Diesel starting problem

Hi All

I've got a 7 year old BMW 530d and it has developed an intermittent starting issue. Normally, it will start with just a flick of the ignition, but now it sometimes takes about 5 seconds. It turns over easily, so I don't suspect a battery problem. The battery however, is one that has a charge indicator, and it is black (insufficient charge). Of course it should be green, but at least it isn't orange (dead)!

Before this car I had another BMW diesel. When starting this one, you had to wait for the instrument panel's pigtail symbol to extinguish before cranking. This was, as you know, to allow the glow plugs to heat up.

The current car does not have this pigtail symbol, so how does it work? It still has glow plugs I assume? My thoughts as to the intermittent starting problem were that there is a loose connection to or from the glow plug relay. Any other thoughts before Mr Local 'tie me up and steal my money' BMW Dealer has a look? Oh, and if anyone knows where said relay is likely to be, that'd be useful too.

PS I've tried some BMW specific online forums, but these seem to have degenerated since I last used them ('where can I find an M3 logo for my

316?' etc).

Thanks.

Reply to
Grumps
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This doesn't sound like the problem that I had with a Peugeot diesel but might be worth checking. It got progressively more difficult to start and it was diagnosed as an air leak in the fuel system. The pipes to the fuel filter were renewed but the problem persisted. It got to a point where I had to prime the filter with the small hand pump every time I needed to start the car. A new complete fuel filter assembley cured the problem.

Kevin

Reply to
Kev

try alt auto bmw, its chock full of BMW nerds who are more than willing to help.

However I'd try to switch on the ignition for about 10 seconds , then starting the car. If it starts first time then then you may have a blown bulb on the dash, behind a 'pigtial' symbol.

(My brother in law used to drive a diesel and never bothered to wait for the light to go out started fine most of the time (he was a plonker of the highest order however))

Iv'e got a c reg 518 that always starts on the button , so you should have a few years left yet in her :)

Reply to
simonsmith.uk

Thanks, I'll try that ng. I have tried waiting before cranking; makes no difference. And there really isn't a pigtail indicator.

Reply to
Grumps

are you sure ? even new diesels need thier plugs warmed first (and have a pigtail light) .... Still live and learn .....

Reply to
simonsmith.uk

Maybe they warm up much quicker so they don't bother with the light. My old Corsa and Current 206 Van both have pigtails. My mate's Mitsubishi and my FIL's Merc don't.

Reply to
Grumps

I thought it was older indirect injection diesels with conventional timed pumps that had the greatest need for glow plugs.

Direct injection less requirement.

Common rail systems less still.

So they may have glowplugs, but the warming time may be very short.

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Reply to
dom

Modern diesels often run the pump and glowplugs to "prime" the engine when you unlock the doors, so there is no need for a light. It also means that starting can sometimes be slightly more difficult if you wait too long before starting the engine.

It is also why, on a modern diesel, if you accidentally fill with petrol, do ABSOLUTELY NOTHING until the fuel can be pumped out. DO NOT touch the keys or attempt to lock or unlock the doors. Otherwise, you can find your petrol has caused several thousand pounds worth of damage to the fuel pump.

Christian.

Reply to
Christian McArdle

Hmm. I wonder. That would certainly be the case when it failed to start when I tried a week ago. We were sat in the car with the engine off for ages, then tried to start it. But surely the manufacturers know this, and would have something 'extra' when starting in this situation.

Reply to
Grumps

Our Freelander also is difficult to start on a low battery. BMW diesel engine. I suspect the glow plugs don't glow as bright..

Reply to
The Natural Philosopher

I imagine turning the ignition on and waiting would give it another boost. If not, lock and unlock the doors.

Christian.

Reply to
Christian McArdle

How does petrol damage the fuel pump?

Reply to
dennis

I'm about 20 years out of date, however: You shouldn't assume that your glow plugs, heaters, etc... are (all) ok. Are they connected in series, or in parallel. If connected in series, one faulty one (open circuit) will affect the others; also a series resistance assembly may be used (for 4-cylinder engines), which could be faulty. Check that each heater has the right voltage on it (12v. on a parallel connection, and 2v. on a series one). How much trouble is it to take them out? Test them electrically, whilst out of the engine; keeping the test to a minimum to avoid overheating. Keep in mind that the voltage for series connected ones will be lower (2v.). It's a good habit to take them out occasionally for a check (best prior to the winter).

Sylvain.

Reply to
Sylvain VAN DER WALDE

The pump is an extremely sensitive precision instrument that gets the fuel up to about 1800 bar. This is a VERY high pressure. Putting the wrong fuel it will seriously throw the pump off balance.

Note that on a common rail engine, getting the pump up to pressure is much more important to starting than glow plugs. The high pressure and efficiency of atomisation means that common rail engines need very little temperature to start, and may not even have glow plugs at all. However, they won't work properly until the pressure has stabilised, so still need a head start, unlike a petrol engine.

Christian.

Reply to
Christian McArdle

Diesel fuel is also the pump lubricant. Left alone, pumps are ultra-reliable - but if damaged replacement is expensive.

Reply to
dom

A diesel pump is designed to run on diesel fuel oil which _lubricates_ the working parts. High hydraulic pressures are also involved, which require very close tolerance parts to be fitted. The smallest amount of wear can be detrimental to the proper working of the pump. Petrol is a good solvent. I'm sure that you can work the rest out.

Sylvain.

Reply to
Sylvain VAN DER WALDE

ITYM 1800 PSI, or abour 120 bar.

Reply to
Paul Herber

Nope. 1800 bar, or about 27,000 PSI. Very dangerous stuff. A leak can squirt out with such force that it can slice right into the human body.

Different designs use different pressures. They're pretty much all above

1000 bar, and some new designs are now edging 2000 bar.

Christian.

Reply to
Christian McArdle

It's also worth noting the following: Always change the fuel filters regularly, and clean the lift pump gauze filter. And to be even safer, check for water in your fuel tank.

Sylvain.

Reply to
Sylvain VAN DER WALDE

Well, well, well, I wouldn't have beliived it but I;ve now found such on google. Had a suitable question been on WWTBAM I would have got the answer wrong.

Reply to
Paul Herber

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