Engine Noise Upon Start--Valves?

[MAYoung]

Gentlemen:

I have had my truck for so long that I no longer remember what it sounded like when new. It has always had that characteristic rumble of the Cummins ISB 24 Valve 5.9L diesel. I hear them all the time. It is a distinctive sound.

My question is this: I think that I hear a light "clicking" or "tapping" sound coming from the valve train upon cold start-up. After about 3-4 minutes, the noise seems to go away and never returns as long as the engine is warm. I have never had the valve clearance adjusted in nearly 263,000 miles. Would adjusting the valves help or am I just hearing a normally starting 5.9L 24 valve engine? I am not sure when I first noticed the sound except that it has been going on for a while---one year?

My ears and mind may be playing tricks on me but I thought that I would run it by the forum.

Thanks again.

 

[GAmes]

You answered your own question. Adjusting the valve lash is long overdue.

 

[DavidC]

Agree,adjust the valves

 

[Joe Mc]

I believe the FSM calls for valve adjustment @ 100k. So you're overdue for sure

 

[MAYoung]

Thank you.

 

[KATOOM]

Its likely the valve system. But even at that, if they're loud enough that you can hear them clacking over the insane noise of the 2nd gen engine then you may want to investigate whats going on under that valve cover asap. You could have a hold down bolt barely hanging on...

 

[Joe Mc]

KATOOM brings up a great point. Better to investigate sooner than later. BTW, you should be able to re-use the tappet cover gasket and rubber bolt seals. I've done my valves 3 times and installed 4 different sets of injectors over the years, re-used the same stock gasket and rubber bolt seals. Should you think about replacing them "just because" be prepared to fork out $40 for the cover gasket and $6.50ea. for the rubber both seals X 5. Total, not including shipping will set you back a full tank of fule depending on price per gallon wherever you're at.

 

[MAYoung]

Thanks for the input. The noise is not that loud and it is difficult to hear with the motor running. I just seem to notice it going away after a few minutes.

In any event, I start tomorrow with the lash adjustment. It appears to be straight forward. I did not notice/see any torque value, however, for the lock nut after adjusting the lash in the factory service manual. Any recommendations? (Manual just says to "tighten the lock nut and re-check valve lash.")

I will advise what I find.

 

[Joe Mc]

Nothing fancy really, typical screw/jam-nut situation. Just hold the screw real good when you tighten the nut. Then before moving on to the next one check clearance to make certain tightening the nut didn't change the lash. Have fun, not a bad job at all. Here's a tip, if you never had a tappet cover off on one of our trucks = place a towel or other cloth item on top of the back of the cover draping it somewhat down towards the bell housing, take the top part of the cloth and tuck under your wiper blades to hold it in place. When you lift the cover up and begin to move towards you make sure the cloth doesn't come with the cover = keep pushing it towards the rear of the engine. What this (cloth tip) does is prevents insulation from under the towel (and other debris) from falling into the top of the head while removing the cover, the back of the cover will contact the insulation as you pull it toward the front to remove. Once the cover is off you can remove the cloth to make it easier to work. I also suggest placing a cloth back on before re-installing the cover = same reason, dirt and other stuff just doesn't get along with shiny internal engine parts...

 

[MAYoung]

Joe Mc, excellent suggestion. I have prepped the truck to do the valve lash adjustment. Since this is a one-man operation, I found enough extensions to connect to the barring tool with a 1/2 inch ratchet and turn the engine over as I stand in front, facing the engine. I turn the socket/barring tool setup counter-clockwise which results in the pullies and belt turning clockwise (toward the starter side of the engine). All motions are as I face the front of the engine, looking towards the cab.

I appreciate the help. I have never touched the valve lash in this truck. I will report more tomorrow.

 

[Cummins12V98]

Use the nut on the alternator to turn over the engine.

 

[Joe Mc]

Use the nut on the alternator to turn over the engine.

After many times using the alternator nut I purchased the barring tool. What a PIA, reverted to the alt. nut = much easier. If you are following the instructions in the FSM you can’t go wrong, a mirror and flash light, a paint stick mark on the gear behind the timing cover breather “TDC” will help you to see the mark as you’re moving from one adjustment point to the next. Enjoy!

 

[MAYoung]

Update Report:

I finished checking the valve lash on my 1998.5 Dodge 2500. And here is the conclusion: After 21 years and 263,000 miles, I did not adjust a single lash. I used the maximum and minimum spec for each valve and really did not find any that were out of spec. For intakes, the best feeler gauge was 0.010"; for exhausts it was 0.020. The only value that showed any signs of needing adjustment was the number six exhaust valve which was 0.015"; this is the minimum specification for exhaust valve clearance.

Could I be off in my measurements? Perhaps. The most difficult to gauge was the number six set so it may be a little closer to the 0.020" measurement. But not by much. So I am reasonably confident that the lashes are close to spec.

So just what is that noise that I am hearing? Who knows. It is not very loud and seems to go away after a few minutes. Oil pressure? The oil pressure comes up immediately. It could be anything from minor to the potentially catastrophic. I will just have to drive it more until any problems become more pronounced.

Overall, it was not a bad job to do. The biggest challenge was removing the breather tube and its circular housing.

I also took the time to install a new alternator.

This is the final "big" maintenance item that I wanted to do on the truck. I now feel confident enough to let my daughter pull a trailer and a horse with the truck without having to travel with her.

Thank you for all your assistance.

 

[KATOOM]

Well its good that you at least checked and now you know... Without hearing the noise you're hearing, maybe the noise you're hearing is injection pump timing. Not sure. Can you video the sound?

 

[MAYoung]

I did take a video and ran it by the diesel repair mechanics at the local Dodge dealer. They could not hear anything but it was only an iPhone recording. I will try and upload the file. The noise, if anything, is very subtle and does not present itself as an obvious failure. The mechanics thought that it sounded like a 1998.5 5.9L, 24V Cummins. Nothing out of the ordinary.

 

[sag2]

Fire it cold with the valve cover off so you can hear it better.

 

[MAYoung]

I am attempting to send the two short videos that I took of the engine in operation. You will have to go to YouTube to see the videos. They are very short, less than a minute each.





If you hear anything that may be suspect, please let me know. Thanks, Mark Young

 

[MAYoung]

1998.5 Dodge Cummins 5.9L 24V Cummins on a rainy February 2019 afternoon. The truck is in decent shape so that I work hard to keep it in working order. It is far cheaper to repair it than new truck payments.

 

[DavidC]

I personally did not hear anything different than mine

 

[dblake]

That’s a clean engine!