HDi Injectors

fastandfurryous · Post by **fastandfurryous** » 27 Apr 2005, 02:37

Right.. Having dragged the "HDi clutch pedal" thread thouroughly off-topic, I though it would be better to start a new topic:
I'm fairly sure now that a rather nasty pre-ignition rattle under load from my mothers 306 HDi 90 is due to worn/damaged injectors. 2 reasons for this: As you accelerate through 3100 rpm, the noise instatly vanishes, which is the same engine speed as the pre-injection system gets turned off. Also, I can't find anything else it can be!
Advice given so far has been invaluable:
Never disconnect HDi injectors with engine running as there is a risk of Hydraulic lock. (What about disconnecting with engine stopped, and starting it on 3?)
Bosch injectors are coil type, Siemens are Piezo.
Contrary to Peugeot dealers assurances, these injectors do wear out.
As I really don't want to spend the arm-and-a-leg (and a kidney) that Peugeot want for a set of new injectors (well over £1000!) I am now looking at second-hand ones, possibly from a scrapped car. Is there any easy way of telling which manufacturer a set of injectors is? and are they interchangeable? (I'm guessing not). Also, was there any difference between HDi 90 and HDi 110 injectors?
I don't care if the injectors that go into it are a little worn already, as the car doesn't see a big mileage. I just HAVE to get rid of the pre-ignition. Not only can it not be doing the engine any good, but it's also damn irritating when driving the car.
I'm also wondering if there's any diesel injection specialists who are reconditioning these injectors yet. I know the injectors for the TD engine are a completely different kettle of fish, but I know somewhere that does them for £12 each exhange recon.
Any and all advice on this is VERY gratefully received.
David.

wheeler · Post by **wheeler** » 27 Apr 2005, 02:48

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by fastandfurryous</i>

Is there any easy way of telling which manufacturer a set of injectors is? and are they interchangeable?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
the manufacturer is printed on the top of the injector & also on the pump.on bosch injectors the return line comes out the top of the injector,on a siemens it comes out the side of the injector.
injectors are in different classes X,Y&Z.the clasification letter should also be clearly visible although you may need to pull off the return pipes to see it.bosch & siemens injectors are definitely not interchangeable.

rossd · Post by **rossd** » 28 Apr 2005, 15:12

I was looking at prices on getting mine reconditioned (They dont need it, just out of interest really) and prices of about £130 per injector were quoted. The only problem is, I think this is only the physical injector itself, and not the electrical gubbins on tht top of it, which is the bit that seems to be at fault I would have thought.

fastandfurryous · Post by **fastandfurryous** » 28 Apr 2005, 15:23

I'm not sure. I think the electrical "gubbins" will be fine, the problem (certainly in my case) is that when they "pre-inject" a bit of fuel, they don't shut off properly, or maybe as quickly as they should, and too much fuel gets injected.
Insead of being a tiny bit of diesel, which burns smoothly, bringing the cylinder temperature & pressure up smoothly ready for the big injection, it injects ever so slightly too much, which means that the cylinder temp rises too fast, with excess diesel present. Once it gets sufficiently hot, the excess diesel burns expolisivley rather than progressively in a flame front, and hence the knock (or rattle as it sounds like).
The amount of fuel to be pre-injected is both tiny, and critical, so this is undoubtedly where any wear will show up.
Certainly this is an explanation that fits the symptoms. My knowledge of the theory of combustion within a piston engine is quite good, wheras my knowledge of the workings of the HDi engine is rubbish, but getting better.... all thanks to this forum [:D]
was the £130 per injector from an Independent diesel specialist, or is this main dealer prices?
David.

rossd · Post by **rossd** » 29 Apr 2005, 22:26

£130 was from an independant, I'll try and dig out the web address. Reading the Peugeot tech docs, the injector is actually opened by the fuel presure within the injector body. All the electrical solenoid does is open a tiny valve so a 'leak' is created within the injector and a presure differential is caused two chambers. I also have some nice cross sectional pictures of an HDi injector...
In fact the tech doc is online, http://www.christiantena.pwp.blueyonder ... index.html

rossd · Post by **rossd** » 29 Apr 2005, 22:28

Address for HDi injectors: http://www.uniteddiesel.co.uk/diesel-in ... icles_id=5
They do them on an exchange basis.