Thread: 300Tdi Fuel usage

If it was a pristine motor to begin with ID agree but

I then had the Intercooler and manifold leaks fixed, the timing belt replaced, the injectors overhauled

that can easily imply a 50% improvement in its own right

The overhauling of the injectors leaves me a might sceptical as 90% of places wont touch them. And just because the pros have been paid to do the work does not mean they got it all right, everyone makes mistakes.

Not having it in front of me Im essentially doing the faultfinding by process of elimination, and since I cant see it or hear it running then I have to cover all the bases. I generally apply the KISS principal to it I mean it could be the automatic advance control on the injector pump but hows he going to check that without removing the pump?

Look at it this way I remove the pump and it was just a gunked up line from the manifold or a fuel line (I clean out and/or replace the filters + lines any time I do any work on a FIP that requires internal work) and it clears as part of the removal then its going to look like I got it right with the diagnosis of the advance unit so when i go "yeah mate its fixed, that'll be 30 squillion dollars and nuptual rights to your wife for the fix" it'd seem like a reasonable bill.

actually checking the timing on these things is straight forward if you have the pins or can make them.
The crank is locked at TDC No. 1 cyl with a flywheel pin into the corresponding slot in the flywheel. (5mm pin. I used a 1/4" BSP brass bush to screw into the wading plug hole tapped to take a 6mm bolt with the end turned down to 5mm) and the inspection plate or a/c idler puller dropped off the front of the timing cover and it's either a 9.5 or 10mm pin inserted (can't remember the size exactly. I use the shank of a suitable masonary drill bit as it is the exact size)
If this pin goes straight in without any resistance, the timing is standard OE setting. If it doesn't, loosen the three pulley retaining plate bolts and with a socket on the centre nut adjust it.
Once you get it to the factory setting, you can then advance it if the pump fuelling has been increased, but at least you have a base line.


Dave, does anyone in Oz have the gear to do the two stage injectors ? All the shops I've talked to ( all two of them ) reckon not.

FWIW Tony, mine has 255/85's, bull and side bars, usually 1-3 ladders on top, standard canopy and around 400kg in the back at any one time, pump fuelling wound right up and it gets no worse than 12l/100km.
Towing anything would knock that figure around, having extensive experience with a Patrol and horse float.

Originally Posted by rick130

actually checking the timing on these things is straight forward if you have the pins or can make them.
The crank is locked at TDC No. 1 cyl with a flywheel pin into the corresponding slot in the flywheel. (5mm pin. I used a 1/4" BSP brass bush to screw into the wading plug hole tapped to take a 6mm bolt with the end turned down to 5mm) and the inspection plate or a/c idler puller dropped off the front of the timing cover and it's either a 9.5 or 10mm pin inserted (can't remember the size exactly. I use the shank of a suitable masonary drill bit as it is the exact size)
If this pin goes straight in without any resistance, the timing is standard OE setting. If it doesn't, loosen the three pulley retaining plate bolts and with a socket on the centre nut adjust it.
Once you get it to the factory setting, you can then advance it if the pump fuelling has been increased, but at least you have a base line.


Dave, does anyone in Oz have the gear to do the two stage injectors ? All the shops I've talked to ( all two of them ) reckon not.

I know of a couple of specialist places but they wont touch the little ones in the rover as by the time you faf around with them and get them back in spec 90% of the time its cheaper to install new ones.

If you only want to check them theres an old field servicing trick that coupled with the right kind of pressure gauge will give you the initial opening pressure, If thats right and the spray pattern is right then the odds are in favor of the injector still being good.

The fuel filter won't make any difference to fuel economy. On a diesel it is the amount of fuel delivered that controls the speed, i.e. the injector pump action functions in a similar way to a petrol engine throttle. A blocked fuel filter will cause the engine to hesitate, cut in and out and eventually stop altogether. My 1996 110 wagon does between 10 point something & 11L/ 100Km at 110Kms/ Hr depending upon the load.

Originally Posted by Blknight.aus

I know of a couple of specialist places but they wont touch the little ones in the rover as by the time you faf around with them and get them back in spec 90% of the time its cheaper to install new ones.

If you only want to check them theres an old field servicing trick that coupled with the right kind of pressure gauge will give you the initial opening pressure, If thats right and the spray pattern is right then the odds are in favor of the injector still being good.

yep, last time I spoke to the local diesel blokes they basically said the same thing. Pattern and initial crack pressure is fine to test, it's the second stage that is tricky, and the damn body is crimped together which really limits serviceability.

a clogging fuel filter can cause excessive fuel consumption if you cant get the engine to sit on the peak of the torque or power curve as its starving for fuel you'll have to grab a lower gear and then push it again.

As the total amount of fuel that can be delivered is now metered by the filter and cant change in a lower gear your going to spend longer going the same distance at higher RPMS. more time on a given fuel delivery rate= more consumption. But thats not why I mentioned it initially, I was aiming at the lack of grunt at full pedal.

Well I checked the timing today, with the pin in the pump timing hole the slot in the flywheel is 8.7 +or- 0.1 or 0.2 past were it should be so, the timing is some what retarded.
Any reason why a crowd that "should" know what they are doing may have set it like this?
Any reason I shouldn't set it as per the manual?

I also made myself a throttle o meter and took it out to a known hill on the fwy and drove it repeatedly it would seem that my "seat of the pants" theory that it goes better at less than full throttle does not stand up. Starting at a particular sign at 100 km/h at full throttle gives an exit speed of 82 and 81 for the two runs, at 90% throttle I get 81 and 80 exit speed for two runs and at 80% throttle I got an exit speed of 75.
I then swapped the fuel filter and got much the same results.
But this was with the truck empty and only short bursts.

Tony