DIY Coolant Change

I just refill them until it stops, that's just me

 

If Heisenberg were an auto mechanic.

 

Thanks, I was hoping I could just buy 1 gallon jug of coolant since I don't need to do the inverter but I guess I'll get 2.

 

Our dealer will take back unopened bottle of coolant. You might ask yours.

 

He's going to need to crack the second bottle though, by all reports, it takes one-point-something gallons.

Addendum: ok, I see your point now: if he gets two but manages to squeak by with one bottle, he could possibly return the second.

 

How far do you need to turn the bleeder valve for it to open? I turned it maybe 3/4 way around and did not get anything out while refilling. Does the engine need to warm up first?

 

This is in my experience with other cars, hopefully still the case with Prius:

If the bleeder valve is open enough to be effective, as you are filling with fresh coolant mix, you'll feel a strong gush of air coming out of the valve, then coolant will start coming out.

 

Im going to be performing the coolant change on the ICE system and the inverter system with a Mity-Vac. I read the manual and it clearly states that I need at least 90psi of air to perform its function.

Question:
I picked up a 3 gallon pancake compressor that rates at 100psi. 2- jugs of undiluted Genuine Toyota SLLC Will I be able to perform the job correctly? Any suggestions?

 

Did mine without compressor

 

That's ok for psi (pressure), but any venturi vacuum pump (like the Mity-Vac) will also need a certain air flow (there should be a rating in SCFM) to develop its rated vacuum. That number ought to be in the Mity-Vac literature somewhere (or available by asking them). You might find the rating on your compressor to be too small for that; Mity-Vac probably designed their venturi for shops that have a big shop air system.

I have done coolant changes both ways, and currently, with my Gen 3, I have reverted to just-pour-it-in-and-bleed like the old-school fossil that I am. It's not really that bad (in Gen 3, anyway; Gen 2 might be harder to bleed).

The vacuum-fill approach seems really cool, but you do a bunch of prep (bring out the compressor, arrange the valves and hoses, make sure no air's in the hose and the coolant supply is higher than the system, etc.) and then there's the moment you say "here goes!" and twist the valve and watch it slurp in, and it turns out that various minor oversights in your prep will mean that you still have air in the system needing to be bled anyway. It's dandy when everything goes right.

 

Just checked the user manual for both compressor and the Mity-Vac. The compressor is rated at .6 SCFM @90 PSi. Cannot find anything regarding the rating for the Mity-Vac. I will call them when I get a chance.

Is the Venturi effect analogous to blowing across the top of a drinking straw that is submerged in liquid in which the flowing air creates negative pressure inside the straw, forcing the liquid upwards? If not, how exactly is it achieved?

 

Exactly:



If you assemble your own "vacuum coolant refill" rig and buy the venturi directly from an industrial supplier like Vaccon, you'll have access to complete specs on your venturi, and even the ability to choose a low-flow one better suited to your compressor capacity. Some of the Vaccon models will work at a lower, 60 psi pressure, where your compressor can probably do better than .6 SCFM, and if you find one that matches the available flow rate, it would take longer to evacuate your cooling system, but develop better vacuum. A venturi designed for a higher flow and used on an inadequate compressor just won't achieve as much of a vacuum as you want.

The AirLift/MityVac systems will have a lot of patent numbers splashed across them. In my understanding, the only currently live patents cover details like how their fancy multi-radiator-neck-size fittings work and such. The basic idea of using vacuum to refill a cooling system goes way far back, and I don't think you can infringe it by using, say, a venturi pump, basic hoses and rubber stoppers. Some time ago I did more research and posted that in another PriusChat thread, but don't have time to search for it. I am not a patent lawyer. Or any kind of lawyer.

 

Thank you for taking the time to share the info. I just got off the phone with Mity-Vac and they said that the SCFM rating is not stated anywhere in their literature. So I guess this will be a fun experiment. Will definitely report back my findings!

 

Did both engine and inverter coolant changes on mine at our meet ups in the last 6 months, just drain, refill, bleed air and done.

 

Hey Grit, what meetups you referring to?

 

Out in the Bay Area of California we do meetups every so often:

Possible Monthly install meets. Bay Area-Fremont

We do a fair bit of work and have a good time.

Always good to meet other members in person when you can.

 

You know if anything like that happens over here on the east coast near Philadelphia?

 

Not sure, but there’s little traffic for meetups outside of what we’ve got going on, except for the So Cal folks that meet up at @RightOnTime and @sfv41901 ’s shop regularly.

Maybe you could start a meetup.

 

You need to MAKE them happen. Start inviting Prius owners to your place.