3.0TDi Lockup on startup when warm, no smoke at all though

[zit501]

Hey guys,

My 3.0TDi (BMK engine) has fairly frequent lockup on cranking when the engine is warm, roughly 5 to 10 minutes after switching off. Like when one pops into the shops and comes back out. It usually cranks, there's a "click" when it jams/holds, then resumes cranking and fires fine. Sometimes it cranks, locks, can't continue so it gives up. Then on the second attempt it cranks fine and starts up. No funny noises after the start or anything. No smoke from "cleared" fuel.

I know that this is quite often a sign of leaking injectors, however here's some background:

• I bought the car 2 years ago with the classic white smoke leaking injectors.
• I replaced all 6 with refurbs from EPS Diesel (who I later learned were pretty shady)
• No smoke anymore, all is well
• I didn't have any lockup when warm for about 6 months or so. Then, the occasional lockup. It wasn't very often, so I sort of lived with it whilst looking for a good deal on other injectors
• When checking out the injector adaption values, none were out of spec, and none were very close to -45, etc. Still no white smoke on idle, in traffic, etc. Even when I do get the lockup, after it starts there's no puff of white smoke from fuel it's "cleared".
• Then about a year ago I was checking the injector values, and although all were still well within spec, I saw two were further out than the others. So I decided to try swap 2. I got 2 more refurbished ones, this time from a supposedly more reputable place.
• I fitted these two and all seemed well. The frequency of lockup seemed to reduce, although it still happened every so often.
• I finally about 2 months back, decided I needed to solve this properly. I found some Bosch official refurbished units on eBay. Bosch buys back old injectors, refurbs them, then sells them on under a different part number. (0986435358). These all had 2015 date codes on them and were from a totaled car. They're effectively the same as the BD revision injectors, so they should be good.
• I fitted these 4 to the engine, and the lockup is still happening. Maybe the frequency has even increased again.
• BUT, still no smoke at all.

So, the questions:

• Is it possible to have leaking injectors with no smoke at all?
• How can I check which of these is leaking, if any? What would that return flow test that people do tell me? Anything?
• Is it at all possible that my starter is actually at fault? It starts strong when it's cold, doesn't sound like it's struggling. It doesn't sound like it's struggling on the second attempt on these hot starts, or on hot starts where there isn't any lockup.

I know that I've been buying refurbished and second hand injectors, and would love to buy new, but even with the costs of the injectors I've bought so far I could have only really bought 3 new ones. Like I say, I have no white smoke at all, ever. And I can't seem to find anyone else with the exact same set of symptoms. I'd like to check my injectors now, either the ones in the car or the spares I have. Any advice?

Thank you
Mark

[lynalldiscovery]

I would say dodgy injector, it was the beginning of the end for the injectors on my wifes first audi a 3.0 tdi A4, after a few months this did start to smoke bad at idle, engine had to be hot and idling for at least 4/5 minutes then it would start sending smoke signal, we fixed it by getting an A6 3.0 tdi whiuch she then promptly wrote off

A few weeks ago I had a slight misfire on my land rover, one injector at max trim at idle, so fitted a new one and also now get the occosainal lock on start up, so its going to need all new ones!

Sadly I think a lot of refurbs are nowhere near as good new ones.

[zit501]

Hey, thanks for the reply,

Ya, you may well be right. I'm just so reluctant to go and have all of these injectors tested now, which will be the cost of a brand new shiny one.

I'm thinking that it might be an idea to try and get them on one of those old school diesel injector pop testers. Although they only reach max 400 bar, a leaky injector is in this case still leaking at the 300 bar rail pressure. (and even at lower rail pressure after the engine switches off)
If I can get an injector on one of those pop testers and hold the pressure on them, I should see a pressure drop off if it's leaking not so?