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Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6899
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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My 2002 montaro 3.8 v6 suddenly started a loud raping noise.

Customer Question

My 2002 montaro 3.8 v6 suddenly started a loud raping noise. the noise seems to be comming from the front of the engine. The engine idles smoothly has lots of power.
The noise is very loud and sounds like metal hitting metal
Submitted: 11 months ago.
Category: Mitsubishi
Expert:  Doug replied 11 months ago.

Hi,

Is the sound dependent on engine RPM (Rev the engine, frequency increases)?

Do you have a stethoscope you can use to listen to the pulleys on the engine as well as valve covers etc to try to narrow down the origin?

Customer: replied 11 months ago.
noise tops out a 2k rpm no noise above 2k, when the rpm drops down past 2k the noise sounds like a bearing ringing
Customer: replied 11 months ago.
right now i dont have a stethoscope but have held long screwdriver but unable to determine exact location
Customer: replied 11 months ago.
noise seems louder on right bank
Customer: replied 11 months ago.
noise really loud from undernearth engine
Expert:  Doug replied 11 months ago.

Thanks, ***** ***** increased RPM you are noticing the sound get fainter, not just drowned out by other noises right?
When was the last time the oil was changed and how frequently is it usually changed?

Customer: replied 11 months ago.
waiting for your call
Customer: replied 11 months ago.
when you ask an aircraft mechanic with 50 years experance about oil its ok.
Expert:  Doug replied 11 months ago.

My concern with the oil is that this vehicle... Mitsubishis of this era in general... are extremely sensitive to oil condition. To the point, the lash adjusters develop noise as early as 3500 miles in most cases, sometimes sooner if the vehicle is regularly stretched to long intervals.

Customer: replied 11 months ago.
when you get the chance to call me i would like for you to hear the noise.. Ive overhauled at least 30 engines but never heard a noise like this one. Engine runs to good to be a valve train problem, The starter is up tight, so I'm thinking it may be in the timing belt area, If you have an idea what may have come loose and is banging against the crank gear let me know.
Expert:  Doug replied 11 months ago.

Unfortunately I will not be taking phone calls this evening. If you would like I can opt out in case someone else is able to take a call tonight for you.

With regard to running behavior... the lash adjusters will not affect the running condition when they are noisy, supposing that were it.

With regard to timing belt area... if the hydraulic tensioner fails they get real tappy, however they will not usually get quieter over a certain RPM like lash adjusters do.

Customer: replied 11 months ago.
Oil was changed on a regular basis around 3500 miles. I use synthetic oil. the engine has 220k miles on it never even
hinted a problem. This problem was sudden, drove up to a parking spot no noise, 1hr later started the engine and the noise was there.
Customer: replied 11 months ago.
Can you get in touch with me tomorrow, that would be fine with me.
Customer: replied 11 months ago.
noise is too rapid to be a valve problem.
Expert:  Doug replied 11 months ago.

If you would like respond back here tomorrow morning/afternoon and I should be able to make a clearing for a call. In the mean time if you are able to take a video of it that would actually be even better; audio over the phone is incredibly difficult to interpret compared to recorded video due to the quality of audio for phone communication.

Customer: replied 11 months ago.
Doug, I'm sorry but none of your answers were the right ones. You went ahead and charged me. I fixed the problem myself and the engine hums like new.
Expert:  Doug replied 11 months ago.

Hi,
I didn't provide any answers at all, as I never heard back from you so I never had an opportunity to even hear the noise!

I'm glad you were able to get it squared away, may I ask what the problem was?

With regard to charges... I charged nothing of you at all (in fact it is impossible for me to get paid without providing an answer). You paid a deposit on the site, a deposit which is still there and was never used. You can have the deposit refunded by contacting customer service, or you can leave it on the site if you wish to use it in the future.

Customer: replied 11 months ago.
Doug I had no intention of agrevating you, I had posted what the problem was, and I had requested a phone call, All I had to do was retorque the crank pulley. I am very sorry if I offended you. You mentioned the timing belt tensioner and the tappet tensioners. Turns out that neither of thes ideas were correct. I was charged for these comments. Again I'm sorry.
Expert:  Doug replied 11 months ago.

Oh no aggravation, I'm sorry if that came across wrong!

Thanks for letting me know what it was; great thing you caught it.

Again your deposit is unused on the site still, you can leave it there for the future or have it refunded. If you would like I can send the refund request for you.