Borrowed FIL's truck, now it is leaking. 6.6L LB7

grundyo

New member
Dec 12, 2022
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All,

Hoping this group can help me out. I've been using my father-in-laws truck (2003 3500 Duramax 6.6L) for the past few months for a house project and it has recently (last 2 week) developed a leak. I've tried to track down the issue but I'm not really sure what I'm looking at and having a hard time figuring it out.

While the engine is running and moving this leaks, when stopped and engine is off no additional leaks once cooled. This appears to be at the rear of the head on the passenger side. The leak is small, but after a longer drive it appears to leak significantly more

Photo 1 shows the general area, photo 2 shows the specific area the leak is coming from.

Any help or guidance you can provide is appreciated.

engine 1.jpgengine 2.jpg
 

clrussell

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Sep 23, 2013
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Is it dripping from above onto it?

Looks like a heater fitting leaking onto the cyl head
 

TheBac

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What color is the fluid thats leaking? That alone will tell you where to start looking.
 

1FastBrick

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Dec 1, 2016
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What is the fix for this? I've never dealt with a heater core on these trucks. Is it the plastic leaking or the hose. Hose is easy to replace, but what if it's the fitting (kind of looks that way from the pic)?
Its likely the plastic fitting. Sometimes they crack, sometimes its just the O-ring inside. But they are cheap enough to replace as an assembly. Hose with the fitting.
 
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clrussell

pro-procrastinator
Sep 23, 2013
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Its likely the plastic fitting. Sometimes they crack, sometimes its just the O-ring inside. But they are cheap enough to replace as an assembly. Hose with the fitting.

Yup. Replace the heater fitting. Any good parts store will have them.

You’ll more than likely break the old brittle one removing it.

Cheap easy fix.

Not so cheap if you don’t fix
 

1FastBrick

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Dec 1, 2016
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I have only seen the PPE Stainless unit. Do either of you know who makes the the one for the parts stores? Like is it a doorman part or something?
 

Bdsankey

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I have only seen the PPE Stainless unit. Do either of you know who makes the the one for the parts stores? Like is it a doorman part or something?
Dorman makes stainless ones that also don't carry PPE's "we copied someone" tax (so Dorman is ~$5-$8 cheaper per connector).
 
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1FastBrick

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Dec 1, 2016
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Dorman makes stainless ones that also don't carry PPE's "we copied someone" tax (so Dorman is ~$5-$8 cheaper per connector).
Ok , I found it. Thanks. I didn't know they had those and they are stainless.

Dorman 800-409HP Coolant Connector​

 

1FastBrick

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Dec 1, 2016
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GM 15032062 is the White Inlet side connector.

The Black Outlet side comes on the hose assembly.

Should always verify The part number is correct for your application but I found these assembly's
GM 15768212 for 01-04
GM 15196471 for 04-05
GM 25800640 for 06-10
 

grundyo

New member
Dec 12, 2022
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Follow-up, it was the
What is the fix for this? I've never dealt with a heater core on these trucks. Is it the plastic leaking or the hose. Hose is easy to replace, but what if it's the fitting (kind of looks that way from the pic)?
it was the plastic fitting. Somewhat easy fix, just had to get the right tool ($10) to remove the integrated clamp that was part of the fitting.
 
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