Is this purge valve really necessary. I accidentally broke the bottom nipple trying to remove a dried out silicone hose 🤦‍♂️ I actually broke two oil purge valves. Their so brittle.
75 bucks is pretty steep for this valve.
Maybe I should put something heat ressistant to prevent the solenoirs from getting brittle as well.
cant find any on ebay and no rx7 in the junkyard for a long while now.

 

IMO, it's better to have it than not. It's there for a reason. Always best practice to slit the hose along the nipple before attempting to remove. All that old plastic is brittle and replacement parts are expensive if even still available.

 

alright I have 3 broken purge valves from the same nipple.
I decided to cut one open. I sacrificed one for the forum.
heres what I found out. The opening is about 2.8mm and we actually have a good distance of 7.5mm. Anything below 7.5mm should not hit the diaphragm. Either use a 2.8 or 3mm tube and melt it in. Im sure we could also tap it for a 3mm
here are some pics.








There seems to only be probably 2.0mm thickness
not sure id thats enough to tip.
Theres is 7.5mm before hitting the diaphragm.
I ordered some things to see if we could find a fix for this valve or find an alternative.
I just dont know what kind of valve this is caled.

 

I may have found an alternative part for this oil purge valve.
seems to do the same. Just has a bigger nipple. Mayve tap something to it.

the upper nipple sucking the diaphragm open just like our original part. Bottom nipples one w ont lets air in unless theres alot of pressure applied to it. The other nipple bottom wont push or suck air it all. So its the same to out original part. It just doesnt have 2 nipples pointing down like the original part.

 

If you send me all the dimensions, I can model it and we can try to figure out how to make one cheaply.

 

The new valve is found is

Dorman 994-093

If anyone is interested in finding a new alternative

 

Hi,
While going through everything as I get ready to install another rebuilt engine on my 1988 GXL, I found the purge valve to have a crack in the side of the top part.

I had another one on hand, so I twisted the top part off and found the spring and thin diaphragm. I also noticed that the small vacuum line nipples have just a pinhole sized opening down in the nipple! Both the top and bottom have this restriction molded into them!

So, any attempt to fabricate or replace it with another part that does not have the exact functionality, (spring tension, diaphragm flexibility, and restriction size) will not work properly.

For those who don't know what the purge valve actually does, it pulls the HC vapors from the charcoal cannister on a cold start. Where they accumulate overnight after shutdown.
As the engine runs it produces "blow-by gases" that get past the apex and side seals during the combustion part of the cycle.
The purge valve also pulls these vapors out of the oil pan area, it is very important that these vapors are evacuated and not allowed to accumulate!
Think positive crankcase ventilation that used a PVC valve on older cars back in my day. And before that they used a pipe which vented to the outside air using the same airflow across the pipe opening to pull out the blow-by gasses.

I traced the path of the vapors to a small hole at the top of the primary throttle bore, where airflow across the face of the hole pulls the vapors into the primary part of the dynamic chamber. This makes for a little amount being pulled in at idle, and a larger amount when the rpms go higher.

I also reasoned that the 3000 rpm for a short time on a cold start is to get the stored vapors out of the charcoal. Along with the accelerated warm up of the cats.

So, for all this, $75 sounds like a bargain.
What do you think?

P.S. I read on the forum somewhere that during an oil change they get a larger amount of oil out when draining then what they put in! Considering that the oil metering system is injecting a quart of oil through it over 500 to 1000 miles if it is working properly. What is building up in the oil to increase its quantity? Is it the HC vapors from the gas tank condensing on the cold oil on startup then mixing with the oil diluting it? Oil dilution, I will have to do some research on the subject.

 

@gsmithrx7
thanks for the input. I honest do believe the part I found functions the same.
i also am getting ready to install my s5 n/a

I cant say for sure since I dont have the motor back in.
hope someone is able to rest this alternative valve.

In the meantime I have fixed my original valve. Its a temp fix but looks good.
its a mini barb. M6 x 3.5mm
I used a 3/16 drill carefully. Dont drill more than 4mm in to avoid hitting the diaphragm. Also it as slightly loose when installing the hose. I would say to use a little glue stick to get it to sell better.










I could confirm that they replacement check valve i found. Uses about the same pressure to open and close the valve.

 

Nice repair! If anything, the larger 2.3 mm passage will flow more vapors and change the cold idle quality.

If you notice anything off, you can fabricate a restriction to add to the part!

Do you still have the broken nipple? You could measure the size of the restriction from that, or perhaps adapt the broken piece into the line.

 

@gsmithrx7
quick measurement post


the outer diamter nipples is 4.7mm
The inner diameter is 2.8 which I established on an earlier post.
The barb nipple is
3.5mm outer
2.3mm inner
the size difference is .5mm but i dont think it'll cause an issue. Unless someone could find a bigger size.
the 6mm to drill is already too big. I wouldnt go Any bigger than 6mm to drill.
maybe a 4mm nipple would have a slightly bigger inner diameter.

This other might be a better fit for the fix.

 

Hi, I see what you are measuring, what I suggest is that you take your smallest drill bits and see what size passes through the top vacuum port on the purge valve that is not broken.

I have not done this as I have an intact purge valve. This small restriction in these two ports is engineered into the valve for a reason.

As a Do It Yourself amateur I have to respect what the designers have done. They have looked into what they want the purge valve to accomplish!

I hope my discourse on this subject has convinced you to have a purge valve on your engine.

Here is a picture of my latest perception:


using spring clamps on a vacuum line


As I reused my 35 year old vacuum lines I noticed that they have a loose fit to the rat's nest and the parts that they connect to.

So, I have some 8 mm spring clamps that fit nicely on the stock lines.

I am using these spring clamps to make sure that these old hard vacuum lines seal without leaks over time.

For the next person who has to deal with these old lines, I am coating the inside of the lines with silicon grease, so they do not become stuck to their connections!

 

@gsmithrx7
yeah im not removing the valve from my car. I was mainly asking to force myself to find a fix or an alternative.
with the new fix. The oem would work. And hope new people find this useful to fox their own. Since thats the main nipple that always breaks.

I will still try the new alternative part to see if it works. I will still need to find barbs to make it works.

 

Over the years previous owners have deleted various parts to make the engine less confusing and more reliable.

This time around I deleted the EGR valve and the secondary air valves. I changed my mind and rebuilt the OMP system when I found out about the fuel cut when decelerating! Anything to assist in making the engine last longer.

This will be the third and last engine I do, need to do it right.

These are fantastic vehicles and fun to work on. And you WILL be working on them quite a bit. For me it is a pastime, and along with beer, is the reason I get out of bed every afternoon!

Have a great holiday season everyone.
This is Rexy, all dressed up & nowhere to go!

I remove the two engine lift brackets once the engine is in place.

 

Alright for the alternative purge valve all your really need to do is use a barb wire but i dont like this bend. Might need to find a U elbow or a 90 degree elbow would work

everything else should connect the same

 

How did you connect it? Also did it end up working?