2500 Ram Cummins

So I went to start my truck this morning and it made a metallic bang sound that startled me. I intially though crap I threw a rod but when it was sitting there running it sounded perfectly fine. So after calming down I shut it off and there was the same bang sound. I ended up having my wife start and stop it for me quite a few times trying to figure out where the sound was coming from but never could pinpoint it at all. I even checked the motor mounts as I thought maybe I had busted one but they all looked good.

I thought at first it may have been the starter but I check ed all the wiring and voltages and everything checked out fine. The sound definitely echoes through the frame rail and if it was a starter I don't understand why it would do it when you shut it off.

Anyhow in a moment of panic I called the Cummins guru from around here since he knows me pretty well though some other acquaintances of mine and explained the situation. He ended up telling me to bring it over and he would give me a ride home. I let him listen to it when I got there and his first response was maybe a cracked fly wheel? But then he started leaning towards a transmission mount?

O well either way I feel a decent bill coming on. I was curious though if anyone else has heard a similar type of sound or experience with a vehicle and what it ended up being. Crappy part is we are supposed to leave this week for our camping trip to lake Erie.

 

Trans mount went on mine but didn't have the noise yours does. I had a vibration like a bad universal and when I checked them found they were fine but the mount was shot. It was cheap and only took a few minutes to replace.

 

Could be a loose flywheel or something of that nature to do it only when starting or shutting it off. What year is your truck?

 

Nothing worse the a loud metallic bang as ya crank it over... hope it's a quick fix for ya. I've replaced the transfer case in 13' and transmission in 14' in my 02 3500 Cummins, no loud bangs though.

 

2004.5 HO with 135,000 miles....... Yeah it was a weird sound for sure. Sometimes it didn't make the sound on startup or shut down but I would say 90% of the time it did it on startup. It seemed like it would do it on shut down depending on the position of the front tires. I am usually pretty good at figuring stuff out but this one had me stumped. I never thought to check all the tranny mounts though.

I told him if it ended up being a flywheel issue give me a call and I might have rebuild the tranny while it is already out of the truck. I haven't had any issues with it yet but I do run a tune on it and he will rebuild a tranny for the best price I have ever seen. Everyone around here swears by his tranny mods.and I already have the valve body mods on it. This is the only time I have had it break on me but at least it wasn't on my trip up there.

 

I did check all the universals and couldn't find any play in them but I didn't check the mount.

 

Harmonic balancer maybe???

 

Never thought about that but that could be an issue other than it ran as smooth as silk when I drove it down there.

 

That is a weird sound for sure. I had a clanking sound with a transfer case before.

 

Starter hanging up for some reason?

 

Had one go on a Kubota recently. Ran smooth from idle up to full trottle. Knocked slightly on shut down. Just a thought.

 

That was my initial thought right after thinking I threw a rod lol. That is one of the reasons I threw a voltmeter on it to see if the starter was dropping out.

Man I am going to be chewing my fingernails until I get the call from him with what it is. I guess I'm not patient when it comes to things being broke and not knowing the issue lol. It doest help I have big dollar signs running through my head........

 

A quick Google search led me to this conclusion... It's probably the A/C compressor.

http://www.cumminsforum.com/forum/2010-2012-general-discussion/605979-one-loud-bang-start-up.html

http://www.dieseltruckresource.com/...-2010-up-201/loud-noise-when-starting-292608/

http://www.dieseltruckresource.com/...train-2003-2007-102/after-start-clunk-149568/

 

BTW, I have an '06 with 87,000 miles and have never heard a noise like that...

 

I read that also but I had my AC off when I was starting it.......

 

Hmmm. Not sure then. Now I am really interested in finding out what it is.

Mine is a 6 speed, so I won't be having any auto trans problems... but with the Smarty, I'll need to upgrade the clutch pretty soon.

 

A broken flywheel will do it for sure.

 

Ugh, haven't heard a word yet........
I am not a patient person when it comes to this type of stuff and I am needing my truck by Saturday.

Always frustrating when you are a huge stickler about maintenance and really particular about keeping stuff in tip top shape when these type of things happen. I always tend to be the person where I change the timing belt at 75k when it says to do it at 100k. If there is anything even questionable I always replace it.

 

I had a flex plate break on a Cummins at work. That thing rattled and made such a noise that you would have sworn the entire engine was gonna leap out from under the hood at you. Only at idle though. Give it a little throttle and it would hush right up. I bet you have something similar.