just anything that helps reroute the egr. Lotta people just say cap it off, but Cali doesnt like that. Was not able to find anything aftermarket, prob for legal reasons. Hopefully smog doesnt question the yellow paint haha.

Leave a Reply

Your email address will not be published. Required fields are marked *