fbgh2o

In replacing the alternator, I noticed that the upper radiator hose (drivers side) is leaking a bit at the clamp on the engine side. As such, I am going to replace it. Does the coolant need to be drained to replace this hose?

TIA

fortysixandtwo

The coolant system holds 2.2 gallons (or 8.3L if you prefer) of which about half will drain when removing the upper radiator hose.
I would just drain the system and replace with fresh coolant if it hasn't been replaced in a few years.

Spidey944

Sound advice 46and2. Us Tool fans need to stick together!!

If you are quick with it, you can just change the hose, or if you are already low on coolant, you may not spill THAT much. But you will loose some and need to rebleed, and rebleed, and rebleed.

fbgh2o

Thanks for the advice. I am reluctant to drain the system as I am leery of not being able to properly refill the system and bleed it properly. Seems like many people have difficulty with this.

KLR

Unfortunately, even if you didn't fully drain it, you'd still have to bleed it after replacing this hose. The air gets trapped at the top, not the bottom. I can also confirm that you will lose about half the coolant if you pull the upper radiator hose, which will make a huge mess.

Bleeding the cooling system is really no big deal. You just need to keep carrying around a wrench for a while and openning the bleeder valve after every drive (perhaps 3-5 times total)

Spidey944

Agreed, I carry a 12mm socket/ratchet combo for over a week of driving after opening the system. And I check it periodicly afterwards too.

fbgh2o

Okay, sounds reasonable. What are the potential risks in having air trapped in the system?

Spidey944

if you have air trapped it will run warmer then usual. The temp sender needs coolant running past it to read properly and if it's got air trapped in it, it will read high.