EGR control valve

[darom]

Hi guys,

I converted my electrically operated EGR switch solenoid on my 76 to the 78 EGR control valve (1978 FSM, EC-11) which is temperature operated. This allowed me to get rid of the potential battery drain condition in the future (after my alternator had been upgraded to the internal voltage unit, the solenoid was constantly energized).

The 78 EGR control valve is installed in the aluminum block which is located under the air regulator. The problem is the temperature in that block doesn't get more than 52-55C. I tested it with my laser thermometer. The valve doesn't open, thus it doesn't allow the vacuum to operate my EGR valve. I tested the valve in the pot, and it opens at around 65C.

I would like to install the adapter in the top radiator hose and screw that EGR control valve there, then block off the thermostat housing hole for this block and get rid of the snake coolant line going to the RH side. The top radiator hose temperature would be the best source to operate that valve.

What is the thread size of the 78 EGR control valve? Is the top radiator hose size 1 1/4" or 1 3/8"? Rockauto comes up with both sizes.

Thank you!

Edited June 2, 2011 by darom

[darom]

I took the plug out - it measured OD 17mm with the 1.5 thread pitch. Does M16 x 1.5 sound right?

The thermostat's housing radiator hose pipe's OD is 36 mm, ID 30mm. Will a 32mm adapter be a nice tight fit?

Thanks!

[FastWoman]

That's very interesting that the block under the air regulator never reaches the operating temp of the EGR system. FAIW, the 1981 (?) ZX has a rubber boot around the air regulator. Perhaps that stops some of the heat loss. You might also have a kink in the rubber "L" hose connected to that block or a blockage somewhere in the tubing. Surely the system designed for the '78 must have worked at some time. I would think fixing it would be easier than modifying it.

Or just stick with the '76's electric EGR. Something's wrong if power isn't interrupted to the system. Did you install the diode when you upgraded your alternator?

[darom]

Hi FW! Thanks for checking my thread out.

The tubing is indeed very small to allow for a nice water flow from the thermostat housing to the aluminum EGR thermal valve block and back to the lower radiator hose connection. I did want at some time to upgrade the pipes to a large diameter, but to me it was more work than re-routing vacuum lines :-)

I didn't install any diodes when I did the 1979 alternator upgrade on my externally voltage regulated 76. I followed the atlaticz's instructions:

http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

Do I need one? The car properly shuts off and the alternator does a good job charging the battery. I did re-do the brake light relay yellow wire (after the upgrade, the wire had the constant 12V with the key off and the relay was constantly energized). I connected a switched 12V to the brake relay from an unused antenna switch lead).

The old 76 EGR electric solenoid was another drain - there was constant 12V present after the alternator upgrade. I didn't want to run another wire to the cabin's ignition switched lead through the relay to operate it. That's why I picked the later model ZX thermal EGR valve - it cleans up the electrical wiring nicely in the engine bay. I am not using the 1978 back pressure exhaust gas transducer since my intake/EGR exhaust doesn't have a port to connect to.

Thanks!

PS. After talking to my hotrod buddie, he thinks that EGR valve's threads are NPT! The threads are very close to the 1.5 metric. Or British NPT?