Coolant flange replacement - how to minimize coolant loss?

[eljay]

I will be attempting to replace the rear coolant flange on my 1.8T tomorrow, if possible, using a4mods' DIY.
I know that the best method would be to drain all coolant, but is it possible to just swap the flange without fully draining the coolant? I know on my previous car - a 1.8T Golf - my mechanic just replaced the flange without full coolant drain and I believe he only lost a bit of it.

Is there a way to minimize the loss? For example, if I keep the cap on the coolant reservoir tight, it should not drain as fast as if I loosened the cap and introduced air supply into the system, correct?

With this method, I assume that if I position my oil drain pan under the transmission, that's where most coolant will splash, right?

I have about 1.5L of undiluted coolant leftover from the previous job and I also have a new 1.5L bottle. So, with 50/50 distilled water mix, I have 6L, which is probably just what I need for a full fill, but I'm trying not to do that just to be safe.

Thanks for any tips.

[daverdfw]

when I did this job a few weeks ago, I pulled the drain plug and let that drain out, but didnt flush the rest of the system. You will lose some coolant but not a ton.

[eljay]

Thanks.
Do you recall how much you had to add back once you were done?

[S4NIK8]

Buy a fluid extractor, I have the schwaben one, and use that to drain the system. I usually vacuum out of the overflow to expansion tank line and then pull the line that runs to the turbo from the hard line and vacuum that out. Doing this drains enough coolant that I normally only lose a couple ounces doing a water pump.

[eljay]

Well, I'm aboit to tackle this now, so I can't wait to get any other tools.

[old guy]

Well, I'm aboit to tackle this now, so I can't wait to get any other tools.

Here's an easy method to remove enough coolant to replace the flange. I use it to replace the coolant reservoir as well as flush the heater core. Clicky click®

[sa_seahawker]

Wow...this takes penny pinching to a whole other level. LoL

You can get a whole gallon of G12 at a VW dealership for like $20 with a gallon of distilled water, you have two gallons of replacement.

It's been my experience that it's just sometimes best NOT to reuse fluids you take out of the car.

[old guy]

Wow...this takes penny pinching to a whole other level. LoL

You can get a whole gallon of G12 at a VW dealership for like $20 with a gallon of distilled water, you have two gallons of replacement.

It's been my experience that it's just sometimes best NOT to reuse fluids you take out of the car.

I guess I wasn't looking at it as a cost savings. For me, when it's time to change the fluid I change the fluid.

But for making a repair such as a heater core flush, flange replacement, coolant reservoir replacement, etc the method I linked to is quick and easy. No need to get the ramps out, remove the belly pan, pull the lower cts, whatever.

The fluid is neatly contained and you know exactly how much you need to put back in to insure you don't have an air bubble somewhere. Once it's all back in you know you are back to where you started.

[daverdfw]

Thanks.
Do you recall how much you had to add back once you were done?

i mixed a gallon jug with distilled water and coolant and i didnt need all of it. so not a lot.

[daverdfw]

i mixed a gallon jug with distilled water and coolant and i didnt need all of it. so not a lot.

oh and for taking of those crappy black hose clamps. get a pair of hose clamp pliers. they are worth every penny

[eljay]

Here's an easy method to remove enough coolant to replace the flange. I use it to replace the coolant reservoir as well as flush the heater core. Clicky click®

This is exactly the tip I was looking for when I posted this question!
Now, I just need to find a suitable container to collect the coolant.
Thank you!

Unfortunately, between searching for an hour for the CCT tool (I am doing valve cover gaskets at the same time) and other stuff coming up, I didn't get around to doing this yet. :(

[old guy]

Unfortunately, between searching for an hour for the CCT tool (I am doing valve cover gaskets at the same time) and other stuff coming up, I didn't get around to doing this yet. :(

Clicky click®

[eljay]

Clicky click®

Thanks, I have one already. What I meant is that I looked for it for an hour in my garage! :)

[old guy]

Thanks, I have one already. What I meant is that I looked for it for an hour in my garage! :)

Oops! Misunderstood ;)

[eljay]

so, I am, wrestling with the hose on the bottom of the flange. I pulled the clip half way out, which is where I believe it should be in the "unclipped" position. Or should i remove it completely?

[old guy]

so, I am, wrestling with the hose on the bottom of the flange. I pulled the clip half way out, which is where I believe it should be in the "unclipped" position. Or should i remove it completely?

Clicky click®

[eljay]

Clicky click®

shortly after i posted i did exactly that and it worked!
The next sob that's giving me a hard time is the bracket holding the hardline over the lower flange bolt. Can't get it off.

[old guy]

This visual might help. There is a nut, then the bracket and beneath the bracket is a stud. The stud has to come out.


Here's the stud.

[eljay]

It's the bracket under the top nut that I cannot get off, But I just found that there are two bolts holding the oil hardline to the head, so I will undo those and try again.

Is there any torque rating when putting those back on or just hand tight is good enough?

[old guy]

There probably is but I just use gudentight.

[eljay]

The flange is out!! Halfway there!

[daverdfw]

The flange is out!! Halfway there!

putting it back together is faster for sure. just start the bolts to the flange by hand and then just snug them.

[eljay]

Well, I put it all back together. Thank you for the excellent guidance old guy! It took forever manly because of those hose clamps and that's even with the hose clamp pliers!
Oh yeah, and my back is killing me.
So, I installed the new flange with new bolts (the new ones have a flanged nut rather than a separate washer), new temp sensor with o-ring, and a new coolant reservoir. I have not refilled the coolant yet. Is it as simple as filling up the reservoir, leaving the cap off, then starting the car, let it warm up and add coolant to the reservoir when it drains down?

I emptied the reservoir with the excellent tip from old guy up above and that was just over 1L. When I disconnected the lower hose from the flange, additional 0.7L or so came out. I collected about half of windshield washer bottle, so ~1.9L.

Before I do that, I hope to replace the valve cover gaskets and CCT gasket and the spark plugs. You can read about that adventure here.

Hopefully, I won't forget that coolant refill. :)

MANY THANKS again.

[daverdfw]

Well, I put it all back together. Thank you for the excellent guidance old guy! It took forever manly because of those hose clamps and that's even with the hose clamp pliers!
Oh yeah, and my back is killing me.
So, I installed the new flange with new bolts (the new ones have a flanged nut rather than a separate washer), new temp sensor with o-ring, and a new coolant reservoir. I have not refilled the coolant yet. Is it as simple as filling up the reservoir, leaving the cap off, then starting the car, let it warm up and add coolant to the reservoir when it drains down?

I emptied the reservoir with the excellent tip from old guy up above and that was just over 1L. When I disconnected the lower hose from the flange, additional 0.7L or so came out. I collected about half of windshield washer bottle, so ~1.9L.

Before I do that, I hope to replace the valve cover gaskets and CCT gasket and the spark plugs. You can read about that adventure here.

Hopefully, I won't forget that coolant refill. :)

MANY THANKS again.

Just put the coolant you drained back in as long as its clean. you might have to burp the air out using the various bleeding methods.