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Duramax 6600 Discussion Forum for the Duramax 6600 Diesel Engine, including the LB7, LLY, LBZ, LMM & LML engine specific topics.

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Old 06-28-2011, 12:51 PM
daakota daakota is offline
Join Date: Sep 2007
Posts: 2
Default coolant leak

looking for any help I have a 2001 chevy 6.6 turbo 2500 hd allison trans. Original owner. Today I developed a antifreeze leak my light said low coolant well then the trans temp started to rise slightly up to 210 from norm 190 stopped truck smelled antifreeze and looked under there was drops on the bell housing of the trans and wet from there back couldnt find anything above that was wet or leaking. any sug would be helpful. have 195000 on truc did the head thing at about 80000. doest act the same as that, there is no pressure when opening tank? leave message or call 586-246-9853 need help. thanks

Last edited by daakota; 06-28-2011 at 01:29 PM.
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Old 06-28-2011, 01:50 PM
Kennedy Kennedy is offline
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Location: Loyal WI US
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A dye in the coolant will really help track down the source, but I'd be looking at teh turbo coolant hoses as well as heater hose/tubes for starters.
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Old 06-29-2011, 11:14 AM
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More Power More Power is offline
Join Date: Feb 2000
Location: Big Sky Country
Posts: 10,267

Like Kennedy suggested, look for a leak at the top of the engine, and work your way down. Eliminate the easy and inexpensive possibilities before suspecting something more.

That said, these engines employ an aluminum bellhousing adapter that bolts onto the rear of the engine. Aside from allowing the trans to bolt to the engine, it also has coolant passages that distribute coolant to each side of the block. I know of at least one that developed a coolant leak. You may have to pull the engine to re-seal it - or it might be done by first pulling the transmission, and working beneath the truck.

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Old 07-11-2011, 10:30 AM
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jjcsnlynn jjcsnlynn is offline
Join Date: Dec 2010
Location: Felton, DE
Posts: 35

Have a look at the coolant block off plate just behind the engine (on the adapter) on the passenger side. If yours is leaking, read the links below. I was able to change it without pulling the engine/trans. It's tight, but I was able to get my paws up there to work the two bolts.
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Old 07-11-2011, 02:30 PM
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More Power More Power is offline
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Location: Big Sky Country
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Here's a pic that shows where the coolant block-off plate is located on the aluminum bellhousing adapter. I've needed to tighten the two bolts on an engine before to stop a slow oozing leak. Jim

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Old 08-21-2011, 10:48 AM
Mighty Mac Mighty Mac is offline
Join Date: Aug 2011
Posts: 1
Default coolant leak

I overheated my 2002 DM and breached a head gasket. One of the copper lines going to the heater core broke off at the hose clamp inside the engine compartment at the firewall and dumped the coolant. I had been adding coolant every couple weeks, as I was unable to find a leak. I looked everywhere BUT there...
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