Moly Diesel Purge

[Waynedance]

Has anyone used this Moly Diesel Purge?

Watched a few videos and read lots of reviews and seems to look very good.

Looking at doing the clean via the fuel line from the pump in the engine bay.

https://youtu.be/xYsXHC2-PSw

[skyship007]

Originally Posted by Waynedance

Has anyone used this Moly Diesel Purge?

Watched a few videos and read lots of reviews and seems to look very good.

Looking at doing the clean via the fuel line from the pump in the engine bay.

https://youtu.be/xYsXHC2-PSw

Yes, I use it every time my oil analysis results show traces of diesel in the used oil.
There is no real need to disconnect fuel feed and return lines, just fill up the fuel filter housing when replacing the element. Then the instructions say to vary the idle RPM etc.
The fuel filter housing trick does waste some of the additive, BUT LM Purge works well as a fuel additive, so the excess from the fuel return line that finishes up in the tank is not wasted in cleaning terms.

[Waynedance]

Thanks for the feedback, ordered 1lt. Not sure where the fuel filter is, could not see it in the engine bay.

May just do some through the fuel line as in the video as it's neater.

[prc68]

I've used it once a year on my old Mercedes C -class. Excellent results even after racking up close to 700000Km on the same injectors.

[skyship007]

Originally Posted by Waynedance

Thanks for the feedback, ordered 1lt. Not sure where the fuel filter is, could not see it in the engine bay.

May just do some through the fuel line as in the video as it's neater.

With some Volvo diesels the fuel filter is under the fuse box.

It's a good idea to carry a spare filter element just in case you get unlucky with a bad fuel incident one day.

[Tannaton]

LiquiMoly can transform a tired engine.

Whilst any amount may be beneficial, to get the best results you should interrupt the fuel supply so the engine runs on neat diesel purge and the return line goes back into the diesel purge can. It’s takes about 40 mins to run a full 1 litre can through and I usually stop it half way through and let’s the car sit with neat fluid in a warm fuel system for 30 min or so.

If you just fill the filter housing then the majority of it will end up back in the fuel tank via the return line and will not go through the injectors. Once back in the tank it will be severely diluted.

[skyship007]

Originally Posted by Tannaton

LiquiMoly can transform a tired engine.

Whilst any amount may be beneficial, to get the best results you should interrupt the fuel supply so the engine runs on neat diesel purge and the return line goes back into the diesel purge can. It’s takes about 40 mins to run a full 1 litre can through and I usually stop it half way through and let’s the car sit with neat fluid in a warm fuel system for 30 min or so.

If you just fill the filter housing then the majority of it will end up back in the fuel tank via the return line and will not go through the injectors. Once back in the tank it will be severely diluted.

Always read the instructions before using any additive. The LM web site does describe both methods and is very specific in terms of how it is supposed to be used in terms of varying the idle RPM. One can will fill my fuel filter twice.

If you use a direct feed injection system cleaner to fill the filter housing when changing the element, there is no need to prime the system. There is also no need to use top of the range diesel or any other fuel additive, unless you are heading for the Artic.

Most of the contents of the fuel filter housing does get fed to the injection pump (I timed it at 15 minutes for half a liter) and LM Purge is similar to most in tank additives.
Never use normal diesel fuel additives as direct feed cleaners, they might be similar in contents terms but lack lubricity, so can damage the HP pump.

[Tannaton]

Originally Posted by skyship007

Most of the contents of the fuel filter housing does get fed to the injection pump (I timed it at 15 minutes for half a liter) and LM Purge is similar to most in tank additives.

All of the contents of the fuel filter housing will get fed through the high pressure pump but the vast majority will then be returned straight back to the tank as it is bled off by the fuel pressure regulator. Remember that the pump will always pump more fuel than is needed by the engine at full throttle/boost, that which is not needed is returned to the tank without going through the injectors. The primary benefit from LiquiMoly is cleaning of the injector valves and nozzles.

I have read the label an it clearly says should be used neat for deep cleaning or as a fuel additive for “preventative maintenance”

[Waynedance]

looks like I may have a problem doing it the neat way!!!!

https://www.volvoforums.org.uk/showthread.php?t=228591

[skyship007]

Originally Posted by Tannaton

All of the contents of the fuel filter housing will get fed through the high pressure pump but the vast majority will then be returned straight back to the tank as it is bled off by the fuel pressure regulator. Remember that the pump will always pump more fuel than is needed by the engine at full throttle/boost, that which is not needed is returned to the tank without going through the injectors. The primary benefit from LiquiMoly is cleaning of the injector valves and nozzles.

I have read the label an it clearly says should be used neat for deep cleaning or as a fuel additive for “preventative maintenance”

Yes but if you look at the German PDS it lists using the fuel filter housing as an alternative method.
Most of the fuel at idle is not fed back to the tank, it's only about one third (The amount varies with the condition of the injectors).

LM have recently changed the UK PDS (The entire web site has been upgraded) and for some reason it now says that the fuel return line does not need to be disconnected. No idea why they changed that instruction, although it might be to reduce the chances of the user causing a leak. With the fuel return line not in use, you are in fact doing exactly the same as the alternate method that just involved using the fuel filter housing.

New UK & US PDS:
Application Preventive use Add to diesel fuel according to the inspection intervals
Remedial use Unclip the fuel pipe and immerse the end in the Diesel Flush. Close the fuel return pipe or feed that into the Diesel Flush. Start the engine and allow the engine to run at different speeds with the Diesel Flush unmixed. After the cleaning process, assemble the vehicle's system. In extreme cases, repeat the cleaning procedure if necessary. As an alternative to remedial procedure, our Jet-Clean Unit can also be used for cleaning. To do this, pour 2-3 litres Diesel Flush into the Jet-Clean tank. Further instructions on use are given in the instructions for the Jet-Clean unit.

Oddly enough the alternative method of use is still shown in the LM video clip:
https://www.youtube.com/watch?v=Bgg3Y2vzWes

In safety terms I would try and avoid disconnecting the fuel line from some types of diesel, although with the VW one in the clip above it's easy. Most good Indy garages in Germany just use it the same way I do, as it's much faster and saves priming the filter when the element is changed.