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mate if it was leaking air you'd get a load of white smoke pouring our while trying to start it.
the glow plug light should come on and stay on for 20ish second every time you turn the key when the engine is cold (even in the summer), you should also hear a click a while after the glow plug light goes out on the clocks as they stay on longer than the light does.
do the wire test first, i don't think its fuel leaking back, and most audi tdi's have a non return valve near the filter too from factory.
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If there was a fault with the glow plugs would the light not stay up all the time?
Also what makes me suspect fuel issues is that its still a pig to start even if the light does come on.
Its very hard to go through a diagnostic procedure over the internet and if the car was in front of me glow plugs would be one of the first things i would check. But i would use a multimeter instead of a length of wire.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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would all depend what the fault was, if it was the temp sensor reading wrong it wouldnt and that would be my guess as he says it sometimes comes on when its really cold.
i did suggest the multimeter first but not every one has access to one, and running a piece of wire is a quick simple alternative.
hey it could be and air leak aswell, but from experience of a few diff diesel engines(one been vw/audi) when they leak air into the fuel lines when they do finally start they do kick out a massive cloud of smoke.
fact is the glow plug light should come on and stay on for a good few seconds, all year round in this climate when the engine has cooled down. If the engines warm it shouldnt come on and should start pretty much straight away.
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bl1300
Posted a lot
Posts: 1,678
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When I test glow plugs I remove them and connect them direct to a battery with jump leads if they glow red they are ok if they don't there goosed. Not a good way to test the glow plugs in some of the modern VW engines. They are designed to work fom a pulsed lower voltage, whacking 12 Volts across them make them melt. Fair enough you learn something new everyday. I shall resort to searching through the store room for the multimeter in future if I have a modern VAG in. |
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Current fleet.
1967 DAF 44
1974 VW Beetle 1303s
1975 Triumph Spitfire MkIV
1988 VW LT45 Beavertail
1998 Volvo V70 2.5
1959 Fordson Dexta
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would all depend what the fault was, if it was the temp sensor reading wrong it wouldnt and that would be my guess as he says it sometimes comes on when its really cold. I did suggest the multimeter first but not every one has access to one, and running a piece of wire is a quick simple alternative. hey it could be and air leak aswell, but from experience of a few diff diesel engines(one been vw/audi) when they leak air into the fuel lines when they do finally start they do kick out a massive cloud of smoke. fact is the glow plug light should come on and stay on for a good few seconds, all year round in this climate when the engine has cooled down. If the engines warm it shouldnt come on and should start pretty much straight away. Have you ever seen a diesel start without glowplugs, they smoke a bit too. |
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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My mate with a frontera 2.  has always had issues...... the glow plug light comes on....longer in winter, but starting no different. he changed the plugs etc, no change. It turned out that the light which is linked to temp, was not linked to the plugs! Bypass and a big push button on the dash.....starts better than ever! Just shows, we rely on what we think is heppening, but it may not ! lol |
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insig
Part of things
Posts: 32
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I've come across a few Octavias with starting issues. When investigating they have started pefectly with the engine coolant temperature sensor disconnected, apparently according to a local auto electrician, it's an ECU fault. What we have done is to wire in a 5 pin relay triggered from the starter solenoid wire to disconnect the temperature to ECU signal wire when the starter is engaged. The sensor has 4 wires, 2 for the gauge and 2 for the ECU, I think that the signal wire to the ECU is purple. The warning about melting glow plugs is on page 36 of this PDF. www.volkspage.net/technik/ssp/ssp/SSP_316.pdfI know that this isn't the OPs engine, but useful to bear in mind for the future. |
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Last Edit: Nov 9, 2011 7:33:29 GMT by insig
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Bit off topic... I used to have a '72 landrover which had a button for the glow plugs, the button slowly warmed up when pressed, when it became too hot to keep your thumb on you knew the engine was ready to be started ;D I tried shorter times, pulling my thumb off before it started burning but the engine would never start unless you felt some pain! Lol Could you not fit a switch?? Only with a relay  |
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Last Edit: Nov 9, 2011 10:16:12 GMT by cairyhunt
Remember the days when sex was safe and motorsport was dangerous. Vintage bling always attracts pussy.  |
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I'm starting to wonder if all the above suggested issues are true! (fuel run-back, air leak and glowplug temp sensor) This morning it was cold, but not really cold - it turned over for about 20-25 seconds (no joke!) before starting with mucho white smoke & running fine  Today for the first time I sensed it starting to slow down as it turned over, so really want to get this sorted, especially as it's dark 90% of the time I'm driving now..  Thank you all very much for your help - I have got a fuel filter already, can probably get glow plugs & temp sensors by the weekend if it's likely to sole the problem..? |
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mate seriously just go and either check u are getting 12v on the glow plug rail when u turn the ignition on, or do the wire test like I said!!! if it starts straight away with the 12v direct to the glow plugs, you know its a fault with them getting power (or u have 4 dead glow plugs, but seen as u don't have the usualy glowplug light working its gunna be then not getting power imo.) if it still takes ages to start you will have a air leak into the fuel pipe. theres no point buying stuff when you don't know what the problem is, do what I said and you will then know where the problem is, and you can buy the correct bits and save yourself cash and effort in fixing something that isnt broke. ive had about 15 diesel engine'd cars and when you have starting issues these are the first things to check if it doesnt start after adding power to the glow plug rail, ill tell you what to do next oh and anyone using a direct switch please either make sure the switch can handle it or use a relay setup, before something starts to melt and burn lol. |
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Glow plug light is sometimes shared with the engine management light. On our Skoda the glow plug light came on when a brake light bulb failed ! Paul H |
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Nov 10, 2011 23:03:24 GMT
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This morning it was cold, but not really cold - it turned over for about 20-25 seconds (no joke!) before starting with mucho white smoke & running fine Not that many years ago I would have been so pleased to have had a diesel that would start in 20-25 seconds of churning - how times have changed. Try the jump lead to the glow plug power bar tip and see it it starts then. |
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Nov 14, 2011 16:44:49 GMT
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& the answer is.... *drumroll* Fuel pump seals! Botherations  |
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Nov 14, 2011 21:31:12 GMT
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Doesn't running it on real derv swell the seals back up?
Or is that urban myth?
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...proper medallion man chest wig motoring. |
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Colonelk
Posted a lot
Posts: 3,742
Club RR Member Number: 83
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Nov 14, 2011 21:41:06 GMT
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Doesn't running it on real derv swell the seals back up? Or is that urban myth? don't know about that, but the seals were proper fooooked. Like a waterfall down the side of the engine  Read online a lot of Diesels have issues with Low Sulphur diesel causing leaks on pump seals, don't know how true that is. |
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Nov 14, 2011 21:46:23 GMT
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Dunno about pump seals but I know it can cause injector seals to fail. That's supposedly one of the main causes of the dreaded 'black death ' in merc diesels.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Nov 14, 2011 22:27:00 GMT
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^ you mean the "how the F%$£ did the engine oil get in the F%$£ing diesel tank" problem?
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Nov 14, 2011 22:45:27 GMT
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Not quite, its more like the 'who the f%$£ tarmaced the top of my engine' problem.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Not quite, its more like the 'who the f%$£ tarmaced the top of my engine' problem. This! ;D   |
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Nov 15, 2011 11:06:23 GMT
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That looks nasty!
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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has always had issues...... the glow plug light comes on....longer in winter, but starting no different. he changed the plugs etc, no change. It turned out that the light which is linked to temp, was not linked to the plugs! Bypass and a big push button on the dash.....starts better than ever! Just shows, we rely on what we think is heppening, but it may not ! lol
