2 questions about the 1.9td engine.

caveman_si · Unread post by **caveman_si** » 26 Nov 2005, 19:55

Two questions
1st one and the easiest i hope. What size fuel line does a 405 1.9td have? 8mm or 10mm? same as few of the citroens but im not going to embarass myself by naming them and getting them wrong.

2) Ive looked but cant find it. What is the test to find out which glow plugs have gone using a multi meter without taking any of the glow plug out of the car cos its too cold to fiddle about?

edit : what size are the coolant hoses?? knew i forgot something

cheers simon

jeremy · Unread post by **jeremy** » 26 Nov 2005, 21:02

To test the glowplugs with a multimeter take the thick wire off the top of the plug and check the resistance - ie lowest resistance setting, one terminal on the engine, other on plug top. There should be negligible resistance - as the plugs take an enormous current - about 12 amps each.

They usually fail together - or rapidly in sequence as they were all made to the same spec at the same time! It'll probably start quite well on 3, and may start on 2. 1's getting too difficult.

Unread post by **citroenxm** » 26 Nov 2005, 21:06

There should be a resistance across the plug.. Remove the heater plug wireing, then with a multi meter, hold the red on the part that the wiring screws to and hold the black to the body - ie: were your spanner goes when removing/fitting them. If (assuming you have a Digital meter) it stays on for examply "1 . " they can be assumed dead, but other wise you should get some resistance, Ie: 0.005 for example....

Thats how I've tested mine and been correct each time..

Good luck

Unread post by **citroenxm** » 26 Nov 2005, 21:07

Argh Jeremy you just pipped me to the post there! Amazing two people replying at the same time!

Regards

AndersDK · Unread post by **AndersDK** » 26 Nov 2005, 21:13

Never been under a 405td looking.

I'd say the diameter of the fuel lines is exactly adequate for the fuel consumption

Naaah ...
- get an 8mm drillbit in hand and bend down under comparing by feel. It is a very fast and easy method

What coolant hose may we take for the size ?

Dave Burns · Unread post by **Dave Burns** » 26 Nov 2005, 21:29

Glow plug resistance is about 0.5 ohm (1/2 ohm), measure the resistance of your meters leads by connecting them together, subtract that reading from any test measurements to give a true reading.

Dave

Unread post by **Peter.N.** » 26 Nov 2005, 21:35

Unless you have a very good quality meter with high quality leads and you can get a near perfect connection, you will have difficulty in getting an accurate resistance reading across the glow plugs. If the plugs take 12 amps, at 12V that should read exactly one ohm, but if with a basic meter you can get less than two or three it will mean that the plugs are at least working. If you have a really good meter the resistance across all the plugs connected together will be 1/4 ohm, or if two are o/c, 1/2 an ohm and so on. A more accurate way would be to remove the feed wire and connect an ammeter between it and the plugs which if all are working will give a reading of about 50 amps, an old 45-45 amp car dashboard meter would do. You could also check the voltage drop across the battery when the plugs are switched on....but I wont go into that!

pmhpmh · Unread post by **pmhpmh** » 27 Nov 2005, 10:00

Peter N

Are you sure that hot R and cold R are the same? Do some of the modern plugs have built in technology to ensure quicker heating of the plug tip??

However my advice would still be look for about 1ohm but compare 2 readings for each plug ie thro plug and from body of plug to the engine block to make up for errors in multimeter and connections.

I recently changed a plug that was apparently faulty (about a consistent 5ohms when cold) I meant to check it, but it went to the bin straight away!

Unread post by **Peter.N.** » 27 Nov 2005, 16:15

Ah well! I only know about the plugs up to and including my XM which are fairly straightforward. The resistance would be higher when hot, but then you wouldn't be measuring it with volts across the plugs. I very low tech way of testing them has just occured to me, how about turning them on a few times and the feeling the outside to see if it is warm, I would think that some heat would travel up the centre connection.

Yes, they can go high resistance, if you look at them out of the engine, sometimes only the tip will glow, but I would have though it would still have started the engine.

mike_zr7 · Unread post by **mike_zr7** » 27 Nov 2005, 16:52

To check the glow plugs, I used a 12V test lamp. Disconnect each glow plug and connect the 12V test lamp in series, if the bulb does'nt light the glow plug is duff.

pmhpmh · Unread post by **pmhpmh** » 28 Nov 2005, 08:10

The test lamp is a rudimentary method , it will find open circuit plugs only.Not those that have failed to a high resistance , say 5ohms.

Using a couple of headlamp bulbs in parallel as a test lamp is a better test, then measure the voltage drop across the plug using a simple multimeter, and work out the plug resistance to see if it is in the 1ohm range. This will give a better indication.

I have tried the warmth test and could find no discernable finger tip difference when ambient temperature was 0 degree C after several repeated heating periods.

AndersDK · Unread post by **AndersDK** » 28 Nov 2005, 16:11

I'd say using a single headlamp bulb as testing device is just fine for the glow plug.
Dont forget the aim here :
If the bulb does not light up bright & clear - there is no reason for further testing as the plug will never do its work then.
Really it is as simple as that.

fastandfurryous · Unread post by **fastandfurryous** » 28 Nov 2005, 16:40

Peter.N. wrote:Yes, they can go high resistance, if you look at them out of the engine, sometimes only the tip will glow, but I would have though it would still have started the engine.

That's how modern glowplugs are supposed to work. The tip of the plug should be almost white hot after about 6-8 seconds, with progressively cooler bands working back to the threads. If the plug gets hot in the "middle" (about 10-15mm from the tip) before the end, then it's damaged.

tony1 · Unread post by **tony1** » 28 Nov 2005, 18:02

As I have just got my first diesel this topic got me looking on the internet, I found the following document on the Beru site which is very comprehensive.

http://www.beru.com/download/produkte/TI04_e.pdf