2.5L Knock/Banging noise at idle. Help needed Please!

[victorgallas]

Hi everyone,

 

Been a while since Ive been here, mainly its been due to spending time working on the body of the comanche to get it painted, as I am doing a full restoration on this. We got the truck back and now I am finishing up the assembly and fixing some of the issues here and there.

 

Since we got this truck is would do a little knock/noise at idle. Initially I thought it was bad lifters, so I put a whole new set of lifter and rods, and cleaned up everything. It would still do the noise once a while but figured it would go away after a while.

Then after driving back and forth around town a bit I noticed the same noise is there at idle all the time. 

The noise comes from the lower parts of the engine a the front. I was wondering if it was the camshaft rubbing against the timing cover, but I checked it and its clean. i also upgraded the retaining bolt with the hollow bolt and spring and pin to keep the cam pushed back. Noise is still there. The noise is this pinging noise. It seems to only occur at idle, as soon as you rev it goes away. 

Oil pressure is right at 45 and steady at idle. Doesnt matter if the engine is cold or hot, it still does it.

Now, i will admit that the gas in the truck is probably about a year old, since its been there since I started working on it. I know old gas can cause problems too, so I am dumping the old gas out this weekend and putting fresh one, i will report back on what the gas does. But figured to post here in the meantime to see if anyone recognized this noise and has any advice.

 

Any ideas?

 

I read on other places people talking about carbon build up on the pistons could cause this, Chrysler had a technical notice about it. Then others cay its piston slap. 

 

Here is a link of the video, turn up the volume.

 

https://dl.dropboxusercontent.com/u/104532481/VID_20160807_151718335.mp4

 

If anyone can give me any suggestions, that would be awesome. 

 

thanks!

 

 

[airspeed]

I had a similar problem on my 2.5l, I chased that around in circles for 2 weeks.I'm not sure how it made the knocking sound but it was quite pronounced and consistent.  I was looking and listening at the engine and saw a slight wobble in the harmonic balancer, the big bolt was tight but the balancer could move in and out.  Root cause, here was no oil slinger behind the balancer on the crankshaft nose, there was enough room for the big bolt to bottom out in the crank and not secure the harmonic balancer.  I think you have to pull the front seal and maybe the timing cover to get the oil slinger in there.  I found a large precision washer (shim) .020” and cinched it down between the bolt head and the harmonic balancer.

[victorgallas]

yeah I replaced the damper I did make sure the oil slinger is there on the right orientation, I did check that before. plus when I pulled the timing cover out, there was no signs of scrapping or rubbing anywhere on the inside of the cover. One thing I did notice was that the noise you can hear on the video link I posted was after putting a thicker 10w40 oil. Before I was running 5-30 and the noise was not so pronounced, it was there but not so loud. So it made me think, maybe a bad oil pump? I do have another one that I will try too. Also just out fresh gas, gonna run it in the am and see what I get. Chasing this has been a pita

[victorgallas]

Turn out the knock is due to failed bearings. Gonna order me some. And replace from underneath... Damng it