knocking at idle

[fredws]

I have noticed lately that I get a knock at low idle, what it reminds me of is a diesel. I can't really tell where it is coming from. It only does this at an idle. Sounds great taking off, or cruising. Oil pressure is about 20 psi at idle. Could this be piston slap?

[gsmikie]

check the bolts that hold the flex plate to the tourque converter

[PhilSine]

Is it a loud knock or more like a rapid tap? Or is it a tick? A knock could be a timing issue, a tap could be a lifter issue, and a tick could be an exhaust leak issue.

If it knocks at idle but is great at take-off then your vacuum advance on your distributor could be stuck in the advanced position.

[fredws]

Thanks for the suggestions guys!
I will check them out this evening.

[JeepnFirefighter]

I had the same problem on mine. Mine was coming from underneath but sounded like from under the hood. I pulled my tranny back a little and i had a sizable crack in my pressure plate. You might want to check that too.

[M/Z]

I too had the knock at idle. It turned out to be that the mounting holes for the flex plate were elongated. A new flex plate and rebuilt torque converter were the cure.

[mtn goat]

I had a knock at idle...turned out to be a spinning bearing on #6 :(

[Aaron]

I second checking the flex plates bolts. Mine were loose, and it made a knocking noise.

[Cliff]

I have a noise, that I cannot locate. I have narrowed it down to one of the engine accessories though. When I first heard it, I was afraid it was a bearing knock. Drove it my mechanic who verifoed it was not a bearing noise. So I'm not too worried about it.

[fredws]

Well, I checked out the flex plate bolts, no problem there. While I had it up on the jack stands, I started it up and crawled all over underneath, put my ear to the pan, used a long screwdriver to listen to the side of the block, nothing.
I did notice that my power steering pump seems to be going out, has a pretty good vibration at about 1400 rpm, I am begining to think it may be causing the noise. Kinda hard to tell where it is coming from, but it sure sounds like a diesel! I am going to replace the ps pump in the next week or so, will let you know if that takes care of it.

[fredws]

Well, replaced the ps pump. Still has a bit of a diesel sound, but doesn't seem to be too bad. I am getting a noise at about 65 to 70 mph, sounds like a whining, like a farm tractor in high gear. Any ideas on that one?