Duramax Diesels Forum Truck of the Week
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Old 02-12-2019, 08:12 AM
LBZ_tom LBZ_tom is offline
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Default LBZ Coolant leak dripping on front driveshaft

My lbz has a leak that has been running down the bellhousing only when cold. Resealed oil cooler, checked turbo lines, upper radiator hose is not hard in the morning. I have searched everywhere and this leak is driving me insane. What else could possibly be leaking coolant?
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Old 02-12-2019, 08:26 AM
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Could be a Rear Freeze plug or it could be something leaking in the engine valley thats running out the back side of the engine.
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Old 02-12-2019, 08:27 AM
LBZ_tom LBZ_tom is offline
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What is the "easiest" or most direct way to check this?
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Old 02-12-2019, 08:39 AM
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Probably a inspection camera if your have one.
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2001 2500HD Red on Black.
ATS Dual CP3, and S369, ARP 625 head studs and main studs, LBZ Rods, Delipped pistons, Hamilton valve Spring, 30 over injectors, 5in Turbo Back exhaust, ATS Transmission, Fass 150, and Running on Moonshine.
DIED AND NOW HAS BEEN RAISE FROM THE DEAD

1971 C10 Restoration/ProTouring Project, LBZ/4L80E Inprogress

1967 c30 12v VE/NV4500 tow rig for above truck Inprogress
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Old 02-12-2019, 10:09 AM
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Get a coolant leak test kit. With the engine cold, pump the cooling system up to 20 PSI. Now crawl around and look for the leak. It will be easy to spot. I've done this several times, adding pressure when the engine is cold is really convenient, since seals and everything are still loose, and you don't burn yourself reaching around/under things to check for wetness.
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Old 02-12-2019, 11:21 AM
LBZ_tom LBZ_tom is offline
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Already done, seems to be dripping from the valley/head gasket maybe
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Old 02-12-2019, 10:24 PM
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Valley can be head gasket, but it can also be turbo coolant feed or return, cracked turbo center section (never heard of this but theoretically possible), EGR cooler feed or return, the cooler itself, thermostat gaskets, coolant crossover pipe gasket, or the heater core feed or return. You might have to borrow a borescope and look around for the leak, as you can't really get your hands down in the valley.
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Old 02-13-2019, 12:05 PM
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Quote:
Originally Posted by LBZ_tom View Post
Already done, seems to be dripping from the valley/head gasket maybe
You only want one stiff hose in the morning and if what you said is true about your Dmax hose being soft , then it is less likely a head gasket and more likely one of the other things DAVe said !
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Old 03-11-2019, 05:06 AM
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UPDATE: Rear cover was cracked, Coolant was leaking out of crack above the oil filter adapter 90, got that replaced and holds 15 psi no problem.
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Old 03-11-2019, 08:17 AM
SAC owner SAC owner is offline
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Quote:
Originally Posted by DAVe3283 View Post
Valley can be head gasket, but it can also be turbo coolant feed or return, cracked turbo center section (never heard of this but theoretically possible), EGR cooler feed or return, the cooler itself, thermostat gaskets, coolant crossover pipe gasket, or the heater core feed or return. You might have to borrow a borescope and look around for the leak, as you can't really get your hands down in the valley.

I see he found the leak, but for information the head gasket can not leak towards the valley as that is where the push rods and oil pass there is no coolant passage on the upper portion of the block or head to seep out.
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Old 03-11-2019, 06:14 PM
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There is also coolant dye that works like ac dye pour it in pressurize the system and look with the black light
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