Coolant change with vacuum evacuator

[Michael]

So I am going to change my coolant in the next few weeks. Instead of the normal drain and bleed route, would a coolant evacuation machine be preferable? Seems like it would be much easier, less messy, and eliminate any chance of leaving air in the system.

If I attach at the expansion tank, I would be drawing from both sides anyway, would I need the thermostat to be open?

[Josh]

I only fill by vacuum now. Honestly everyone with a delorean should. If you do it properly it takes about 30mins for a bone dry system (engine block included) to fill with zero air pockets. Just hop in and drive.
No fussing around with bleeder valves and jacking the car up etc. The same vacuum fill setup can also evacuate the coolant.

No need to concern yourself with the thermostat it will get around it as it will be drawing from both sides. You will see both the hoses collapse.

[David T]

The thermostat should have a "jiggle pin" or a 1/16" hole so air will pass through. I also use a vacuum evacuator to fill but it is not 100%. You still have to bleed some air out from the radiator and water pump but it is minimal. To use it you must have a large enough air compressor to get a low enough vacuum so you pull all of the coolant in before you use up your vacuum. Depending on your equipment you may also have to block off the overflow tube so you don't lose vacuum through it. Some set-ups don't block that tube under the rad cap properly and you can't build up vacuum because it leaks out the overflow. This evacuator doesn't remove coolant, only air so the system will draw the new coolant in. And you only get one shot. If you don't pull it all in you have to start all over, draining the coolant and then filling it up again. If you don't use a coolant recovery system you will have to remove some coolant in the header tank so it is 1/2 full when cold.

[Michael]

I have access to several professional coolant evacuation machines. I didn't consider the overflow tube so that will be plugged. If I bleed the thermostat housing, I can only assume any air trapped in the radiator will eventually get pushed into the overflow tank and be dismissed without any more help from me?

Also it seems like it would be safer to intentionally slightly overfill the tank and just let it push out the excess through the overflow. I would rather have a little mess to clean up than having to start all over again because I let the tank get too low. Is that logic sound?

[Helirich]

Could you explain how this works? Google didn't help much.

[Josh]

you suck all the air out of the coolant system with a tool (vaccum filler/evaculator) and use this vaccum to draw in new coolant. It is the reverse operation to remove the coolant.

[David T]

There is always a minor amount of air in the system, especially if you don't use a coolant recovery tank. The system will "self-bleed" and yes, it will eventually wind up in the header tank. By using a recovery tank you can fill the header bottle all the way up so there is NO air in your cooling system. Just like a modern car, and you can check the level even when hot. The header tank always remains full, the coolant expands and contracts and the overflow is captured in the recovery tank and sucked back into the system as it cools and contracts. Of course your cooling system can't have any leaks or instead of going into the recovery tank, it will leak out and when it cools down you will suck in air where it leaks.

[Helirich]

you suck all the air out of the coolant system with a tool (vaccum filler/evaculator) and use this vaccum to draw in new coolant. It is the reverse operation to remove the coolant.

Well that part sounds great, but when you say vacuum, do mean like an AC pump? Are you saying that everything in coolant evaporates without a trace? What about rust and scale? I wouldnt think the coolant system could take a complete vacuum. Where does the coolent go in if you have this thing attached to the filler neck?

[David T]

It doesn't make that hard a vacuum as an A/C vacuum pump. It uses compressed air in a venturi to create the vacuum. All of the old coolant must be removed first by draining it out. You turn on the compressed air to create a vacuum inside the coolant system, shut the valve and then open another valve to draw in the new coolant already mixed in a pail. If you go over to You Tube I'm sure you can find a video of the process.

[iflights]

Michael, did you end up performing this task with the vacuum technique? Anything to share on the process unique for a DeLorean? Planning on doing this myself this spring when the car comes out of hibernation.

[Michael]

Michael, did you end up performing this task with the vacuum technique? Anything to share on the process unique for a DeLorean? Planning on doing this myself this spring when the car comes out of hibernation.

I did not because I wanted to replace some hoses. I am 100% confident it would work. I'm sure there would be a small amount of air to take out but not enough to lock the system up, (if that's even possible given the return side is larger) but doing it the old fashioned was not that hard. I will use a evac unit next time though.

[Mark D]

Even though our cars were built in Northern Ireland with an assortment of British, French, and American sourced parts, I have found that the Swedish made coolant vacuum evacuators work best, and are of the highest quality. The rated vacuum capacity is second to none, and the actuator pumps require the fewest number of cycles to build vacuum quickly and efficiently.




I recommend this type shown here:

https://dmctalk.org/attachment.php?attachmentid=68284&d=1648523275



Doing it the old fashioned way was not that hard. I will use a evac unit next time though.

Yes, the old fashioned way definitely also works.

[iflights]

I did not because I wanted to replace some hoses. I am 100% confident it would work. I'm sure there would be a small amount of air to take out but not enough to lock the system up, (if that's even possible given the return side is larger) but doing it the old fashioned was not that hard. I will use a evac unit next time though.

Thanks. Concerned about that last bit of air. I'll give it a try.

[dmcman73]

Thanks. Concerned about that last bit of air. I'll give it a try.

I used the vacuum fill not to long ago and it worked very well. Here is what I did and my setup:

1. I do have a self bleeder on the thermostat housing to the header bottle, I left the valve I have on it open during the vacuum and fill
2. I vacuumed the coolant system out to the recommended vacuum bar stated in the instructions
3. I let the system sit for 15 minutes (or whatever the time listed in the instructions) to see if the pressure would rise substantially which would indicate a leak
4. When I filled the system, I placed the fill tube on the vacuum tool into a 1 gallon bucket and I filled the bucket with coolant. I then opened the valve on the tool to have it start drawing coolant from the bucket into the cooling system.
5. As the coolant in the 1 gallon bucket went low, I kept topping it off by filling it with more coolant. This allowed me to keep filling the system constantly without having the turn the valve off on the vacuum filler tool, remove the fill tube from the empty coolant container it came in and insert it into a new coolant bottle and re-open the valve again. Doing it that way does introduce air into the system. If you do it with the 1 gallon bucket and keep filling it with coolant none stop until the system is filled, it will be faster and not introduce any air.

Once completed, just clean everything up and run the engine and always check for drips.

[iflights]

1. I do have a self bleeder on the thermostat housing to the header bottle, I left the valve I have on it open during the vacuum and fill



Thank you. I don't have a self-bleeder.

Never had any problems with cooling in the past, and don't want to create any for myself which is why I'm being cautious here.

[Ron]

Thank you. I don't have a self-bleeder.

$.02

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[iflights]

$.02

68295
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Thanks. Got it. Put a valve in that line and I got myself a bleeder or connect/re-connect as needed.

[Ron]

Thanks. Got it. Put a valve in that line and I got myself a bleeder or connect/re-connect as needed.
The "connect/re-connect" port is at the tank-cap...it already self/auto bleeds (on level ground). :deviltail:
Vacs are great when it comes to controlling the mess. Yet I don't see it helping with air in the system since the stock system takes care of air itself. From what I've seen here, if it isn't maintenance, it's not keeping the reservoir full while the thermostat cycles a few times when first filling the system.
(When cleaning or flushing, I always try to drain from the lowest point, which calls for a lot of catch pans instead.)

[iflights]

The "connect/re-connect" port is at the tank-cap...it already self/auto bleeds (on level ground). :deviltail:
Vacs are great when it comes to controlling the mess. Yet I don't see it helping with air in the system since the stock system takes care of air itself. From what I've seen here, if it isn't maintenance, it's not keeping the reservoir full while the thermostat cycles a few times when first filling the system.
(When cleaning or flushing, I always try to drain from the lowest point, which calls for a lot of catch pans instead.)

Thanks Ron. Appreciate the insight here.