Last week I was driving for about an hr on the highway when I heard a loud pop noise come from under the engine. A few minutes later, the engine overheated and shut down. I was pushed to the nearest gas station, where I saw that my overflow tank lid popped off. I added water, and made the 27 mile drive home (not using highway) without overheating and monitoring engine temps the whole way home, which never even went over 200 deg F. I drove again for about 30-40 miles total the next week. I just did an oil change, there was no milkshake, is that long enough for milkshake to occur if the head gasket was blown during the overheat? Nothing has run weird, everything has been totally normal since the overheat. Anyway, I went to swap the mostly water out for coolant, and I noticed the thermostat hadn’t been changed in this discos 20 years of life and 150,000 miles. However, the hoses were remarkably supple and easy to remove. I’m attaching some pictures of the thermostat here, it was pretty messed up. (Besides this time, the engine never overheated for me since owning for the past year. ) I’ve already ordered a replacement, but I’m just curious if there’s anything else I need to look for as a result of these events while I’m under the hood. Thank you.


Looks pretty messed up in there

Hose bulbs snapped off when removing the hose, heard rattling in the thermostat and saw it was all messed up inside

 

Good lord.

Most of the plastic cooling bits under the hood will be brittle by now. I'd replace all the cooling hoses, especially the plastic tubes that run from the expansion tank to the throttle body heater, and the expansion tank to the radiator. They snap with age. The Y-connector at the water pump will break with age too. Same with the plastic T (where the bleed screw is) at the top of the motor.

 

do a really good cooling system flush normal and reverse, that looks terrible.

 

I’ll be sure to check those plastic parts, thank you.

 

will do, Thank you.

 

Daaaaaamn...... you are replacing it with a 180 deg thermostat? Now I'm guessing mine should be replaced, it's a white plastic original one too.

 

yeah replacing with the “softer spring for warmer climates” thermostat from Atlantic British. Not sure if that’s 180 but it will definitely open up sooner.

 

If that was original and you said you never went over 200 degrees I highly doubt that’s original tstat

 

Maybe, manufacture date on the t/stat showed April 2000 anyway. I work from home so this gets driven on the weekends mostly.

 

Those hoses are soft because they are 20 years old and about to split. While you have the coolant out replace ALL the hoses, the radiator, and the coolant bottle. Your head gaskets are probably compromised now and will fail in less than 10k. Classic Rover situation.