Coolant Leak

mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
Does anyone have an idea about where this coolant leak is? I traced to dripping from the drivers side of the truck coming off the rear main on the transmission. It is very hard to see, but it is for sure Antifreeze. It is leaking enough to worry me and needing to get it fixed. Thank you in advance.
 

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Deerwashed

New member
Dec 10, 2010
114
0
0
i have never seen a leak there, only thing i could think of is an external head gasket leak but i dont know much about the lmm.
 

mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
I was thinking the same thing to that I might have a head gasket issue, but the truck runs great, but I do not want to chance it. I am nervous to even drive it at this point due to that leak and the place that it is in. Thank you.
 

mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
I only drove it this past Saturday and it leaks when it just sits in my garage so as of now I am not driving it and it leaks enough that I want to fix it even while just sitting in my garage, but need to know exactly where to look so I can pinpoint the leak. I am a newbie when it comes to this truck and I might have my buddy fix it as soon as I can get a hold of him.
 

OregonDMAX

NOT IN OREGON, NO DURAMAX
Apr 28, 2013
3,964
8
38
37
Goodyear, AZ
Oil cooler leak? Coolant crossover to oil cooler? It don't look that bad, how often are you refilling it?

Winner winner. This is the exact leak I had and it turned out to be the oil cooler elbow to block side. Other possibility is the crossover tube from the water pump as it goes into the oil cooler. The elbow from cooler to block also has 2 gaskets.
 

mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
Winner winner. This is the exact leak I had and it turned out to be the oil cooler elbow to block side. Other possibility is the crossover tube from the water pump as it goes into the oil cooler. The elbow from cooler to block also has 2 gaskets.

Does anyone have any pictures of it? The exact locations that you are referring too? I am not so mechanically inclined when it comes to fixing these trucks. Thanks.
 

Cougar281

Well-known member
Sep 11, 2006
1,962
384
83
St Louis, MO
The Expansion tank. Would need to grab a radiator pressure test kit that has the screw on adapter for it. I don't recall if the last one I 'rented' had that or not - I was testing a radiator with a regular cap.
 

Cougar281

Well-known member
Sep 11, 2006
1,962
384
83
St Louis, MO
An update on this - The truck hasn't leaked a drop of coolant since it's been in my driveway. On Friday, I finally pressurized the cooling system. I pumped it up to 10psi and let it sit for over an hour. Not a drop of coolant and after that hour plus, the gauge showed about a 1psi drop of pressure, which could potentially be accounted for with the fact that when I started the test, the sun was shining full on the engine, and by the time I took it down, the sun had been off it for at least half an hour. I would have thought that since it was leaking while sitting, 10psi should have made for a nice stream of coolant, but no dice. Any thoughts?
 
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mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
An update on this - The truck hasn't leaked a drop of coolant since it's been in my driveway. On Friday, I finally pressurized the cooling system. I pumped it up to 10psi and let it sit for over an hour. Not a drop of coolant and after that hour plus, the gauge showed about a 1psi drop of pressure, which could potentially be accounted for with the fact that when I started the test, the sun was shining full on the engine, and by the time I took it down, the sun had been off it for at least half an hour. I would have thought that since it was leaking while sitting, 10psi should have made for a nice stream of coolant, but no dice. Any thoughts?

I read a previous post above to try 15 psi. Would that help out any? Thanks!!
 
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02greysixer

Active member
Jun 4, 2011
1,829
7
38
North Central FL
When you pressurized the system was the engine hot or stone cold? Try it both ways. I've seen trucks leak worse cold and not hot or vice versa. 15psi won't hurt.

Sent from my SAMSUNG-SM-G870A using Tapatalk
 

mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
So the truck has been sitting at Cougar281's house and it was pressurized like Cougar281 stated and did not show any symptoms of leaking. I brought the truck back to my house and put in the garage low and behold it started to leak again and only has been sitting in the garage for a week. It is leaking from the drivers side and comes down next to the rear main seal were the transmission connect up. Does any one have pictures of the cooling system on the drivers side and what fitting could be leaking? I am including more pictures of the leak. Thank you in advance.
 

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Harbin_22

Active member
Dec 4, 2010
3,858
7
38
Southern Indiana
Almost guarantee it is the oil cooler elbow to adapter housing. I had one do it to me only after the truck cooled off. As the temp dropped, it would get worst. It finally gave out all the way before I decided to fit it. Pain in the ass to fix and get a little messy, but not to terrible to do.
 

mbc230

Member
Apr 18, 2013
57
1
8
St. Louis, MO
Leak Located

So Cougar281 came over my house and we found out where it was leaking from. I borrowed the picture from ty_LBZ and circled the area in "RED" of where the leak is coming from and attached it to this post. What we are looking for are the part numbers for the gasket set needed to fix the leak along with any other parts / gaskets we can replace while we have the elbow off the motor since we already have it apart. Thank you in advance.
 

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