NEED HELP 1999 Suburban Leaking Coolant from Rear...

southsidesmoka

Original poster
Member
Jul 21, 2018
121
Columbia, SC
To Whom It May Concern:

My '99 Suburban is losing coolant through damaged connections to the rear heating and cooling apparatuses. I bought the truck used approximately one month ago; everything's been great...the problem arose when an unbeknownst retreaded tire disintegrated at 85 MPH at night, causing an amount of decimation to my undercarriage, as can be seen in the photos below.

The Aftermath...Inner fender broken loose...The line that actually leaks coolant...

After having her towed home and then to Firestone the next day for a complete, new set of tires, I'm left with the above damage - broken connections, heavily bent lines and some sheet metal damage.

I did a little Binging and Googling which lead to some literature and videos. :book: It seems there are two aluminum lines which run the length of the truck from the engine bay to the rear. I've gathered that these lines supply coolant and refrigerant to the rear heating coil and cooling evaporator, respectively. Thinking this was the problem, I found, purchased and installed a rear A/C block off kit which didn't stop this coolant leak as I thought it would. :duh: What the hell did I plug??? :confused:

"I'm stumped", said the tree to the lumber-jack. I'm not sure what is connected to my radiator and allowing it to leak, but I could certainly use a little insight.

No puddles up front. When I parked her, there was only a remnant trail of coolant from the road test and a gargling noise accompanied by some light steam emitting from the mangled line pictured above.

Any and all admonition and counsel is GREATLY appreciated.

- southsidesmoka
 

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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Is the A/C still working? Rear Block off kits that I know of are for A/C system, not coolant. If your Sub is anything like TB EXT, it could be a coolant line that was damaged. You could just bypass the coolant lines at the front, basically just loop from one to the other.

But that particular line in your pics looks more like A/C. The coolant metal pipes are usually bigger than that.
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
I agree with @Mooseman on this one. Find where the coolant lines in the front go to the rear, and run a bypass hose.
 

southsidesmoka

Original poster
Member
Jul 21, 2018
121
Columbia, SC
Is the A/C still working? Rear Block off kits that I know of are for A/C system, not coolant. If your Sub is anything like TB EXT, it could be a coolant line that was damaged. You could just bypass the coolant lines at the front, basically just loop from one to the other.

But that particular line in your pics looks more like A/C. The coolant metal pipes are usually bigger than that.
@Mooseman Howdy, brother...hope all is well on your end. The A/C is still working. It didn't drain like the radiator did. It wasn't until a few moments ago that I realized that my heater hoses must be damaged and not the A/C lines - which I needlessly disconnected and plugged. So, with a hard lesson learned...

I crawled underneath the rear end and look what I saw:
90578

Refrigerant lines intact; coolant lines broken loose and hanging. Now, I question as to whether or not these lines are salvageable or do I have to run new ones? Can I simply replace the obliterated connectors? Also, when the connections were forcefully broken, could the coil itself have become damaged? Trying to minimize expense and mitigate damages all at once.

All of this because I didn't know the previous owner opted to retread old tires instead of spring for new ones... 😡

Thank you, @Mooseman et al, for your direction and advice thus far. Now that I know what is leaking from where, the task at hand is to figure out how to repair it.

- southsidesmoka
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
The question is, do you really need heat back there? Unless you regularly have passengers back there, you could just bypass it as previously mentioned.

This is an old how-to I did to replace the EXT's rear heater core. Since it's a similar system, it might give you ideas.
How to: Replace rear heater core without conversion kit
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
@southsidesmoka - Dont knock retreads to harshly. Tires do just fail, Regular tires and Retreads. Some of the guys on this forum use recaps on their daily drivers, and I am even considering getting them for my Envoy. 85% of the commercial trucks on the road use retreads. I would say about 50% of my fleet of 150 trailers, and 85 trucks use retreads.

But that being said.. It looks like the push pull connections broke, and you make just be able to cut off the plastic end off the rubber hose, and get the remaining connector off the metal end of the heater core, and just use a worm style clamp, and reconnect it all back together.
 

southsidesmoka

Original poster
Member
Jul 21, 2018
121
Columbia, SC
@southsidesmoka - Dont knock retreads to harshly. Tires do just fail, Regular tires and Retreads. Some of the guys on this forum use recaps on their daily drivers, and I am even considering getting them for my Envoy. 85% of the commercial trucks on the road use retreads. I would say about 50% of my fleet of 150 trailers, and 85 trucks use retreads.

But that being said.. It looks like the push pull connections broke, and you make just be able to cut off the plastic end off the rubber hose, and get the remaining connector off the metal end of the heater core, and just use a worm style clamp, and reconnect it all back together.

I do agree that retreads are viable; however, they have their place - 85 MPH on a Suburban over hot South Carolina interstates for hours on end is NOT it, though! :eek: Commercial fleets, 18-wheelers and other vehicles that don't haul ass like I do fair much better on retreads.

As a whole, I believe this incident is a result of tire failure which CAN indeed happen to a tire of any condition. However, had I known they were retreads, I wouldn't have been travelling at that speed.

Now, to fix the problem...with preference to keep the heat in the rear, I just need to reconnect those lines to the heater core. The best way to go about it is...as of yet unknown. Do I try and replace the quick disconnects or simply get hose clamps and appropriate hose? I'm leaning towards a permanent fix, if such a thing exists. 😁

Thank you, all, for your time and assistance.

- southsidesmoka
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
Now, to fix the problem...with preference to keep the heat in the rear, I just need to reconnect those lines to the heater core. The best way to go about it is...as of yet unknown. Do I try and replace the quick disconnects or simply get hose clamps and appropriate hose? I'm leaning towards a permanent fix, if such a thing exists. 😁

Thank you, all, for your time and assistance.

- southsidesmoka

It looks like the push pull (Edit: Quick Connects) connections broke, and you make just be able to cut off the plastic end off the rubber hose, and get the remaining connector off the metal end of the heater core, and just use a worm style clamp, and reconnect it all back together.

This is what I would do..
 
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southsidesmoka

Original poster
Member
Jul 21, 2018
121
Columbia, SC
This is what I would do..

So...I do believe I'll be cutting the crimp fittings off of the heater hoses and connecting them directly to the heater coil with hose clamps...is this the procedure in mind, @TollKeeper ? Just trying to measure twice and cut once. Thank you for your time, all.

- southsidesmoka
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
@southsidesmoka - Yea, cut the hose as close as you can to the metal crimp fittings, and then try to get off the plastic quick connects off the heater core fittings, than use a worm style hose clamp and reconnect.
 
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