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Anybody know how to troubleshoot a diesel?
I'm babysitting my friend's Vectra 1.7td POS while he is away on holiday. He told me that it's hard to start in the mornings because air gets into the fuel system. He said if it gives trouble just to spray some quickstart in the intake or just keep cranking it until it starts.
Anyway, I made the mistake of parking it at the end of the drive, blocking my other cars in. And nothing I can do will make it start. I spent two hours messing about spraying quickstart and cranking it but no luck. It fires momentarily on the quickstart and then dies immediately. When the battery went flat from all the cranking, I got upset with it. I put my legacy battery on it and used the starter motor to inch it out of the driveway into the road. I've just left it by the side of the road for now. But if I leave it there too long it will get towed or burnt. Which I can't help thinking would be the best thing for it, although my friend might disagree. I need to get it started so I can move it to the back of my driveway where it's not blocking anything. I know almost nothing about diesel engines, but it seems to me that there isn't much to go wrong. Provided the fuel gets into the cylinder, the compression should ignite it. So what is the most likely problem with the fuel system? There are lots of pipes in the engine bay that may or may not be fuel pipes. I really don't know where to start. (no pun intended) Each cylinder seems to have a metal pipe and a thin braided pipe running to it. I pulled off the braided pipes and there was no fuel in them. Does a diesel have separate piping for fuel and air perhaps? I'm going to give it another go after work tomorrow and if I can't get it going I'll have to call out the AA. Any suggestions welcomed. Enduring a 10 year old Vauxhall reminds me to be thankfull for my 16 year old Subaru.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II Last edited by b3lha; 03-30-2008 at 05:06 PM. |
#2
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Phil
I'm not an expert on diesels, but I have some experience so I will give you some pointers. When your friend says there is air in the fuel system, I suspect what he means by this could be the engine is getting "air locked" This means the fuel pump is drawing air somewhere, and is not "sucking diesel". So possibly no diesel fuel is being lifted from the tank to the injectors. Being compression ignition, if no fuel is going into the cylinders, the motor can't fire. If this is your problem it is usual to bleed the fuel system by releasing the banjo bolt on the injector nearest the fuel pump, then turning it over until the air is expelled and fuel is spraying everywhere, especially on your clothes. Once you have fuel reaching the injectors it is usual that the engine will fire shortly afterwards. You may need to keep the engine turning while you are closing off the banjo bolt [sometimes there is a bleed screw, some diesel websites might inform you about where it could be found] If airlock [non lifting of fuel] is your only problem, and compression is good, it should fire right up. Other than that, the next place I would look is at the glow plugs. Diesel engines generally have a glow plug to heat the cylinder before fuel is squirted inside. This has a light on the dash which looks like a curly wire. You switch on the ignition, this plug heats for maybe 5-10 seconds, and only after the light goes out do you try to start the engine. If the glow plug is dead, the light only indicates a timer, so the cylinder is not heated, so it remains difficult to start. But it occurs to me if your friend is using easy start, maybe the glow plug is dead for a while and he is using a less than perfect solution to the problem. Get the fuel up to the injectors first and foremost. Joe
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#3
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Phil, I think you're first instinct was the right one...........
Air leaks in the LP side of the fuel system, ie from the tank to the pump would bleed air into the system, the most likely places are the air-bleed port on the top of the fuel filter, the seal of the fuel filter element, or the priming bulb pump somewhere in a low pressure fuel line feeding the distribution pump. Leaks on the high pressure side of the distribution pump will most likely result in the aformentioned fire......... assuming the fuel reaches something hot enough to ignite it, like the turbo !! It could be that the injectors themselves are leaking into the engine too, which would result in a very rich start up with plenty of smoke and ultimately a knackerd engine due to bore washing. If the bores are washed out, and the crankcase is pressurising the breather system, the engine could "run away" by sucking up the sump oil and fuel vapours from the crankcase into the induction system via the breathers until it either rev's itself to destruction or melts due to lack of oil. Once this situation starts you can't shut the engine down until it fails........ This would be my prefered solution partly because it's so destructive and scary, but mostly because a rod through the block means it's unlikely ever to be resurected !! As Joe said you can bleed up the system by cracking off the injectors and cranking until you spray everything including yourself in diesel.......... Also as Joe says the glow plugs are an electrical heater in each cylinder to aid that initial start-up. Check the fuse for the glow plugs, but my guess is they are buggered. They usually need to be changed when the mileage/operating hours on the engine are high, but no-one ever does because of cost and faff factor. This is why most industrial diesels like fork lifts require some burning newspaper down the intake.......... Hope you get rid of it soon, from experience of an early Vectra TD when they were new they are horrid to drive too............ Phil. As a matter of interest modern "diesel" engines are closer in design to the Hornsby Ackroyd oil engine than the early designs of R. Diesel (monoblock direct injection vs pre-combustor, preheated chambers, medium/high vs low compression, ran on so-called "lamp oil" hence "oil engine" rather than vegetable oil or blown particulate fuels)............. By the time Diesel was experimenting (for MAN) Ruston and Hornsby had something like 600 engines in various applications all over the world........... including powering the light of the Empire State Building !!
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Only the depth varies.............. Last edited by Phil Hill; 03-31-2008 at 10:32 AM. Reason: Additional info. |
#4
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Thanks Joe and Phil for your advice.
I spent another hour tonight messing with it. I tried my best but I couldn't get the b***ard to start. Tried bleeding the fuel lines and so on. Then I gave up and called out the AA. He spent 45 minutes on it and then he gave up too. "I'm sorry, I don't know what's wrong with it and I can't fix it." We managed to push it to the back of my driveway where it's safe, off the road and not blocking my other cars. Quote:
You're not kidding. Vectra's are horrid when new and they get worse with age. It's one of the nastiest vehicles I've ever driven. It is crap in every respect and does not have a single redeming feature.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#5
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Errr, sooo....
You don't like it all that much?
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
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