Thermostat Rattle?
 

Just completed my Dexcool to Peak coolant flush and now noticed that when I grab the hose going to my thermostat and give it a good wiggle I can hear a rattle sound coming from my thermostat.
Is that normal?
Could it be a something that broke lose during the flush process?
Could i of jacked up the thermostat? The thermostat is about 6 months old, and yes, I did leave it on during the flushing process.
I did not add the water wetter yet and before I put the stuff in I wanted to be sure the stat doesn't need some attention and removal.
....assuming the rattle is not normal.

It shouldn't rattle. I would replace. If your lucky it is a plastic piece that may have broken off the bleeder screw in the past.

Take a peak on the inside. Look at the larger disc, at about the 2:00 position. That round spot in the flange would normally hold a ball bearing that acts as a "jiggle device" so that steam pockets can't be trapped on one side of the stat or the other. Would be normal for that to make a slight rattle. BUT, if it is busted off trash inside the stat, the rattle will move around inside the stat as the parts move.

Took it apart...the 2 top hoses.
nothing in the thermastat in the way of debris. Shook it while top hoses were off and it still has a little rattle. Hope it is just the "jiggle device".
Gauge stays where it was before...right in the middle at 3 oclock so I assume it is functioning properly.
What would be the symtoms to look out for if a thermostat is not working properly?

re: right in the middle at 3 oclock so I assume it is functioning properly

The ECU monitors the engine coolant temp (ECT) sensor. Sends that info to a couple of places, and uses it to compute a range of "X" to "Y" for the "normal" range" and while in that "normal range" display the fixed midpoint reading. Once the "normal range" has been exceeded, the gauge moves the pointer up.

So human nature being what it is, we believe that everything has been fine for the last month, when in fact we've been running a little warmer each day or so. When the guage finally decides to move, we think that it is just a little warm today... when it has been warm for a month, and now we are way hotter than normal. And we keep driving, we'll check it soon.... The digital signal has been computer filtered to a pointer equipped idiot light. Keeps obsessive owners out of the service shop, until damage is done and they can be hosed for a bigger repair bill. Heck, those pesky owners don't need an oil pressure gauge either.

At this point of the "DISCO" disease, (Discovery IS Completely Overheated") the use of an Ultra Gauge can be comforting and more precise. It takes the raw data from the sensors, which is at the OBDII diagnostic port, and displays that for you. You establish what is reasonable and proper for your truck, and can even set a reminder alarm for that. About $70.

For the D1 owners, you too can have a rattle thermostat (best if you do), and you can see the rattle device, and it goes at 12:00 position when stat is mounted. You can also have an ultra gauge. Here's a pix of just how "precise" the exist temp gauge is. Ultra Gauge fits D1s that have OBDII port.

In a D2 the rattle is OK if it sounds like something the size of a BB, not a quarter, or multiple pieces of glass shaking aroud.

Savannah,
Is that a gauge you have installed in your truck in the first picture? Pretty slick little unit.

That would be Snafu/Disco Fries. See UltraGauge Automotive Information Center and OBDII Scan Tool

You should replace both the t/stat and the coolant pressure cap when switching to a new coolant or every 60,000 miles, and no, it should not rattle.

IMHO should not rattle would depend on source of stat and when it was produced. So many today are made with that device. In some it is a pin, in some a small ball bearing in a tiny sleeve. But either should also be a tiny rattle, not like the marble inside a can of spray paint (yes, it is a glass marble). And the sound should not move around inside the "can".

Of course if the source of supply (where shop bought it, if indy) could be checked to see if a brand new out of the box of that model rattles. Did it rattle when you installed it? See pix of a typical bypass design stat, not the exact innards of a Rover stat.

I will officially call myself an expert on stats for the D2 considering I have had five (5) in my truck over the last year lol. Yes, as Buzz said, there is a little metal ball bearing inside that lets bubbles up. It rattles like a mini paint can ball. They were all different kinds too. 2 oem LR ones from dealer, 1 from AB, 1 from Auto Parts Warehouse and 1 from who knows.
I put up a post after I cut one open if you want to see what it is all about (buzz posted pic of it cut apart)