Engine knock?

[Tim]

Hi

I have recently bought a Mitsubishi Galant VR4 1999, automatic twin turbo. I cannot remember if I hear this knock when I was inspecting it before purchased it (about 2 weeks ago). I know the lash adjusters are noisy, but I cannot remember engine knock. It could be valve sound muffled the knocking sound. The knocking is not overly loud but if you pay attention you will hear it, even with hood closed, door closed, inside cabin. It is more apparent with the hood open. The noise does seem to subside randomly, and only to come back 10 seconds later. It could be my brain adjusting to the sound idk.

I was told by the previous owner to put in 98 RON fuel (premium here in NZ) to which I forgot and put in 91 RON (regular). I do not know if this caused the knock or what might have. It have driven the car for about half a tank on 91, and refilled yesterday with 98.

Below are some video clips of the engine noise. Please if you know what is making this noise let me know. 🙁

Start up: https://youtu.be/Es-zJJSlFF4 (loud knock at start up)
Idle: https://youtu.be/Es-zJJSlFF4
Idle 2: https://youtu.be/1t1jHRonVd8 (knocking at about 1:07)
Light revving: https://youtu.be/becTXaxmALc

Cheers.

Topic

[zero]

I would say most of that noise is valve train related. Most of what I found seems to indicate that it has valve lash adjusters, like a Honda. I personally couldn’t easily identify a repair procedure online.

[Tim]

Yes indeed most of the sound are the lash adjusters, however if you listen closely to the 3rd clip at about 1:07 you can hear a definite knock when I move the camera around. That is my main concern as I do not want to replace the valves knowing the engine is on its way out.

[Andrew Phillips]

If you do not know the prior maintenance history of the vehicle, I would say it is quite likely that oil changes were neglected and there could be some sludge blocking oiling passages up to the top. I agree with DaFirnz that the noises all sound valvetrain related. I couldn’t hear any bottom end noises, even at the video marker you indicated. Bottom end noises typically do not come and go.

[Mike]

Not familiar with your engine, but does it have hydraulic lash adjusters (not lifters) acting on rocker arms? On startup, the knocking is horrendous, making me think that an adjuster has failed or isn’t receiving adequate oil pressure from the get-go, with things quieting down after a few minutes of running.

Before diving in and tearing things apart, it might be worth running an oil flush compound through the engine, followed by an oil and filter change. Might be nothing more than some grunge restricting oil flow to the top end.

[Tim]

[quote=”cap269″ post=186757]If you do not know the prior maintenance history of the vehicle, I would say it is quite likely that oil changes were neglected and there could be some sludge blocking oiling passages up to the top. I agree with DaFirnz that the noises all sound valvetrain related. I couldn’t hear any bottom end noises, even at the video marker you indicated. Bottom end noises typically do not come and go.[/quote]

That is a relief, I would have thought that it is just valve noises, just that the knocking sounded horrible. I will check at the weekend to see if I can hear any bottom end noise from below, as I never thought of that. However if it is piston slap, wouldnt the noise come from up top?

[Tim]

[quote=”Evil-i” post=186785]Not familiar with your engine, but does it have hydraulic lash adjusters (not lifters) acting on rocker arms? On startup, the knocking is horrendous, making me think that an adjuster has failed or isn’t receiving adequate oil pressure from the get-go, with things quieting down after a few minutes of running.

Before diving in and tearing things apart, it might be worth running an oil flush compound through the engine, followed by an oil and filter change. Might be nothing more than some grunge restricting oil flow to the top end.[/quote]

From what I read online it is hydraulic lash adjusters not lifters. So you think the hard knocking at the start is also because of the faulty valves? I dont know it seemed to subside into knocking, I might be wrong it is just so hard to listen to everything with all that noise.

I have actually bought an engine flush but I read somewhere on the internet that we shouldnt be using oil flush on a turbo engine? I have changed my oil and filter with Nulon 5w30 (made in Australia) with a litre of Rislone engine treatment. Car has 191000 km though.

[Author]

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