I had a 1994 200Tdi manual discovery which I did 40,000k in. I've just recently upgraded to a 1997 300Tdi automatic which I've done 5,500 k in.
Fundamentally, the vehicles were the same. Both Discoverys, both turbo diesel (albeit 200/300) but the transmission made the overall package behave like two all together different vehicles.
The manual box had very good ratios for a stock vehicle. I found first was very low [3.692 on the tdi] for general around town driving, and not low enough when towing. 5th was not high enough when cruising at 110, but was perfect when towing at 110. They key thing with the diesel manuals though is that you cannot be lazy. If you need hill climbing power, an increase in speed etc, they wont pull from 1200 rpm by just sticking the boot in. You really do need to downshift - you will find that there is a very narrow band between 2000 and 3000 rpm where the engine is working at its best. In hilly areas I found that I had to drive to an engine speed in any given gear, not a road speed. It is however reported that the 200Tdi had a very undriveable torque curve. Whilst they say that correlation does not imply causation, I found it very "mysterious" that as soon as I had the fuelling tweaked, the gearbox started to let go...
With the auto, the engine seems to have good torque across a wide spread of rpm. I tow an 8x5 tandem regularly and the auto makes much better work of it than the manual. However, the top gear ratio is very high - this a problem when towing at 110, such as on the Hume when you hit a hill. Where the manual was doing 2800-3000 rpm, in its prime, the auto is doing around 2350-2400. It will lose speed very quickly!!! I want to find an auto shop than can modify the valve block so that it locks up in third. I know that it would benefit from driving a 1.000:1 ratio locked up as that is the equivalent of 4th in the manual, and the old one towed flawlessly on hills in 4th!
Given that I do 200k a week just getting to Uni along the monash carpark, I'm much happier with the auto, but there are lots of things to consider, depending on how you want to use it.
When I test drove the autos, I took them well away from the owner's residence and gave them a decent testing. Find a flat bit of ground and bring the revs up to 1,000. Cycle between R and D 20 times. You'll get a good idea of condition by the noises it makes. Take the Shift speeds/engine speeds data from the RAVE with you and make sure its all within specification. Find some hilly areas and see if the auto is confident in its gear selections and holds appropriate gears - or if it carries on like a pork chop and hunts to buggery. If you can have a trans place do a line pressure test - all the better. The tdi autos are slower to get off the line until about 2000 rpm, but if its painfully slow until 2000, there can be a fault with the torque converter giving essentially no torque multiplication (its on the ashcroft site somewhere, i forget the specifics). Also, find a bloody bloody bloody steep hill. Stop halfway up and restart. I tried this with one I looked at and it wouldn't pull away, just revved to buggery. RUN!


Reply With Quote
. Take the Shift speeds/engine speeds data from the RAVE with you and make sure its all within specification. Find some hilly areas and see if the auto is confident in its gear selections and holds appropriate gears - or if it carries on like a pork chop and hunts to buggery. If you can have a trans place do a line pressure test - all the better. The tdi autos are slower to get off the line until about 2000 rpm, but if its painfully slow until 2000, there can be a fault with the torque converter giving essentially no torque multiplication (its on the ashcroft site somewhere, i forget the specifics). Also, find a bloody bloody bloody steep hill. Stop halfway up and restart. I tried this with one I looked at and it wouldn't pull away, just revved to buggery. RUN!



Bookmarks