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Duramax First Generation: 2001-2004 (LB7) Discuss the first generation (2001-2004 LB7) of the 6.6L Duramax diesel engine & associated components. Engine related discussion ONLY. is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
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Old 05-05-2008, 08:33 PM   #1 (permalink)
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Coolant drain plugs on engine block

This is my first post under the LB7 section of the forum, im having a hard time trying to fiugre out which generation of engine my truck has in it but i found out it is a 400cid so i guess its an LB7. so heres my question: I have a 2004 chevy silverado 3500, Im going to change the coolant and i want to know if it would have any coolant drain plugs on the engine block and where they would be at? If there are drain plugs on the block and i use them would i just have to wait until the thermostat opens for coolant to go into the block? If so is that safe for my engine?

Thank you for any help

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Old 05-05-2008, 09:40 PM   #2 (permalink)
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No drain plugs I know of. As for the engine generation look at the 8th digit in the vin number. 1 is LB7, 2 is LLY. 2004 have change in mid season on engine.


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Old 05-05-2008, 09:43 PM   #3 (permalink)
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IIRC, there are two drain plugs on the block. If I am right, they are small threaded plugs, and I believe they are toward the front of the engine on both sides. I seem to remember seeing one in front of the block heater plug on the pass side, so it stands to reason theres one on the drivers side too.

You're going to have to get a flashlight and check your block.

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Old 05-05-2008, 09:47 PM   #4 (permalink)
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I remember a question about the drain plugs a few weeks ago, and I remember someone saying they were almost impossible to get to with all the accy on the engine. I don't remember what engine that was on though. Try searching for it.
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Old 05-06-2008, 09:03 AM   #5 (permalink)
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There's two coolant block drains.
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Old 05-08-2008, 12:05 PM   #6 (permalink)
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They are not hard to get to, mine are painted yellow so easy to see.
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Old 05-11-2008, 04:20 PM   #7 (permalink)
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Rather than removing dran plugs you can disconnect the heater hose near firewall and backflush block. I remove the radiator drain plug, cap and Tstat vent bolt and flushed until clean.
Afrer draining, you can use air hose to blow out almost all water in block.
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