Time for fuel filter - Diesel Purge good idea?

jesus_man

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My car has the original HPFP (assuming) with a 135k miles. I looked back thru the recommended maintenance schedule to see that I have neglected the fuel filter. So it's time to change that out.

Would it be a good idea to run Liqui Moly's Diesel Purge thru the system at this time? I am somewhat concerned about introducing air into the system for a pump that's known to be an issue. But if I am careful, perhaps I could minimize that. I have the treatment already, so it's a matter of some inexpensive tube and fittings to get the job done.

I have two cans, so the BMW may also get the treatment...
Thanks!
 

PRY4SNO

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Keep it simple.

Pull the old filter, and replace with a new one. Be careful to not introduce contaminants into the fuel. Top up the filter canister with the treatment fluid and run the rest through a full tank of fuel.

Be sure to purge the pump for about 30 seconds, three times, with your VAGCOM or similar device before starting the engine.
 

jesus_man

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It is recommended to run the purge at full strength. I get the impression it does little diluted with fluid.

I appreciate the input, but I don't want to waste the purge fluid.
 

PRY4SNO

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According to the product page:
Can contents are sufficient for up to 75 l fuel.
...
Preventive use
Add to diesel fuel according to the inspection intervals
So a little to top up your fuel filter canister and the rest through the 55L tank won't constitute a "waste," but by all means, it's up to you.
 

jesus_man

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I already run a fuel treatment, so my goal was to potentially clean the system from the first 100k miles that were not under my ownership. I just worry about the HPFP which seems to be a ticking time bomb.
 

turbobrick240

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The purge stuff is really supposed to clean the injectors. I honestly can't see it benefiting the hpfp in any way.
 

jesus_man

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Please don't misunderstand me, I am not trying to do anything for the HPFP, but I know that introducing air into the system is hard on that pump. Perhaps it's a non-issue?
 

turbobrick240

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Ok, I get your meaning now. Seems like too much hassle for something the injectors probably won't benefit much from at this point/mileage. I'd either dump it in the canister and tank as previously suggested (maybe a nearly empty tank if you don't want to dilute it a lot) or save it for use at more like 200k+ miles. But that's just me. Now I'm curious just what is in the purge juice.
 
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turbobrick240

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Looks like it's basically 80+% highly refined diesel fuel. Should be good for a placebo effect at the very least.
 

jesus_man

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I'm not expecting a miracle here. Just trying to do everything I can for the car for longevity...at least within my budget. My plan is to keep her for a LONG time, but sometime life changes things.
 

PRY4SNO

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It seems to me you're over thinking things. Nothing wrong with trying to be proactive, however. :)

After you change the filter, purge the canister with VAGCOM or equivalent three times for 30 seconds (wait about a minute in between purges to allow the pumps to cool down), and carry on as normal.

The fuel treatment you run (Power Service?) should already be giving you the added benefits you seek to maintain the HPFP.

Maybe after the tank following the filter change go ahead and run the injector cleaner through the tank (as it's intended to be applied) and do that next year as preventative maintenance. Seems a little overboard to me though, the fuel treatment you're already using likely helps clean the injectors on it's own.
 

jesus_man

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I see what you're saying. Perhaps the treatment I am using is doing it's job. (Schaeffer's FWIW). And maybe just putting this Diesel purge in the tank is the better idea for now.
But it can be used full strength as per Liqui Moly's site:
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.
But maybe that is for cars that aren't running well and aside from a drop in MPG's from what I believe could be winter blend diesel, it's running fine.

I rec'd the fuel filter today. May tackle this yet this week.
 
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