Changing Coolant but drain plug is beat..

[Maxima98SE]

so I tried changing my coolant following the Motorvate tutorial, and without touching the plugs on the block.

My drain plug is stripped and seized, I didn't even get a screwdriver near it and I had noticed this.

My question is since Ive never done this before as this is my first car; Is it as easy as pulling the bottom hose off the radiator and draining out the coolant and then pushing water through the radiator with a garden hose till It runs clear. Then replace the coolant, and clean the reservoir up.

Thanks, did a search and found the how-to but didn't cover outside of having no drain plug..

[knapp9]

Actually yes! It is that easy.

I've not loosened the radiator plug at all the last few times I've changed the coolant. Simply pulled the lower hose instead. Drains faster too. However, this does not drain the coolant from the engine block. Nor will running a garden hose in the radiator the way you described clean the old coolant out of the engine either. To do that you must refill the radiator with clear water, run the engine until the thermostat opens, and then drain the radiator once again. Do this 2 or 3 times and you should have practically all of the old coolant flushed out. Simply add 5 quarts of new coolant, and you've got a 50/50 mixture of coolant in the total system once the new coolant mixes with the water remaining in the engine block. I've never seen a post on this site where someone was able to open the engine block drain plugs without 1st taking off the exhaust pipes. So you have to do some sort of drain/refill routine to clean out the engine coolant.

Now, if you feel real frisky, and I've done this a couple of times ... drive the car about 3-4 miles (no more) after refilling the radiator with clean water the 1st time ... just long enough for the thermostart to open. Then remove the lower radiator hose and let the radiator drain again. Then open the radiator cap. Syphon action will pull the coolant out of the engine since the thermostat and radiator cap is open inaddition to draining the radiator. This is dangerous. You have to move fast. Work from the top of the engine compartment reaching down with your arm ... not from under the car reaching up.... and wear rubber gloves to protect your hands from getting scalded by the hot coolant coming out as you pull off the lower hose.

I've found that this takes so much fluid out of the engine that I only have to do 2 refills with clean water to have totally clear fluid coming out of the radiator. Then I refill with new coolant. I always use distilled water for the flushes, not the garden hose, and I clean the resevoir as you describe as well. Lastly, I recommend Nissan's expensive coolant. No other brand.

If this sounds too dangerous, just wait for the engine to cool off a little before pulling the lower hose, and the do the radiator drain/refill routine a couple of times. No syphon action of coolant out of the engine this way, but the drain/refill/run-the-engine routine eventually cleans out the engine coolant just as effectively. Takes a little longer, thats all.

Good luck.

[Maxima98SE]

Awesome, very helpful thanks alot. I was under the car today checking out the lower main hose, is there a special technique at getting it to break free from where It's connected.

When you say; "Run the motor, till the thermostat opens" does that mean once the temp guage goes up?

I have the Prestone 50/50 that I bought when I was going to change it via the DIY/How-To, also have a bottle of the Prestone Radiator Flush. 3 Gallons of distilled should cover it right?

[knapp9]

You probably still have the factory clamps on the hoses. I use a regular pliers to squeeze the clamp and pull it back off the end of the hose. On my car at least, a 3-4 mile trip gets the engine hot enough to open the thermostat. The only way I know to get a good feel if the thermo is open is to hold or touch the upper radiator hose. If you can feel hot water moving thru the inside of the hose, it means the thermostat is open. The temp guage on the dash usually goes to normal before the thermostat is actually open. You can probably use Prestone. I've read others on this site doing that. But be sure to flush out all the old coolant so there is no mixture of the two different coolants. I would not use it in my car, but that's just me.

[SilverMax_04]

Originally Posted by knapp9

. . . I would not use it {Prestone} in my car, but that's just me.

I agree.

There are many posts in Fluid & Lubs that one should only use Jap antifreeze (Nissan, Honda or Toyota brands). My car is worth enough that I will follow that advice.

[MichMaxFan]

I'm no pro, but I've read something on this site about warnings in draining hot coolant because the engine is hot and the coolant helps to dissipate the heat. W/out it, heat is not handled well and problems can occur. Also, don't put in cold fluids into the hot engine. Just somethign to read up on when changing fluids. I try to make sure the engine cools down a bit b4 draining and refilling...takes a lot of time if you have to do a few back-to-back drains, but once you're on an interval of changes, you only have to do it once at a time and then its much easier.

[1993-VG30E-GXE]

Knapp9, do you know if it's necessary to loosen the plastic bolt on the top of the rad too, when doing your procedure? This bolt isn't the air release valve according to my manual.

I notice the manual doesn't mention what this is. A guy told me it's a pressure release valve.