Crank Sensor Woes

[JB750]

Hi all,

new to the forum and have a major problem so thought I'd ask here.

To cut a long story short, I have a 300TDi Auto with EDC/EGR. Running rough and white smoke (unburnt diesel) every time I press the throttle.

Things done so far:

Compression test

Timing belt changed and timing checked

Injectors checked

(Thanks Les)

Diagnostic run and gave 4 codes - all related, 3 cleared but the fourth (code 9) pointed to the crank speed sensor.

Apparently this is used to advance the IP timing as the revs rise.

Tried to get the old one out (real pig on the auto as it's right next to the engine bulkhead). Problem is it's left the main part of the magnet/sensor in the casing.

It's too close to really get in to drill it out and I have a nasty feeling that I could be looking at a gearbox out job

Any help/ideas would be gratefully received.

John (JB)

[cipx2]

Try using a hex head wood screw or an extractor, maybe they 'catch' and you can pull the rest of the sensor out.

There are 90 degree drill adapters or even cordless drills, maybe you can borrow one. Mind that you shouldn't drill all the way, only what's necessary to screw an extractor.

[JB750]

Well, the issue rolls on (which is more than can be said of the truck!

Gave Les a hand to get the gearbox out enough to remove the offending article (took all damn day!). Replaced the crank sensor, and after all put back together, fired her up and......

.....Bloody fault is still there, the only thing that had changed is the engine check light had gone out.

The engine will now start fairly well, tickover OK with a small amount of smoke, then when I press the throttle pedal, the revs rise and so does the level of white smoke. The engine lumps as if it's not firing on one most of the time, then after about 1600rpm the engine check light comes on again. It goes out wheh I release the pedal.

I now have the head off, it has been checked and the rear core plug is leaking (explains the fluid loss) and it also needs a skim.

I've had the injectors checked and they are all fine. I have been told by more than one source that it has been known for a conrod to bend slightly if water gets into the bores, this would cause incorrect burn in the offending cylinder. I would have expected a fair amount of water to cause this, but not sure I lost enough (if any) into the bores, I think mine was from the failing core plug. A colleague at work also said he would have expected to see a rather clean piston crown if water was present in the combustion chamber and they all look identical to me (black!).

My next step is to measure the protrusion of each crown and hopefully they are all the same, a low one will indicate more grief

Any comments or observations are more than welcome.

JB

[Les Henson]

A bent conrod would give low compression on one cylinder and cause excessive smoke. A continual leak of water into the cylinder would be noticeable as the piston crown would in effect be steam cleaned.

In case you need it - measuring piston protrusion

http://forums.lr4x4.com/index.php?showtopic=24508

Unless you went through some deep water and sucked some into the engine - I can't see that you would have a bent conrod.

Les.

[TheRecklessEngineer]

Have you checked the simple things - Is it getting enough fuel? Replaced fuel filter? Checked sedimenter/lift pump?