Hi guys,

I have an '02 D2 with about 165k on it. This morning my wife was driving to work and all of a sudden she had a bunch of "smoke" coming from the engine compartment. She was able to pull over immediately, so the car was shut off pretty quickly. Turns out the hose coming off the top of the thermostat was off, and the tip of the nipple was broken. I've ordered a new thermostat, but I'm wondering what could have caused this.

Any thoughts?

 

If the thermostat could not open, pressure built up and blew the hose. Once you get the thermostat on check for leaks, and replace the OEM clamps with a good stainless steel clamp. Probably a good idea to pressure check the system, but it looks like it was just time for a thermostat change.

 

-I'd have to agree with the above member, it was probably a bad thermostat. I would buy the 180 gray warm weather stat to install.
Low Temp Thermostat

-If your hoses look old, cracked, or you have the stock hose with the bleeder in the hose, then now is a great time to replace those also.

-What little nipple broke? The one on the bottom of the expansion tank?

 

Since you are doing the Tstat, you should at least do all of your hoses while you are at it. If all of your coolant system components are old, then this would be a good time to begin making replacements.

 

My 2 cents worth is get upper and lower hoses and a new thermostat. Sounds like things are a little weary in that department.

I hate to mention it but I would watch it real closely unless you are sure no plastic parts traveled elsewhere in the cooling system.

 

As I read what the OP wrote it was the 1-1/4" "nipple" that is the upper inlet of the thermostat itself. The plastic of the thermostat housing and its inlets and outlets deteriorates and becomes brittle over time.

That's exactly what happened on a friends truck last year; the upper inlet cracked and crumbled. That's one reason why replacing the thermostat regularly is so often recommended on this forum.

I don't like replacing parts that are functioning just fine but a new thermostat every few years is good insurance. At a minimum inspect the thermostat carefully when you change the coolant every two years to see if there's any sign the plastic is about to crumble.

 

When looking in the hose, the flared part of the thermostat hosing was sitting in there. I did have the entire ring in two pieces so I'm confident I didn't lose any plastic. I have the Thermostat ordered, and I unfortunately didn't order the hoses at the same time so that's awesome.

 

That's good news as to the plastic!

I got my hoses on Amazon and they were here in two days... maybe they could beat the thermostat! Not super expensive...

When I replaced my hoses I honestly thought that my old ones were FINE, but they were cracked a little on the end past the clams so OK. When the new ones arrived, I realized that all of my hoses were old, and even ballooned out. Anyway, you can probably get by without them... until you can't

 

You're right. It's the "until I can't" that worries me. I've taken a look on Amazon since I'm a prime member. Would you happen to have a link to the ones you got?

I found this:

Discovery 2 Upper Radiator Hose

So I'm moving in that direction.

 

Looks the same. I am a prime member, too. I got this and this . I did not get the same lower hose as you because I was doing the inline thermostat mod. This should be your . So the three together are 104 dollars.

On that second hose, be sure and check yours before you order. That is the one I bought but when I took my original one out, it had a different setup--the heater hose (smaller hose) shot out from a main hose and not from a plastic manifold as pictured in that second one. I had to improvise to make it work.

If you want to be a TRAIL BOSS, use your savings and add and to the highest point on your hose--makes bleeding air a snap and has a place for a temperature sender if you ever want to know what your coolant temperature really is.

The AB hose you linked looks fine, too.