2.5 TDi cold starting

[CRC]

The carpets may well be saturated within an inch or so of the door, as it comes down the inside of the door and straight out onto the carpet there. If not, you may find that the spare wheel needs a swimming lesson.

 

Oops, sorry, this isn't a Jazz forum ....... won't do it again.

[dieselV6]

Interesting!  Ours is a 52 plate, not spent a penny on it except annual oil service (DIY) and recently new pads, and one wiper.

Corrosion is dreadful on these, I tried to change the air filter but all screws are corroded to such an extent that removal is impossible.

So left the old one in there until I can find some new screws and drill the old ones out.

On the body as well, look underneath it and it is a scary sight.  The Superb is same age but so much better protected corrosion wise.

 

All I can say to this is pure zinc spray - apply everywhere where rust starts showing (after rudimentary cleanup), and recheck after every winter. Any money spent on this will be trivial compared to the cost of replacing exhaust, various bolts and bits of bodywork and suspension. Plus after zinc covers significant portion of exposed parts prone to corossion, you start getting the benefit of cathodic protection over entire car's engine and bodywork.

[rotodiesel]

If only... Every piece of metal has two sides.

 

rotodiesel.

[dieselV6]

Exactly, and electrochemistry says that every metal in contact with another metal and exposed to electrolyte becomes a battery. Why do you think they bury sacrificial anodes next to oil and gas pipelines? Basically, given the right combination of metals (eg zinc and iron), it's only/mostly the anode metal that gets corroded. A sacrificial anode buried next to the pipeline protects a good piece of the pipeline despite being connected to it only at one point. 

 

Don't trust my word, here is what NPL have to say on it. Section 5 outlines requirements. Here is another one.

 

It is common practice to galvanize parts then paint/coat them. While this protects the specific parts better and for longer, my advice once the car starts rusting anywhere is to clean and zinc the troublesome areas and leave the zinc exposed. Zinc is easy to top up with a spray can, and a large surface area of exposed zinc protects more of the car against corrossion, at the cost of wearing out the zinc slowly.

 

In most industrial applications, corrossion has been dealt with for several decades. Yet when it comes to cars, planned obsolescence makes manufacturers seemingly incapable of protecting the cars against corrossion. Superb might have a galvanized body, but engine and exhaust would have been completely rotten in my car were it not for generous application of zinc. Part of the problem are brass and aluminium parts in close proximity to mostly steel engine. As it stands, I have little or no corrossion on the car..

Edited 27 January, 2015 by dieselV6

[oh_superb]

I will try the zinc application on my cars.

Just need to hunt down a suitable product.

On the original subject of cold starting issue, subsequent diesel filter change having resulted in fuel leak, well...

I have stayed with the OEM filter and ordered new Tee piece, it is made by Meyle.

And today I took the old (VAG genuine part) off and inspected closely. Could not see anything wrong with it with a bare eye inspection.

New one was lubed up with Vaseline and fitted after removing the O ring again for an inspection which showed it was ok to re-use.

So fitted the new Tee piece and immediately I noticed that the fitting is much more "positive", it fit easily onto the O ring without resistance and it felt snug and good. Unlike the old Tee, this one could not be rotates or wiggled when fully home.

I then took the car on a 24 mile test drive and it is dry!!! Yippeeeee!

Furthermore the cold start after the Tee change was almost perfectly smooth.... I shall see tomorrow for certain but I suspect the old Tee might have been letting air in and at least contributing to cold start lumpiness.

But I'm getting new fuel spill lines (NBR rubber) and reinforced silicone vacuum lines too to tidy up the engine compartment. Most of the spill lines are wet so they deserve a freshening up and many vac hoses are tired. They are also tie wrapped on in many places, not pretty.

Edited 27 January, 2015 by oh_superb

[jimbof]

Brilliant, nice to hear you are sorted!  I think I'll be doing some vac hoses soon too...

Edited 27 January, 2015 by jimbof

[iob]

Nice... Sometimes complicated problems have simple solutions, glad to hear that changing the "T" helped. BTW, how much was it?

As for my cold starts, the positive temperatures we had the last days didn't allow an honest evaluation (smooth starts @ 3 deg C), but winter is not over yet...

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[oh_superb]

The "T" was £12. OEM "T" was £45-50 or so. Crazy.

I must say the Meyle T seems better made than OEM.

Now my cold starts are good but now it is apparent I have a very noisy tappet for 5 seconds. Annoying. I guess it was previously masked by combustion lumpiness.

[iob]

The price is indeed crazy...

I paid here at the local stealer 10 £ for the OEM version, that is quite a difference... I didn't look closely at it, maybe they gave me the Meyle, anyways no leaks so I am happy with it.

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[CRC]

Just for info, I've been monitoring my cold start GP burn times and have come to the conclusion that when the car was been left for a really long time so that the the water temperature must be very close to the outside air temperature, it seems to me that any temperature under +10 Centigrade results in a 6 second burn, and for the first time for a long time, the air temperature today was +10.5 and I had a 3 second burn period. Car starts fine at all temperatures so far experienced  this winter.

Edited 28 January, 2015 by CRC

[rotodiesel]

The noisy tappet is normal on this engine. When the engine is stopped, at least one valve is open. This puts the associated hydraulic tappet under pressure and causes it to to partially drain. On a re-start the engine has to provide oil pressure to pump it up again to restore the correct valve clearance. For some reason, the V6 is nowhere near as good at this as the 4 cyl PD units. Every one I looked at was the same.

 

My gut feeling is that they c o c k e d up the anti-drain in the oil filter bowl - but I'm afraid I lost interest in this engine before analysing this fault. It's an old engine and was probably originally designed for higher viscosity lubricant.

 

rotodiesel.

[oh_superb]

The noisy tappet is normal on this engine. When the engine is stopped, at least one valve is open. This puts the associated hydraulic tappet under pressure and causes it to to partially drain. On a re-start the engine has to provide oil pressure to pump it up again to restore the correct valve clearance. For some reason, the V6 is nowhere near as good at this as the 4 cyl PD units. Every one I looked at was the same.

 

My gut feeling is that they c o c k e d up the anti-drain in the oil filter bowl - but I'm afraid I lost interest in this engine before analysing this fault. It's an old engine and was probably originally designed for higher viscosity lubricant.

 

rotodiesel.

 

Thanks Roto.

When I had the glow plug snapped scenario, the cylinder head that was removed at 74k miles already had several soggy tappets that one could compress with bare fingers… the other head is still original and how now done 133k, so it won't be a pretty sign.

The advice I have been given is to run fully synthetic oil on this engine of low-ish viscosity, synthetic to stop it oxidising (apparently the pickup gauze in the sump can get blocked with varnish/oxidisation on these, hence lower oil pressure at the cams and destroyed cams) and low viscosity (I run 5W30) to enable the flow to the cams as quickly as possible on a cold start.

So I am going by that advice, I just hope the followers haven't worn to an extent where they drop out on a cold start before the oil pressure is generated at the hydraulic tappets - which is of course another concern on these AYM engines - but mine, touch wood, is still soldering on, probably because most of my mileage is long distance and 7000 mile intervals on oil changes.  A year ago I pulled a cam cover off (driver's side bank) and there was absolutely no soot build up on the surfaces - so the oil is doing a good job indeed - one could see aluminium coloured aluminium.  Also the engine does not burn any oil even at this low viscosity.  I very much oppose the logic of 20-30k interval oil changes, and one day when I get a more modern motor, I will carry on with 7-8k oil changes as I like to look after my engines.

[rotodiesel]

I absolutely agree with the use of a fully synthetic oil - the turbocharger bearings need a continuous oil film to work which is often disrupted by varnish deposits (usually on the shaft) which can occur with mineral oil on heat soak-back. As you don't need the ultimate high pressure film strength performance of the 507.00 oil specified for the PD, you could possibly consider a good quality fully synthetic 10W - 40. In general though, I'm not a fan of heavy lubricants and 5W - 30 is probably about right. Make sure the engine warms up quickly (VAG thermostats are junk and hard to get at). I blank off 2/3 of the radiator on my 1.9 in Winter.

 

Obviously, engines and their wear patterns vary, but a drained hydraulic tappet always sounds a lot worse than it actually is because there can be about a 3 mm valve clearance for a few seconds. Engines usually seem to survive this without much damage as the remaining oil film on the cam is thick when cold and the relative speeds are low.

 

Oil change intervals are a hotly contested topic. One problem is that many endurance/wear tests are carried out under conditions where soot loading and fuel dilution are not significant. Out there in the real world, they are. Water/acid corrosion damage can also cause as much or more damage than wear on an engine used with frequent cold starts.

 

For what it's worth, I change the 507.00 oil about every 7k miles on my PD. I would not consider the VAG long life regimen. Engines like to warm up quickly to the right temperature. Unfortunately the dashboard coolant thermometer is a liar and reads "normal" over a stupidly wide range. A faulty thermostat cannot be diagnosed on the dashboard unless it's completely useless. VAG thermostats tend to open a little early and then stay open when they fail. The French (surprisingly) make the best wax capsule thermostats, but they don't fit VAG housings properly.

 

rotodiesel.

[oh_superb]

My thermostat is kaputt. I'm blanking 2/3 of my rad area from October to May. Unfortunately it sits behind the timing belt so it will have to wait until the next timing belt job at 150000 miles.

It takes 30-40 miles of driving until it gets to 90 degrees indicated on the dash.

Edited 29 January, 2015 by oh_superb

[oh_superb]

OK, next stage, as my cold starts are not where they need to be /used to be. Better with the new Tee, but still not happy.

Whipped the inlet manifold off (the one joining the left and right banks) to access the pressure regulating valve on top of the VP44 injection pump.

Came off in about 20 min, I guess the biggest hassle were the hex capscrews holding the EGR pipe onto the inlet manifold.  Fiddly.

When it was off I had a good look inside the individual bank inlets, the one on the right was wet and more gummed up than the one on the left.  So this is the side of the engine with the original cylinder head.  I hope this is not bad news with the head/cams on that bank.  Could be just a function of the oil blowing past the turbo bearings getting sucked into this manifold more than the driver's side (for those in the UK).  The boost pipe heading up to the anti shudder valve is wet too, so perhaps this is where all the oil is coming from.  Mind you, I do NOT have a problem with oil consumption.

So, I got to the VP44, took the pressure regulating valve out after thoroughly cleaning/brake cleaning the surrounding area to stop crud being dropped into the IP, and I am not sure if the valve is OK or not, hence this post:

There is a retaining washer on the bottom of the PRV to retain the guts of the moving part of the valve.  Now the valve moves in and out as you rotate it, i.e. due to the force of gravity.  The travel of the piston is from the bottom (where the retaining washer holds it in place) and up around by 3-4mm.  At that point I think it sits against a spring and I think it can be compressed up, but I only applied around 1 kg of force through the bottom with an allen key and I think the piston went up by only a fraction of a mm.  The spring rate at that point seems very high.

 

So does anyone VP44 knowledgeable know if the seemingly loose piston over 3-4mm of travel is "normal" or not??

[oh_superb]

I have been communicating back and forth with a diesel specialist, and depending on who I spoke to they either didn't have a clue what I was talking about or just didn't know what a new valve should look like or what purpose it serves on the VP44!!!

But, I have found a very friendly and knowledgeable outfit no closer than Latvia, and with some internet chat they found the part number I needed and are sending me a new valve over, 19 GBP all inc of P&P too.

For reference if anyone should need it, the Bosch part number is F 00N 300 348.

I have also bought some 3.2 mm ID fuel spill hose too, high grade NBR rubber, as the current ones are all diesel sweaty, so will be installing that too in the next few days.

Edited 7 February, 2015 by oh_superb

[oh_superb]

Replaced the spill pipes on one bank.. but when trying to remove the one way valve (plastic) it broke!  Damn!

So at the moment no check valve 

The actual removal of the old spill lines was harder than I expected.  They were difficult to pull off without weakening with a Stanley knife locally around the nipple.

So, I will have to get a new check valve.  Does anyone know the VW part number of the fuel return line check valve, pls?  There are some cheap Chinese ones out there, but material compatibility, functionality and actual durability worry me, so I would rather go OEM on this.

Edited 7 February, 2015 by oh_superb

[oh_superb]

Ok, update time. Been running the new heavy duty spill pipes for a few days now and must say that the machine starts very well each morning! Almost no perceivable shake at all. Yes, it is a high mileage diesel, so it won't be a Lexus V8, BUT, very happy. No smoke either. So word of advice to all V6 tdi owners, if your spill pipes look a bit wet or perished, take them off and put some new ones on. I think what was happening was that the engine was sucking air in through a pinhole in the spill lines and on a cold start the air sitting in there would get sucked through the injection pump and it didn't like that.

What was also possibly a giveaway sign is that a month ago it cut out on warm-ish re-start multiple times.

But as it happens, I have also received my VP44 pressure regulation valve today, so will see how that compares to the one fitted to my engine. But I think there is nothing wrong with that valve.

[iob]

Interesting update regarding the fuel spill hoses, makes sense...

I will check mine as well for moisture with the first opportunity.

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[oh_superb]

Just an update. It continues to run well with the new spill lines.

Still planning to pull left can cover off but it is a much bigger job than on the right bank which I have tackled before. Water bottle and inlet manifold are in the way and need to be removed or moved to the side. Must inspect those cams and tappets.

[iob]

An update from my side as well: checked yesterday for moisture around spill hoses - clean as a whistle... Around injectors' o-rings - the same... Baffled [emoji53]

Did it right after passing the MOT with flying colors - good thing they don't require a perfect cold start-up...

I am back to square one now, no clues as what to check for next, I guess I will just let it start the way she wants it for a while, especially the winter is almost gone now...

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[oh_superb]

Iob,

Does yours chuck out white/ blue smoke for a few seconds on a cold start too?

Mine is much better than before, at leadt it does not shake much at all, but still an embarrassing puff puff puff of smoke. And that loud tappet has gone quiet too. If I could get a set of good price nozzles I would change them but the best price so far is not good enough at £55 each, it's just too much to spend without being certain it will fix it.

The high flow ones are cheaper as they appeal to the masses by I don't want to open another can of worms with that, idle stability, transient smoke etc.

[iob]

Yes, it does puff a little bit of white smoke (my magic dragon [emoji12] )and some shuddering for a couple of seconds, after which runs/starts perfect for the rest of the day...

Glad to hear you ironed out a little bit the starts by changing the fuel spill hoses, but in my case I don't think it makes sense, as they are bone dry...

You are right about the nozzles, they are as well expensive here and wouldn't change them unless being sure they are causing something (in any case I wouldn't fit anything else besides the original, don't want to jump from the pond into the well)...

I guess I will just live with it for now, as winter comes to closure here and I am fresh out of ideas... [emoji20]

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[oh_superb]

Same here I think, but one final thing I will try (and I have seen it being successful on another forum on an Audi) is the valve on the injection pump body. I actually have the new one now, ad it is much tighter than the old one, and at 19 quid it is worth a shot so to speak. The theory being that the injection pump case pressure is better controlled and hence the pump has an easier life in targeting the correct timing in the first few seconds of operation. But I have also seen evidence that the nozzles once they go past 200000km are well past their best, and poor atomisation won't help with smoke and finally if one of them cracks at a low-ish fuel pressure then that one will inject a lot more than the others that now either have a bit of fuel going in or are being starved as the one that cracks at low fuel pressure (say at 120 bar instead of 190) takes all the fuel at the low cranking speeds. So it may be just a matter of resetting the injections to all crack at the same pressure. That's why I was thinking of new nozzles.

Edited 17 February, 2015 by oh_superb

[iob]

Is this the topic you mentioned: http://www.audi-sport.net/xf/threads/cold-starting-problems-2-5tdi-afb.175303/ by any chance? The guy exposing the issues/solutions is from Romania as well...   (I remembered seeing somewhere mentioned both issues (IP valve + injector nozzles)).

 

However, at the time I read it, I did not consider the valve to be an issue in my case because he mentioned having trouble with both cold and warm start-ups and he had the fault code for the N146 - I have issues only on cold starts and no faults read on VCDS... but, since you already got the new one (and so cheap), why not try? Please post some feedback after changing the valve, I am curious if there is any improvement...

 

I fully agree with you on the injector nozzles being out of spec at >200000 km (maybe even sooner than that, depending on fuel quality) and this is something on my to do list as well, but it will have to wait a while, I just paid taxes and insurances (heavy fines due to the engine cc   ) - I need a bit of time to recover...