Thread: 300tdi fuel pump - advanced or retarded?

Isn't it easier to set the lift rather than swapping over pumps? Ok, once you've pinned the flywheel and timing gear you still can't be 100% sure that the cam gear is spot on unless you pull off the timing cover; but if pinning those and checking the lift on the pump show's it's out, set it right and then listen for the knock. Maybe you'll need to replace the pump, maybe you won't.

Well the plot thickens, just a little.

In an attempt to reduce the general clatter and smooth things up I've added some CW10 Anti Wear (Cost Effective Maintenance) and poured two tins of Diesel Purge (Liqui-Moly) into the remains of the tank.

When I say 'poured', what I mean is that I neglected to put the return fuel line into the can and instead sucked the two tins into the tank via the fuel pump.

When running the Diesel Purge in I noticed something else. The knock is traveling up the exhaust pipe. As in the noise is traveling up the metal pipe, not with the airflow.

Over the weekend I took The D'Fer for a blast up the M1 and back, using the last of the quarter tank. Smooth? Yes? Quieter? Very much so. Apart from the knock it is a very different beast.

Cold there is a definite metallic ring to the knock, which progressively softens as the temperature increases. Once the engine temp gets past about 88 degrees it could almost be mistaken for part of the injection.

With the Diesel Purge run through, it also sound like the truck is idling fast. A quick adjustment and The D'Fer is quiet as a kitten, except for the knock.

There are no noticeable oil stains on the intake/exhaust side to indicate a leaking gasket, nor are there any swooshing sounds (i.e. like a compression leak from a poorly fitted injector) or obvious flows of air on that side of the motor.

But what I did notice (apart from the knock sound traveling up the exhaust pipe) is that there is warm air moving back up the intake and exiting from the rubber port at the underside of the air filter housing. Given that this port is for excess dust and water to exit, I suspect I've now found the missing clues.

Could this be a combination of loose exhaust/intake manifold or suspect manifold gasket?

My thinking is that some exhaust air is venting into the inlet tract and the knock is the loose intake or exhaust manifold knocking under the changing pressure. As things heat up, the gap closes hence the knock reduces. At higher revs the airflow is increased which results in a positive air flow through the intake. The airflow out of the bottom of the air filter reduces as the knock softens either by increased revs or the engine coming up to operating temperature.

And in case you're wondering, I added the AW10 a few weeks ago and yes, there was a noticeable improvement in the ability of the motor to rev when cold. I'm due to change all other oils and will add a little to see if there is any noticeable change. There is a little diff whine at speed from the rear so watch this space.

Cheers,

Mathew

Im reckoning you've got a sticky rocker, stuck valve follower or a sticking valve. you might also have a cracked rocker shaft, snapped pedestal bolt

time for a hot V cold compression test and a leak down check. and do it while youve got the rocker cover off.

You've given me something else to ponder.

I'll keep you posted as work progresses ....

Cheers,

Mathew

When you say you've checked the timing, have you checked the cam timing? I once owned a 300 tdi with a strange rattle & it ended up being a piston lightly kissing a valve because the timing belt was 1 tooth out.

Another possibility is that the wrong head gasket has been fitted again allowing pistons to kiss valves. Tdi head gaskets are supplied in different thicknesses & are identified by the number of small holes on a tab sticking out one 1 side. The easiest way to check piston to valve clearance is to line up the flywheel groove centrally in the wading plug hole, this puts pistons 1 & 4 at tdc with the valves on #4 "on the rock". Then remove the rocker cover & push the valves down by hand or levering with a screw driver or the like & see how far the valve can be pushed down before it contacts the piston.

Hi Everyone,

I didn't get to work on The D'Fer over the weekend, apart from running some CEM Flushing Oil Concentrate through and doing an oil change (or two) to complete the process.

I was hoping that this might work its magic if a sticky lifter or such is the culprit.

Alas, the knock is still there. Although all the tidy up work means that apart from the knock I've got one sweet and smooth running tdi. There is virtually no blow-by.

If it was pistons and valves hitting, wouldn't this occur all the time? My knock is loud when first started and softens as the temperature rises.

Once it is at operating temp, it is far less noticeable.

The knock is also clearly around #1 rather than at the front and rear of the motor. There does not appear to be a knock from #4.

I also hit the motor with some degreaser. There does appear to be a little oil around the #1 Exhaust manifold so borrowing my nephew's torque wrench and checking the exhaust manifold is back on the radar.

I've asked my nephew if he's got the bits to do a compression test. I want to be certain before I really start pulling things apart.

Cheers,

Mathew

So just an update.

I've bitten the bullet and booked The D'Fer in for some diagnostic work at West End Diesel after the Easter weekend. A compression test to start with and take things from there.

Turns out that Greg who works there might be LR friendly having owned a '94 Discovery.

I'm realistically at the limit of my DIY resources and running out of time fast!

She Who Must Be Obeyed is increasingly disapproving of the growing pile of Land Rover pieces in the garage.

Her less that subtle hint last night was pointing out an almost 3 year old Great Wall 4x4 Ute for sale in the paper. $11k and 27000km.

I explained that there was no way you could compare the character and essence of owning The D'Fer to such a travesty.

People nod, smile and wave at The D'Fer. In a Great Wall they'd frown and look away from the horror.

It was an interesting discussion. Apparently I am sleeping on the lounge for the near future.