This morning on the way to work I heard a new noise coming from the engine. It sounds like a light tapping noise, and I hear it the most when I am cruising at speed with O/D off at 1800~ RPM. I don't know what it could be. Loose valve, a bearing, a dropped oil jet. There is no loss of power that I could notice, no unusual amount of smoke, and , no loss of oil pressure, temp was good, and fuel pressure was OK. Any ideas?

 

Where's the sound coming from (front, middle, rear of truck)? Does it sound like its under the hood, or maybe underneath the truck? Have you gotten under the truck to look for anything lose, or something that may be dangling, such as a wire harness or something of that matter? Does it sound like metal on metal? Try and be little bit more specific and we'll take it from there.

 

Check your driveshaft to make sure no one put a big zip-tie on it.

I remember that trick being brought up in numerous "revenge" threads.


phox

 

It's definetly engine. Sounds like its someone tapping on the engine with a hammer. Its heard best at ~1800 RPM cruising.

 

What kind of repetition rate does the tapping have? Engine speed, 1/2 engine speed, etc?
Get me some TDY/TAD orders to Guam and I'll be happy to look at it for ya. It's been years since I've been there.

Shortround out

 

What about in park at 1800 RPM? Any Noise?

 

If you cant isolate it maybe adj. valves as that will take care of that question and thay all need it cause they come from factory way loose.
from there..well will it do it on coast dwn,under pwr, or ??

 

Thats what I got from another dieselhead(he owns another Dodge/Cummins). He said he would help me out with it. Valves was the first thing he thought of when I told him about it.

As far as 1/2 engine speed or engine speed, I couldn't tell, its audible but its hard to hear.

 

Sounds like all valves need adjusting. They allow quite a variance on the min/max before adjustment is required right from factory. As thumper 549 stated, I have found also they are usually on the very near upper end of tolerances(too loose).

Disconnect both batteries first. Set valves to the lowest minimum for both intake and exhaust. Intake valve range is .006"-.015" set at .006". Exhaust valve range is .015"-.030" set at .015".

Just be sure to have mark set exactly on TDC mark(12 o clock) when adjusting, and use a step feeler gauge(more accurate). Double check so no valves are set TOO TIGHT(THIS IS CRITICAL). Then rotate engine 360 degrees to do the rest(again get on mark exactly but now mark will be straight down from previous TDC mark at 6 o clock) .

By using the lowest valve setting it will quiet engine down(clacking noise), and increase engine efficiency,and will not need to be set again for a long long time.

 

Well I adjusted the valves today. Set the intake for .010 and exhaust for .020. Adjustment went fine until I drove home. On the way home I heard the tapping noise come back, and it got louder. The tapping became thumping after a while. Then I heard BAM, and THUMP THUMP THUMP... as the engine ran, coupled with the loss of power and a engine light. Pulled her off the road and shut her down. I pulled code with the key method, got a P1693 (companion code) and the ECU gave me a P0112 ( Intake air temperature circuit low input).

Well I then popped the valve cover again, and to my dismay I saw #5 exhaust rocker arm at an odd angle and the Y that pushes down both valves had fell down. I also found the pivot stud that pushes down on the Y in 2 pieces. After finding the piece of the stud and putting the Y back on the valves we were able to put the stud back together, reset the lash and start her up.

Theory on what happened :

The original tapping noise was caused by this rocker arm/pivot stud ( i think). The re-adjustment put more strain on the stud which came apart and cause the Y to fall down. Since the exhaust valves are now closed the cylinder fired but could not relieve its exhaust gas or combustion pressure which went into the intake. Cylinder #5 is the closest to the IAT sensor. The excess heat caused it to give a voltage out of its normal range to the computer which set the trouble code.

Anyone got a part # for the exhaust rocker arm and pivot stud?

 

I just got home after the car wash and the pinging noise jrsdodgediesel described happen on my rig with the P0112 code. Mine started to shutter and sounded like it wanted to stall I figure it was water in the air filter on the acccount I have the BHAF.

so did anybody figure out what this problem was?? I'm gonna test drive it soon.

thanks for any input

 

Do not drive it until you pop the valve cover. On mine the exhaust valves were closed and were not opening. After that cylinder fired, the exhaust gases would re-compress (since the exhaust valves weren't opening). And when the intake valves would open at the top of the exhaust stroke they would get released out through the intake making the thump noise.

 

i just came back from driving it around the block a bunch of times and it didnt make any noises, no popping or shuddering. The engine light is on and the P0112(Intake Air / Charge Temperature Sensor Low) code is still there. I think the BHAF sucked in some water cause it was wet. I guess the code has to be cleared by DC, which for 10seconds of work will cost $60

jrsdodgediesel did your trouble code go away or was it cleared? and was the exhaust valve the problem?

 

My code went away on its own. Well not really, the code itself is still in the computer. It takes so many start/run cycles for an inactive code to be cleared by the ECM. The check engine light turned off after I fixed it. That exhaust valve still works good and is still in the motor. It was just the pivot stud that let go, but it still works fine to after it was re-tightened.

 

thanks for the info jrsdodgediesel, i plan on adjusting the valve back lash ...as soon as I find a qualified diesel tech around here so I'll have the top end looked at as well