Strange coolant leak

[DirtymaxLB71904]

So i just changed my water pump with a dirty hooker high rpm water pump this past weekend changing the bypass tube thermostats and coolant reservoir after running and truck getting to temp i shut it off and called it a night i woke up in the morning to a puddle of coolant with drips coming from the back of the engine on the driver side on the transmission housing i seen A small stream of coolant running from the top to the bottom along the driver side i couldn’t figure out exactly where from and im completely stumped on the whole thing. Asking if anyone can help and assist with where i can narrow down the areas to look and replace what is broke

-2003 6.6 lb7 with ali trans

 

[2004LB7]

Bleeder screw, turbo coolant line, thermostat housing, rear crossover tube....

I'd look at whatever is on top of the engine valley that you would have touched or worked on first

 

[DirtymaxLB71904]

im not sure where to look for the rear crossover tube. This is my first diesel but i got home and seen it dripping. I cant really see past this bolt. I took off the turbo heat shield and didnt see much except for old gunk, i did wipe it off. But no leak consistent with the drips

 

[DirtymaxLB71904]

I did try tightening that nut and its pretty tight already

 

[Chevy1925]

You are going to need a mirror and start looking above that oil cooler. I’ve seen the oil cooler gasket leak on the mid plate and I’ve also seen coolant leak out of the mid plate above it. There are 2 o-rings under the mid plate that seal it to the block and I’ve had 2 trucks in the past year leak out of there. You will see a wet spot about half way up the up pipe on the bottom side between the midplate and block. To fix that specific leak, trans, flex plate and mid plate all have to come off.

Pressurizing the system will really help point it. It’s likely to be an oil cooler gasket too so don’t fret yet.

 

[DirtymaxLB71904]

You are going to need a mirror and start looking above that oil cooler. I’ve seen the oil cooler gasket leak on the mid plate and I’ve also seen coolant leak out of the mid plate above it. There are 2 o-rings under the mid plate that seal it to the block and I’ve had 2 trucks in the past year leak out of there. You will see a wet spot about half way up the up pipe on the bottom side between the midplate and block. To fix that specific leak, trans, flex plate and mid plate all have to come off.

Pressurizing the system will really help point it. It’s likely to be an oil cooler gasket too so don’t fret yet.

Even if it leaks on the driver side?

 

[DirtymaxLB71904]

Also, only leaks after it cools down

 

[Chevy1925]

Even if it leaks on the driver side?

What I stated is specific to the driver side

 

[DirtymaxLB71904]

Would you think it would be best to just replace the whole oil cooler if i might be the oil cooler gakets

 

[Bdsankey]

Pinpoint the leak first. As James (@Chevy1925) said, it could be many things. Too often people turn into a parts cannon and become frustrated that their issue cost them a bunch of money when it can be something relatively simple.

If the oil cooler has to come off there is no downside to replacing the cooler. I will say the Banks kit is nice but slightly overpriced.

 

[JoshH]

Coolant leaks in the valley will often find their way down the driver's side of the bellhousing. Can you see coolant pooling in the valley? If not, then it is likely the oil cooler like James stated.