EGR valve (1 Viewer)

[avicenna110]

Hi all,

I’m getting close to putting my ‘77 CA spec FJ40 together and have to eventually smog the car. I’d like to understand what are the differences between EGR valves between the different years, or even within the same year. My questions are only about the EGR valve, not the cooler, pipe to manifold, etc.. I’m aware of those differences.

So as a I understand it, VSV sends vacuum to the diaphragm, the diaphragm lifts a valve open, and exhaust gases are recirculated into the carb/manifold. For my car I have the right valve but it doesn’t hold vacuum very well (when tested with a hand vacuum pump), it loses vacuum after about 15-20 seconds which suggests that there is a small hole in the diaphragm. I had sourced two other ones, one is for a high altitude which is much smaller than mine, and another which is the same size but doesn’t hold vacuum at all. (If you’re buying an EGR make sure it’s vacuum tested, otherwise it’s worthless). So here are some questions:

- are EGR valves interchangeable? What dictates the size? I guess the smaller ones with smaller diaphragm open with less vacuum? With my hand pump they function quite similarly

- assuming the function is just opening and closing when vacuum is applied, is there any aftermarket valve, or one from some other car that can be made to fit? I saw no post about this. With all the used EGR valves slowly developing holes in their diaphragm, passing smog would be impossible in the future.

- has anyone rebuilt one before? Also didn’t see any posts on this, some have talked about it but none have actually done it.

Thanks

 

[mattressking]

1. Interchangeable only if they are the same fitment. EGR valves don't change in functionality, they are only a diapgragm that opens based upon its brain (EGR modulator/vacuum switch depending on year of 2F). All it does is transmit ported vacuum on carb to opening of egr valve to allow engine vacuum to pull in exhaust gas into the intake manifold. That is it.
2. None that exist aftermarket anymore. Only used. I've had luck finding NOS ones but it's not to be relied on.
3. Not reliably, it requires separating the crimped edge, getting the correct diaphragm and retrofitting/recrimping. Totally doable with the correct tools or willingness, just nothing commonly documented.

If you have issues with passing smog, you're better off finding a good used valve and making sure your air pump is hammering air into the exhaust, that's the biggest aid to help pass smog. I'd also recommend stock sized tires to help with speed on dyno.

 

[avicenna110]

1. Interchangeable only if they are the same fitment. EGR valves don't change in functionality, they are only a diapgragm that opens based upon its brain (EGR modulator/vacuum switch depending on year of 2F). All it does is transmit ported vacuum on carb to opening of egr valve to allow engine vacuum to pull in exhaust gas into the intake manifold. That is it.
2. None that exist aftermarket anymore. Only used. I've had luck finding NOS ones but it's not to be relied on.
3. Not reliably, it requires separating the crimped edge, getting the correct diaphragm and retrofitting/recrimping. Totally doable with the correct tools or willingness, just nothing commonly documented.

If you have issues with passing smog, you're better off finding a good used valve and making sure your air pump is hammering air into the exhaust, that's the biggest aid to help pass smog. I'd also recommend stock sized tires to help with speed on dyno.

Thanks for the comments, it all makes sense. Here are more questions:

1- why wouldn’t Toyota make them all the same and the same part? Seems like a lot of variations if they all do the same thing.

2- is there any reason you don’t find rebuildable EGRs? The size is very similar to a valve/diaphragm on my carburetor. I suppose the internal spring is much stronger so the exhaust gas don’t just open the valve, any other reason?

3- I’ve been looking at EGR valves in other older cars and like my 22R engine they bolt directly to the manifold with a gasket. Whereas FJ40 has a tube like this:

And it gets attached to the bottom of EGR like this:

The valve goes up and down inside that small hole in the picture. So I could in theory cut the connection on the FJ40 EGR, remove the top and valve, and weld just the threaded part to a plate, and put it on an EGR with a gasket in between. That EGR would be readily available. It’s feel like the current solution (using used EGRs from older FJ40s) is not sustainable. Maybe I should quit my job and dedicate my time to solving this pressing problem

 

[charliemeyer007]

Depends on how desperate and resourceful you are. Back in 87 my expensive electric fuel pump quit working while I was away at school. I cut the crimp in several places with a hack saw. Pried open the sealed unit, made a new carbon brush from a "D" cell and installed it. Glued up the gasket on both sides with aviation Permatex and pounded the crimp back in place with a hammer and an extension. Didn't leak and lasted for many years. All done in my dorm room in a few hours total time. I like the cheap diode electric pumps now.

 

[45Dougal]

Could you pean it open while slowly turning it on a lathe? You'd have to grind up a special tool for it...??

Otherwise how about abandon the diaphragm but keep the valve body, and replace with a modern motor / solenoid to actuate it, and a vac switch?

 

[mattressking]

Could you pean it open while slowly turning it on a lathe? You'd have to grind up a special tool for it...??

Otherwise how about abandon the diaphragm but keep the valve body, and replace with a modern motor / solenoid to actuate it, and a vac switch?

Yes - there’s a tool that actually opens and closes the crimps.

You’re digging into a world with low volume for another option….which is why nothing exists. Go engineer something yourself or just stick with OTS used and keep it moving down the line.

Better off keeping these things original for value sake nowadays, no one actually drives them big miles except for the .01%. If you do drive big miles, you know how to skate around regulations…it’s really easy.