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Mike S.
Mike S., Mechanic
Category: Car
Satisfied Customers: 7499
Experience:  25+ years experience as an auto mechanic.
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I got a knock in the engine how can i diagnose this?

This answer was rated:

Hey mike i got a knock in the engine how can i diagnose this?

Using a mechanics stethoscope listen by touching the end to several different places on the engine such as the valve cover and the oil pan to first of all determine if the nosie is coming from the top or bottom.

Then canceling out each cylinder to determine which cylinder it is, by listening for the noise to change when that cylinder is killed. If it is determined to maybe be a rod knock try some STP or a pint of straight 50 weight motor oil and see if the noise gets any quiet. If so, it could quite possibly be a rod knock and a worn out connecting rod bearing because the thick oil will temporraily help fill in and cushion the extra space made by the worn bearing and help prevent the slamming of the rod against the crank for now.

Customer: replied 1 year ago.
I had no idea they would give me another Mike. I have a 1999 Mitsubishi Diamante I had another Mechanic Mike help me get it started yesterday lol. I also have they sound like bearings from a pulley and the knocking noise only starts when the car is warm I don't have a stethoscope can I use a tube

Most of the time when an expert is requested they are offline anyway and that opens the question up to all experts. It's just a coincidence that my name is mike also. It didn't request me by name, I pulled this from the full question list.

A pulley? Then remove the belt and see if the noise goes away.

Customer: replied 1 year ago.
Now i believe its coming from the timing belt cover.what can cause that

Are all of the accessory belts off? Which side of the timing belt cover, isn't there 2 sides?

This is the 3.5l, correct?

Isn't that a dual overhead cam?

Customer: replied 1 year ago.
Customer: replied 1 year ago.
3.5 yes

Are all of the accessory belts off?

If so then I would suggest removing the timing chain cover and look for signs of something hitting it on the inside.

Customer: replied 1 year ago.
Ok and what kind of oil should I get again and should I replace the filter and how much oil

Kind of oil? Are you asking a question you already sked the other Mike?

Customer: replied 1 year ago.
No you mentioned putting some 50oil how much or stp and to see if they would stop the noise. Also can you pull up a fuse box diagram for the interior and exterior for me please

That was when I thought it might be a rod bearing knock, because STP and 50 weight oil is really thick. If it the timing belt cover and maybe a cam sprocket or gear then never mind about that thick oil.


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