New purchase, '01 2500 Magnum 5.9, about 250,000 KM. Has an engine noise, a "clack", more like a knock than a lifter tick. Previous owner had the truck for about 1 month, previous owner to him about the same. Both said the truck came with the noise and didn't get worse.
Doesn't use oil. Oil pressure is good according to the stock gauge.
Starts and runs fine. Idle is good with no noticeable miss, but doesn't have as much power as I would have thought it should have.
The noise appears after about the first 5 seconds or so after start up and gets worse as the engine warms up. It is particularly noticeable at idle.
A mechanic's stethoscope shows it loudest any place on the oil pan.
Second loudest would be either rocker cover.
It is almost impossible to determine if it is louder near the front or the back.
Not particularly noisy on the timing chain cover. Without the stethoscope it seems to be a bit louder toward the front of the engine.
Pulling one plug wire at a time does not change the noise, so I don't thing it is a rod bearing, wrist pin or collapsed piston.
The noise seems to be less at revs above idle, but hard to tell for sure.
An interesting observation is that if I crack the throttle, the noise disappears for an instant but goes "clackety clack" a few times just as the engine returns to idle.
I'm suspecting the timing chain, but would like to get some opinions before I commit to pulling everything off to get at the thing.
Oops, forgot to mention. The Check Engine light is on. The previous owner told me the codes are:
P0138 - O2 Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0442 - Evaporative System Malfunction, Small Leak
P0445 - Chrysler: EVAP Large Leak Detected Conditions
I don't know what the symptoms of these codes would be or what the results would be, but I doubt they have anything to do with the noise.

Thanks.

 

At that mileage, it's about time to replace the timing chain anyway. They do tend to stretch some... May want to check the plenum as well, and see if you have oil pooling inside the intake. (usually, toward the back.... pull the throttle body to look. Have a read of the stickied plenum thread for more info on this issue.) See what the chain looks like... and see if there is any evidence of it hitting anything.

O2 code is for the sensor AFTER the cat. Probably wouldn't hurt to change 'em both though. NTK, or Denso sensors only please. Our truck don't like Bosch.....

Small leak may be as simple as the gas cap. Large leak is likely a rotted out line somewhere.... You can download a service manual for your truck from here, I do believe there is a diagram of the vacuum lines for the evap system. Check 'em all.

Welcome to DF!

 

I don't doubt the chain is very likely due for replacement. I'm just trying to gather as many opinions as I can as to how this would relate to the noise.
According to the previous owner, there is no excessive oil consumption, which leads me to believe the plenum is still sound (not to say it couldn't fail at any time).
Hmm. If the sensor fail is after the cat, does that affect mixture and therefore mileage and possibly power?
I'm not too concerned if it just affects emissions as this engine will not be used for long before I do the swap to the V10 with custom EFI. We don't have emissions testing in our little corner of the world.
I have the service manual now.
Thanks so much for your input.

 

It's open to debate just how much influence the post-cat sensor has on fuel economy/engine power..... Ranges anywhere from none, to minor...... (its main job is to monitor cat efficiency.) There may be something on that in the service manual.

The cat clogging up due to even minor oil consumption would most certainly compromise power though. Could try removing the FRONT O2 sensor, and going for a drive, and see if things improve any.

 

Well, the symptoms seemed to point to a very worn timing chain, and the weather was decent, for a change, so I decided to just get at it and have a look at the chain. Fortunately for me there is very little rust on the truck and I was able to get the timing cover and all the stuff to get at it off with no bad scenes.
When I had a look at the chain it was obviously worn, but there is no evidence of the chain hitting the timing cover.
With one side tight, the other side has about ¾” of deflection at the centre of the span. “This has to be my problem” Sez I to me.
Well, not so fast. I did a chain stretch measurement as outlined in the service manual. The manual allows up to 1/8” stretch before replacement. I measure about 1/16”, possibly as much as 3/32”, but certainly not 1/8”.
I wonder what the deflection would be with 1/8” stretch?
This troubles me, but I’ve ordered a gasket set and timing chain and sprocket set. I expect it will take about a week before I get them, and then I’ll have to wait for weather to install.
Has anybody else experienced this?
I’ll report back when things are up and running again.

 

That noise might be due to a cracked flex plate or loose flex plate bolt(s).

 

Well, it looks like I called that one wrong.
I installed a new timing set and appropriate gaskets. Drained the oil, re-filled with 10W30 and changed the filter. Checked oil and filter element for traces of metal. None found.
Fired the engine up and the knock is still there, but not quite as loud. There is no noise at all for the first second or two after start up. Then the knock can be heard. It gets worse as the engine warms up, but still not as bad as it was before the timing set and oil change. It is worst at idle and almost disappears above ~1500 RPM or so.
Perhaps this is because of the new oil?
I warmed the engine up to operating temperature and tried to determine the location of the knock. It might be a bit louder on the right side, but it’s very hard to tell. I decided to do a compression test with the logic that if I had an intake valve with excessive clearance it might show up as lower compression. I don’t think an exhaust valve with excessive clearance would affect compression.
I tried to get the connection for the starter solenoid off the starter to connect a remote starter button, but no success. I referred to the shop manual and it just said to disconnect the coil to do a compression test. I couldn’t get the primary connection off so I just shorted the secondary to ground.
I thought that just disconnecting the coil was rather strange as the fuel injectors would still be firing and possibly washing down the cylinders a bit and affecting the readings, but I went ahead with the test anyway. These are the results in order of how they were taken:

1 = 170 PSI
3 = 137 PSI
5 = 137 PSI
7 = 125 PSI
2 = 170 PSI
4 = 170 PSI
6 = 162 PSI
8 = 100 PSI

As you can see, this is not very good, but the engine starts well and runs quite smoothly.
Now, I found an interesting thing with the plugs. They were well worn and looked like they had a lot of time on them, but all were quite uniform in a light grey colour, except for # 8. The tip was OK, but the insulator and body were quite black and crusty, as in oil fouling, yet the engine does not miss and the previous owner said it doesn’t burn oil.
I don’t know if this might be pointing to my noisy cylinder or not.
The next step is to pull the rocker covers and rotate each cylinder through it’s cycle to see if I have any valves with excessive clearance, but that will have to wait until the weather smartens up again.

 

Run a wet test as well. See if the low numbers change at all.

You can pull the fuel pump relay to prevent cylinder washdown.

 

Wet test is a good suggestion, as is pulling the pump relay, but I suspect there is still a lot of residual pressure in the rails so fuel will still be injected until that pressure is used up. Wish I could get that starter solenoid connector off but it is extremely awkward to get at and I'm not sure how the locking tab is supposed to work. Same with the coil primary connector.

 

You can plug a remote start into the starter relay socket....... wiring diagrams are in the factory service manual.