The oring that goes into this hose: https://i.imgur.com/ekKD9jN.jpg

Ended up looking like this: https://i.imgur.com/AfH6WF5.jpg

And dumping all my coolant all over my engine, the ground, and many other places. It's an incredibly dumb way it's designed, I can think of a thousand better ways to attach a hose. Had I not caught it, it would have completely nuked.

I took everything apart, thinking there was no way that that ring's condition would have caused all this. However, when popped a new one in, fired it up, let it warm up, took it for a spin, ran it hard, not a single drop of coolant escaped.

 

I feel your pain but I am not so sure that is a 'dumb' design. My question is why wasn't that o ring changed earlier as part of your regular maintenance?

 

Is that the original O-ring that came from the factory or has it been changed before. It almost looks like it has deteriorated and not installed wrong.I assume the design is adquite enough as your installation was leak free.

 

That o-ring wouldn't be subject to change, or even inspection during typical maintenance. It did deterioriate, likely due to age, pressure, and exposure.

The thing I don't get is, you have a hundred points where hoses connect to metal, they slide over, and have a band going around them to keep them attached. It's standard practice, no o-ring involved to fail. However, this one hoses is different, and seemingly doesn't have to be. So why add a point of failure(o-ring) when you could do it like every other hose in the car?

Edit: After giving it some more thought, I think I figured it out. I bet it's a blow-off hose. The type of connection that the clip has is not very strong at all, compared to a slip over and tighten type connection. I think the hose may be designed to blow off if the pressure gets to high, such as due to a failed t-stat. This would result in a mess on the engine, but it would be pretty clear you'd want to stop right away, but it wouldn't ruin the engine.

 

I agree with you, that is an odd choice in the design. In every car I have ever owned coolant line connections are clamped or compression fitted. I can't recall many matings that had an o-ring. You would think they would just have the hose go over a nipple and have a clamp ring on it...

 

That was what I didn't understand, it's design is much weaker and adds a point of failure that isn't there normally. That's why I think it might be by design, to let loose and blow off if the pressure gets to high.

 

That doesn't make much sense though, this is the purpose of the pressure release and coolant expansion tank. I can't think of any car manufacturer designing a blowoff hose that dumps all the coolant.

This is what you said, an unusual mating method. I can't say whether it is a bad design though, you are the only person to have a problem with this so it doesn't seem to be a widespread failure point. For you it is for sure! Finding an o-ring that fails in an 8 year old car isn't a terrible surprise, the location and use is the strange part.

 

I think O-rings have their place, especially where the sealing surface is narrow. But, O-rings have a nasty habit of slipping out of place on assembly, hence pinching and subsequent leaking.
For many years I have smeared a very, very light coat of silicon sealant on O-rings, just enough to hold it in place. Never had a subsequent leak.

 

At least it's done. I've added a few gallons of distilled water to deal with it until I could fix the issue, now time to flush the system and put in the proper mix for the approaching winter.

 

I found the same O-ring connection on my '15 Corvette Stingray. Not the main radiator hoses but, a smaller coolant return hose that runs coolant from the engine block through the water-to-oil cooler and back to the bottom of the main coolant radiator. I had to disconnect/reconnect that O-ring connector when I installed a factory secondary coolant radiator for improved high RPM cooling.

Not sure if I understand the rational for using such connector vs. the "normal" hose-clamp version as, no doubt, this connector is more complex and costs more than a slip-on, clamp-secured one.

 

Well, there you go, maybe the same dumbass engineer left Jag and went to GM!

 

For me it would be a part subject to change. Whenever, I buy a used car that is a few years old I always have my mechanic put all new hoses and ancillary parts [o-ring in this case].