Coolant leak at quick connect repair tips please

[billschroeder5842]

Hey all I discovered a leak in my coolant system on my 91 with about 85k on the clock.

I drove the car to work today and it was great. I pulled into my garage after work for my obsessive, dust off and quick clean before the car cover went on and I found a puddle of coolant on the floor. SH*T!

I checked it out and it looks like the leak was coming from the "quick connect" fitting for the heater core inlet hose down (way down) on the thermostat housing.

I had the metal fitting (from Jerry's) that threads into the thermostat housing replaced a couple of years ago as the original was heavily corroded. At that time I put in a new plastic quick connect fitting. The hose is original to the car.

So, what do you all think? Is this a "take it apart" and see what happens or is there a common theme to this piece leaking. Also, Id appreciate any tips on the repair, as that part is really a PITA to put a hand on.

Thanks!

[1991 Corvette ZR-1]

Bill, leaking diff and leaking coolant. What?s next right? Sorry to hear about that but I have been wondering about this as that entire setup of coolant hoses is a complex array of crimps and hard metal lines. I wonder what a replacement option would be for the entire assembly.

[billschroeder5842]

I have to keep reminding myself that this is the fun part of the hobby.

I took at look at the FSM and looks like the best way to attack this situation is to remove the whole housing from the bottom of the car.

[A26B]

I have always thought that if I was ever faced with replacing the hybrid alum tube, hose & fancy fittings....... that I would install a hose barb on the thermostat in the threaded hole and run both hoses all the way to the heater core, either silicone or black heater hose.

[Locobob]

I was just thinking about this. I don't currently have a leak but those hoses are 30 years old and I'm in the process of redoing my radiator set-up so it crossed my mind that maybe this would be the ideal time to freshen things up. Has anyone installed AN fittings on the thermostat housing and run new hose all the way back like Jerry mentioned?

[1991 Corvette ZR-1]

Originally Posted by Locobob

I was just thinking about this. I don't currently have a leak but those hoses are 30 years old and I'm in the process of redoing my radiator set-up so it crossed my mind that maybe this would be the ideal time to freshen things up. Has anyone installed AN fittings on the thermostat housing and run new hose all the way back like Jerry mentioned?

I swiped this off CF for a 427 ZR-1 for sale. Not sure of exactly what is going on but could be what Jerry mentioned.

[billschroeder5842]

I had a shop do that last fitting as the "pot metal" fitting broke off and it needed to be retreaded before we put a Jerry's steel fitting into the housing.

Since I was "hands off" on this last one, is there something "internal" to the connection that could cause a leak? Like a bad "O" ring?

[WVZR-1]

Originally Posted by billschroeder5842

I had a shop do that last fitting as the "pot metal" fitting broke off and it needed to be retreaded before we put a Jerry's steel fitting into the housing.

Since I was "hands off" on this last one, is there something "internal" to the connection that could cause a leak? Like a bad "O" ring?

The nylon retainer could certainly fail. The sealing surface is internal to the fitting. GM# 10089613 retainer, discontinued years ago but after you check it's probably best to do another coupling/fitting.

**A friend mentioned a newer GM# 12543621 might work.

[billschroeder5842]

Originally Posted by WVZR-1

The nylon retainer could certainly fail. The sealing surface is internal to the fitting. GM# 10089613 retainer, discontinued years ago but after you check it's probably best to do another coupling/fitting.

**A friend mentioned a newer GM# 12543621 might work.

Thanks for the heads up. I'll be getting after this project this weekend now that I'm back from a week long business trip. First order of business is to rent a "pressure pump" from AZ and confirm the location. Funny, the fitting has been bone dry since the last time I ran the engine about a week agoso pressure and not gravity are the issue.

I do have an extra thermostat house that I picked up as a spare so an inspection is in order before I start taking things apart!

[billschroeder5842]

***UPDATE***

I got a pressure tester from the parts house and confirmed that it was the heat hose leaking at the quick connect. I attacked the situation from the top of the engine loosing the water pipes on the top along with the AC condenser to get enough room o put a hand on the fitting.

Once the fitting was out I discovered that the end of the male fitting was corroded and broken off so much so that there was no way to have it seal correctly. I decided to go another route and took out the quick connect fitting and replaced it with a standard water heater nipple. A Dremmel took care of the crimped end of the hose and i replaced it with a rubber hose and two worm clamps. Everything went back together straight forward and there are no more leaks.

All totalled it was a 3.5 hour project with the bulk of the time spent running to the parts store twice and a stop for beers.