Engine noise KV6 2,5 R75

[Azur]

Hello,

one of my 2.5 V6 engines recently started making two different side noises:
1: ticking noise from intake manifold. Check showed that the power VIS motor was faulty, since replaced. Also, the oil level was not too low but on the low side. By adding extra oil up to the maximum level, the noise decreased considerably. Check of the internal manifold arm driven by the power vis motor is good, no play present, just in and out. Possibly switch to 5W40 oil?

2: Buzzing/abrasive noise, stronger while driving and loading the engine (accelerating).
What is most likely to cause the noise? Bearing of the alternator drive roller?

I have made a movie with a stethoscope:

https://youtube.com/shorts/-7iOXThKBR8?feature=share

From the post-purchase lore, the timing belts, water pump, tensioners were replaced in 2018 (at 36K miles).
Current odometer reading 50K miles.

It is not super present, but I like to drive as quietly as possible.
Where is the noise coming from and what to do about it?

Thanks in advance.

Emiel

[SD1too]

Originally Posted by Azur

1: ticking noise from intake manifold ... By adding extra oil up to the maximum level, the noise decreased considerably .... Possibly switch to 5W40 oil?

Hello Emiel,

Did you follow the official procedure for checking the dipstick level on your KV6? Here is MG Rover's guidance:

"A significant amount of engine oil is retained in the upper levels of the engine. Should a level check be carried out on an engine that has recently been switched off, a low oil level reading may result. This may mislead dealers and customers into concluding that the engine has consumed a quantity of oil.

A revised oil level checking procedure has been developed and will be introduced into future editions of the owners handbook. The procedure is as follows:
1. Ensure that the engine is at full working temperature. Turn off the engine.
2. Remove the dipstick and allow the oil to drain down for 5 minutes.
3. Clean the dipstick and insert it gently into the tube until the 'O' ring on the handle moulding is about to enter the tube.
4. Slowly push dipstick fully home.
5. Wait for 5 seconds, withdraw the dipstick and take the level reading.

Should a second reading be required it will be necessary to repeat operations 2 to 5 to allow the dipstick tube to drain down. Similarly, should it be necessary to add oil to the engine, operations 2 to 5 must be repeated.


Having said that, the ticking noise you've reported from the inlet manifold area is almost certainly contamination of the hydraulic tappets. This can be addressed by a session with flushing oil (temporarily replacing the engine oil at a fast idle only). In the UK we have Comma Flush Out which is very effective.

It should not be necessary to use 5W40 oil whose viscosity won't be any different at normal operating temperature anyway.

Originally Posted by Azur

2: Buzzing/abrasive noise, stronger while driving and loading the engine (accelerating).
I have made a movie with a stethoscope:
Where is the noise coming from and what to do about it?

I'm afraid that I cannot detect a buzzing/abrasive noise from your video. Subject to the limitations of laptop sound reproduction, your engine sounds fine to me.

Simon

[Azur]

Hello Simon,


many thanks for your response, I have checked the oil-level on a cold motor. Thanks for sharing the formal procedure though. I will for sure follow your advice to flush the oil in the motor. I have just bought 15 liters of 10W40 and I will have a look at the comma flush out your have mentioned. I have changed the oil 8,5 K miles ago (9 months) and I used castrol GTX ultra clean and I tend to use this oil after the flush.

The buzzing/abrasive noice is indeed not loud luckely. Maybe when the temperature goes down a bit I can make a movie if the sound is stronger (maybe the 28 degrees at the moment is of influence, don't know).

Anyway, thanks Simon and for starter I will go with the oil flush.


Cheers from Holland,
Emiel

[SD1too]

Do come back to us Emiel after you've used the flushing oil, refilled with 10W40 and checked the level at normal engine temperature according to MG Rover's procedure. I'm hoping that you'll hear an improvement!

Simon