I'm about to tackle a coolant change this weekend and just need one thing clarified. This DIY states to keep the radiator cap OFF, while Billman's How To says to keep replacing the radiator cap after filling. Can it be done either way?

 

This is how I did it. The only reason I didn't put the cap on and run the engine was to keep pressure from building in the system- you NEVER open the rad cap when the engine is hot. Unless you really hate your skin.

Now, you can put the rad cap on to help push the rad fluid around with the engine OFF. I put my hand over the rad to create a seal, and squeezed the top rad hose to help flush the coolant around. Sometimes when you squeeze that rad hose and the cap is off, you shoot coolant out of the rad itself.

good luck, hope this helps.

darcy

 

Why not just use that big yellow funnel thing, that seals/attaches on the top and lets you burp air out. That's prolly the most fool proof way. Ez pZ

 

It almost does the job perfectly, I still like to crack the bleeder one time for peace of mind.

 

Just wrapping up from doing this on my S.

Two issues I was having:
- I couldn't get my fans to turn on, even though the car was hot and heater air very hot.
- Like an idiot, I kept burning my hand on the top rad hose while squeezing it. Hahaha.

So wear an oven mit or something while you do this!

Awesome write up!!

 

ive raised the car up to help with the process at times... ive also revved the engine to help get bubbles out, the yellow funnel for rads really does help.

 

Excellent write-up. Accurate, thorough and funny! I actually followed MOST of it, and I would like to add a little bit to make this even easier:

I do think that leaving the rear air bleed off is fine. I left mine off until I saw coolant coming out of it. I then capped it off.

You can skip the whole 'squeeze upper radiator hose, open air bleed, etc. by buying an inexpensive service tool that DOES ALL THE WORK FOR YOU!
I bought a "SPILL-FREE Funnel" that is used especially for this task. The way it works is that instead of burping the radiator hose and using the air bleed, it allows you to place a large, spill-proof funnel into the radiator cap opening that completely seals a large funnel into the opening.
This way, you simply allow the car to warm up fully, and as the air travels through the system, the air goes to to the top of the radiator opening, where the spill-proof funnel sits, full of coolant.

By being full of coolant, this does a couple of things -

A) It allows the air to simply bubble up and out and
B) It allows coolant to automatically replace it (Since the funnel is full of coolant)





I purchased mine from NAPA, part number 77-4000. It is around $30-40 as I recall (I bought mine years ago). Doing it this way, allows you to completely avoid the issues of needing to shut down if/when the coolant comes out the radiator filler hole, and eliminates needing to sit and burp it and turn the vehicle on and off. You do NOT run the risk of scalding yourself with the hot coolant. You don't need to touch the hot radiator hose, and you don't touch the air bleed when it is hot. You don't need to tun the car on and off. I would also argue that it does a much more-thorough job of eliminating air, as all you do is keep waiting until the car is completely hot, and the thermostat is wide open, and all the coolant is circulating. Other than these recommendations, I think this is an excellent post.



Sincerely,

Y2K4S2K

 

The yellow funnel works great. Looks like the Napa ones are made by Lisle. I can't imagine doing a coolant change without one as it's quicker, less messy and whatever coolant is left in the funnel can be used for the reservoir. Squeeze the coolant hose and watch air bubbles come out.

 

only way to go right there! no other way!

 

so is it just set heat to max, drain the old coolant out, loosen front bleeder, attach funnel, fill till some coolant comes out of the bleeder, close bleeder, fill funnel halfway, turn car on, wait for a few fan cycles or until the bubbles stop, celebrate?