Coolant Leak

[Big T]

Previously mentioned this in my Rough Cold Start thread, but figured I should make it a separate post.

Have a coolant leak at the heater core pipes. Hoses were just replaced thinking they were the culprit, but the leak is still there dripping down onto the turbo down pipe and steaming off.

As was suggested here, I purchased a coolant pressure tester. It works using an air compressor to draw a vacuum on the system. I was able to draw it up to 24.5 lbs and then watch it slowly decline like 2 lbs over 5 minutes.

So I have a slow leak. Instructions then say to work on the coolant system to correct that. Great, I already knew I had a leak and the general area of the leak. I thought this tester would pressurize the system to show me exactly where the leak is without having to run the engine up past the operating temp to show the leak. This was a lame purchase. I guess I can use it down the road to fill the damn thing with coolant, but pouring coolant in was never an issue for me.

 

[MrMarty51]

Here is the pressure test system that I have. It requires some adapters to use on certain vehicles but so far has worked on all of My GM equipment.

https://www.oreillyauto.com/detail/c/stant/tools---equipment-16488/tools-23747/mechanics-tools-16816/diagnostic-16546/cap-testers---adapters-19037/a59a38c76cc3/stant-pressure-tester/sta0/12270

 

[Will L.]

@Big T
Which one did you get? Post pics

 

[Big T]

It’s cheaper to just replace the heater core.

 

[Will L.]

Yeah, thats a knock off of an actual complete test kit. You need a pressure test kit wether rent or buy if you want to test.

 

[MrMarty51]

Might be one of the parts stores would have a coolant pressure pump kit You could borrow.

 

[Big T]

Pic of the leak puddle after sitting overnight:

 

[JMJNet]

There is a few coolant connection (plastic quick connect) right under the passenger door?
Please check there.

It is also the lowest point of coolant flow.
So when it leaks, it leaks.
I had replaced the quick connect in mine with metal barb to barb.

 

[93detroit]

The 88 to 94 GMT400 trucks have the easiest heater core replacement of any vehicle I have ever worked on. Don't remember if the updated interiors in the 95 and up were any different.

 

[Big T]

There is a few coolant connection (plastic quick connect) right under the passenger door?
Please check there.

It is also the lowest point of coolant flow.
So when it leaks, it leaks.
I had replaced the quick connect in mine with metal barb to barb.

Thanks, I will be checking those today.

 

[FellowTraveler]

Thanks, I will be checking those today.

I recently had a leak at one of those rear heater hose connectors under the passenger door, changed out the "o" rings and still leaked...it turned out to be the metal fitting itself was leaking at the crimp...so, I used a UV resistant self sealing tape and leak is now in check until I can get AN fittings to convert to braided hose there.

 

[FellowTraveler]

The 88 to 94 GMT400 trucks have the easiest heater core replacement of any vehicle I have ever worked on. Don't remember if the updated interiors in the 95 and up were any different.

95/99 easy too.

 

[Big T]

I checked underneath, including the rear heater hose connectors and they are not the problem:



You can see the drip wetness starting much further forward on the Dow pipe:


Also, here’s a pic of the oil leak area around the starter. The leak fan ends just in front of the starter and comes from above the starter:

 

[Will L.]

That oil is gonna kill that starter quick.
If you can’t find/fix the oil leak right away, at least do a thorough job cleaning the starter frequently.

 

[FellowTraveler]

Well, its time to pull the passenger side rug and mat and see if a heater core leak has eaten away at the firewall.
I mention this because my GMT425 Burb core had a micro hole "never notice coolant loss" that acted like a blow torch and with the GM coolant being acidic it ate through my firewall.

 

[Big T]

Well, its time to pull the passenger side rug and mat and see if a heater core leak has eaten away at the firewall.
I mention this because my GMT425 Burb core had a micro hole "never notice coolant loss" that acted like a blow torch and with the GM coolant being acidic it ate through my firewall.

I am not getting any coolant smell in the cab. It is outside.

When I was in there replacing the glow plugs and wire harness, I replaced the hoses to the heater core because the heat insulation was soaked with coolant at the bottom bends to the heater core. Unfortunately, this did not fix the leak. It could only be the heater core itself or the coolant reservoir, which are the only two coolant sources that could be dripping down onto that upper portion of the turbo down pipe.

The oil leak is perplexing. I initially thought it was comping from the CDR. It does seem to have slowed down after I replaced the hose connection the drain pipe from the ATT to the pipe going into the engine. I guess the only way to trace that down for sure is to pull everything off that side for a look. If I'm doing that, then I might as well replace injectors.

 

[FellowTraveler]

Heater core is an easy fix.

 

[Big T]

Pretty sure I found the leak. Outermost heater hose at the heater core. Although the clamp was tight, apparently not tight enough. See drip on 28 hose in first and third pics. Since it was dripping whenever I filled the coolant reservoir, regardless of running the engine, I extra tightened the clamp, wiped everything dry and filled the reservoir to test. No drip so far.

 

[MrMarty51]

We be Happy You got that solved, I bet You are tooooh.

 

[Big T]

We be Happy You got that solved, I bet You are tooooh.

I'm happy.....even though my new heater core arrives later today.