Please help - Rocky F78 2.8 Turbo lacks revs (max 3500rpm)

[Southern Safari]

Engine smokes (black) somewhat, has fair power but refuses to rev above 3500rpm. Consumes 8km/l at best at 100km/h on open road.
Could it be the max speed setting on pump? Blows smoke already so maybe mixture setting also incorrect. Have tried injection cleaner additive, new fuel filter, cleaned aircleaner, no luck.
Any tips would be appreciated.

[RockyF75]

What the hell are you doing revving it above 3500 You don't need to take it to red line EVERY gear change

Does it lack any power below 3500? Or does it just hit a wall at those revs?

[Southern Safari]

Specified max no load revs of DL52 according to Manual page EM14 of http://www.warfs.org/manuals/F70_F75_F7 ... anical.pdf is 4500rpm!

[RockyF75]

I know. But if your saying there's no power above 3500 you obviously take it past that usually

[Southern Safari]

Mine has a fair amount of power up to 3000rpm, struggles thereafter up to 3500 max, blowing lots of smoke and never goes above that.
Being new to diesel I would not dare to try 4500 no load.

[RockyF75]

How long have you had it? it sounds fairly normal to me

Goes great guns between 2000-3000, then you really can't feel much power, but I'll bet its got plenty of torque around there. Only redlined mine prolly 8 times, 6 on the same hill

Normal driving on road, there's really no point to go above 3000 IMO. But if it just wont rev above 3500 then somethings up. Will it rev up that high in Neutral?

[Southern Safari]

Engine was previously tuned by 'diesel expert'. I expected more performance and better fuel economy. Presently the car cruises nicely at approx 100km/h for 8km/l on the level. In between 100 and 115km/h it flat spots a bit then eventually peaks at +/- 120 km/h and for est. 6km/l.
What performance can be expected typically and will the max rpm. adjustment improve performance? If so, how to do it?
Advice please...

[Southern Safari]

Sorry I missed your post just now. No it does not get to 3500rpm no load. Mechanic tried it stationary (on gravel sidewalk and it blew a huge cloud of dust and some smoke, passersby ducked )

[RockyF75]

Consumption sounds about right. Mine gets worse the faster you go, I try and stay below 100 cause it means about 2L less fuel per 100k's. About 90-95kph, unless I'm in a hurry.

Still doesn't explain why it wont rev above 3500 though. There is an adjustment on the top of the fuel pump where the accelerator cable connects. It might be set to limit the amount of travel on the accelerator.

That said, being able to rev above 3500 isn't going to help on road performance. It will increase your top speed, but if you want to consistently travel faster than about 120kph, you need a different car

[Buggerific]

I had a problem once offroad...

Coming up a hill it just died in the ass. Couldn't get revs up, BLACK smoke and lots of it, no power with the little revs she had... then it stalled. Started back up and was fine ever since.

So maybe something in the fuel line, something blocked? I dunno.

[Spartacus]

I had a problem once offroad...

Coming up a hill it just died in the ass. Couldn't get revs up, BLACK smoke and lots of it, no power with the little revs she had... then it stalled.

when the car is worked hard my induction piping used to collapse...
well that what happened to me before i used stiffer pipe.

[Southern Safari]

No play in accelerator cable when pedal fully depressed. On most inclines the last 1/3 pedal has virtually no effect if above 100km/h going in.
I bought the car 3 weeks ago and have done 3200 km since. Beforehand checked out two others, both with larger diameter tyres, but higher milage and they seemed to have slightly more power. Mine was cheaper, better outward condition, new tyres etc. Drove the 1600km home overnight fine. Little engine oil used (250ml). Found slight improvement in fuel at alitude.
Recently did 1200km, last 40km chasing laden Hilux 3l Diesel (maybe KTZE?) cruising at 120km/h. Midrange power no comparison to Hilux i.a.w. trying to accelerate from 100 to 120 km/h when overtaking very slow, but entering incline at 120 could keep him in sight. Paid for it i.t.o. fuel consumption though 6km/l.
I also have a '82 Datsun Safari L28 (2.8 6cyl) which I think the Rocky was maybe inspired by. Datsun's best is 7km/l at +/- 120kmh, typically 6.0km/l with heavy steel canopy. I bought the Rocky as closest alternative today because wife couldn't drive the Datsun - no powersteering or aircon and just to large.
So overall I still have to learn a lot since overhere it's very difficult to find competent mechanics. Thank you for this brilliant Website and enthusiastic contributors.

[Big-Stu]

Check the small vacuum pipe that goes from the top of the injector pump to the turbo charger. It is a small metal pipe with flexible rubber hoses at either end.

Mine had a small crack in the rubber and it made a big difference to the power. Once I found the problem and fixed it, it was just like I had a new vehicle.

While you're at it check all the other rubber vacuum pipes that go to the turbo charger area for cracks or loose fittings.

How long since the fuel filter was replaced?

You might have to put a boost gauge on the turbo to see if it is working properly.

Anything above 110KPH in a Rocky is not good for the fuel economy.

I seem to get 9.5l to 10.0l per 100K fuel economy.

Stu

[Southern Safari]

Thanks All.
Big Stu and Spartacus I'll check it out. There is this rising sound, besides other 'normal' sounds occuring around about 115km/h. Bragging to my wife it's the turbo : Sounds vaguely like a higher pitched fan running up and modulating with speed as you cruise at 110 - 120km/h.

I know now the turbo comes in at lower speed than that so I'll check it out as soon as the rain lifts here - typical early winter in our Western Cape.

I love these cars, such character. Demo by a seller, it drove straight up a steep dongafilled firebreak to the top of local Parrot Mountain without any hesitation, which gave me a new perspective on Rocky's as well as the countryside

[RockyF75]

Pretty sure you can hear the turbo whistle around 115. I think. I don't go that fast much tho, only when I'm overtaking. Sucks being a tight wad but thats the way I am

[Southern Safari]

Yes F75 I'm with you on the speed issue. I can hear the turbo whistle on rapid gear change, but this modulating fanlike sound puzzled me. Thanks to all the advice I checked the tubing around the turbo this morning, lots of grime around outlet from turbo to intercooler, hoseclamp very loose - tightened it up and cleaned up. But side of nearby vacuum pipe from alternator to brake servo almost completely chafed through - can only be a mm or so left...

Anyway motor no load speed now gets to 4000 rpm on some quick stabs and amazingly less smoke!

So I'm truly relieved and owe you all - probably saved some lives...

[Southern Safari]

Replaced hoseclamp on turbo outlet hose, old clamp ran out of adjustment and left substantial leakage. Now a clear power increase around 2000 rpm, more responsive - tempting for stoplight dragging
Replaced brake servo vacuum hose - imagine wife trying to slow down this little tank without servo assist.
Can't wait to do some open road cruising tests. But still have to sort out sticky manual freewheel hub, loose passenger side balljoint, front wheel alignment, worn front prop UJ, Gearbox/TB oilleak, very noisy tappet etc. Despite all shows how gutsy this car is to not have anywhere dropped me!

[HotFourOk]

Good to hear you got it sorted out! Leaking boost is never good.

A mechanic once left my vacuum line to the brakes off... scariest moment I've ever had! Lucky its got good compression braking, that's for sure.

[DAT MAN]

[quote="Southern Safari"]sticky manual freewheel hub quote]

I've had 2 ferozas whith this problen allways the left hand side
it was the spring that screws into the sliding spline that locks the hub' It wasent screwed in enough so wasent retracting the spline far enough
quick fix

Hope this helps

[Big-Stu]

Now a clear power increase around 2000 rpm, more responsive - tempting for stoplight dragging

Good to see you are fixing things.
It's a diesel so don't expect to beat anyone at the lights. Even them lowly Ferozas can probably beat you!

However with the intercooler and turbo it will just 'pull the skin off a rice pudding' as the saying goes.

Give it a couple of months and you won't even notice the turbo whine. It's only when you get a new passenger and they wonder what that strange noise is.

Stu

[HotFourOk]

It's a diesel so don't expect to beat anyone at the lights. Even them lowly Ferozas can probably beat you!

As if!

[tabrocky]

It's a diesel so don't expect to beat anyone at the lights. Even them lowly Ferozas can probably beat you!

As if!

x2

The biggest problem i'm having is getting the power down to the bitumen (when in the city).

Now i'm not a hoon (normally anyway...) but the power the little rocky posseses is some times a bit unexpected and can come on board just at the wrong time. It certainly shouldn't be underestimated.

We've had a fair bit of wet weather over here recently and so far I've nearly lost it going around a round about, spent a few seconds sideways on a curving freeway entry ramp and broken traction from the lights countless times.

I actually had to jack up the back wheels to make sure I didn't have a broken axle... I was that concerned.

I think sticky-er rubber will go a long way... however an LSD would be nice.

[HotFourOk]

It's a diesel so don't expect to beat anyone at the lights. Even them lowly Ferozas can probably beat you!

As if!

x2

The biggest problem i'm having is getting the power down to the bitumen (when in the city).

Now i'm not a hoon (normally anyway...) but the power the little rocky posseses is some times a bit unexpected and can come on board just at the wrong time. It certainly shouldn't be underestimated.

We've had a fair bit of wet weather over here recently and so far I've nearly lost it going around a round about, spent a few seconds sideways on a curving freeway entry ramp and broken traction from the lights countless times.

I actually had to jack up the back wheels to make sure I didn't have a broken axle... I was that concerned.

I think sticky-er rubber will go a long way... however an LSD would be nice.

I would hate to see an open diff, as mine comes unstuck even with the LSD and 31" MTRs!

The LSD however, when it spins, spins them both and gets all out of shape