Merry Christmas everyone,
today my lovely discovery decided to **** coolant everywhere and overheat. It is a 98 disco 4.0 auto trans with 173000 Miles. So before today I did noticed I had a slow coolant leak wasn’t sure where it was coming from and have been working nonstop so I haven’t had time to check. I just keep and eye on fluid levels and temp. Today I started to notice loud waterfall noises coming from the heater core followed by slow warmup temps and then the temp going up to 220. I pulled over to let it cool down to try not to blow any head gaskets. I popped the bonnet and noticed coolant was leaking out of the top of the expansion tank. The radiator was just record 5months ago, I figure the initial leak is a hose. I did notice some thin bluish white smoke coming out of the exhaust upon startup the second time. My question is should I be looking for head gasket issues? Can air in my system cause overheating issues and possible smoky exhaust? Thank you for any help!

 

This could be a related to a bad cap, a small crack in the coolant reservoir, or a hole in one of the hoses.
You are going yo have to find the source that is causing air getting into your closed system. Do a search and you'll find my post when this happened to me in 2018.

 

If you system is pressurizing, the first thing I'd check is for exhaust gasses in the coolant. A test $25 test kit will give you some indication. They are not always 100% accurate, but they are a good first and low cost first step.

I hope I'm wrong but what you describe sure does sound like a blown head gasket.

 

I’m hoping it’s not head gaskets but leaning more in that direction. I’m not seeing any oil or coolant mixing yet