Grinding noise on newly purchased car

Maintenance/Repairs
,
1

Hi everyone,

Bought this 2015 manual transmission Jeep Patriot from an out of state dealer. The car had one owner and is in really good condition.

However, it’s making this intermittent noise that has spoiled the fun already. It seems like the noise is more pronounced when the car sits overnight and is cold in the morning. I can sometimes duplicate if a rev and when the RPM comes down I can hear (in neutral). When it does make the sound, if I push the clutch in and repeat the process there is no noise. I took it to a local dealer and they told me they couldn’t duplicate it. My dilemma right now is should I take it to another dealer for a second opinion? If it turns out to be clutch/transmission related how would they actually diagnose the issue? Would appreciate some advice on how to proceed.

Here is the video of the sound:

2

You can make noise. And show mechanic?

3

Do you hear this sound when driving the car down the road, or when idling & rev’ing engine in the driveway?

I’m not able to listen to your u-tube sound file, but if I had that sort of problem I’d be looking at these first, given the clutch-related clue

  • Compare sound when coasting in gear vs neutral with clutch pedal out, and in both cases w/ clutch pedal depressed.

  • When you press on clutch pedal that puts an axial force on the crankshaft. The crankshaft should’t move much b/c of the crankshaft’s thrust bearings. But maybe there’s something amiss there. Ask shop to check the crankshaft axial play. They might be able to do that fairly easily at the crankshaft pulley.

1 Like
4

The vehicle is not “in really good condition”. In fact, i think you just found out why it was for sale.

2 Likes
5

Your right. I meant cosmetically but thanks for your super useful insight.

6

I know you mentioned when you cycle the clutch pedal the noise tends to go away. However, when it is making the noise, what happens if you push and hold the clutch pedal down? No change? The noise immediately goes away? The noise slowly diminishes and then goes away?

What about just partially pressing the pedal and releasing?

Trying to see if it is transmission, clutch/bearing or engine side noise…

1 Like
7

I know people already mentioned testing clutch in or out. Possible thrust bearings when pushed in. Possible transmission (idle bearings) when let out.

  1. I did not hear any uniformity in the noise repeating - likely not the engine itself.
  2. Does the noise fluctuate with speed or stay constant - another engine indication.
  3. Maybe get an auto mechanics stethoscope to better isolate where the noise is coming from.

Check drain plugs in engine and transmission for metal fragments. - Be sure to have replacement engine oil and gear oil. If you see metal fragments, not a good sign. Gear oil is tricky to replace, usually needing a pump of some type.

1 Like
8

Other possibilities:
Water pump.
Alternator.
Power steering pump.

Hopefully it is one of these and not the transmission.

1 Like
9

(post deleted by author)

10

I haven’t tried partial clutch application. Will have to try this when I get home. However, with full clutch application there is no noise which leads me to believe it’s something related to it and not the engine.

I don’t think it’s drive belt related since it’s coming from the backside of the engine compartment.

11

hank you for the suggestions. I’m going to change the transmission oil and see if that does anything. With 35k miles I was initially thinking it wouldn’t be necessary but at this point it won’t hurt either.

Just to confirm, you did hear the noise I’m describing in the video?

12

Yes. I heard the sound from your video and the noise it was making.
Safari browser on a Mac.

1 Like