EGR time.

[The Bear78]

Well, it's EGR time again!
I bought the van nearly 5 years ago at ~99000 miles. I'm sure I saw a receipt for a new EGR' in the paperwork but I can't find it now. Either way, the date of manufacture of the old (aftermarket) EGR is 2018 and the van (Euro 5, 140) was registered in January 2016!!
A few months ago the EML came on and Carista told me that I had the classic "insufficient flow". I reset it and it lasted a couple of months only to strangely come on again after a 220 mile trip home on the motorway from Cornwall. Reset, lasted 2 weeks. Reset, now one week. Reset again and it was on every day.
I had considered blanking it off but as this one has lasted this long and must have done at least 60000 odd miles (i'm currently on just over 150000), I went the safer route.
Luckily my wife's Uncle owns a garage so Mot's and servicing etc. is virtually free as I just cover parts and pay a nominal labour fee. Usually in liquid form...
So, with a new EGR assembly installed, I've got time to clean the old one.
Nothing new here really, to be fair but, I'm keen to get all the way inside and hopefully create a usable spare in the process.
So far I only have the cooler seperated and the vacuum solenoid removed. I wonder if there is anything to gain (or lose) by popping the plastic cover off the electrical enclosure?
I've tried soaking it in a few solvents but, unsurprisingly nothing has broken down the carbon. I picked up some oven cleaner earlier so will give that a go tomorrow.
Typical discoveries: valve seized shut and the inlet side of the cooler is virtually plugged up. I can move the valve but it takes a lot more force than a vacuum can provide with this little solenoid!!
Below are some progress pictures. The link is to a terrible video of a video of a borescope inside the cooler (I didn't have the hardware to transfer the file). I wanted to see if the end cap of the cooler is empty like a radiator/intercooler and not full of U-shaped pipes. It is, which should make clearing the tubes easier.

EGR cooler inside

 

[The Bear78]

Mods.
Please could you move this to the Engine section. My bad...

 

[The Bear78]

Some progress today. The plastic cover comes off (1 sheared screw...).
The mechanism:

The cover and electrical contacts. Judging by their location, I assume that the small brown/yellow components are thermistors?

With the gears removed:

Motor removed. The other part doesn't fully lift out and appears to have a magnetic bar inside. I think this is feedback for the poppet valve position.

The gate valve bushing. Opposite the actuator arm:

Lots of carbon in here. While it is open to the air path it probably gets missed during normal flushes/cleans. The valve moved much more freely with this off...


Video of the poppet valve in action here . This is ellectronically controlled and slides open and closed via rotation of the bellcrank here:

While fairly sooted up, there was no restriction in this.

The cooler is currently soaking in oven cleaner. I'll add this to the bag once I've sorted the sheared bolt and popped the plastic cover back on. I'll have to protect the plastic somehow and I'll see how reactive the aluminium casting is too.

 

[The Bear78]

Well, unsurprisingly the aluminium body fizzed! I filled the internal cavities with oven cleaner but the reaction was instant and it frothed up and started overflowing all over the casing. No damage done, just an inconvenience as I wasn't keen to leave it soaking too long.
An oversight on my part was not clearing the cooler tubes by some mechanical means before soaking in oven cleaner. The acid has done a good job but the tubes are narrower than they look and most remained clogged after several hours in the acid. I used a long series drill to clear the tubes on the heavily clogged side. Some of the "swarf" that came out was almost as hard as plastic. No wonder it wouldn't clear just with the oven cleaner.
I have put some more cleaning fluid down them since and given the whole lot a good jet wash. It's a lot better but I will give the whole lot another going over when I get the chance.

The cooler tubes are actually ribbed/corrugated after a short plain section at each end. This is a pig to clean as a lot of the carbon is held in the recesses.

 

[Ali-G]

And to think that all that sh1te normally gets passed back into the engine.