At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.
With the engine warm, there is a light knocking noise coming from the engine area at idle. As rpm's increase the noise appears to go away. This noise is present at idle in drive, park and neutral.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
It could be if the noise comes back at idle . If not then the problem is else where. It may be a faulty hydraulic valve lifter that is draining down and taking longer to fill with oil at idle. If you have automatic cam adjuster it may be in there (V V I or VETEC type of engine.)
it could be a wrist pin, and im not sure if those amc's had hydraulic lifters but sometimes with old lifters when the oil pressure is lower at an idle the lifters arnt filling up all the way so they develope a little valve lash, and when the rpms are raised the oil pressure raises and fills the lifters. you could try chasing the noise down with an automotive stethoscope.
After it's warmed up to operating temp, if it makes the noise at idle but goes away reving the engine, I would guess that a lifter has gone bad. Rod bearings as a rule knock all the time. It's hard to diagnose these things over the internet, because there are so many variables when it comes to noises.
You need to warm the car up and then while it is running, open the hood and try to pinpoint the source. lifter noise will sound like a "tick" and come from somewhere near the top. Rod bearings will sound like a 'knock" and will come from the bottom of the engine.
Could be a starter sticking but that would cause more of a grinding noise, my best guess is that your flex-plate(flywheel) is broken if the noise is coming from between the engine and transmission. Remove the access cover for the bell housing and take a look at the flex-plate.
Does the oil light come on or the knock occur during the engine warm up after a cold start?
There could be a couple of problems causing the issue. You could have an oil pressure pump or pump pressure regulator sticking. I would have a mechanical oil pressure gauge installed and verify oil pressure at idle and 2500 rpms to make sure oil pressure is in normal ranges.
You could also have excessive piston rod bearing, crankshaft bearing or cam shaft bearing wear that will cause oil pressure to drop too low to prevent the rod knock your hearing at 2500 rpm.
You said a knock and not a ticking noise,so I don't believe a lifter is the issue at 2500 rpm.
Start with the oil pressure check and go from there.
Let me know.
Regards,
×