306 Diesel starting difficulties

Jimbo Mahoney · 21 May 2010 at 08:18

These past couple of mornings, my usually reliable 306 DTurbo (1994 model) has had a bit of difficulty starting, requiring two "pre-warms" and still feeling like it might not start.

I've had this twice before in the time I've had it (7 years) - once was glowplugs, which were all replaced about a year ago and once was because the battery was dead due to a dead alternator, replaced a couple of years ago, albeit with a used one as far as I can recall.

I've measured the battery voltage when the engine is off - 12.6v and when it's idling - 13v. Does this mean the alternator is fine?

Surely the glowplugs are also fine, having been recently replaced?

What other things could cause starting problems?

Thanks!

Gaverick · 21 May 2010 at 09:20

What make of Glow plugs did you replace them with? When I have my 306 I got the glow plugs replaced with some cheap ones and within 6 months they were shot again. Apparently the best are the Bosch duraterm chromium

jumpy · 21 May 2010 at 09:34

12.6v or greater = 100% battery.
Flick your lights on for 10 seconds to dissipate surface charge. Disconnect + wire to battery. Test.

What's the cranking voltage to the starter motor?. You'd need to prevent the engine from starting though (fuel pump cut-off solenoid switch), then crank the engine for about 15 seconds whilst measuring voltage. 8.5v - 9.6v is good depending on temperature.

Alternator charging should usually be between 13.5v - 14.8v idle.
Rev engine to 1800-2800rpm and hold. Voltage should not deviate from the idling voltage by more than 0.5v.
Check tension of alternator belt etc.

Your starter motor could be on the way out. I had an old ford that gradually became a pain to start from cold (especially in winter) turned out the starter motor was a bit 'slow' so wasn't giving the best chance for compression ignition. Wasn't cheap though.

Could always check the supply voltage to the glowplugs as well as the plugs themselves. Would be careful of removing the plugs though; they can shear off :eek:

I'd definitely get them checked if you can though.

I'd guess it's a mechanical injection system? Check fuel injectors/pump? When was the fuel filter last changed?
If it runs ok, then I'd ignore the fuel system for now, it's usually expensive - do the starting/charging systems first.

Check any earth straps in the engine bay to make sure they have good connections, and if there's nothing wrong with the battery or the alternator or the glowplugs, glowplug relays/wiring, I'd be looking to the starter motor.

Bill101 · 21 May 2010 at 10:48

you should not really need the glowplugs in this weather, but check that the main fuse for them has not blown( they take one hell of a current) as on some systems the orange dashboard light is not in the circuit!

Dogbreath · 21 May 2010 at 12:14

Gaverick said:
What make of Glow plugs did you replace them with? When I have my 306 I got the glow plugs replaced with some cheap ones and within 6 months they were shot again. Apparently the best are the Bosch duraterm chromium

I'll second this, cheap third party glowplugs can have a life expectancy of a mayfly.

ScoobyDoo69 · 21 May 2010 at 12:22

Another vote for glowplugs, mine was terrible at starting, sometimes starting and only running on 2 by the sounds of it!

Changed them and all was well!

s0ck · 21 May 2010 at 13:10

Any smoke out the back when it eventually starts?

TaKeN · 21 May 2010 at 13:55

Does sound like crappy glowplugs!

Jimbo Mahoney · 21 May 2010 at 20:32

s0ck said:
Any smoke out the back when it eventually starts?

Loads.

Strangely, it's only the past couple of mornings. When I finish work, after the car has been idle in the car park for ~8 hours, it starts perfectly.

Thanks for the suggestions, I'll do some more tests.

s0ck · 21 May 2010 at 22:22

White? As in proper cloud white?
You might have an air leak. Check the leak off pipes that run from the injectors. The squeezy bulb thing can let air in too. Prolly best searching a pug forum for various ways of fixing drainback.
Usually, the longer it's been sitting, the worse it is.

jumpy · 22 May 2010 at 05:56

White smoke is most likely going to be unburned diesel.

dalin80 · 22 May 2010 at 08:27

13v at idle is a bit too low, raise the revs at tiny bit and see if it comes back up to the 14v range.

But i thinks thats a seperate issue.

white smoke is unburnt diesel caused by low compression temps either as a results of incorrect timing, low compression or faulty plugs although plugs usually give black smoke its not unheard of for them to trigger white.

MikeHunt79 · 22 May 2010 at 08:49

Nice info jumpy, I need to test my battery when i can.

Jimbo, If you have access to a clammp multimeter, you can see if the glowplugs are pulling any current without having to remove them. That way you can see if the glow plugs are working before having to replace them. I have replaced only 2 glowplugs out of 4 on my 205 in the past few years and it starts fine every time!

jumpy · 22 May 2010 at 09:06

^^
clamp multimeter mmmm I always wanted one of those, bit expensive though last time I looked.

dalin80 said:
white smoke is unburnt diesel caused by low compression temps either as a results of incorrect timing, low compression or faulty plugs although plugs usually give black smoke its not unheard of for them to trigger white.

Timing is probably ok if it runs fine once started. If it's the plugs it's s nice cheap fix. Low compression could be lots of things from piston rings to hgf.... or a weak starter motor - this has the added bonus of flattening your battery in next to no time at all with all the cranking.

MikeHunt79 · 22 May 2010 at 09:48

jumpy said:
^^
clamp multimeter mmmm I always wanted one of those, bit expensive though last time I looked.

A Fluke one will be pricey, but I've seen other brand ones for around £30.

I don't own one myself, but a mate of mine is a sparky so I can borrow his when I need to...