Frustrating car problem

Factual Questions
1

I’ve asked a lot of people and they’re all baffled. I know there are some mechanics on here so I turn to you for suggestions.

The car is a 2000 Galant with the 3.0 SOHC V-6 engine. A few weeks ago, it developed a loud rattle in the engine, somewhat like a pulley bearing going out. It doesn’t always do it though; when driving, it stops when it gets over about 2,000 RPM. I could drive around Dallas with the overdrive off and it would only do it at stoplights. It also doesn’t always do it at idle; sometimes it has to run for a minute or two before it starts.

I’ve pulled both of the belts and that doesn’t stop the noise. Using a stethoscope, it seems loudest at and around the tensioner pulley for the power steering pump which mounts just below the left head. I’ve verified the timing belt is good (replaced it over a year ago) and the timing is set. I’ve pulled off the valve cover and made sure everything is tight and the valves seem to be doing what they’re supposed to when the engine is slowly rotated. It’s definitely getting oil pressure. I’m probably forgetting some other things I checked.

So I and everyone I’ve asked are out of ideas. I need something to check tomorrow. It sucks buying groceries on a sportbike in January.

2

A bearing going out wont generally sound like a rattle. Have you checked the exhaust system? Namely catalytic converters and heat shields.

3

Have you checked your engine mounts?

4

It’s not the exhaust. There isn’t much noise coming from it and the sound is too rythmic. It’s not a motor mount either.

5

Ok. You checked your belts, what about the tensioner?
http://www.aa1car.com/library/belt_tensioners.htm

6

The tensioners were my first suspicion but the noise is still there with both belts off (timing belt on of course). It doesn’t sound like it’s coming from the timing belt tensioner which is closer to the right head.

7

Oops. That link is for automatic tensioners anyway. Your car doesn’t have an auto, does it?

Well, anyway that’s exhausted my list of engine bay rattle causing problems I’ve had to fix on my cars. I’m sure more posters will be along with suggestions shortly.

Good luck.

8

Since you said you heard it near the head, could it be lifter (or the DOHC equivalent) noise or tick?

I found this link searching for Mitsubishi lifter noise.

9

There’s also this from Mitsubishi themselves.

10

I am listening, but cannot hear his engine revving :dubious:
Good post pinmin, I hope this is his issue.

11

I wasn’t aware that my car had such a thing but I see vendors on eBay are selling them for my exact model. It’s really louder than any lifter tick I’ve ever heard, but this is definitely worth a shot. I’ll try the fix with diesel.