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Discussion Starter · #1 ·
Ok as title states I suddenly developed a clunk as I slow down. It sounds like metal on metal, only happens as slowing; seems most pronounced coming down a slope and slowing , as truck slows I’ll hear a distinct single clunk. Seems to be as truck down shifts from 3-2 . What should I check? And how?
 

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Discussion Starter · #2 ·
Wow anyone ? Well now I have a shift range light and I noticed a crossmember under transfer case soaked ,it’s not pump rub ; found the bolts holding transfer case to tranny were extremely loose! I tightened the ones I could but the one on the very bottom I can not get to :/ tightened the rest and the transfer case now doesn’t move as it did when I push On drive shaft. But pushing up on drive shaft it makes noise inside transfer case see vid clip. What should I do next? Can the transfer case be causing the shift inhibit issue? I did pull fill plug and fluid came out so it’s not empty. I will have codes read as soon as I can get it to shop to read them. I did check Tcm plugs since I did move it around when I did balancer replacement. I also checked resistance between I think it was Pin 32 and 29 On C-1 and got 60.5 which I believe is fine.
 

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Discussion Starter · #3 ·
 

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Discussion Starter · #4 ·
First vid shows leak and clunk sound when I push up on drive shaft yoke
 

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Discussion Starter · #5 ·
 

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Discussion Starter · #6 ·
Second vid is after I tightened the bolts I could get to still clunking sound when I push up on yoke; is that normal or is my transfer case toast?
 

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Discussion Starter · #7 ·
Wow no one with any knowledge / experience with this?!?
Well after tightening nuts I checked trans fluid level it dip stick was dry! So I drained the remainder of fluid and and changed out filter and refilled With BP TES-295 transmission fluid . I Also checked level in transfer case which was high as it flowed out of full hole ; So I drained till flow out of fill hole had slowed but not stopped. Took for drive shifting was good engaged n all gears no shift range warning . But leak is still present just not as xtreme; and that clunk on down shift still there; I also feel/ hear a very slight Clunking noise at low - coast speeds. Nothing on acceleration I haven’t stomped on the gas as I’m pretty sure something is not right and don’t want to shred what’s left.
My question Is What is causing that clunk and movement in video when I push up on slip yoke?
looks like I’m going to be pulling the transfer case what should I order and from who? Case has been apart before looks like tail section is newer as sticker is still in good shape ;I’m assuming pump rub in its past So I shouldn’t need that kit. But what else?Should I upgrade slip yoke ? Buy a rebuilt or rebuild self? Any one on here have any experience with a place called Kodiac Truck? They do some very interesting things to these transfer cases.
 

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Its hard to tell on the second video because the phone is moving around when you're trying to get it on video. But, you need a gasket and probably a seal there where the trans/t-case meet. The audible clunk is amplified by these aluminum driveshafts, so before you tightened the t-case up I'm sure it was really loud. Being that there is a fair amount of movement from your description, I would definitely pull the t-case and split it to inspect at the least. Maybe it just needs the rear bushing, maybe the bushing and bearing, hard to know until you're inside it and can see the damage.
I've never heard of Kodiac truck, but supporting vendors like Lincoln Diesel and Merchant Automotive carry a pretty good line of parts as well as full assemblies for whichever way you decide to go
 

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Discussion Starter · #9 ·
Thx for reply, I am contacting Merchant Auto today to order some parts, they seem to have great customer service and knowledge. What about the case filling up? What gasket failed for that to happen?
 

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Discussion Starter · #10 ·
If you get a chance just check them out they machine a section of shaft and put bearings in very interesting, if your looking for whole t case they also use aluminum rear half. They only do t cases and some differentials.
 

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Discussion Starter · #11 ·
So I ordered the gasket/ bearing kit from merchant auto. I wanted to get The nickel plated slip yoke, u joint And strap kit from them too but the price for spicer yoke was 159 compared to under 100 at other sites; that’s just too much difference same with spicer u joints I got spicers lifetime u joint which is the upgrade from the ones sold at merchant for 35 for lifetime ones instead of 45 for light duty ones on merchant. The light duties were 27-30. I’m just way to broke right now to justify the extra expense. But there is a reason to still shop there and that’s customer service! They know their stuff and did NOT try to up sell me when I called. I asked what he thought I might need by my symptoms and He gave me an honest answer, the gasket/ bearing kit ; and said beyond that, I should open it up first before I go spending on parts I may not need; I appreciated that. I think I know where my transmission is going to come from; their “work series” seems to fit my needs, for a trans that will hold up to my 500 hp goal and allow me stomp on go pedal without worry , no boosted launches but lots of messing around with ricers and raptors. And Still be able to tow what I want.
 
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Discussion Starter · #12 ·
Ok update time ... opened up transfer case , and found previous owner did have pump rub issue but instead of fixing properly he goobered up the hole with silicone put it back together, no pump rub kit not even the stock metal tab was present. There were some other areas like shift fork that had some pretty serious wear also so I decided best bet to just replace the whole thing! So I bit the bullet so to speak and bought a new Tcase. I went with the one from Kodiac Truck Llc . I believe it’s about the best NP263XHD t case you can purchase. It comes with an aluminum rear half so NO more soft magnesium case to worry about pump rub with, they also cnc the main shaft to accept roller bearings! So while your cruising in 2 wheel drive that main shaft isn’t just spinning inside a metal sleeve it is actually spinning on bearings like you would think it should. The difference in how much easier it spins is dramatic. There are some you tube videos I’ve seen on it, I’ll try to link. Anyway he shipped it out super quick to me and spoke to me on phone too. It came very well packaged and ready for me to stick in the old one to ship back.
So I went to reinstall my very pretty new tCase with new nickel slip yolk and spicer joints and....#!¥%#^ !! The adapter plate ( part between trans and tcase)is cracked! I didn’t notice when I removed the old one as it was getting dark when I did it. For those that don’t know you need to drop the tranny to replace this part!A few have tried to do while in truck but most fail and the failure can be epic! The truck is up on ramps also so no way I’d try this with front end up etc. so after much swearing and maybe a small temper trantrum, I decided to go ahead and have tranny replaced now too. If I’m paying to have it R &R d plus the rear plate install I might as well fix my limp issues now too.
After much research and a few very trusted recommendations I decided to Go with “Elevated Ingenuity” as my builder. Their rep is impeccable and the EI 550 fit my needs to a t . The price I believe is super fair and it comes complete with triple disc torque converter. They have been great with responding to my questions and shipped it out quickly. It just left there today and is scheduled to arrive 11/25 . The install will be handled by H&H in Bristol Ct. (860) 543-4352 if anyone in north west Ct area is looking for a Great diesel shop that know their sh&t, and won’t BS you, H&H is the place to go the owners name is Eric. I know a couple of guys who have house payment trucks, unlike my little humble lb7, and they all swear by his shop! So truck is going to be flat bedded the 25 min drive to shop( more money) at the end of week not sure exact install date but I’ll keep y’all posted.
Well it’s been rough few months with truck as I just did the balancer after it sheared the crank pin and spun causing a serious vibration( I’m thinking that could have caused the adapter plate to crack as the bolts holding the t case on were all loose when t case leak started) any way new balancer rekeyed crank. And now a new Transmission, transfer case and u joints. Truck should be a blast to drive I can actually enjoy the tune in truck without worrying if I’ll limp her again.
 

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Discussion Starter · #13 ·
Fist pict is crack in adapter plate second is the new Kodiac Truck transfer case aluminum rear half
 

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Former GM Tech and parts
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I doubt the crack is from the engine shake, but it could have added to or worsened the situation. The cracked housing was likely due to a driveline vibration- driveshaft out of balance or bad u-joint or something like that. But its hard to say since the t-case has obviously had issues before so who knows. Let us know how it all turns out and how you like the new feel afterwards
 

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Discussion Starter · #15 ·
I never had any odd vibration issues accpect when that balancer spun. Then it was a sudden onset shake! not vibration. Well all new now ; can’t wait 👍. Thinking of adding the t-case brace too. Any opinions truck will never be over a 500hp truck. And no crazy 4 wd launches etc. just some playing around on on ramps etc.
 

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Ok as title states I suddenly developed a clunk as I slow down. It sounds like metal on metal, only happens as slowing; seems most pronounced coming down a slope and slowing , as truck slows I’ll hear a distinct single clunk. Seems to be as truck down shifts from 3-2 . What should I check? And how?
Did you ever find what caused the clunk? My 2011 2500hd duramax with allison is having a single bone jarring (whole vehicle) clunk that is occurring on downshift and in reverse when decelerating. A remanufactured tranny was installed and it didn't fix the issue.
 
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