Hello All!

I just bought 2 gallons of Nissan Long Life Coolant for my '99 Nissan Maxima. I want to drain the radiator and re-fill with new coolant. After driving several days, I want to repeat the same steps again to get a higher percentage of new coolant mixed in.

I read on some boards that changing out the coolant on a hot engine is bad as it can warp the heads?

I will be doing this at my mechanics shop so the engine will be hot from driving. Should I wait for the engine to cool or is it safe to drain on a hot engine w/o re-precautions.

I would think most shops do not wait for engines to cool before they do radiator service on customers cars. Are they changing the fluid in an incorrect manner than?

Also, am I doing the right thing by changing the fluid twice so that a higher percentage is mixed in as I am not connecting the radiator to a flush machine as I am strictly sticking to Nissan Coolant to keep things safe.

 

I suggest you rethink your plan.

1. If you drain the coolant while the engine is hot, you're going to be in for a very painful experience.

2. there are coolant drain plugs on the block. where, I dunno on a VQ, but there's one on each side of a VE and VG. remove those and the radiator drain, and you'll get about 90% of the coolant out in one shot. refill and flush the system with water, then drain again. then refill with new coolant and you're done.

 

do shops also wait until customers cars cool before they drain the old fluid?

 

I would say they do, because if you take off the radiator cap (you want to do that, so it doesnt create a vacuum when you take out the drain plug, which would make it take about 3 hours to drain if you didnt) then scalding hot radiator fluid would explode out, making a gyser about 2 feet high, I know, I've seen it. 3rd degree burns are nothing to laugh about. They should let it cool if they value their skin

 

I just got my car flushed at The Nissan dealership and they did the engine blocks and the radatior and they said the job should take about 2-1/2 hours to do the work I got there thirty minutes before they opened up the shop. I think 30 mins of cool down was enough so they started as soon as they opened.

 

No, most shops do not wait for the car to cool down completly. 10-15 minutes is enough time for it to cool off so that the coolant will not come spraying out. You just throw a couple rags on top to catch any steam and turn the cap slowly.

Notice, I am not advocating ANYONE do this, I'm just relaying past experience, if you get burned its your own fault.

 

10-15 min won't harm the engine either right?
because warp heads are not good.

 

whats the hurry? just wait till the damn engine cools off, why risk getting burned? if your curious to find out then i dare ya.
go to the fluids section and they have plenty of threads about coolant flush and have very detailed how to's on them. search and learn my man.

 

for the record, if you can't hold part of your hand directly on the radiator fins then DO NOT remove the radiator cap or any other part of the system..

 

Whats the big rush? Let it cool and de-pressurize. More chance of getting burned than warping anything.