Range required to cross the nulla

[bagmaker]

Blocked fuel tank breather William? -I am no mechanic but I wouldn't think filters would recover from their blockage like that, once blocked they are not likely to come good for a little while (from the top of the hill)
Is there something else pulling engine power -we are talking a lot of power hmmmmmm, you would probably notice with squeeling belts or hot smelling clutch or wheel brakes as you pointed out.
Is there anything else in the intake air side of things that would restrict flow? Check the air-filter, nothing collapsed? The intake tube cannot fold or collapse?

Just my 2c, good luck!!

[T1 Terry]

William the primary filter (water seperator) has a drain on the bottom of it.
The dirt/water will build up in the middle of the filter material until it blocks up.
Most times IF that is the problem you can drain it on the side of the road (several times!!) and continue until you fix the contamination.
Look to see if there is a drain on the bottom of your fuel tank. If there is, leave the bus overnight for everything to settle.
In the morning undo the drain until pure fuel comes out.
Some will advise you to put a litre or 2 of metho in the tank.
If it's a bug growing in the tank you may need some additive to kill it.
If it's been standing for some time in a cold area it may have gone waxy ........ that will quickly block up filters.
Terry will elaborate I'm sure.

If it was cold I'd go with the fuel going waxy and blocking the filters, I doubt it's algae growth as it is after such a short run. If it is waxy fuel, 20ltr of kero into the tank and mix it around by syphoning some out and pour it back in a few times.
Do not put metho in the diesel, you do not want to absorb the water and take it through to the injectors, it will separate again in the injector under the high compression temps and blow the tip off the injector, one dead injector and a complete dead engine if you keep driving it like that as the piston, bore and eventually crankshaft will be destroyed due to fuel washing, just like the scenario Tanks went through after an injector service
Use purpose designed diesel fuel treatment as it will kill the algae growth and separate the water from the diesel and it will settle on the bottom of the tank, either syphon or drain the stuff off the bottom, separate the water, pour the diesel through a rag back into the tank, repeat the treatment and do the job again a few days later, the only way to get it out of the fuel.
Avoid buying fuel from a servo that doesn't sell a lot of diesel, it does go off and it does grow algae, summer diesel will grow wax strings in the cold and water will build wax strings that seem to turn into glue and stick to everything in the fuel system.

The other possible is something in the tank blocking the fuel pick up, had this on one of the Kenworth trucks, the driver had stuffed a rag in the filler after loosing the screw on cap, it eventually found its way into the fuel pick up pipe resulting in rather poor hill climbing ability, yet it idled just fine and drove empty ok, so have a look in the tank with a good led torch

T1 Terry

[Busman]

Well seems to be getting worse, the first run was 150 K +, the second 20 K + and the third about 3 K
I am waiting for a mobile guy to finish the job he is on, worked for McAffertys for many years so is familiar with 6V92's. As he has access to filters I will wait and see what happens when we pull them.
He has also experienced something in the tank blocking fuel pickup so diagnoses should be ok I think.
Both primary and secondary filters are disposable types, no drain taps.

Scenario is that VP has sat since March over a cold winter only being moved around when necessary for jobs to be carried out (not very often)
Then driven to CPF in Brissie for service which included changing the fuel filters, back to Caboolture, about 80 Klicks each way. Then filled up yesterday and left this morning, did about 150 + K's and someone put the brakes on.
Classic non venting tank maybe ? Checked the breather, clear as. Unlikely to be something in tank, I have had it out to fit a fuel gauge and was spotless inside and I made sure nothing went into it at that time.

For me the problem getting worse points to some sort of contamination ? Laying itself on the filters ? Stop for a bit and allows a bit of fuel past ?
I know one of the guys from WA came to Brisse and bought a coach that had algae in the fuel, to drive back to WA. They also gave him a dozen of each filter. Changed the first ones at 50 K's, next at around 100 and so on, by the time they hit Victoria the thing was running sweet as.
Very similar symptoms in the beginning as VP at present.

Jeez gets cold and windy here don't it ?
William

[Greynomad]

Busman,
The wind will ALWAYS be in the wrong direction when you're crossing from East to West.
You just have to decide if it's strong enough to cause you fuel economy problems...

[Busman]

Well its, all a bit inconclusive, full set of fuel pressure tests showed nothing wrong, pulled primary filter and emptied, nothing in there, diesel was that slight yellow colour of fresh diesel, so contamination is ruled out. Fuel pump has a relief valve which is dumping as it should, blow line back to tank, then suck through with a venturi also showed heaps of flow, run with tank return into a bucket, no problems there either.
What he did notice was jakes were not releasing as they should, hung on for a bit, so tomorrows run will be without jakes to see if that is the cause. If so I can live without them, if not will head back to Brissie to get CPF to fix it on Monday. Staying tonight at the Caltex in Warwick, was just too late to start out and maybe have a problem at night. Will keep you posted.
William

[BruceS]

Got my fingers crossed for you William.
A bit of a worry that it appears to be getting worse each time you go for a run.
Is there plenty of slack in the emergency, manual kill cable?

[T1 Terry]

First thing to check, oil pressure, is it higher than usual? Thick oil will cause issues with the Jake brake as the drain down time is longer. If you think the Jake brake is the cause, each tappet cover has a spacer and a wires and spade connection (usually) that can be unplugged, try each side of the V to determine which side has the problem or if it is both sides. Much easier to diagnose if you can isolate where and when it happens.

T1 Terry

[marashkar]

My thoughts are with Bruce on this if it has a manual shut down ( pull cable) is it something on the accelerator side pulling it slightly on but I have been wrong before and could be on this as well steve

[BruceS]

A Detroit without a manual shutdown (pull cable) is a recipe for sore ears!! I won't mention what the heart does!
A run away Detroit is something to be seen & heard to believe!
I'd think the mechanic would have checked that out though.

[Busman]

Sitting in Narrabri at a caravan park at the moment as we have no hot water at the moment, the Liths pack has been behaving too well.
VP ran like a dream, it will not sit on 100, wants to do 115 all the time !
Jakes switched off.
As an aside, this is the first real test of running all my thermatics off the solar, it has always been a short run or a mixture of solar and alt power.
As soon as I switched the main 2 banks to the solar/liths which I run at a slightly higher voltage I found I only needed the 2 banks 98% of the time, this was towing the trailer at about 98 kph which is where the cruise control likes to sit. AND VP took off, I am amazed at just how much extra sting there was available.
All in all happy chappy, I think the Jakes not releasing fully have been found guilty.
Thanks for all the suggestions.
I do not have a shut down cable, I got sick of being de nutted by the handle every time I got into the seat, so fitted a solenoid that does exactly the same thing. Not engine protection to cause this either, I drive with one eye on the gauges!
I am not bothered trying to solve it at this stage, my guys from CPF Detroit Specialists tell me it is unusual but definitely not unheard of. pretty flat around here, don't need engine brakes much !
Cheers
William