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This is a bit of a vague question, but I know very little about diesels so I'm hoping someone will be able to give me some pointers, even if they're just general ones... BMW e34 525TD is sometimes difficult to start. The glowplug light comes on as usual, then once it goes out and you try to start it, it just turns over. It took about three attempts before it fired up this morning. Once it fired up, it was fine. I'm thinking maybe the glowplugs or the relay? But it's a total guess. How do I test these things? And would the glowplug dash light still come on if something wasn't working?
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Darrel
Posted a lot
Posts: 1,167
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Nov 18, 2008 10:00:45 GMT
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I tghink the fact the light is going out proves the relay is ok, however does not prove power is getting to the heat plugs. Put a multimeter on the connector thats on the end of the heat plug and turn the ignition on. You should get 12 volts on it for a bit.
Hope that helps
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Nov 18, 2008 10:02:14 GMT
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not sure on a BMW but on our old van you just unwire the connector off the glowplug and measure it to earth with a multimeter should read a few ohms normally 1 would go it would still start and then another it struggled if they are gone you wont get a reading , or you can compare against another one if your not sure you have to unwire as they are sometimes connected together off one supply and will read ok when connected
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Nov 18, 2008 12:48:09 GMT
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First thing I'd do is give it two bursts on the glow plugs - turn the ignition off and then turn it on again before starting up. If it starts fine then, your glow plugs are probably in need of replacement.
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1986 Citroen 2CV Dolly Other things. Check out my Blog for the latest! www.hubnut.org
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Nov 18, 2008 13:02:56 GMT
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Thanks for the advice guys - much appreciated . I've dug out my multimeter but the battery has ran out! It's an obscure 12v cell thing too so nothing in the "junk drawer" to replace it with. I'll test them with a test lamp to see if there's an obvious dud one.
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Nov 18, 2008 13:30:44 GMT
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or just try the two turn-over technique above first as I had a similar problem and my glow plugs had had it - covered in cack and worn out, new plugs - no problems starting at all Kirsty
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I have determined that my sole purpose in life is to serve as a bad example...
CURRENT vehicles - '84 Saab 900 turbo classic, '93 Nissan 200SX S13, 2021 Volvo V90 Inscription.
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Nov 18, 2008 14:14:18 GMT
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Right, my car electrics skills are about at the same level as my abilities as a brain surgeon, but I went out there with a test light and only the vaguest clue of what I was doing. I hooked up the test lamp between the 1st and 6th glow plugs to see if I was getting a current through the whole thing. Got someone to turn on the ignition... nothing. But for all I know that could be normal. Petrol and carbs (or even injection) I can do. Diesel and electrics... not a clue. I'm thinking about removing all six glow plugs and propping them up on the engine to see if they all glow as they should, but it looks like I'll need to remove at least the plenum to get to half of them and I don't have time at the moment.
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chrisw
Part of things
Posts: 171
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Nov 18, 2008 14:26:00 GMT
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Had this in the Pug, turned out to be water in the fuel. It hadn't been serviced in a couple of years so water had collected in the fuel filter, changed it and the problem went away...
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Nov 18, 2008 15:55:09 GMT
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Right, my car electrics skills are about at the same level as my abilities as a brain surgeon, but I went out there with a test light and only the vaguest clue of what I was doing. I hooked up the test lamp between the 1st and 6th glow plugs to see if I was getting a current through the whole thing. Got someone to turn on the ignition... nothing. But for all I know that could be normal. Petrol and carbs (or even injection) I can do. Diesel and electrics... not a clue. I'm thinking about removing all six glow plugs and propping them up on the engine to see if they all glow as they should, but it looks like I'll need to remove at least the plenum to get to half of them and I don't have time at the moment. Dean, whip the plugs out one at a time. Give them a clean up with a wire brush. Without screwing them back in connect the cable back up, have the case touching earth and turn the ignition on till they should glow......don´t touch them they get very hot but you can see if they´re working or not...without a multimeter or test light. If they all light up and you know the engine has compression change the fuel filter and try again. If it still won´t start loosen off the fuel lines at the injecters and see if the pump is pumping diesel through.......i´m assuming it´s not freezing over there yet? ;D
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Last Edit: Nov 18, 2008 15:55:45 GMT by Oldbus
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Nov 18, 2008 16:28:12 GMT
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Oldbus's method of testing the glow plugs is spot on and probably more accurate than looking for a 12V feed because some glow plugs systems run @ 6V (or other voltages too!) Just make sure the case/body of the glow plug has a good solid connection to earth.
Also give the busbar a rub down with wire wool/fine wire brush around any contact points. This may mean disconnecting more connections than just the glow plugs, but worth doing anyway because if these are slightly corroded then the performance of the glowplugs will be badly affected.
Before removing the glowplugs, spray a shed load of plusgas (or similar) down the threads and leave to soak for a while. Glow plugs can be a real bu@*er to remove sometimes.
Once you've checked all this, the next stage to look at is fuelling (new filter etc)....but the glowplugs are certainly the first step to check.
BTW - fuel filters on diesels should ideally be changed around the same intervals as the oil filter i.e. fairly regularly.
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Nov 18, 2008 16:47:26 GMT
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Thanks again chaps . The car is in use at the minute so I'll have to wait for a clear day or two before testing them, as I reckon the plenum chamber will have to come off and possibly some other stuff - the glow plugs are pretty well buried in the engine! ;D
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Nov 18, 2008 17:01:58 GMT
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and buy yourself another cheap multimeter;)
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Nov 18, 2008 19:43:30 GMT
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Maplins do an awesome multimeter for about £25. It'll measure current up to 20 amps and it has trip switch rather than a fuse. Thats what i use for testing glowplugs. They should start off at about 17-18 amps and drop down to about 10 as they heat up.
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Nov 18, 2008 20:01:19 GMT
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I dunno how they are wired on Beemer oil-burners, but sometimes you find if they are wired in series, it only takes one of them to go down and all the ones further down the wiring go down too. Series-wired glowplugs caused thousands of diesel leaf-sprung Land-Rover owners to go out of their minds when they couldn't get the b***ard things to start- so much so that they brought out a parallel wiring kit! My Pug had the same problem last year when my ol' man's GF owned it. 4 new glowplugs later, cured.
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Last Edit: Nov 18, 2008 20:03:12 GMT by briandamaged
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