need glow plugs every time

[citronut]

why is it some BXs/XANTS wont start unless you let the glow plug light go out evedry time you try to start the car, my own cars have never suffered this prob, but i have two or three customers that do
regards malcolm

[XantiaMan]

why is it some BXs/XANTS wont start unless you let the glow plug light go out evedry time you try to start the car, my own cars have never suffered this prob, but i have two or three customers that do
regards malcolm

I would have thought the answer is obvious and the reason why glow plugs are fitted. DI's will start without glowplugs but IDI's need help apart from in warmer weather.

[deian]

I think it's because the newer cars have higher pressure diesel systems... think tdci, hdi, etc. The pressures are so high that they start without a glow plug.

Obviously a car that has glow plugs fitted need them to warm the air in the cylinder for the diesel to combust at first shot, once the engine starts, the cylce is everlasting as long as the fuel is supplied.

An old workmate of mine couldn't get his head around that a diesel engine only needs diesel and air and that it will literally run forever if fed diesel and air. No spark to control. The diesel engine is pretty superior really, and nowadays getting better than petrol ones (?).

[uncle buck]

I think citronut is comparing like for like engines...not an indirect injection with a direct injection....or that's how I read it.

[jeremy]

Curious one this - our ZX 1.9D has done 95,000 miles and we've had it since 53,000 and as we've only changed the filetr and the leakoff pipes - is probably it left the factory (ie no new components - even glowplugs.) Start it from cold using the glowplugs - and there is never any need to use them again.

My BX TD at 205,000 always starts first time (like the ZX) but probably turns over 1 more turn before starting (possibly due to the electric advance device not working)- and likes the plugs to be used for most subsequent starts. If I don't use them it will crank over for a few seconds before starting - which I think is while the plugs get hot enough to assist starting. There is a small puff of white smoke.

Both have Roto-Diesel pumps.

I'd put the BX's behaviour down to its extreme age - Its possible wear in the pump retards things a touch and it might even be that advancing it a touch would improve it. It's really a case of leaving well alone.

[DickieG]

Td's have a lower compression ratio compared to normally aspirated diesel's so they need the glow plugs to help them start (unless they are direct injection HDi's).

[citronut]

my 1.9D BX with 250k on the clock once started in any one day would fire up almost instantly every time for the best part of that same day, but on a virtualy identical 1.9D BX would need to wait for the glow plug light to go out every time before she would start readaly, both cars are normly aspirated
regards malcolm

[Peter.N.]

In my experience it's all down to compression. This varies with age, general engine condition and the thickness of the head gasket. The speed at which the starter turns the engine is also a factor - starter, battery condition.

I ran a number of vehicles with Perkins 4/108 engines, a very early IDI. they were never easy to start at the best of times, except one. This particular one I had the block reconditioned, bored, pistons, crankshaft reground etc. The pistons sat proud of the top of the block and were supposed to be machined to give a reccomended clearance, they didn't machine them at all so they must have been nearly touching the head. That was the only engine I had that would start without using the 'thermostart' unit.