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Diesel smokey starts - advice requested

Quick tale first...

My S reg 306 TD was suffering from smokey starts a while ago. It wasn't engine oil; it was light in colour and I could smell chip fat so I changed the glowplugs. Well, I changed three of them; one was badly rounded off by a previous owner. The smoke had almost gone (just a tiny bit on cold starts) so I just left it in but the smoking increased so I finally decided to get the plug out and fit a new one, which I did yesterday.

The smoking is still there. Only on cold starts. It is fine when warm.

Could one of the ones I fitted in the meantime have failed? Could the one I've had stored in my toolbox(...) since I bought the set of four failed somehow? Is there a way of testing them? Could the problem be something else which is causing inefficient glow plug operation?

Reply to
Abo
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Yes

Maybe

Yes, if you've got a DC current clamp it's easy, otherwise measure the voltage drop on the feed to each plug. If they're wire seperately it should be about the same, if they're wired one after the other it steps up on each one. Or disconnect the lead to each plug & connect a headlamp bulb between the plug & lead.

The glow plug relay. Check they're actually getting volts. You can also take them out & see if they glow.

Reply to
Duncan Wood

How about not glowplug related at all? Weeping injectors? Cylinders get diesel weeping in and when left a long period it smokes.

Reply to
Conor

Hmm not thought of that one, I'd never done diesel before the 306 lol

Reply to
Abo

always look at the easy option first, glow plug failure is usual, sometimes within months for crap glowplugs.

undo all the glow plug leads, put a jumper cable to each glow plug in turn, you should get a healthy crackle as you connect, if you do it is almost certainly (99 per cent) ok

Reply to
Mrcheerful

It is a single feed to plug 3; a common cable then links all the plugs.

I'm assuming they *do* get voltage, the car starts after one crank once the GP light has gone out so it's not actually grumpy starting or anything.

I think whipping them out and checking they glow might be a good next step. I guess they earth through the body of the plug?

Reply to
Abo

Then 3-4 chould be V, 2-3 be 2*V, 1-2=V

If they come out easily

Yes.

Reply to
Duncan Wood

Well, you need to take the intercooler off but that's only two jubilee clips, three bolts and a retaining screw so no big deal. They should come out easily now I've replaced them all except the one next to the fuel filter housing, it's a bastard to get the 8mm nut off to remove the DC feed wire...

Reply to
Abo

I wouldn't expect the voltage drop on the bus bar to high enough or consistent enough to use to check to see what plugs are (or not) working.

Reply to
moray

Fused jump wire with a 15amp fuse is my preferred method. Small spark = ok. No spark = open circuit Big spark/fuse popping = short circuit.

Next most accuarate method is to use a 30A ammeter (with suitable fuse) to compare the current draw/drop on each plug.

Reply to
moray

The drop on the busbars normally obvious enough that you can spot the dead one. Thereagain I normally just stick the clampmeter round it.

Reply to
Duncan Wood

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