Power of 300TDi

On Mon, 01 Nov 2004 07:19:02 +0000, Austin Shackles

The gears are lubricated with engine oil. The kit includes a new inner timing case and this picks up the oil via a banjo plug from the oil gallery below the camshaft.

You can see the result at this link

The oil galleries within the case spray feed out of the two idler gears (between pump and camshaft gears, and camshaft gear and crankshaft gear).

The oil then gravity feeds back into the sump via a drain hole in the bottom of the timing case.

I will be publishing some more photos in about a month as the gears will have then covered their first 100000kms.

Cheers

Phillip Simpson

It's going to be when you take your foot off the throttle that any backlash in the drive system shows, and I doubt the pump would be trying very hard to maintain a speed. It has to do work to deliver the fuel.

Now, chain wear is going to increase the effective pitch on a tensioned run, and affect the relationship between the input and output of the drive. Eventually, in systems carrying a heavy load, the effect will concentrate the forces on one sprocket tooth at a time. From what I've seen, chain driven timing gear is grossly over-specified in terms of chain and sprocket contact surfaces, so that sort of wear will be minimised. Besides, they're in a much friendlier environment than the chains on the average combine harvester.

the amount of stretch is almost imperceptable on modern timing belts. When i compared my old belt against the new belt for wear when i changed it last, i could not tell any difference due to stretching. Can`t say i was looking too hard though. Looking at the length of the belt fitted to a 300tdi and assuming a 2 degree error would be noticeable in the timing, the belt would need to stretch 5mm in length!!! Mine certainly hadn`t after being used and definitely abused for 60,000 miles!

You`ll probably find that was more to do with fuel and air filters and lack/need of a service than the timing belt. Defenders are very prone to clogging up air filters with dust and it makes a huge difference to the performance. I didn`t notice ANY difference in power before and after the belt was done. None at all. And i use low rev power ALOT as its constantly used offroad and for dragging caravans around. However about 3000 miles after a service it gets very sluggish and i usually end up doing a mini service to replace the air filter. normal power is then returned.

You`ve never driven mine then! My defender 300tdi is completely standard (engine wise) and pulls like a trojan horse from tickover. A properly set up tdi is a brilliant engine. More likely factors in performance would be injectors, air and fuel filter, correctly set up injection pump, lift pump working properly (amazing how many tdis suffer poor performance from weak lift pumps not supplying enough motion lotion!) and carbon build up in the head.

I may be swayed if you were able to give independant comparisons of rolling road / dyno tests of brand new engines before and after the conversion.

Nick

"Peter Seddon"

Agreed, although this comment was about chains, not belts. The weaknesses of the belts are well-known, but the question was on the advantages of gears over a chain.

Rich

Hi Nick, can't agree on the fact that modern timing belts don't stretch. I have seen on the 300Tdi where the belt had stretched to the point that the amount of slack between the pump and cam shaft had reached the point that you could push the belt all the way up to the inside of the timing case. In fact in one case we could have gone further but the case stopped the "experiment". We checked the tensioners etc and they were still properly tightened, so we could only put the looseness down to belt stretch.

As to a before and after study, if you look at the bottom of the page at the address below you will find such a study. This was done at the Chisholm Institute which is a "technical college" that trains apprentice mechancs, amongst a number of science based disciplines,, and is the closest 4wd dyno to me.

The before had a new timing belt fitted as per LR specs etc by local dealer. After nearly 4000km the before test was done. After this, nothing was changed, except the Zeus gears were fitted, and then after they had run for a while taken back for the after study. If anything there was a potential for problems because the air filter was the same used. Fuel is always purchased locally from the same place so this is unlikely to be a factor.

As a double check, the experiment was run on a Defender with only

20000kms on it and the results were the same. This vehicle is owned by an ex Navy man, who is very particular about his servicing-runs a engine running hour meter so can be described as fairly precise on how he does things.

Hope this helps answer or address some of your queries.

Cheers

Phillip Simpson

Was it definitely fitted as per workshop manual ?

Steve

Hi Steve, it was fitted by Land Rover in Solihul, so we must assume that it was. This was interesting as the 2 owners who used to race to their favourite fishing spot, had both purchased new vehicles. One was a disco and the other the pajero. As I said the disco won the hill race for the first 12 months and then slowly the pajero was catching up and then eventually overtook the disco. Had both drivers present when we opened the disco up, and the various comments from both drivers was predictable and very funny. It should be noted that both these guys were retired, and what could be described as "mature gentlemen". After fitting the gears the pajero driver was to become very familar with the disappearing rear end of the disco, and as far as I know that this is still the case after 2 years.

Cheers

Phillip