2001 v6 heater hose quick connect question

I had replaced the Heater Core and Evap core on the car and reassembled. Took it for a test drive. the 5/8" heater hose quick-connect failed, and the hose blew off the heater core tube, spraying coolant all over the engine and smoking like crazy. Stopped immediately and got a tow back home. Admittedly, I had issues when I had re-installed that quick-connect and it's very possible that I did not push it on far enough.
Replaced the $4 clear plastic clip that goes on the end of the quick-connect. It seems to be very snugly in place now. Refilled the coolant and am in the process of bleeding the air out.

However I took a look at the 3/4" heater hose beside it, and there is a bit of wiggle on the quick-connect. If I grab the plastic quick connect and really pull hard on it, I can pull it off of the heater core tube. (which is weird because they were a nightmare to get off originally). the clear plastic clip stays on the heater core tube - the quick connect comes of the plastic clip.

So I bought replacement plastic end of the quick-connect for that hose and put it on. No difference - still a bit of wiggle, can still pull it off if I yank on it hard. I do not see any wear or damage on the black plastic part of the quick-connect. The washers and spacers are still inside it. I don't understand why it is now loose.

How much pressure does the 3/4" hose come under? How snugly does it need to fit? I was considering buying a new heater hose - but since my existing one looks fine and I replaced the plastic clip - I'm afraid that the fit will be the exact same.

I'm thinking about using some high-temp jb weld to epoxy the quick connect together. I've never worked on heater hoses before and I'm not sure how tight they need to be. I'm very worried about another catastophic connector failure - I was lucky that the failure during my test drive was only a few kms from home and happened in a parking lot.

Also - if I do decide to buy a new hose, is the 3/4" line the supply or return? (MOTORCRAFT KH1054 or MOTORCRAFT KH1104)
thanks

Update - after comparing my original heater core (which I pulled out) with the 4seasons replacement that I put in, the 3/4" tube on the core is different.

The connector is supposed to be a 3/4" tube, with a ridge about 1" back for the quick connect to latch onto. The tube is supposed to remain 3/4" past this ridge. On the original heater core, t remains 3/4" and then tapers down. On the new heater core, the diameter of the tube reduces immediately after the ridge. This causes a loose, sloppy fitting for the quick connect. It also means that if you pull the hose hard enough, there is enough slop in the clear plastic clip that the tabs can be squeezed far enough inward that the quick-connect can slide off over the top of them.

First lesson - if it ain't broke, don't replace it. I should have never touched the heater core.
Second lesson - don't trust aftermarket parts to match, even if they say they match (I learned this a long time ago, but guess I forgot)

So replacing the heater hose will not work. I can either:
1. Tear my entire dash out again and put the old heater core back in.
2. Find a way to make the quick-connect work on a narrower tube. I think I might be able to add a thin layer of jb weld inside of the plastic clip. The idea is to reduce the inner diameter of this clip by thickening the wall on the inside. - primarily on the two release tabs. I don't know if this will work, and if it does work - it will be very difficult to get this quick-connect off again without cutting it. It's going to be tricky as it still needs to clear the 3/4" diameter section of tube in front of the ridge.

gkomo said:

Can you put a metal screw type clamp over the hose after the 'ridge' to help keep it on tight?

Click to expand...

unfortunately not. The entire quick-connect mechanism is plastic - which extends past a 90 degree turn into a crimped connection to the rubber hose. I can't even swap out the quick-connect due to that crimp, I'd need to replace the hose to the next clamp.

So I would need to replace that hose with an aftermarket hose that doesn't use a quick-connect, and can fit the rubber hose over the heater core tube and then spring clamp it down. But it is unpleasant to swap the heater hoses on this car, it is very difficult to reach the spring clip and connection point on the other end of the hose. Not as bad as the other hose though.

But I'm thinking of another option. The whole problem is that the outer diameter of the heater core tube is too narrow - so maybe I just build it up by wrapping it with hvac foil tape until it's 3/4"

I am also considering putting some jb weld to bulk up the tabs on the clear plastic clip of the quick-connect.

Not sure which would work better. I think wrapping tape around a tube might be easier than getting a consistent application of epoxy.

Any opinions on which approach might be preferable, or anything I've overlooked?

Noobz347 said:

I would get a cooling system pressure tester.


Something like this:

Amazon.com

You can use it to test the connections without making everything hot.

What year is your car?

Click to expand...

Thanks. That looks very usefull.

It's a 2001.

Looks like the culprit was the new heater core.
But it would still be good to be able to monitor and test pressures.
Though I'm accumulating quite a few one-time-use tools during this project. Don't expect to be using my vacuum pump ever again (I hope)

The first two pictures is of the original heater core and the next two are the 3/4" tube fro. The new core coming through the firewall. The final picture is the new core as it is being put in. I wrapped it with some neoprene rubber as a spacer.

The part is 4Seasons 90082. It shows as a match for 2001 mustang 3.8L.

The actual core itself didnt have any identifiers on it, but the box it came it said 90082 and other than the discrepancy on the tube tapering, it looked the same as the old core.

What makes you think is the wrong core?

Here's a picture after wrapping the heater core tube with hvac tape.

Seems to be holding pressure so far. I've filled with coolant and let run for 10 to 15 mins. I have very hot air coming through the vents.

The system will.still need to suck some more coolant in from the reservoir - I'm letting it cool to.do that now.

One thing I noticed, the upper rad hose is still cool to the touch after running, but the heater hoses, especially the one I just re-attached, are incredibly hot. Hope that's normal.