Mysterious coolant leak from the rear of the engine

[Big T]

Could be worse...

View attachment 80366

In all seriousness, I really hope Ratchet gets back to us with more info. I'm curios as to what he finds.

That’s just wrong. So wrong.

 

[Rachet]

Hi guys, just wanted to let you know that I am getting close to checking out the leak. I have rented a cooling system leak tester and hope to complete the test this week. Thank you all for your input.

 

[Paveltolz]

Hi guys, just wanted to let you know that I am getting close to checking out the leak. I have rented a cooling system leak tester and hope to complete the test this week. Thank you all for your input.

Thanks for letting us know. My wife says, 'everything is figureoutable' so I'm sure you'll sort it out.

 

[MrMarty51]

 

[Rachet]

I nominate "figureoutable" to be added to a dictionary...LOL
Update: Pumped up the coolant pressure tester and low and behold the dreaded quick disconnect at the thermostat housing is leaking. Apparently when the engine is running the new Duramax fan is blowing the the coolant that is leaking through the valley and leaking out the back. At least I hope that's what it is. I fooled around with it for about an hour and got it clicked in and tried to get the aluminum tube at the right angle it to and no mas. Still leaking.
I found a new fitting with seal, just the seal, and a tool to remove the pewter fitting.
What do you guys recommend?

 

[ak diesel driver]

Most are removing the quick connect completely

 

[dbrannon79]

I second removing that junk quick connect and using a steel hose barb with some clamps. someone already did mine for me before I bought it. it's simply a hose barb threaded into the crossover with a short section of heater hose clamped to it and slid over the aluminum pipe that once went into the quick connect. there is a lip on that aluminum pipe to help keep the hose from slipping off when clamped.

if your feeling mechanically inclined and full of energy LOL you could replace that entire pipe with the pre-formed hose at the heater core with a long section of silicone heater hose. the connection at the heater core should only have one of those dreaded squeeze clamps there if it's the original. Just route it away or wrap it with some high heat wrap near the exhaust area!

 

[dbrannon79]

I hate those connectors, they will break and have to be extracted in pieces every time! iirc you'll need a 1/2" or 3/4" pipe tap to clean the threads. if your lucky a large EZ-out will get the threaded part out. most of the time I have to use a small chisel and a cut section of a hack saw blade to get them out. be prepaired to pull the whole crossover housing off the engine if a part breaks off and goes into the cooling jacket. also makes it much easier to get to when it's on a bench rather than stretching your back over the front of the truck!

 

[dbrannon79]

Now if your wanting to keep the factory line and quick connector. I do recall back when I was working as an auto mechanic someone did make a steel version of these connectors. if you can find one that isn't made of that junk pot metal. it might be worth getting.

 

[dbrannon79]

I found this on summit, be ware it's a dorman part, but their site claims it's made of steel and not aluminum.

https://www.summitracing.com/parts/rnb-800-401/make/chevrolet

 

[Big T]

I second removing that junk quick connect and using a steel hose barb with some clamps. someone already did mine for me before I bought it. it's simply a hose barb threaded into the crossover with a short section of heater hose clamped to it and slid over the aluminum pipe that once went into the quick connect. there is a lip on that aluminum pipe to help keep the hose from slipping off when clamped.

if your feeling mechanically inclined and full of energy LOL you could replace that entire pipe with the pre-formed hose at the heater core with a long section of silicone heater hose. the connection at the heater core should only have one of those dreaded squeeze clamps there if it's the original. Just route it away or wrap it with some high heat wrap near the exhaust area!

This ^^^ but I used a brass barb.

 

[Rachet]

Thanks guys, I think I will get rid of the quick disconnect with a stainless steel barbed fitting. I feel that it is a weak link in the cooling system.

 

[Big T]

Thanks guys, I think I will get rid of the quick disconnect with a stainless steel barbed fitting. I feel that it is a weak link in the cooling system.

Steel and aluminum don't mix well and will see electrolysis and corrosion. Stainless is better, but brass is best.

 

[MrMarty51]

Some parts stores might carry an actual heater hose type fitting made of brass.

 

[jrsavoie]

A plastic pex barb will also work.

I've had more leaks with stainless barbs.

Seems like we had more issues with hoses sealing to the stainless barbs

Also have to make double dog sure you use good tape and dope on the threads.

 

[dbrannon79]

Yes to that. if you have to cut and chisel the old broken one out. surely use some pipe dope liberally LOL. in some cases I have cleaned out threads free of any grease, oil and moisture and use some red RTV on the threads for a good seal.

 

[Rachet]

UPDATE: Turns out that in addition to the quick disconnect leak the thermostat housing was leaking at the attachment points. After I replaced the puter quick disconnect fitting with a stainless steel 1/2 NPT/ to 5/8 barbed fitting and added gaskets to the thermostat housing, I did have a coolant hose leak which was fixed by tightening the hose clamp. No More Leaks! I hope to post photos tonight.

 

[SnowDrift]

Here is a pic of my engine I have on the stand. I circled the two block off plates There in the same location as if they were the last intake port on the heads if they makes sense

What is the sticker about on the firewall side of the valve cover which can almost never be seen except if the engine is removed?

The pink engine from the earlier post might look better if in a Barbie Jeep.

 

[Rachet]

Here it is. There's more work to do but I don't have enough time to finish it. We are selling the house and moving and I won't take Rachet with me.

 

[dbrannon79]

What is the sticker about on the firewall side of the valve cover which can almost never be seen except if the engine is removed?
View attachment 81223
The pink engine from the earlier post might look better if in a Barbie Jeep.

Honestly I have never taken the time to read it. I will have to look.