Car: Pug 306 2.0Hdi (90), 2000W, 85000miles.
Hi some advise please.
Background....
2-3 miles into journey home thursday the engine management light came on, car lost all power and died when I put the clutch down to roll to a stop. Car would not restart. Recovery guy suspected the fuel pump in the tank as no fuel was entering the fuel filter and a common hdi problem. Had a new in tank pump fitted friday and mechinic (pug specialist) said it has a rough idle when cold. (it generally does when cold in cold weather so thought nothing much of it). The fuel filter has been replaced also (but after the mechanic reported rough idle).
Current problems...
Car is not happy. Initially on the way home from the garage it was making a snorting sound at idle every 30 seconds or so. This would change the revs slightly up and down a couple of times. On the way home when reving it gently it would also make the snorting noise at 1500 to 2500 revs. I've experieneced Vauxhall DTi's doing this noise when you put the clutch down to change gear but my hdi has never done this. The car was significantly coughy generally when on a part open throttle to hold speed.
Have put 120 miles on the car today and the snorting noise has generally gone however it is now making a fairly distinct but not excessively loud clicking/tapping noise roughly in line with the speed the engine is turning (but I only notice it at idle) and a low drone, and only intermittmently. This is definately a new noise but strangely I only seem to be able to hear it in the car and not when outside listening under the bonnet. When its making the noise at idle it is coughing on a part open throttle again whilst driving. Even my girlfriend has commented on the noise and the coughing when I've kept quite and haven't mentioned, it so I'm not being paranoid!
Acceleration etc is fine. The car has over the last year got significantly more smokey on hard acceleration and also in the winter it does get a little sluggish/coughy on a cold start and last winter fuel consumption rose to 35mpg (normally I get 48). However it improved in warmer weather this year and at the mo is around 45-48 still. I'm a little worried as the garage and mechnic told me scare stories of the front high pressure pump going soon after the back one and big bills to come etc etc. So much so that I've been shopping for cars today.
I plan to take the car back to the garage and get them to listen to it and get it analysed on the machine hopefully.
Any ideas what is causing the poor running as only the pump and filter have been touched.
Oh I think this is a coincidence but think the battery was low before breakdown as the morning and evening before it was slow to turn over and the speedo/rev counter went round to 110/5000rpm on starting and all the segment of the mileage display lit up - I assume because of low voltage. I'm wondering if the low voltage as reset the ECU or anything and the car needs 're programming?' which is causing the coughing/knocking noise.
Much appreicated
Mike.
|
|
Friend of mine seems to get a steady stream of HDi's for repair. He has said to me in the past that once the lift pump is replaced the HP pump usually follows shorly afterwards. Best get someone local to check it out. If HP pump is suspect then get shot of it ASAP - its won't be a cheap repair.
|
This is exactly my observation; I needed a largish diesel towcar and ended up with a VW PD unit as a result.
I have a theory that this problem might be a really simple design fault - so simple that it's hard to believe that PSA have overlooked it.
The earlier generation (XUD engined) vehicles had the same plastic fuel filter on the engine, but because the lift pump was incorporated in the fuel injection pump, the filter ran at negative pressure. A plastic fuel filter housing will become soft when heated by the engine.
On the HDi system, the same plastic housing is fitted but the lift pump is in the tank. The consequence of this is that the filter housing is pressurised when the engine is running - in fact you can feel the housing bulge when you start the lift pump. If the housing bulges, the element is probably no longer a secure fit in the housing, so swarf gets through. This becomes critical when the electric lift pump disintegrates - as they are all inclined to do before the engine is worn out. Swarf in the high pressure pump spells instant and expensive trouble.
The VW engines have a mechanical lift pump on the engine and a fuel filter in a steel can. Together with Bosch fuel injection this represents, in my view, the correct way to configure a diesel engine.
659.
|
On the HDi system, the same plastic housing is fitted but the lift pump is in the tank. The consequence of this is that the filter housing is pressurised when the engine is running - in fact you can feel the housing bulge when you start the lift pump. If the housing bulges,
Its true, it does bulge. Surprised me the first time I played with one of these. Doesn't give much confidence though...
|
Opinion is sharply divided about whether you should ever change the elements in these HDi housings, or always swap the whole unit.
If the element is disturbed after a tank-pump failure, there must be a high risk of an invisible fragment reaching the HP pump [and with micron clearances, that's all it needs to wreck it!] so whole-unit replacement must be a safer option.
|
If a filter which is designed to be maintained, ie have its element changed, lets swarf into the fuel system when worked on, it defeats its own object. It's a while since I've looked at one of these, but would I be right in thinking that the fuel outlet connection is somewhere near the bottom of the plastic "can"? If so, the likelihood of contamination is high.
My area of detailed experience is with very much larger engines (some too big to go on the road) but all of the fuel filters with renewable elements I've seen have the connections at the top and a bowl (usually with a drain tap) at the bottom. I seem to remember that the PSA filter assembly does at least have a drain.
659.
|
659
The HDi filter unit is essentially a lift-out bucket with two quick-release fuel-line connexions on it's twist-off lid. The open-ended tubular element is left sitting in the fuel with - hopefully - all the contaminants on it's outer surface and clean fuel in the central void. As soon as you lift the element, inevitably, you dislodge the frag and it falls to the bottom of the housing and can now by-pass the lower annular seal into the "clean" centre.
Although you're obviously supposed to drain the housing and meticulously clean the plastic; I've seen many instances where time-pressed techs have just pulled out the old element and dropped another into the broth of frag and fuel. Whether this practice has a bearing on the failure rate of CR HP pumps can only be guessed at......
I'm firmly on the side of those who say that you should never change the element; but always replace the entire unit. It's quick, simple and the risk of contamination is minimal.
|
Thanks for outlining the details of the PSA filter unit. It sounds like a half-baked design which is by no means resistant to the average automotive technician, even if it works properly under all operating conditions.
What a pity they may have spoilt the HDi ship for the sake of a decent fuel filter. Detailing is everything in diesel systems design.
659.
|
Another problem with this design is, of course, that the bowl stays on the engine. If the filter head is fixed, as in most other desgns the bowl and the element have to come off and can (hopefully) be cleaned out.
659.
|
These comments make sense to me, if the filter was right how could the HP pump get damaged. So what means is there of fitting another filter either before or after the existing one? Does anyone make a filter suitable for this? What sort of pressure are we talking that makes the housing bulge? I obviously have reason to ask!
Steve.
---
Xantia HDi.
Buy a Citroen and get to know the local GSF staff better...
|
Go to your local Bosch agent, and ask them to show you a fuel filter for an early (pre PD) VW diesel. These are perfect for retrofitting as they just need the hoses fitting to the stubs provided on the steel filter can. There is a drain tap too.
659.
|
|
Hi
From some of the many comments I'm now pretty certain all the petrol heads are still not trained diesel heads so here is my input : Diesel engines are and always have been very fussy about cleanlines with the fuel system and I dont just mean a wipe with a clean cloth. I mean meticulous care when changing filters and any component of the fuel system. Do not use any wipes that could leave micro fibres - alway wash carefully with clean fuel. Diesels do have a low level knock with combustion that useually disappears with load on higher speeds. If the knock is excessive it may be mechanical ie crank or pistons worn. Any rough running is not normal with any diesel. HDIs use common rail fuel distribution
and the injection is controlled by electronic injectors therefore loose wires or chaffed shorting wires will
have a direct impact on smooth running.
|
659FBE - Thanks for the info. Do you think it will take the pressure from the lift pump OK?
Steve.
---
Xantia HDi.
Buy a Citroen and get to know the local GSF staff better...
|
In my judgement, yes. It's a well made filter in a steel can which must be more rigid than the plastic offering from PSA. To do the job properly, you could ascertain from PSA the lift pump output pressure, then check with Bosch technical that the filter is suitable for this application.
659.
|
Thanks. You're right of course. Maybe some of the veg oil convertion filters may do. I suppose it's a case of finding the flow/pressure/particle size that's important.
Steve.
---
Xantia HDi.
Buy a Citroen and get to know the local GSF staff better...
|
Having owned a 306 and now a 1.9 VAG TDI I can agree with Number Cruncher. The VW filter looks like some sort of bomb! Seems very well built.
The Peugeot housing always seemed a bit flimsy to me.
|
|
|
