Evap purge valve clean-out and testing

[jreed]

I recently had a P0440 code appear on my '97 855 GLT, indicating a problem with the purge valve in the evaporative emissions control system (the Evap Purge Valve). This is Volvo part number 9135444 and Bosch part number 0 280 142 300. It seems to be used on a lot of vehicles besides the Volvo (including VW, Saab, Audi) and is available new for about $40-$50.

TheCheat wrote up a great post on how to open up, clean out and repair the evap valve, inspiring me to do the same... You can read his original post here:
https://www.matthewsvolvosite.com/forums ... =1&t=31691

Like TheCheat I opened up my evap valve using a sharp knife and a small flat blade screwdriver to scrape and score away the glue hold the two halves of the case together.

After cutting through the glue seal

Overview of valve after cutting around edge.jpg (106.83 KiB) Viewed 9543 times

Lift off the top half of the case, being careful to avoid bending the two metal prongs:

After lifting off the top half

Valve after lifting off top.jpg (77.25 KiB) Viewed 9543 times

It was here that I realized that the internal configuration of the valve is different from the one pictured by TheCheat. My valve has a thicker metal crossbeam and rubber ears at the ends.

Next you slide the valve body out of the bottom half of the case:

Solenoid body after sliding out of the bottom half of the case

Sliding valve out of bottom case.jpg (102.61 KiB) Viewed 9543 times

The I removed the o-ring and the rubber elbows from the metal crossbeam:

Remove the rubber elbows and oring.

Removing Rubber wings and o-ring.jpg (98.67 KiB) Viewed 9543 times

I noticed that the o-ring has an unusual angular profile. I haven't seen this kind of o-ring before:

The o-ring profile has an angled cross-section

Angular profile of o-ring.jpg (75.56 KiB) Viewed 9543 times

While I had the solenoid out, I actuated it by applying a 9V battery to the terminals. I saw the plate underneath move in response and heard a click at the valve opened. I took a short video clip of this action (see the movie link at end of post)

Then I cleaned out the orifices in the metal crossbeam with MAF cleaner (hexane) and swabbing with the corner of a clean towel:

Area cleaned with hexane spray

Cleaned valve orifice and lubed electrical feedthrough o-ring 2.jpg.jpg (162.9 KiB) Viewed 9543 times

After cleaning with the spray and wiping, I applied some silicone grease to the oring around the electrical feedthrough.

Next I put a little more silicone grease on the angular o-ring and re-installed it in the case:

Lubed o-ring with silicone grease

Lubed angular o-ring.jpg (65.52 KiB) Viewed 9543 times

To reseal the case together, I used silicone RTV rubber. I applied a small amount around the bottom half of the case and pressed the two halves together:

Thin layer of silicone rubber sealant applied to bottom half of case on mating surface

Silicone sealant applied to case.jpg (71.65 KiB) Viewed 9543 times

I held the two halves together in a vise during curing of the RTV:

Firm pressure applied with a vise during silicone curing

Vice applied to case during silicone cure.jpg (79.36 KiB) Viewed 9543 times

After the cure was complete (I gave it overnight), the repaired valve is ready for testing:

Sealant cured, ready for valve testing

Evap valve after re-sealing.jpg (86.93 KiB) Viewed 9543 times

I made a short video clip of the solenoid being actuated (first part of clip) and then of the valve being tested (second part of clip):

Before I took it apart and cleaned it out, it would pass air even when not actuated. The valve definitely controls the flow of air now.
I haven't actually installed this valve back into the car yet. I bought a used valve off of eBay for about $20 and have been using that in the car for a couple weeks now -- no more P0440 code.
Having a good working valve in the car made me feel free to dig in and open up the old valve to see what I could see. Hope this helps!