Diesel Purge and fuel filter change...

geeknik

Member
Joined
Aug 25, 2021
Location
Hazard, KY
TDI
2013 Sportwagen TDI
I have watched a few videos on youtube performing the diesel purge process with a jar and the fuel lines... most are older models than mine and I'm a little hesitant to do this procedure without some more detailed instruction...

I've also heard of people topping off the filter housing itself with diesel purge and starting it up. Is this sufficient?

I purchased my car 13 JSW with 60K miles on it and unsure how well it was taken care of etc...but seems to run fine...I want to do this more for piece of mind than anything else...might not even be necessary.

Definitely changing the filter and thought it might not hurt to dump a bottle in at $8.

Any input is appreciated!
 

hskrdu

Top Post Dawg
Joined
Oct 17, 2003
Location
Maryland and New England
TDI
2003 Golf GLS 4D 5M, 2015 GSW SE 6M
Just as with the older models and threads (available with a search here), DP is best used in a loop from the bottle to the injectors and back. Dumping it in the fuel tank is generally considered to have no impact, and just filling the fuel filter is limited. When you run a full can of DP through the system, it can take 20 minutes with varying RPM, and (with older injectors) you can often hear the difference as the DP circulates. Newer systems often have injectors where a DP process seems to have very little impact.
 

rocky raccoon

Veteran Member
Joined
Jun 11, 2020
Location
Greater metropolitan Beaverdam
TDI
2014 Jetta Sportwagen
I have always done a yearly full Diesel Purge on my old Benz OM617 engines and am a believer in it. I too would like to do it on my CJAA TDI but; my filter has four fuel lines. How can I know which is input from tank and return? Until now, I have been simply topping the filter can off when doing a filter change.
 

geeknik

Member
Joined
Aug 25, 2021
Location
Hazard, KY
TDI
2013 Sportwagen TDI
I have always done a yearly full Diesel Purge on my old Benz OM617 engines and am a believer in it. I too would like to do it on my CJAA TDI but; my filter has four fuel lines. How can I know which is input from tank and return? Until now, I have been simply topping the filter can off when doing a filter change.


I saw you had asked this a couple of times. I too am trying to figure this out.

Apparently 6 & 7 are to the engine in the direction of the arrows.

1 and 3 are to the fuel tank.
 

rocky raccoon

Veteran Member
Joined
Jun 11, 2020
Location
Greater metropolitan Beaverdam
TDI
2014 Jetta Sportwagen
Thanks geek. So, if we replace 5 with the supply hose from the bottom of the Diesel Purge supply tank (clear plastic bottle) and run a hose from 6 back into the DP tank upper section, the car will start and run on the DP.

Sounds good. You First!
 

geeknik

Member
Joined
Aug 25, 2021
Location
Hazard, KY
TDI
2013 Sportwagen TDI
Thanks geek. So, if we replace 5 with the supply hose from the bottom of the Diesel Purge supply tank (clear plastic bottle) and run a hose from 6 back into the DP tank upper section, the car will start and run on the DP.

Sounds good. You First!
rocky, after further research it seems the diesel purge process could be detrimental to the HPFP in my vehicle. From what I keep reading the diesel purge itself may effect the lubricity of the pump and damage it. Not to mention introducing air bubbles.

there seems to be a lot of folks who wouldn’t even do a fuel filter change without using VCSD to prime the fuel system to get rid of any air before starting.

There also seem to be plenty who clear out the canister and replace the filter, and top off the canister with diesel …without issue. Given no vcsd in my possession, I’ll opt for this route and try to do it quickly so as not to lose as much fuel in the lines as possible.
 

rocky raccoon

Veteran Member
Joined
Jun 11, 2020
Location
Greater metropolitan Beaverdam
TDI
2014 Jetta Sportwagen
Actually Geeknik, that's sort of what I do. I do not have VCDS so when changing fuel filter, I simply fill the canister with Diesel Purge, slowly submerge the filter so it soaks itself full without making a mess, then top the canister off and call it good. I have never had a problem and always have an instant restart.
 

geeknik

Member
Joined
Aug 25, 2021
Location
Hazard, KY
TDI
2013 Sportwagen TDI
Actually Geeknik, that's sort of what I do. I do not have VCDS so when changing fuel filter, I simply fill the canister with Diesel Purge, slowly submerge the filter so it soaks itself full without making a mess, then top the canister off and call it good. I have never had a problem and always have an instant restart.

So you don't feel there is any downsides to using diesel purge on the engine? Researching these forums gives you so much information one way or the other and it's hard to make a decision! lol

I read somewhere that it has benzene in it which would have a negative effect on the lubricity of the pump.
 

rocky raccoon

Veteran Member
Joined
Jun 11, 2020
Location
Greater metropolitan Beaverdam
TDI
2014 Jetta Sportwagen
Compared to my stone-age 36 year old Mercedes Diesel, the CJAA engine is a modern miracle and I have heard on this grapevine that the injectors and the fuel system are robust and don't need periodic servicing. Nevertheless, being Old School I still do a yearly cleanout of the fuel pump and injectors. It MAY BE that running the engine exclusively on a compound such as DP is not good in the long term but I don't think it can do any harm to run a cleaning cycle through every now and then.

That's my story and I'm stickin' to it.

Perhaps there is a True Expert on here that can give us both a definitive answer. Anecdotes are not evidence.
 

robzrr

Member
Joined
Sep 14, 2021
Location
Cumbria UK
TDI
POLO 1.2
Has anyone carried out a diesel purge on a 1.2tdi polo ?

I set up to do a diesel purge on the Polo (1.2tdi 6r 2013 model bluemotion) as its got 105k on it and is a bit lumpy at low revs and has a bit of a diesel knock.
Anyway, I rigged up the supply and return lines from the high pressure fuel pump to the purge liquid container and looped the supply and return from the fuel lift pump pump together as I have done on a few cars before . Then tried to start it and it wouldn't, it just kept turning over without starting. So I tried again, ensuring that everything was primed but still no good. Hmmm.... As soon as I reconnected the pipes back it to standard it started up literally instantly so there must be I suspect a pressure sensor on the fuel pump or supply that signals that there is pressure in the supply line...Any ideas?
 

B100

Veteran Member
Joined
Jan 7, 2003
Location
Berkeley, Eastbania
TDI
2003 Golf
Actually Geeknik, that's sort of what I do. I do not have VCDS so when changing fuel filter, I simply fill the canister with Diesel Purge, slowly submerge the filter so it soaks itself full without making a mess, then top the canister off and call it good. I have never had a problem and always have an instant restart.
The DP you run through the IP is all inside the fuel filter canister? Then it's getting diluted by the diesel fuel being pulled/pushed into the filter as the engine is running.I thought the idea was to circulate a can's worth of Diesel Purge through the IP until it was almost all used up - no diesel fuel dilution beyond what was already in the inlet and return lines.
 

robzrr

Member
Joined
Sep 14, 2021
Location
Cumbria UK
TDI
POLO 1.2
Thanks for the replies all. I have a solution....
The system has a fuel pressure switch to prevent the engine running with little or no pressure, although it will turn over on the starter motor it won't start.
So this is what I did to achieve a recirculating moly diesel purge :-
1.disconnected supply and return from fuel pump and attached them together.
2.filled a glass jar of liquid moly diesel purge
3.attached a return line hose to the jar
4.attached a supply hose with in line filter to the jar AND put in a hand pump primer bulb that I took off my boat and primed the line and pressurised constantly, the engine started and the recirculating flush worked, I just had to keep pumping the hand primer bulb to maintain the pressure...a bit tiring but worth it.
So all good. Hope this helps others out
thanks
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Never let anything past the fuel filter.
These are 10 micron or smaller. Only prime the filter with whatever going though. No filling it.
 
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