Diesel knock when reving after start up

DaveM-sport said:

I was thinking it could well be lifters to be honest considering the knock is most evident when giving the engine a hard rev towards the redline from idle.

With the big change in rpm then, the lifters can't keep up if not operating perfect.
If build up the revs slower, it'll rev all the way to 4900 and can be held there with no noticeable issues.

Its quite a bad diesel knock and once back do idle just after the split second of high rpm when it knocks, it runs lumpy and mild miss for a moment or two.

With the head being off and the engine rebuilt last year, the lifters might be acting up with being in and out of the engine.

For changing them, can I just lift the upper cam box off and then replace the head bolts without taking the head itself off?

Don't really want to go taking the whole head off yet again

Click to expand...

or an oil supply to the lifters ...like I say mate mine failed in a different way but then all of a sudden come to life

seirraferry posted a good illustration of the oil flow
its on the first page aproxx 10 posts down

https://www.landyzone.co.uk/land-rover/the-td5-go-into-de-compresion-mode.309823/

DaveM-sport said:

I was thinking it could well be lifters to be honest considering the knock is most evident when giving the engine a hard rev towards the redline from idle.

With the big change in rpm then, the lifters can't keep up if not operating perfect.
If build up the revs slower, it'll rev all the way to 4900 and can be held there with no noticeable issues.

Its quite a bad diesel knock and once back do idle just after the split second of high rpm when it knocks, it runs lumpy and mild miss for a moment or two.

With the head being off and the engine rebuilt last year, the lifters might be acting up with being in and out of the engine.

For changing them, can I just lift the upper cam box off and then replace the head bolts without taking the head itself off?

Don't really want to go taking the whole head off yet again

Click to expand...

Are you saying you rev your TD5 diesel to 4900RPM's

Thor1950 said:

Are you saying you rev your TD5 diesel to 4900RPM's

Click to expand...

Governed speed of a TD5 is 4850 RPM overrun speed 5460 RPM.

wammers said:

Governed speed of a TD5 is 4850 RPM overrun speed 5460 RPM.

Click to expand...

That is screaming

Thor1950 said:

That is screaming

Click to expand...

Yep not bad for a doozel.

So was chatting to Gary at Alive about it to see if he came across it before.
Said he could alter the map a little if I wanted as it could be a little hot in places but first check the turbo in case the actuator isn't opening properly by wedging it open a little and see how it revs then.


Wedged it open 3 or 4mm to see and then gave it a rev as before.
Knocking disappeared!
Still abit smokey but don't mind that as long as the knock that would make your stomach turn isn't there.

Adjusted the actuator stop then until it cleared the knocking again. Haven't taken it for a proper drive yet as had a loaded trailer on it yesterday but will know later today when have the trailer off again.

Bit of a relief if it means not ripping apart the engine again lol

sounds to me the injectors are being told to dump in more fuel at idle or low RPM
this means you maybe see some slight boost pressures at idle speed as its dumping in fuel but on take off there is to much fuel for the engine to handle (diesel knock )

now that you have opened the waste gate the map sensor values have changed you have bypassed some of the exhaust resulting in lower map readings for the desired engine load


turbos work off kinetic energy ie heat in the exhaust expands pushing the turbine ,,to generate boost you need fuel and oxygen to burn this bunt fuel generates heat
for example I have a boost gauge installed on my stock ecu TD5 if I hard thrash the engine sand hill then let the engine idle my boost pressure gauge manifold pressure reads 1 psi at idle until it idles down back to temp my boost gauge reads zero

may be a software issue in the ecu or it needs to be refined tuned

this is why I don't remap to many conflictions I squirt in LPG much easier more power and less of a ballache and the system can be removed and installed in any other diesel engine

but normally the smoke coming out the chimney an indication ..black smoke unburnt fuel white smoke raw fuel and not atomised

ps black smoke doesn't allways result in more power