EGR valve unveiled and some repair ideas.

[retepsnikrep]

Dear Members.

I recently had problems with my EGR valve, and tried cleaning using WD40 as detailed in earlier posts etc without sucess. I now have a new one (herky jerky gone) and decided to explore the old one, and offer a few thoughts and some photos.

The photos are large to give detail. I host them, so bandwidth is not an issue.

http://www.solarvan.co.uk/egr/egr001.jpg
http://www.solarvan.co.uk/egr/egr002.jpg
http://www.solarvan.co.uk/egr/egr003.jpg
http://www.solarvan.co.uk/egr/egr004.jpg
http://www.solarvan.co.uk/egr/egr005.jpg
http://www.solarvan.co.uk/egr/egr006.jpg
http://www.solarvan.co.uk/egr/egr007.jpg
http://www.solarvan.co.uk/egr/egr008.jpg
http://www.solarvan.co.uk/egr/egr009.jpg
http://www.solarvan.co.uk/egr/egr010.jpg
http://www.solarvan.co.uk/egr/egr011.jpg
http://www.solarvan.co.uk/egr/egr012.jpg
http://www.solarvan.co.uk/egr/egr013.jpg
http://www.solarvan.co.uk/egr/egr014.jpg
http://www.solarvan.co.uk/egr/egr015.jpg
http://www.solarvan.co.uk/egr/egr016.jpg
http://www.solarvan.co.uk/egr/egr017.jpg
http://www.solarvan.co.uk/egr/egr018.jpg


The EGR valve is a known weak point, and loads of discussion has taken place on here about it. Some members report sucess with removal and simple soaking in WD40 or Carb Cleaner. This did not work for me for the reasons you will read below. I also believe the cleaning of the valve portion of the unit is a bit of a red herring. I do not believe seizure or carbon build up on the valve is as common as people think.

The postion of the valve is accurately controlled by the ECM using the powerful solenoid the valve contains, this valve position information is determined and fed back to the ECM via a simple linear 5k pot built into the plastic top of the EGR valve unit. Now this pot has a hard life in an uncomfortable environment, and when I tested mine for a smooth change in resistance over its normal range of movement, I was not surprised to find at one point a severe change in value (jumping to 10K+) well outside the normal range of 0-5k. This clearly indicated a worn carbon track or contamination and would inevitably cause problems when the valve was in this particluar position. As a lean burn junky, I suspect this problem area lies right on the worn portion of track. Sadly you can't test the pot thoroughly unless you remove the plastic cap from the EGR body see below.

In order to have any hope of repair we now have to dissasemble the EGR valve after removing it from the engine.

It has a silver retaining ring with pressed in tabs around the top. If you use a very fine blade screwdriver under each tab working your way around the unit this retaining ring can be eased off. The plastic part does not now simply pull out, oh no that would be too easy. It is secured in situ by the connections to the solenoid in the body. If you ease the edge furthest from the connector out of the body, you will see two connections that cannot be easily reached. You could use a thin scalpel blade and cut them. I just eased them out and they pulled free of the plastic top which could then be removed. Note the o-ring around the plastic top, be careful with this mine fell to bits on removal. The solenoid connections can be easily redone by just extending them with two small lengths of wire on reassembly later.

I don't recommend you dissasemble the main body of the valve any further unless there is some obvious problem. The small spring and retaining cotter are difficult to get back in. Lubricate it if you wish, but I doubt this is your problem.

Our problem lies in the plastic cap. Use a resistance meter on 0-10k range and measure how your EGR pot changes in value when you press the centre plunger in and out very slowly. Watch for any sudden change, especially if it jumps out of the normal range. Any spurious readings are an obvious problem. The pot uses the top three connections in the socket. The bottom two are for the solenoid coil.

If your testing indicates a problem then you have a problem! Although I do offer three potential solutions.

The pot can be accessed by carefully drilling out the three obvious plastic peg dimples on the underside of the plastic top with a 3.5mm drill. Watch for springs that want to spring out when you release. it. The ceramic pot carbon track unit is very fragile so don't twist or bend it. I broke mine inspecting it for your benefit and to examine the track under a microscope. It can be taken out by drilling/cutting out the three connections you can see retaining it. It looks very difficult to solder back in however so I don't recommend you remove it!

If you EGR valve is not too bad then cleaning the carbon slider track and the plunger contacts with some proper electrical contact cleaning spray, cotton buds and blowing out with dry compressed air may work. Do not use WD40, Silicone spray or anything similar in this area, it will make it worse!! RS stock contact cleaning sprays. This problem is a bit like having a noisy volume control on your old radio! Excess wd40 in an earlier cleaning attempt or obvious oil/water contamination will increase the problem. Try to remove any excess lubricant in the pot area.

Inspection under a magnifying glass, and later a microscope showed obvious wear on my EGR pot carbon track. I doubt cleaning it would have helped in my case. The pot track/assembly can't simply be replaced sadly, unless anyone knows where we could get the parts.

The pot wiper ploughs furrows over time on the carbon ceramic track, and loses contact which causes us these problems. The plunger wipers are very fragile, but perhaps could be bent left or right very, very slightly to move the contact point on the carbon track out of the furrows! A simple idea which may double the life of the unit. Just be very, very gentle. If you bend them inwards slightly as well to increase contact pressure this may also help. Worth a try before spending $200!

Finally as a last resort we could use an external 5k pot! The top centre of the egr valve can be drilled carefully with a 3mm drill and a metal rod inserted to bring the 10mm plunger travel/movement outside the EGR body. I think a plunger 5k pot, available from RS and suitably enclosed could then be attached to the EGR body and wired into the circuit. A bit of a heath robinson repair I grant you, but probably possible.

Now I have sown these ideas, I did not actually need to do it myself, as I had ordered a new valve. I will def try and repair the next one!

I hope this helps.

Regards

Peter

[Insightful Trekker]

Wow retep,

Thats some effort The greater difficulty may be in calibrating the replacement pot such that the correct amount of EGR is proportioned in relation to its value.

Heath Robinson We have Rube Goldberg here in the states (guess every nation's got one). Reads like you'd end up with one of his versions.

There's also a dynamic test (appling voltage to the sensor) that may reveal some faults that a "static" test would not.

See the recent thread here:

EGR valve swap.
http://www.insightcentral.net/forum/vie ... php?t=4966

and the sub linked thread in the above.

HTH!

[retepsnikrep]

The greater difficulty may be in calibrating the replacement pot such that the correct amount of EGR is proportioned in relation to its value.

I don't think this is a problem. The EGR valve plunger has 10mm 0-5k travel. The RS part I looked at had 11mm 0-5k travel. Variable resistors like this are not normally close tolerance devices, and I expect 10% variation at least between EGR valves. Also the mechanical location of the pot track in the valve body is unlikely to be identical in every EGR valve, so I suspect the ECM works out any discrepancies itself.

There's also a dynamic test (appling voltage to the sensor) that may reveal some faults that a "static" test would not.

This may help, but load current for pot track testing should be very small 12v <10ma in my view.

Peter

[Rick]

Thanks for diving this deep in to your ERG valve! Your at least the second person to have two Insights and swapped EGR's in order to make sure it was the problem so it's deffinitely something to consider for anyone out there with the engine hickup's. Furthermore you gave us a good simple testing procedure!

[dloop]

Most awesome writeup Peter, thank you.

Does any sort of 'preventative maintenance' come to mind after delving into this? Is there any thing we could be doing ahead of time to extend the useful life of our EGR valves?

[retepsnikrep]

Does any sort of 'preventative maintenance' come to mind after delving into this? Is there any thing we could be doing ahead of time to extend the useful life of our EGR valves?

I don't think we can prevent this EGR failure mode due to the hard life the pot leads, it probably experiences millions of operations which is a lot for a wiper pot!

With what I know now, I would def attempt to repair any future valve pot failure by first using contact cleaner spray on the pot track and wiper if it showed any obvious sign of damp/oil contamination. (Not wd40 or the like!) If that did not work I would def try slightly bending the pot wiper arms onto fresh track and slightly increasing wiper contact pressure.

If that did not work, I then might fall back to the external pot add on repair, but that's pretty ugly and likely a last resort when broke!

[Resist]

Great write up about this issue. My EGR valve was replaced under warranty. The Dealership claimed it was a new design but I know better. Now that I'm outside the warranty, I don't look forward to buying another valve when this issue happens again.

[retepsnikrep]

Great post by Mikemo

EGR Valve Repair

My new (to me) 2000 Insight had started to develop a very annoying jerky characteristic when at light throttle, particularly when trying to get to lean-burn. I searched the forums and found lots of info regarding cleaning the EGR system. I also read some opinions that cleaning the valve with WD-40 either will or won't fix the issue. After reading this excellent post
EGR valve unveiled and some repair ideas.
I decided to do an experiment. My car only has 40k miles on it, 39k from the PO, 1k from me, so I don't really know how it was driven. I do know that the lifetime MPG was 49, which concerned me. However, I got 69mpg on my last tank, so I assume the car is working reasonably well.

I decided to remove and evaluate the EGR valve without cleaning anything. I removed the engine cover (three 10mm nuts), the EGR connector and the valve (two 12mm nuts). The EGR valve had two numbers on the top. One, in white paint, was 50800717, and etched on the connector was 13070706. The first attachment is a picture of the underside of the valve. Looks pretty clean to me.

I connected a variable current power supply to the solenoid connectors and started ramping up the current. As the input swept from 0 to 1 amp, the valve opened smoothly without binding. The next two pictures show the valve 1/2 opened and all the way opened. Again, no real grime to speak of.

I put an ohm-meter across the two outer potentiometer pins and watched what happened. As I increased the solenoid current and began to open the valve, the resistance, which should have decreased fairly linearly, started to go down, then would jump up (over 20k ohms), then back down. It didn't always do this, and not always in the same place, but it was obvious that there was a problem with the feedback potentiometer inside the EGR.

Going on the disassembly information in the above referenced post (thanks Retepsnikrep!), I decided to try and clean the potentiometer. I did not want to disassemble the valve. If you look at the above post you'd know why. I have a spray can of something called "Kontact Restorer" made by Chemtronics. It is made specifically for cleaning sliding contacts like this. Since it contains Freon, I doubt you could buy it any more. It also contains a lubricant that stays behind after the freon evaporates. I'm sure you could find a modern replacement at a good electronics supply store. Now I had to get it on the moving parts inside the EGR.

The black top has a "nub" that holds the internal spring in place. I decided this was the safest place to drill. Using a 1/16" sharp drill bit and a drill, I carefully drilled a hole in the very top center of the valve (see the attached pic). The plastic should come out in a twisty-bit (assuming you used a sharp drill bit). It is fairly thick, but I let the drill do the work and made sure not to "punch" through and hurt the insides.

Once the hole was there, I used the tube attachment on the Kontact Restorer and squirted a liberal amount (1 second squirt) into the hole as best I could. It was a little fussy since there was no vent hole, but I got some in there. Then, using the power supply, I excercised the valve up and down slowly to wipe clean the element. I repeated the process just to be thorough, then I tested the potentiometer again. I was happy to see that the jumping of the resistance value was gone. I wiped up the overspray, then sealed the hole with a piece of heavy-duty aluminum tape (used in heating and air conditioning duct work).

I replaced the valve on the car and took it for a spin. I want to reserve my hopes, but at least for now the problem is gone. I have no idea how long this repair will last, or if cleaning the inside of the valve will cause any other issues. I figured I had nothing to lose, since I would have had to replace the valve anyway.

I just want to be clear that I did not clean anything in the exhaust gas path. The only thing I touched was the internal potentiometer which is not in the exhaust gas path.

Obviously, I can't guarantee that this will work for you. I'm just sharing my experience.
Good luck!

[retepsnikrep]

Holy thread resurrection Batman.

Jim Fell a UK CVT Insight Gen1 owner for a short time recently took up an old idea I had about mounting an external pot on the egr valve

He actually completed the mod see photos below. I can't remember wether he tried it in the car, but I have e-mailed him about it. It looks very neat and professional. He sent me the egr valve and some notes and rough sketches which I can make available later if reqd.

The pot is an RS part 317-780.

Once my project car is repaired I shall fit the modified EGR pot to it, as it has been a bit lumpy recently and report back.

[mrkcohen]

Holy thread resurrection Batman.

That is truly a thing of beauty! I'm curious how he connected the little posts to the internal connections under the plastic. Drilled/Soldered?

---

RS has the pot listed at GBP 18 (about $30). Throw in a chunk of aluminum spacer, shipping and the small electrical parts and you can rebuild the top end for under $50.

Of course that doesn't count the time and TLC that would go into such a project.

I am continuously amazed and impressed at the dedication and resourcefulness you G1 Insighters put into your little beasts.

Let us know if this thing actually works retepsnikrep....