Thread: Goes great - heaps of black smoke - back to great

Originally Posted by goingbush

not on a Td5 the fuel pressures are not that high, The Td5 used a unit injector and the pump is in the injector itself, its not uncommon for combustion gasses to leak past the copper seals in a Td5 and into the fuel rail or return line, just as it also is an issue for fuel to leak past the injector o ring seals into the sump .

what am I saying this for ???? , ..... I'm trying to sell my Td5 , doh

Not true, the pump is in the fuel tank. From RAVE.;


Fuel delivery description;
The fuel delivery system comprises a fuel tank, fuel pump, fuel pressure regulator, 5 injectors, & a fuel filter. Unlike other diesel engines, the TD5 engine has no injection pump . The diesel direct injection system receives fuel at pressure from a two stage fuel pump located in the fuel tank. The system incorporates a fuel return to the fuel pump, via a fuel cooler attached to the inlet manifold [ EU2] & a fuel filter. A fuel pressure regulator is located in a housing on the rear of the cylinder head. The regulator maintains the fuel delivered to the injectors at a constant pressure and returns fuel back to the fuel filter & pump via the fuel cooler


the fuel pressure , regulated by the FPR is 4.0 bar, 58 psi. Bob

Bob...

The tank pump pressurises the rail to 4 bar.

The injectors are unitary and have their own plunger driven by the cam shaft... They operate at around 12-18,000psi

None of this answers the question how and where exhaust gases can enter the fuel system???

It will be compressed air/fuel mix that is getting pushed into past copper washer
Cylinder pressure may overcome washers flowing into void around injector it could blow out of top oring then into oil,
Or just into fuel system could cause leaking seals in fuel system if over pressureised.

Usually fuel leaks out of failing washer as its always under 4bar pressure into cylinders then past rings to oil.
Slow cranking as pressure has to build up then black smoke out tailpipe as leaked fuel burns off.

Lots of could may and might haves would had to test oil fuel and washers to be sure.
That's why I said looks like cure in previous post.

Pete

Originally Posted by Tombie

Bob...

The tank pump pressurises the rail to 4 bar.

The injectors are unitary and have their own plunger driven by the cam shaft... They operate at around 12-18,000psi

Thanks for that, apologies Goingbush, I'm reaching for RAVE as I type, to read up on the injectors , there is always something to learn Cheers, Bob

Originally Posted by isuzurover

None of this answers the question how and where exhaust gases can enter the fuel system???

Perhaps if we replace "exhaust" with "combustion"?

Originally Posted by OffTrack

Perhaps if we replace "exhaust" with "combustion"?

That is not the issue. I vaguely recall now that the "fuel rail" in a TD5 is actually part of the head???

In most engines it is impossible for exhaust gases to enter the fuel, as the only possible way would be through the injector nozzles...

Originally Posted by isuzurover

That is not the issue. I vaguely recall now that the "fuel rail" in a TD5 is actually part of the head???

In most engines it is impossible for exhaust gases to enter the fuel, as the only possible way would be through the injector nozzles...

OK. Putting all of the terms in their right place (hopefully):
During the power/combustion stroke a leaking copper injector seal can cause an "airlock" in the fuel system (somewhere in the fuel system which includes the injectors and anything else) resulting in non-delivery of fuel and therefore no power. Engines drops down to idle. After switching off the lock may clear and engine operation returns to normal. The leak generally happens at high loads and may be exasperated by high ambient temperatures.

The question how is it possible is something I cannot answer because I frankly would not have a clue. My diesel experience is with the 2.3 Land Rover oiler...