Diesel injector overhaul

[vitesseefi]

Hi,

Any diesel injector experts on here?

My elderly Audi A6 2.5TDI has now done 276k and the (original) injector nozzles are tired.

I have a spare set of injectors (mileage unknown) and a set of new allegedly Bosch nozzles of the same part no. as original. I also have a pop tester.

Today I've been trying to make a set of working injectors. I started by testing the spare injectors before dismantling. They were all popping around 160 - 165 Bar (should be 190 I think) but only 1 of the 5 was popping cleanly and repeatedly. None seemed to be leaking though.

I then dismantled one of the worst ones and tried a new nozzle on it. Was leaking badly enough to make establishing a pop point difficult, but it was very low. Dismantled again rinsed thoroughly in carb cleaner and tried again. No change.

To try and rule out injector body problems I tried the same new nozzle on the best of the injectors with exactly the same result. Refitting the original nozzle restored the original performance.

I then tried a second new nozzle on both injector bodies. It was a little better, but still rubbish.

I'm pretty sure this is indicating that the new nozzles are fakes (and rubbish too) though the packaging is fairly convincing and the seller swears they are genuine. They weren't especially cheap either. Of course, as I've not actually done this before I may be being stupid........

Thoughts and advice gratefully received.

Also any suggestions on where to get decent quality nozzles without exceeding the value of the car. Bosio, Firad or whatever.

Cheers

Nick

[vtecpowergt]

Hi the injectors you have could be 2 stage if the are then you can only carry out basic testing with a pop tester and then only 1 stage if you do have 2 stage injectors then the kits that you bought should of had a the complete nozzle and shim and spring calibrated and ready to fit and should be just a case of assembly and testing we have at work seen various copy injector parts being sold on the likes of ebay but most seem to be poor quality copy,s that rarely work all that well havent ever used bosio nozzles but have used firad ones and they quite good for the price but as we are bosch diesel agents we normally just buy the bosch nozzles if you want to send me the injector number and the kit you bought i can check the part numbers and try to find out if they are single stage or not and if the kit number is the correct one.

[vitesseefi]

Hi,

Thanks for the answer.

They are two-stage injectors and I realise I'm only seeing the first stage pop. Car is an Audi A6 2.5TDI (140hp AEL I5 engine) and identical engines and injectors are used in the Volvo 850/V70 TDI. The original nozzles are 150P520

The nozzles came in packaging with what looks like Bosch markings and part numbers (though the break-open type tubes don't work very well either). The nozzles themselves are marked "150P520" "made in Brasil" and also carry the Bosch logo. However, only the nozzle and plunger are supplied. No shims or springs.

I've had some contact with the vendor who swears that they are fine and he fits them in his workshop all the time, no issues. I've explained in detail what I've tried and asked him to point out what I'm doing wrong. He's gone quiet.

I've bitten the bullet and bought some Firad ASLA150P520 nozzles and will hopefully get the chance to experiment some more over the weekend. If these do the business then I'll be demanding a refund/going ebay dispute route.

Cheers

Nick

[vitesseefi]

Update:

The Firad Nozzles work without issues. All 5 now pop between 175 & 180 Bar, cycle properly and don't leak at just under the pop pressure.

I tried cleaning the "Bosch" nozzles as I noticed the plungers were much stiffer than the Firad ones. This did have an effect. The first one I did then worked as well as the Firad ones. The second one was much better but still wouldn't cycle properly unless I was really leaning on the tester handle to get the flow rate up. I then tried a third one an the plunger in that was so tight I struggles to get it out. A good clean in carb cleaner did help alot but still tighter than the others and though it did pop at 180 Bar (and didn't leak below that) I couldn't get it to cycle however hard I leant on the tester handle! Still a fail.....

Nick

[vtecpowergt]

They do sound as if the are not genuine ones that you were sold sometimes old stock thats been on a shelf for years can be a bit tight but soon come back to life once they have been used a few times there is quite an amount of fake copys about the worst at the moment we see are the plates fitted to delphi common rail injectors but to someone that dosent see them everyday of the week would never tell the difference.

[mdh]

Diesel bob comes highly recommended

[vitesseefi]

Overhausled injectors with Firad nozzles now installed. Had to swap the nozzle over to the original no4 injector as it turns out that the Audi version has a sensor lead that's about 500mm long whereas the Volvo version is only 150mm. No worries - I'm practiced at it now and the injector popped nicely at 180Bar, same as the others.

Cleaning the injector holes out in the head is a bit of a cow, otherwise pretty straightforward job, though I was glad of my slide hammer again.

It fired up without too much aggro and does seem to run better - less "dieselly" sounding, more stable idle, no smoke at idle. Open road performance not that much changed apart from a bit less smoke under full hoof. Exhaust smells different.

The old injector/nozzle combos popped at 150 - 160 Bar and at low flows would just pop and stream. However if the tester was pumped a bit faster they'd cycle properly. This may explain why the issues were mostly around starting and idling. Will be interesting to see if economy has improved - it's always been pretty good - 45 - 55mpg from a 1600kg car is good even by modern standards.

Nick