Yep, sounds like the lift pump burned up.

 

I'd say it's a spun bearing. Is the knock very noticeable? Do other people look at your truck and make puzzled faces (more than normal should we say. heh)


A spun bearing will be pretty load at idle, and almost non-exsistent on de-cel and coast. I've seen alot of Cummins lose rod bearings around 100K.

Merrick

 

Its noticable at idle and around 1500 rpms in any gear all the way up to 2000 rpms is where it sounds the worst, especially when the throttle is dumped. Is it possible to slap a new bearing in while it is still in the truck. I know I will probably have to lift the engine up so I can get the oil pan off, but is it really worth the trouble.

 

Get a FP gauge ASAP.
Go ahead and get an oil sample and have it checked. don't wanna start throwing money at all the wrong things. The sample should tell you if your bearings are going out.
What's your FP? Oh ya that's right you dont' have a gauge, so go get one!!
It would make diagnosing this problem easier.
Happy New Year!!!!!!!!!!!!!

 

Well, just ordered a fuel pressure test kit from Geno's so I can have a better idea of whats going on with the truck. I didn't get a in dash guage because I see that Quads Adrenaline has been released and Im getting one next month. I will give you fuel pressure readings when I get the guage. Thanks for the help guys. Quads Adrenaline is probably the only reason Im giving this 24V a chance instead of offloading the truck and going back to a 12V.

 

You could get a FP test kit from Harbor Freight cheap.
You might wanna upgade the fuel system any way. Look at the Airdog systems on sale now pretty cheap.

 

well, hooked up the fuel pressure guage, holding strong at 15 psi at ide,13 at cruise, and 8 at wide open throttle. So much for the idea that I wasn't getting enough fuel. Maybe it's time I take it to Cummins Atlantic before I throw a grand down on an injection pump.

 

You're not serious that you were holding hill using the clutch are you? You know it's not good for the clutch and you did it anyway? <insert snide remark about wisdom of Marines here>

There's no way to know what the smell was, especially since you decided to kill your clutch and the smell of that was masking any other smells that might be there.

Can you be more specific in your description of the sound? Is it a sharp rattle like a rod bearing knock?

Do you have a mechanic's stethoscope?


Here's something you can eventually try that might help diagnose what it is: change the oil temporarily to a drastically different weight and see what happens to the sound. Change it to some 20w-50 and see if it gets quieter. Or (better idea), swap in some 5w-20 for some testing and see if the knock gets worse. Either of these weights should offer plenty of protection for short-term testing you'd use them for. But changing oil twice in one day is no fun. You should have an auto hobby shop wherever you are stationed.

You aren't going to smell a failed VP unless that thing is smoldering.

First things first, though--- check the exhaust manifold bolts and other bolts for looseness-- a loose bolt somewhere could be the culprit. Your truck shows no signs of major engine damage, right? No loss of oil pressure? No loss of boost? No high EGTs? NO loss of power?

That's why I think it's probably some stupid little exhaust manifold bolt or something loose causing your "knock".


Did the knock start after any particular event like an oil change or battery replacement?

Just thinking out loud here....

jh

 

If my Cummins did not "knock" I would be worried!!....ha ha. Really though, hopefully it is something minimal. I would definitely exhaust every last EASY fix before I started dumping $$$$ into it unless you have the money to throw around (I mean that in a non-smart a$$ way, some people have plenty of $$). These are tough little engines.
If you took it to Cummins there is a good chance that they will find something to fix.

 

Thanks for the replies guys. I will be doing a compression test and blowby test tomorrow, then probably pulling the head off of that, but I will check all the easy stuff in the morning before I dive into that. To describe the sound better, it is more of a loud ticking under load. It only starts at around 1500 rpms and stops at around 2300 rpms. When i let off the throttle and coast, the ticking is constant with rpm all the way down to 1500 rpms. Hope this helps.

 

What did you find? I have a similar knock on my '03.