03 cummins knock

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03five9

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Hi guys, 1st post. Done ALOT of reading about my issue and can't find the cause.

2003 auto afe blade runner gt turbo header and intake mbrp 5 inch exhaust and edge ez.

So I'm getting this knock at idle seems to be coming from bell housing. Pulled trans and nothing was cracked like I hoped to find. I ordered a bd flexplate since I'm here and will be doing rear main and cam seals.

Bought the truck 1k miles ago and its in immaculate condition original owner LOTS of receipts from dealer and service records. I did a 4hr mountain cruise off road but not beating her actually only in 4 wheel for 30 mins max just to be easier on her(I thought). Now it's knocking. I can really hear it at idle and it's spuratic and sometimes won't do it at all. I may hear a little chatter if I'm driving less than 5mph and let off the throttle.

Flexplate chatter? - YouTube

Flexplate noise - YouTube

Flexplate issue? - YouTube

Tc noise - YouTube


TIA, trans is in the garage waiting for bd plate
 

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Were the flexplate bolts loose?


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FP to TC all tight, FP to crank unsure I took em off with an impact which I know I shouldn't have done. I was thinking MAYBE cause I do see where the rust ran off 3 of em.
 
I had a Suncoast torque converter that rattled really loud like that at idle. It worked great, just sounded like a double disk clutch rattling at idle.
 
Snedge said:
I had a Suncoast torque converter that rattled really loud like that at idle. It worked great, just sounded like a double disk clutch rattling at idle.
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I was concerned about it being a cracked flexplate then flying apart and ruining the trans or sams thing if it's the TC. I have to take it to San Diego on the 5th so was really concerned. Plus it's the 1st vehicle I ever bought with debt so it's driving me nuts. Atleast I'm getting to know her tho lol.
 
Snedge said:
I had a Suncoast torque converter that rattled really loud like that at idle. It worked great, just sounded like a double disk clutch rattling at idle.
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Had a RevMax converter do the same thing in a Duramax. Probably wouldnt be a bad idea to get the converter checked out.
 
Can anyone explain to me why if I'm driving with ac on and put it in park it doesn't happen? As soon as I turn the ac off is when I get the noise! I let it idle for 10 mins with ac on and nothing, click it off and it's back again. Is it just the change in load?
 
03five9 said:
Is it just the change in load?
Click to expand...



Seems to be the case. Activating the AC compressor adds load to the engine. With a load the slack is taken up in your transmission where the rattle is.

Does this rattle only occur in park and neutral?
 
03five9 said:
How's that? I've only spoke to one trans guy and they said they had to cut it open!:bang
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When I called Suncoast about my noise they told me to send it back so they could "cut it apart and look, but it was probably nothing to worry about". I never sent it back and I stopped worrying after a while. :)
 
03five9 said:
How's that? I've only spoke to one trans guy and they said they had to cut it open!:bang
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That's how you service a TC. Cut it open, inspect, clean, replace bushings, slap it together, and weld it on a machine that keeps it balanced.

A lot of people on here like Diesel Performance Converters (Diesel Performance Converters | Best Diesel Torque Converters). Then Goerend is always a safe bet too (Goerend Transmission, Inc.).

I'd call and ask about turn around. You could toss a used stock 48re TC in for the road trip.

Make sure you red locktite the TC bolts, use new bolts, and torque everything.
 
Red Sleeper said:
Seems to be the case. Activating the AC compressor adds load to the engine. With a load the slack is taken up in your transmission where the rattle is.

Does this rattle only occur in park and neutral?
Click to expand...

Yes only in P&N
 
CorneliusRox said:
That's how you service a TC. Cut it open, inspect, clean, replace bushings, slap it together, and weld it on a machine that keeps it balanced.

A lot of people on here like Diesel Performance Converters (Diesel Performance Converters | Best Diesel Torque Converters). Then Goerend is always a safe bet too (Goerend Transmission, Inc.).

I'd call and ask about turn around. You could toss a used stock 48re TC in for the road trip.

Make sure you red locktite the TC bolts, use new bolts, and torque everything.
Click to expand...

Loctite to crank and TC? I think I'm going to slap it together with the new flexplate and If it still knocks I'll do the TC want to save up for full billit trans probably ATS or goerend
 
03five9 said:
Loctite to crank and TC? I think I'm going to slap it together with the new flexplate and If it still knocks I'll do the TC want to save up for full billit trans probably ATS or goerend
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If there is nothing wrong with the flexplate....how does it have a chance to fix it by replacing the flexplate? It's a fairly simple mechanism.
 
YoungDiesel27 said:
If there is nothing wrong with the flexplate....how does it have a chance to fix it by replacing the flexplate? It's a fairly simple mechanism.
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Hoping the bolts at the crank were just loose. I don't think anything is wrong with the TC either. I went and played with a whole bunch and all make the same noise. I guess it's process of elimination I'm replacing the flexplate just because it's a weak link. I know TC is also but don't have a grand to dump in if I don't have too.
 
YoungDiesel27 said:
If there is nothing wrong with the flexplate....how does it have a chance to fix it by replacing the flexplate? It's a fairly simple mechanism.
Click to expand...

If he's planning on going with a billet triple TC, and or more power in the future, it's not a bad idea to replace it anyways. Might as well.

03five9 said:
Loctite to crank and TC? I think I'm going to slap it together with the new flexplate and If it still knocks I'll do the TC want to save up for full billit trans probably ATS or goerend
Click to expand...

I have never Loctite'd the crank bolts. I've never had them do anything they shouldn't either. The TC bolts though, there's many stories of guys having them back out, getting knocked around, and cracking castings. I've always used a thread locker for safety.

Also, I would highly recommend Goerend, Power Driven Diesel, FirePunk, Granby Truck Shop (Goerend shop), or RedLine Diesel before I'd go with ATS. :Cheer:
 
CorneliusRox said:
If he's planning on going with a billet triple TC, and or more power in the future, it's not a bad idea to replace it anyways. Might as well.



I have never Loctite'd the crank bolts. I've never had them do anything they shouldn't either. The TC bolts though, there's many stories of guys having them back out, getting knocked around, and cracking castings. I've always used a thread locker for safety.

Also, I would highly recommend Goerend, Power Driven Diesel, FirePunk, Granby Truck Shop (Goerend shop), or RedLine Diesel before I'd go with ATS. :Cheer:
Click to expand...


Thanks a lot man. I was paying real close attention to the spacer/washer that goes between the flexplate and crank and I actually am pretty confident atleast 2 bolts were loose I couldn't get the bolt to line up with the shiny on the metal no matter what. Hopefully I actually found it. Will know Saturday if not tomorrow, I'll post a video when finished and keep everyone posted.

Thanks again,
Thoren.
 
I have had this same issue for several years, never taken it too seriously though. One part of the noise was a broken weld on a stiffened or laminated flex plate. Switched to a Billet and the noise was noticeably quieter.

Ive had several conversations with my trans builder about it, spent some time looking into it during other repairs, and basically chalked it up to a stator rattle. Mine is the same as yours, most noticeable in Park and Neutral. It hasn't affected the drivability of the truck, and I monitor my fluid level and condition and have never had any metal debris in the pan during services. Been going on 3 years now with it, will swap converters one day when I'm not lazy and feel like tearing the suspension apart to get the trans out.

Mine is a billet triple disk with a 15 blade left cut, low stall FWIW
 
Well I got her back together and if it didn't fix the noise then it went away lol. I broke the oil pan gasket so I'm replacing that tomorrow. Got rear main done and cam seal, slapped her back together ran fine till it started dropping oil. I guess the RTV I used to ghetto rig the broken gasket didn't work. Anyways hoping tomorrow goes easy and I don't have to raise the motor, has anyone replaced the oil pan gasket without picking motor up?:bang:charger:
 
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