When you read the comments that say "Change your thermostat...because they ROT", you should believe it.

I have 4 D1/D2's, gave one to my son a few years ago and extracted a promise from him to keep up with maintenance. His 2004 D2 developed a slow coolant leak at the top center port of the thermostat, that he let go for 2 years. Last week I ordered a t-stat from Rovers North, pulled his truck in the bay this morning and spent a whopping 10 minutes changing it out. Truck now runs 12 degrees cooler. (the fresh chunk missing from where the lip used to be, crumbled under very light finger pressure)







Here's a look at the old t-stat, see if you can guess why it was leaking. (and a word of caution: do not ever let your coolant system wait for attention of repairs, our Disco's are sensitive about proper cooling and crap, or more correctly, "rot" like this can leave you stranded or shell an engine)

 

Is that the original 18 year old t-stat?

 

That's an OEM from 2012 that I put in. The original factory installed stat was in good shape, but I replaced it when I did the hoses in 2012.

That's the first one that I've seen rot, literally, from the inside out. I replaced the T-pipe with an aluminum one, but the original was in good shape so I've shelved it was a spare part for road trips.

 

See also Official Extinct In-line Thermostat Mod…

DRW

 

I just read through that...excellent take on the original problems. Tthis issue gave me good reason to start scratching my head and thinking about an aluminum housing (though I haven't looked in to sourcing the t-stat itself). I'm pretty handy with the TIG and aluminum, so I may give it a spin and see what I can fab. Just not a fan of plastic, or fiber polycarb in high temp applications.

I haven't had the myriad of cooling problems that other folks have seen, all my trucks idle out at around 194F, run out about 188-192F on the highway and the worst I've seen is 201F, pulling about 1500 lbs of bikes/camper. (I replaced the fan/clutch, radiator and hoses on all of them before I ever filled the tank)
Thanks for the heads-up.