Duramax Diesels Forum Truck of the Week
Old 10-19-2018, 06:24 PM
VEfreak VEfreak is offline
Join Date: Oct 2018
Posts: 12
Default LBZ transmission leak, I can not locate it

I got a problem and maybe you can help me.

My 2006 LBZ is leaking off of the bell housing where it mates up to the engine block. I stuck my finger inside the bell housing and felt around. No oil in there so I don't think it's coming from the torque converter. I can't find a trail of oil up the side anywhere. I'm really going crazy trying to find this leak, and was hoping maybe this is a common problem with a well known fix.

I tried to upload pictures but the website keeps saying I'm missing a security token. Maybe a mod can help me with that.

Any help is appreciated. Thanks!
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Old 10-19-2018, 10:13 PM
frankenstien's Avatar
frankenstien frankenstien is online now

Join Date: May 2015
Location: Fairbanks,Alaska
Posts: 484


I've had the security token issue before. I made the pictures smaller and they loaded fine.
Danville Tuned
5'' exhuast
Fass 150
Built Trans w/SC1058
Bumpers built by me
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Old 10-20-2018, 05:21 PM
VEfreak VEfreak is offline
Join Date: Oct 2018
Posts: 12

So I pressure washed the engine/transmission then took it for a drive. I got back and the leak pretty bad, but now I could see where it was coming from. Turns out it's coming from a small coolant hose that seems to feed the turbo housing.
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Old 10-27-2018, 01:15 PM
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Pure Diesel Pure Diesel is offline
Randsburg Drifter
Join Date: Apr 2008
Location: So. Cal.
Posts: 589


I had the same problem, leaking down the drivers side. Some days it was there and then nothing for a couple of weeks. Then finally it started to leak bad. Ended up being the oil cooler leaking coolant. Thought it was tranny fluid with the small amount and almost the same color. Good idea GM on making two fluids almost the same color.

I had checked the turbo coolant lines first and was good.
White GMC 2003 2500HD D/A SLE/CC/SB 4x4] Bilstein 5100~Air bags~Autometer Gauges~33 BFG's~MBRP 4" Exhaust~SD tie rod sleeves~Cognito Braces~Kryptonite upper control arms DMAXSTORE XD TIE RODS~PPE high flow pick up~Fass 95 pump~Titan 52-gal.~Prodigy~New tranny 02/12/2015 Mike L. "Baby Frankenstein " w/Goerend converter w/ Mike L. tranny cooler and pump rub fix~6 speed tap shifter~Siege Engineering Anvil train horns(Very Loud)~LED headlights Hi/Lo
New injectors as of 03/12/2010 @ 80k miles
Injectors started going again at 115k. 07/01/2013
06LBZ engine transplant from Russ @ RPM Motorsports~No more Lb7 injectors to replace
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Old 10-29-2018, 09:18 AM
VEfreak VEfreak is offline
Join Date: Oct 2018
Posts: 12

I definitely plan on replacing all the coolant hoses with silicone hoses in the near future. Cheap insurance, plus the bottom radiator hose looks pretty beat up and feels too soft. Gonna have to wait a few months though, as the wife is already mad at how much I've spent on this truck since I bought it, even though I practically stole it from the last owner
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