Chevy Diesel

thanks for that Dennis, but i have already gone down that road and when i told them that it does 2300 rpm at 100kph, they said that i have the correct diffs fitted.

John

John, whilst I know little about Chev diesels I'd say it seems awfully high.
Specs show max torque is at 2000rpm

My Ford 7.3 only does 1850 @ 100k

2300rpm for 100kph ? That is a gearing problem or even somthing as simple as incorrect tire size.

Interesting point Alloy. It came fitted with 17" wheels.
John

Unless you are measuring your speed by GPS or the speedo has been changed - irrespective of tyre size the speed indicated on the speedo will remain the same - true speed will change of course.

Garry

Good point Garry. He could be doing 150 and not know it :-)
No wonder it needs changing down

Nice looking truck - I learnt to drive on one of them 40 years ago. My dad had one as a work truck - same colour as yours.

GoneTroppo,

The 6.5l diesel does have it's max torque at 1800rpm but it has it's best fuel consumption at 2200 to 2300 revs.

Mine sits on close to 2300 at 100kph and that from the gps. I don't know what is wrong with his fuel system but it definatey has a problem. I find that I tend to change back gears, not because of the lack of lugging torque but because I don't want to destroy the drivetrain.
Have a good one
RA.

Thanks Garry, I enjoy driving the old girl when ever I get the chance. Only trouble is that it takes ages to go anywhere because whenever you stop anywhere everyone comes out to reminisce about the one they had etc etc.

Funny thing is that you get that much more so than you do with a car of that 50's 60' era.

Rockape I totally accept what you say, it just seems a lot of revs for the type of motor. As I said I don't know much about them, was just generalizing. (more of a small block chev man myself)

Out of curiosity at what revs does it run out of "go"

Cheers
Chris

Chris,
mine runs out of puff at about 3900 revs, I would love a powerstar 7.3 as they seem to be a great engine.

RA.

Thanks Joe, I have had the fuel pressure tested at the filter after the pump, and it shoes 9 psi. i believe this is good.
John

gday mick, and thanks for that. the colour of the smoke is black. It was recommended that i install a turbo on it, but after paying 60K for it the last thing i want to do is spend more money on it which seems to be what i am doing at the moment with all the troubleshooting! Nothing is ever bloody perfect.
and yes it has always done this.
John

Hi John,
sounds like a air/fuel problem. Too much fuel, not enough air. I would be looking at the air intake. Start at the cheapest remedy first. Good luck, Mick

Neil,

how would i find out if the air sensor has failed, and where is it?

John

Had a computer connected and it gives all the diagnosis required. I am not sure where the sensor is but not difficult to fit if you are a contortionist I was told. Obviously I never fitted the unit, just took somewhere to see why fuel consumption had increased and power reduced. All is better now. Sorry can't be of more help.

Neil

RA,
yes i do have a manual, and thank you very much for reminding me of the troublshooting pages! Yes it does seem to point to air intake.

thanks,

John

Humvee,
interesting point. my exhaust is a 2" out of the block, then goes to a 3". my intake hose is not a 4.5", but a little less. i dont know the exact size, but definately not 4.5".
John

In the standard config in the Humvee the headers are stainless steel from each exhaust port to the dump pipe which is about three inch into the exhaust from either bank which then feeds into a short (3m max) 3" system with a dirty big straight through muffler, not much restriction in that.
One of the H1 owners tried a 4" dual exhaust but lost a lot of torque so went back to the standard config.
The Humvee intake consists of about 300mm of 4.5" into the aircleaner and then about 500mm of 4.5 into the intake manifold.
The comment about fuel supply in the other post is valid, we find that the standard mechanical lift pump is fine as long as no restriction is introduced in the fuel system. All the fuel plumbing on the humvee is 3/8, anything smaller throttles the engine, I tried to fit a water sedimenter between the tank and the standard fuel filter and the engine then wouldn't rev and was well down on power despite me fitting 1/2" hoses in and out of the sedimenter. I've often wondered whether the standard plumbing in nissans and toyotas was up to the job when they have Chev's fitted.
Also pay attention to those little rubber fuel return lines between the injectors, any leaks or restrictions will also nobble the engine. In fact if you disconnect one of them (let it run into a container) the engine won't even run!
I had a local with a 6.5 in an 80 series that was running a big pancake type aircleaner from a big chev petrol engine and it also restricted the engine, those big diesels want lots of air! Easiast way to check whether the intake system is restrictive is take it for a spin without it or the aircleaner. Just make sure nothing can get sucked in!!