How to: Liqui Moly Diesel Purge a Euro4 D5

[rangerovering]

After finding many posts about people trying to do this and struggling, here is how to successfully do a diesel purge on a 185 euro4 d5.

Actually quite easy in the end but there are a couple of tips which should help anyone else tackling it.

On this engine you need to cap off the return on the HP pump because when pumping the fluid in you won’t build enough pressure for the engine to start without plugging it. I used a hose and stuck vise grips on but any hose clamp would do (the grips are easier to remove if required).

Remove the return hose and the supply hose from the lower right side of the HP pump and the lower connection on the multi stem branch before the HP pump. Join these two hoses together to make a loop back so that the diesel is taken care of.

On the supply side you need to be able to pressurise the fluid to at least 2bar/30psi to ge the engine to start - any less and mine would not fire up. Once running this isn’t so much of an issue but keep the pressure up for the duration of the purge. I used my Sealey power bleeder normally used for brakes, this was perfect with some hose work to suit.

Once running I let the car idle for 5mins, then held about 1800rpm for 5, back to idle, up to 1200 for 5 then back to idle. A bit of up and down to help work the fluid through and do it’s job. A handy bit of stick and the electric seat help hold the throttle 👍

With the Purge fluid used up simply reconnect the hoses where they should go and tidy up. Took about 25 mins for my car to use 750ml.

I listened with a screwdriver to each incjector thorughout and 123 had a clear thack thack thack when running, 4&5 were quite a bit more muted. Afterwards all were much closer with a clear click/thack on each combustion stroke. So something definitely was going on!

Once back on diesel the engine was noticeably quieter and smoother than it’s ever been, I’ve had it 30k miles exactly and she’s now on 147k. Never has it sounded this smooth. Went for a drive and the 5 cyl thrum is much more noticeable when you boot it (even with the DPF) which would suggest those 2 lazy cylinders are now firing better.

So, all in all I highly recommend this for any diesel with some miles on, my one ran well but had the odd lump on a cold morning or just didn’t always sound right. The fuel economy could have been better too I felt so time will tell.

£14 for 2 tins and an hour of time is a bargain when injector servicing is £90 odd each, might make a tired engine much better!

Photos to follow…