Engine sounds loud have been told by dealer camshaft is worn

These nissan serenas with the diesel engine suffer from the camshaft timing gear locating pin wearing out ,,Do not try to start the engine but remove the timing belt then take the camshaft gear off and look on the inside where it should have a cast lug that locates the gearwheel ,fit a new gearwheel if its locating lug is worn away ,then before you fit the big bolt you drill a 4 mm hole through the gearwheel into the camshaft so the hole into the camshaft goes in anout 6/7 mm drilling in from the front of the gearwheel then make a steel pin or cut a maisonary nail down to fit then refit the bolt so the head of the flanged bolt holds the pin in this will stop it going in the futrue ,yes i know its not a recomended type of repair according to the dealer but iam a old fleet vehicle fitter and this is the sort of modification that a proper fleet mechanic would ensure was carried out .

P0340 FORD - Camshaft Position Sensor Circuit Bank 1 Sensor 1Possible causes- Faulty Camshaft Position Sensor
- Camshaft Position Sensor harness is open or shorted
- Camshaft Position Sensor circuit poor electrical connection
- Faulty starter motor
- Starting system circuit
- Dead (Weak) battery
P0340 FORD Description The Camshaft Position Sensor is an electronic device used in an engine to record the rate at which the camshaft is spinning. This information is used by the Engine Control Module(ECM) to control ignition and fuel injection. The camshaft position sensor senses the retraction of camshaft (intake) to identify a particular cylinder. The camshaft position sensor senses the piston position. The sensor system consists of a rotating part, typically a disc, as well as a static part, the actual sensor.

When the engine is running, the high and low parts of the teeth cause the gap with the sensor to change. The changing gap causes the magnetic field near the sensor to change. The change in the magnetic field cause the voltage from the sensor to change.

When the crankshaft position sensor (POS) system becomes inoperative, the camshaft position sensor provides various controls of engine parts instead, utilizing timing of cylinder identification signals.
P0430, main catalyst is worn out.

Sounds like it could either be a spun out main bearing or camshaft bearing or it could be knocking from low octane gas, depending on how loud it is. A main bearing or camshaft bearing that is spun will make an unmistakably loud cyclic noise. While, the low octane gas will cause a softer random rapid knocking sound that sounds like a babbling brook. Check for codes in the engine that might explain why there is an octane related knock, like a knock sensor not working or something like that. Good luck on finding a solution to your knocking problem.

You did not mention what engine you have, but on the vtech engines, the valve noise is usually a result of a worn camshaft and lifters. No adjustment will make it any better.

First, your engine has rocker arms, if you have a 4 cylinder you have 8 rocker arms, and if it is a 6 cylinder you have 12 rocker arms. Now if it is indeed a rocker arm making the noise, the cause is most likely a bad lifter or a worn cam shaft.

Uhh there are no rods in the head. That dealer has a loose rod in his head maybe.
The crank, rods and pistons are all in the bottom end of the engine.
What it likely is is either a broken piston skirt or a spun rod bearing.
Spun crank bearings are rare and sound deep.
A spun rod bearing can be fairly quiet on idle depending how bad it is worn out, but it will be really loud on acceleration. Piston slap from a broken skirt can be pretty loud too but it mostly sounds like diesel rattle only a bit less. Some have described it as a loud pinging sound like detonation.
Drain the oil and check for metal debri. If you can tilt the vehicle a bit for the oil to drain more towards the drain hole that could help. Then look for metal pieces and judge their size. There should be NO glitter whatsoever in engine oil, or any kind of debri. Now a rear end or transmission is different. Those always have a little metalic sheen to them.
Best of luck.

worn camshaft lobe and or rocker assmbly jumped off

Are you losing power as well? if so it sounds like the camshaft is worn, this can be confirmed with a compression test

on 92 models they have no ajustment,they have automatic hydraulic lash adjustment.only time youll have problems is if oil level is low or camshaft is worned out!

Sounds like a hydraulic camshaft lifter that drains down overnight and takes 30 sec to pump up with oil