Coolant in oil

duallydmax06

duallydmax06

six six
Aug 26, 2014
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So I'm working on a 01 lb7 with 320,000 miles on it, it needs injectors again has smoke at idle, exhaust smells like fuel, injector balance rates were within spec but not by much so return rates must be bad, but anyway during disassembly I got one side valve cover off and found the bottom side of the valve cover covered in milky grey sludge and all the rocker arms had moisture on them, the coolant was maybe half gallon low before I drained it, so I drained oil and its all milky but still only drained out about 2.5 gallons so it's not a huge leak, so I have coolant getting in the oil somehow, truck did not have any signs of head gasket failure, no hard rad hose after sitting and no pressure in res, ran fine just had the injector haze. One thing I thought of was the water pump is original could that be it? If I remember right isn't there a weep hole on the back side of the pump as well? Or thought maybe oil cooler but I've never seen a duramax have a oil cooler failure? Any ideas? By the way truck is bone stock
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
I didn't pull the injectors yet, I guess when I do the bad cup or cups should come out with it, wouldn't it be burning coolant then?
 
duramax on fire

duramax on fire

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Apr 15, 2015
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I like to reseal the cups anyways. But if none of the cups pull out, pressure up your coolant system and see if any of the cups are leaking. You can spray soapy water around the cups and look for air bubbles.
 
Mike_S

Mike_S

OOPS!
Nov 18, 2009
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True, but the key there is 90%of the time. We've had oil coolers fail that mixed both ways before. Something to look at if nothing else mentioned here stands out.

Sent From God Knows Where...
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
duramax on fire said:
Mine was doing the same thing as yours. Water pump weep holes were plugged up forcing the coolant into the motor.
Click to expand...

The water pump did cross my mind cause its original with 320,000 on it, how did you pin point the water pump? Cause the weep hole was plugged? When I drained the oil it wasn't really much more than 10 qts and it seemed to seperate from the coolant pretty fast, so I'm thinking the leak it small
 
duramax on fire

duramax on fire

Member
Apr 15, 2015
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dallas
It was a hard lesson learned. I would pressure the coolant system and never lost pressure. But was loosing a lot of coolant in the oil. So I pulled the heads to have them checked. While I had the truck tore down that far I decided to change the 200k water pump. And that's when I found the problem. I couldnt tell the holes were plugged until the pump was off. And I never expected the pump because it wasn't leaking.
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
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duallydmax06 said:
The water pump did cross my mind cause its original with 320,000 on it, how did you pin point the water pump? Cause the weep hole was plugged? When I drained the oil it wasn't really much more than 10 qts and it seemed to seperate from the coolant pretty fast, so I'm thinking the leak it small
Click to expand...

I I lost an engine that way... And I drained more the 2.5qt out
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
duramax on fire said:
It was a hard lesson learned. I would pressure the coolant system and never lost pressure. But was loosing a lot of coolant in the oil. So I pulled the heads to have them checked. While I had the truck tore down that far I decided to change the 200k water pump. And that's when I found the problem. I couldnt tell the holes were plugged until the pump was off. And I never expected the pump because it wasn't leaking.
Click to expand...

Yeah I'm trying to not learn the hard way on this one lol! I gotta pull injectors either way cause it needs them so if cups didn't come out with the injectors I was gonna pull the heads, but I'm thinking I should definitely pull the water pump out first, was it pretty noticeable that the weep hole was plugged and the pump was leaking outta the seal? I've done a ton of water pumps in these trucks and never seen that happen but never did one with 320 k on it
 
duramax on fire

duramax on fire

Member
Apr 15, 2015
419
2
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dallas
No the hole being plugged wasn't noticeable untill I pulled the pump. Dirt dobbbers clogged mine up. Did a good job of it. At 320 it needs to be changed anyways. After mine was off you could feel the play in the bearing. I bought the truck drove in home (2 hours) and had to add coolant. Used a gallon in 800 miles.

Have you pressured the system yet.
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
Well I just pulled injectors and no cups came out with it, I pulled the water pump and the weep holes look to be clear and there wasn't any signs that I could see that it was leaking in the front cover, I measured out the oil I drained out and it was only 10 quarts so it's a small leak whatever it is, I'm stumped on this one????
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
I'm thinking I'm gonna put the new water pump in, hook up the cooling system and pressure test it, that way I'll be able to see in the cylinders and leave the oil filter and plug out and see if I'm getting any coolant in the crank case or out the filter housing
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
malibu795 said:
Can test with oil filter off if the cooler is shot it "should" drip/run our one of the two holes
Click to expand...

Yeah that's what I was thinking, I should probably just take the t stats out too to make sure I get pressure through the whole system when I pressure test it
 
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