Those flat chunks are a calcium buildup that occurs when water that is not distilled is used to top up coolant. They extend left to right over the full length of each row, with very little space between. It blocks the tubes, and the bottom rows are mucho kooler than the top. Pretty soon you have half a radiator. The plastic tank makes the D2 radiator so fragile that most rad shops won't open one up to rod out. Cheaper to get new rad.

The white chunks are not Dexcool, anyone can get this.

If an owner adds stopz leakz, it will try to combine the chunks into synthetic concrete. If you try rad flush, white vinegar, etc., the chunks are usually so large they don't get passed out of the system. Rad flush or white vinegar is a preventative and should be done every 2 years. I believe the owner manuals says coolant renew every 24 months - 30,000 miles. So most new owners of a 120,000 mile D2 should expect there have been five coolant swaps, counting the oem. When donkeys fly....

The bad thing about radiator problems is it has so litle margin for extra capacity, and it is monitored by a heat gauge that is a pathological liar.

 

I thought the white chunks were onions and I swear I saw corn in there some were.

Honestly I believe these are great trucks and just need a little more attention than other makes. The problem is that when you buy a used Discovery you don't know what your getting. We bought ours cheap so we had lots of room (money wise) to fix any common issues and have a reliable and beautiful truck. Now one more issue to do while coolant is still out, the throttle body heater plate.

 

Someone overheated while on the road and put in a thermos of Chicken Noodle Soup since that was the only fluid they had on them.

 

So, I am assuming you have got it running again, better plan on cleaning out your new t/stat again, good chance you still have and past some old crap thru the t/stat and chances are it may be partially plugged.

 

Whole cooling system is new now and should be up and running tommorow.
The new t-stat is the 180* version.

 

I was wondering were that darn can of soup went, next time just broth.

 

So here is an update to our overheating issue:
We installed a new rad, installed a new 180* t-stat, flushed the whole system clean and fired it up with much better results with temps recorded from the Ultragauge.
Idle temps are now 197 degrees (before were 215*)
Slight RPM increase (to get flow moving quicker) are now 187 degrees (before no test)
Driving temps coming up soon (need permit for road test)

I decided to pull the tanks off the old rad and this is what I found:





.

 

Yowsers, that's not good...

 

Thats why you don't use stop leak.
If you didn't flush out the engine with a hose, before installing the new t/stat, it will most likely pick up some of that crap still.

 

It's too bad, because aside from the Insulation looking Sealant, that radiator appears to be in good shape. Nice and clean.