Thread: Refuse to go above 3000 rpm

I find the redline idea strange. I'm used to old MB's and the official word about redline from them back in the late 70's & early 80's (petrol and diesel) was

"Redline is do not exceed - not do not approach." If you wanted to stick at redline all day - the car wouldn't care (your pocket would with the fuel usage!)

But that was back in the day when they would prove the 6.9's before fitting them to cars by (v8 petrol's) at redline and at load for 24 hours solid.


Maybe modern engines produce more heat or modern cooling systems are lighter and less effective?

Hello,
I had a similar problem not going much above 3000 rpm and very slow to respond,.... well I fitted a new Fuel pump yesterday and now it is all okay check your fuel pressure.
Ian

Before my fuel pump failed it used to run continuously with the key on engine off. The new pump runs for a short time and then stops, is there a pressure switch? ( I will stop being lazy and get the Rave CD out tomorrow). If the pump pressure is low due to pump wear is the long running a symptom prior to failure. I need to get the inlet manifold/FPR replacement done before I can check the acceleration and hunting issue. The test will not be at max RPM
Regards Ollie

Opps Double post

Originally Posted by schuy1

4K RPM is not something a diesel likes to do all the time, modern or not! It just stresses the heck outa them for very little gain. Want to do those revs? Get a V8!
( I have a TD5 )

Just having a dig around to see what the actually point the rev limiter kicks in. These are the maximum engine speeds for the Td5 listed in RAVE:

Maximum governed speed 4850 rev/min
Maximum overrun speed 5460 rev/min

I believe peak power output is at 4200 rpm on a stock Td5. Not that you are going to use the rev limit that often - 4850 is around 63kmh in first, or 106kmh in second

cheers
Paul

I VERY rarely rev mine past 3000. No point. The most I've ever gone is around 3600. It gets a bit gruff at 3, smoothes out at 35!!. But as I said, no point. Even with the van on. Sorry im no help.
Regards
Robbo

In normal use I don't usually see much more than 3000rpm and have actually thought I needed to investigate why the engine wouldn't rev above 3-3200rpm.

After a little experiment I think the key is how far you depress the throttle - pretty obvious really The last 5-10% (roughly) of the throttle travel triggers kick down on the Auto and this is what makes all the difference to how easily the Td5 will rev out. If you apply enough throttle to put the auto into kickdown from a standing start the engine will hit 4200rpm with surprising ease.

One thing to watch out for is trying to kick down the Auto when the revs are already high. A couple of days ago I pulled out a side road onto a busy country road and had to gun it to get up to speed, and had revved out to 3300rpm in third when I hit kick down. The Auto instantly faulted with flashing M&S on the dash. These reset with ign on/ign off cycle, and when I checked later the fault logged was "P0721 downshift safety monitoring" which basically meant the auto had prevented the downshift to protect the engine.

cheers
Paul

As said earlier - check your fuel pump.
Engine can run with a non working fuel pump,
Marginal pump will allow you to drive normally, but won't rev over 3000.
Terry