Thread: Catastrophic engine failure on a TD5

Originally Posted by robbotd5

Just be careful before you dirll out the restriction in the fuel return, it is there to maintain pressure in the fuel supply drilling in the head that feeds fuel to the injectors. It is there for a reason. Got my injector seals replaced today, all is good so I will just monitor oil level from now on and hope for the best.
Regards Robbo.

The restrictor is after the fuel pressure regulator so the fuel pressure remains the same in the head. the pressure drop is in the return line. All you get is a increase fuel flow. I think the theory from LR technical is to have the fuel at a lower temp with increased flow, this would make the viscosity of the diesel higher. Which would slow the fuel ingress.

Originally Posted by rick130

Geez, was it that long ago Scott ?

I remember discussing it on the old and now defunct LRE Forum :cheers:

Yep I posted my experance on to that forum. LR Australia (LRA) had no idea what an oil test was and had to refer it to the UK. At one stage LRA said I had "no proof of a problem other than the independant test?"

I kid you not.

In the end they did seemed to have fixed the problem. As I change the oil ever 10,000 and there is no change in the level all seems to be going well.

Originally Posted by woko

The restrictor is after the fuel pressure regulator so the fuel pressure remains the same in the head. the pressure drop is in the return line. All you get is a increase fuel flow. I think the theory from LR technical is to have the fuel at a lower temp with increased flow, this would make the viscosity of the diesel higher. Which would slow the fuel ingress.

OK I’ve read the thread and am confused; which is not difficult being non technical.

If the purpose of drilling out the restrictor is to help prevent fuel contaminating the oil by reducing the pressure (on injector seals?). If the regulator maintains the pressure in the head (injector seals) despite the enlarged restrictor what’s achieved by drilling out the restrictor?

If the fuel flow increases and the regulator still maintains pressure, then that must mean the fuel pump is working harder? At least that’s my non technical take?

Would really like to understand this.

Originally Posted by scott oz

OK I’ve read the thread and am confused; which is not difficult being non technical.

If the purpose of drilling out the restrictor is to help prevent fuel contaminating the oil by reducing the pressure (on injector seals?). If the regulator maintains the pressure in the head (injector seals) despite the enlarged restrictor what’s achieved by drilling out the restrictor?

If the fuel flow increases and the regulator still maintains pressure, then that must mean the fuel pump is working harder? At least that’s my non technical take?

Would really like to understand this.

The pressure on the injector seal is the same and will always have to be to maintain correct pressures for injection (it a bit more complicated than that but we are not worried about injection pressures for combustion, this is supply pressure) All pressures in the system remain the same except the return pressure.
Enlarging the restrictor increases flow in which the fuel will be cooler (the reason TD5s have fuel coolers is that the fuel gets that hot in the head that the fuel can boil in the tank) This will reduce the viscosity of the diesel (most oils when hot are thinner) Having a higher viscosity oil will reduce leakage. ( this mod doesn't stop fuel ingress just slows it)
1 vehicle that was bad for this it had 4 sets of new injectors. and 2 sets of 2nd hand injectors and had all the different models (black blue and green) 2 heads and a engine change and it still leaked diesel out of the injector plungers.

If you want to see if yours is leaking from injectors, remove the rocker cover and clean all the oil out of the head around the injector so there is no oil in there. remove fuel pump relay and bridge it out and let the fuel pump run for a hour. You will be supprized how much diesel has pooled around the injectors

Every TD5 that I have seen that has had a oil sample tested has come back with high fuel dilution. LR say it is with in range.

Originally Posted by woko

[snip]

Every TD5 that I have seen that has had a oil sample tested has come back with high fuel dilution. LR say it is with in range.

Every one ??!!

Anything above 0.5% (and no lab that I'm aware of in Australia can test below 1.0% ) impacts negatively on engine life as no oil commonly available in Australia can cope with fuel dilution long term.

Originally Posted by rick130

Another thing to look for in the blotter test for fuel dilution is a wavy border but it's the rate of the spread that will really tip you off.

I posted this four years ago in another thread, and while it only shows various containment levels, it'll give you an idea.
IMO fuel would show up outside the dark rings.



[edit]
This is better (from Cummins and Valvoline)



and this is a good FAQ FAQ's :: Valvoline ::

Rick,
Are the pics as above when the oil is dry on the paper (ie after a hour or so when the oil has soaked in) or straight after placement onto the paper?

Chris

Originally Posted by rick130

Every one ??!!

Anything above 0.5% (and no lab that I'm aware of in Australia can test below 1.0% ) impacts negatively on engine life as no oil commonly available in Australia can cope with fuel dilution long term.

Last oil test I did (07) came in with fuel contamination of 2%. This was after the injectors were changed? This was down form 6%,4,%,3% taken at 9,000K intervals. I change oil every 10,000K’s.

Report commented “flash point indicates fuel dilution satisfactory”

Might get another one done.

Originally Posted by cjc_td5

Rick,
Are the pics as above when the oil is dry on the paper (ie after a hour or so when the oil has soaked in) or straight after placement onto the paper?

Chris

Chris, I've always taken it as after a minute or two, but bear in mind I'm no expert doing it for a living either.

The speed of spread is a factor to consider and can be an indicator of fuel