Thread: Did You know this 'Can' happen to a diesel (Death by oil)

DO NOT try to prime your engine VIA the compressed air method... If you do and what I suspect has happened has happened all you will do is fill your sump with diesel (probably again)

I strongly suspect that you did not overfill your engine as much as you think you did and you have had diesel dilution of your engine oil.

Disconnect the supply line to the lift pump then pressurise the fuel tank (you can do this by putting air onto the final return line to the fuel tank Watch for fuel or air coming from the supply line to the pump if you get that then you initial fuel system is ok

Remove the delivery line from the lift pump and put your finger on the delivery outlet, operate the hand prime lever if you dont feel pressure on your finger then the pump's diaphragm is knackered.

Do the same for the intake side of the pump if you dont feel suction then the pumps diaphragm is knackered.

IF you feel no pressure on the outlet but do feel suction on the inlet then there will be a tiny split in the diaphragm near the plunger that is getting covered up at partial stroke letting some of the fuel into the sump and giving the rest to the IP.

Heres why it might have contributed to your symptoms. (And I'll try to keep this plain english)

Background 101...... turbo diesel fuel consumption......

A diesel engines fuel consumption is fairly linear in terms of RPM and load at any given work load if you increase the RPMS then the fuel consumption goes up at a steady rate. With a turbo diesel engine the fuel goes up at a more or less exponential rate due to the effect of the turbo, by utilising otherwise wasted energy more air is crammed into the engine allowing more fuel to be used. An over simplified version of whats happening but it will do.

Both engines at idle will use naff all fuel so a semi functional lift pump will supply abundant fuel for the no load condition at pretty much all RPMS. When you start to load up and ask for more power the ability of a barely functioning lift pump will not supply the IP with enough fuel so as the engines load increases the fuel supply deminishes, the boost drops off and the engine will settle to whatever RPMS it can deliver onto the applied load with the fuel available to the lift pump.

Inside the IP is a gallery that provides 3 functions
1. It cools the internal components of the IP
2. It lubricates the internal componets of the IP
3. It provides an initial reserve of fuel for consumption
(how many of the IP parts it cools and lubricats varies between IP type and design)

so long as you're putting fuel in faster than the IP wants to deliver it to the injectors the engine will run and deliver full power. If you only need a short application of maximum power the reserve (if full) might give you 10-20 seconds of full power before the IP begins to draw air instead of diesel and inject that. Air in the injector lines in small quantities lowers the Injection pressure and quantity and once that starts to happen the power output of the engine begins to drop off.

Once the engine power begins to drop off the turbo will start to wind down lowering boost pressure, At this point the Boost compensator begins to push back the fuel control and the fuel supply will begin to catch up to demand. As more fuel becomes available the power will come up and the whole cycle begins again. On a well setup engine (and the TDI/TGV's are in this respect) the system will quickly obtain an equilibrium and so long as you dont increase the load or back off on the applied throttle position your engine will maintain a steady but lowered output.

If you back off the throttle the lift pumps ability to supply the IP with fuel exceeds the IP's demand for it, the gallery in the IP refills and maximum power becomes available.

Hope that helps...

to save me from having to do it heres someone elses how to..

In about 3 weeks time I have to do the lift pump on ratel10mm's series, the basics are the same.

Originally Posted by uninformed

still no sign of Seven

Distress wont get you any where in life, mister socket number seven.

So please mister socket number seven, come home, your owner is missing you and your mates in the tin are feeling so bad about their jealousy when you were chosen to do the job that only you could do.
.

Originally Posted by Blknight.aus

DO NOT try to prime your engine VIA the compressed air method... If you do and what I suspect has happened has happened all you will do is fill your sump with diesel (probably again)

I strongly suspect that you did not overfill your engine as much as you think you did and you have had diesel dilution of your engine oil.

...

Did you read all the posts - Serg has managed to prime it using the hand primer by the sound of it. Would be hard to do that if the diaphragm was split.

How much oil does the engine hold??? An extra ~2L would be 33-50% fuel dilution, and easy for Serg to spot by comparing viscosity.

Serg - just use a paint stirrer or similar to check for oil dilution. Measure (approximately) how quickly the oil runs off the stirrer, and the size of the remaining drop on the end (for your unused oil and the drained oil).

well I have already cracked the injectors and turned the engine over on key. It pumped fuel out of them in a pulsating manner. I then did them all back up and tried to start it...it fire'd and ran a very short bit, rough with some very light coloured smoke. I was very wary of it running away so shut it off quick (not that it did run away or start to rev) I then cranked it again, it wants to fire and small puffs of light coloured smoke come out, but it wont run. I think its not getting fuel. I only used the air pressure method to get fuel up to the filter and thats it. Testing the fuel at the injectors was by cranking only, as with starting it.

So it seems the lift pump is buggered as it wont bring fuel up to the filter by hand/lever.

Dave Im still not sure about it leaking diesel into the crankcase. Like I said before, after the power loss happend, there was plenty of running around and more load put on it than that run out to death by oil Rd. I had checked the oil level leading up to the oil change, around the time I did the turbo, after my mech had it, and it was normal ie max level on dip stick. I drove it to my mates shop to put on hoist. It sat for 2 hrs before I could get on. I drove it on, drained oil, removed filter and refilled. BEFORE I started it I checked the dip stick and the oil level was high. I wish it wasnt me but it was. The loss of power was fixed with the turbo and that was a case of it definitely being broken and repaired.

seven is still missing.....

Originally Posted by isuzurover

Did you read all the posts - Serg has managed to prime it using the hand primer by the sound of it. Would be hard to do that if the diaphragm was split.

How much oil does the engine hold??? An extra ~2L would be 33-50% fuel dilution, and easy for Serg to spot by comparing viscosity.

Serg - just use a paint stirrer or similar to check for oil dilution. Measure (approximately) how quickly the oil runs off the stirrer, and the size of the remaining drop on the end (for your unused oil and the drained oil).

sorry if there was confusion, I could NOT get it to prime with the hand primer on the lift pump. I had to get fuel up to the filter by compressed air in the tank re Rick's method. Yes it seems the lift pump is NOW buggered but if you read my post above I dont think it leaking through the CC. BTW since I drained the 2 litres of oil out of the sump on Sat arvo on the side of the road, It has not changed. It is at MAX on dip stick when cold and drops a little when cranking, but comes back to max if standing....surely If the lift pump was leaking in it would have added more to the crank case?

the engine at max is supposed to be 7 litres...so an extra 2 is 35% plus factor in what burnt off during event......

I just did a quick crude test using the dip stick and stop watch. From time of removing stick and holding vertical, I get 2 drops, the second drop falls at 12 secs....no more drops after 30 seconds

Originally Posted by uninformed

sorry if there was confusion, I could NOT get it to prime with the hand primer on the lift pump. I had to get fuel up to the filter by compressed air in the tank re Rick's method. Yes it seems the lift pump is NOW buggered but if you read my post above I dont think it leaking through the CC. BTW since I drained the 2 litres of oil out of the sump on Sat arvo on the side of the road, It has not changed. It is at MAX on dip stick when cold and drops a little when cranking, but comes back to max if standing....surely If the lift pump was leaking in it would have added more to the crank case?

the engine at max is supposed to be 7 litres...so an extra 2 is 35% plus factor in what burnt off during event......

~35% dilution would flow like water. If the level hasn't risen after pressurised bleeding then you should be fine.

Sounds like the engine is OK then!!!

As an interim measure to get it going you could fit an electric lift pump (~$70).

However there should be places on the GC who have TDI lift pumps in stock???

If I cant get one on the GC I will just get it from MR Automotive or British Off Road. I am still very nervous about the internals of engine, valve train etc. Rick has mentioned also to get the injectors out and look at them.

just to be sure, lift pump wont hand prime fuel into filter, so it must be stuffed, so change it out?