Thread: Discovery 300Tdi - sticking speedo

Have you checked out the transducer on the transfer case, it could be that sticking/ failing as opposed the head itself .

Originally Posted by loanrangie

Have you checked out the transducer on the transfer case, it could be that sticking/ failing as opposed the head itself .

even just a dodgy connection ...

Thanks for the suggestions. Worth looking at but I believe from the behaviour that it's a mechanical issue with the needle mechanism.

A dodgy transducer or connection would, I think, give erratic readings or intermittent dropping back to zero. I can't think of a situation where a faulty transducer would put out a rock steady pulse rate regardless of transmission shaft speed. But then, I've been wrong before...

you certainly see D1 instrument panels for sale - usually cheap enough to use as a test replacement to see if it is the instrument itself

G'day Ian (leo109).
Dont wish to hijack the thread, but many moons ago I used your documentation to "tune" the injector pump on my 300tdi in search of increased performance.
I notice yours has now well exceeded 350k. and I assume that it was tweaked as per your deliberations??
I wonder has the motor stood up well, or has it failed or even hesitated in any way?
Mine is over 250k. without any problems, starts straight up and pulls like a train! Doesn't even drip oil, keeps it all inside for 10k. changes.
Mike

Hi Llandro,

Yes, our 300Tdi has been 'tuned' to the max. for more than ten years now. As per those notes plus, since the last revision, an improved intercooler, boost up to almost 20 psi and a slight tweak of the max. delivery screw. (Will have to revise the notes again, one of these years...) I always ease off when the EGT gets close to 700 C and change oil every 5000 km.

The engine is still going strong. Just slight, 'healthy' oil usage between changes - maybe 2-3 mm on the dip stick. The engine is basically original, just some ancillaries replaced over the years: water pump, starter motor, vac. pump etc.

A few years ago, at around 270,000 km, and while near the workshop of famed Tassie LR Guru, Justin Cooper, we did a pre-emptive head gasket change. Seems these head gasket commonly give up the ghost at around 300,000 km and blow through to the water galleries, leading to over-heating and coolant loss. With access to a fully-equipped workshop and tame LR Guru, it was a fairly painless exercise. The original gasket was showing signs of pending failure (will post photos if I can work out how...).

Had the original injectors tested by the local Bosch agent for cracking pressure and spray pattern and they were pronounced fit for further service. Will have to have another look at them shortly as that was nearly 100K km ago.

All running gear is still original too: gearbox, transfer box, diffs, wheel bearings, even brake discs. (The purists will probably disagree but I never have discs machined. Just replace the pads and give them time to bed into the disc surface before heavy use.)

Unfortunately though, I can't claim a completely oil-tight engine...

Ian

Thanks for that info Ian, sounds like your tdi would now be more inline with the modern crop of high boost donks but I suspect the old tdi may have stronger internals.
Re the head gasket, about 3 yrs ago I set the torque wrench to 80ft.lbs. and applied it to the 12mm head blts. They were all less than that to varying degrees. The 10mm bolts were also checked and set to 60ft.lbs.
I wonder about the "non retightening" procedure, particularly with a compressible head gasket
Also bought a "P" gasket, but not needed to replace so far.
Doing a bit of offroad stuff, I needed to replace the rubber "donut" and recently the 2 belt idler bearings, one of which had become very noisy.
I only wish they had made it easier for this old codger to replace the oil filter.
Still a messy job, even with your tip of a cut down coke bottle!
All else good and am hoping she will see my driving days out.
Cheers Mike