Thread: The ultimate solution to Td5 vibration / knocking

So, tightening the handbrake cable fixed the vibration?.....or just one of your noises?

It fixed one of the noises, but a nasty one. Vibration is caused by the engine, and since many many Discovery 2 TD5 owners all have them around 2200-2400 rpm it must be the 5 cyl. harmonic. To soften the R-R-R-R-R-R-R-R-R-R-R drone replacing the engine mounts might help. In my case, owning the disco since 2004 with 50K on the clock then, it was always there but is worsening over time. Would be great if someone knew that by say, replacing the crankshaft bearings, it would fix it. But the hundreds of threads that I have been reading on the subject were never conclusive.

Originally Posted by dutchviking

<snip>. I am convinced the source of the vibration is related to the Td5, and all of them are causing the most vibrations in the 2200-2500 range as that probably relates to the harmonic caused by a 5 cylinder engine.
<snip>.

I am really surprised that it took several pages for the real answer to come out.

In a four stroke engine a 5 cylinder is always going to be difficult to balance and therefore have a natural harmonic tendency to knock. It is why 4 stroke engines are usually in multiples of 2 cylinders with the boxer type engine being the easiest to balance.

5 cylinders was always going to be a compromise and it is why it was dropped.

Thanks for the confirmation. But why is the engine becoming rougher and the knocking more pronounced over the years, aka what engine components suffer from this constant imbalance and by replacement might reduce the knocking?

The more heavy weights spin around at 3K+ RPM the more wear there is to bearings and the noisier the engine will become. Grind worn journals and replace worn bearings and your vibrations should be pretty well back to when it were new.

mines actually quite smooth and quiet from about 2500 rpm up to redline. got a rough spot between 2100-2500 thats quite pronounced.

Originally Posted by Lotz-A-Landies

and it is why it was dropped.

thats a big call,,,

Before we sign this off as a 5 cylinder harmonic, can we explore a previous comment. Mine is a TD5 AUTO...a couple of posts back, someone with a manual indicated they did not have the 2300 harmonic. I know that is a sample of "1", but do manual owners have this harmonic, or not?

And for the record, mine is perfect up to 2200, and from 2350 on.