XF2 coolant

I am getting ready to try XF2 waterless coolant, and I have two questions.

One, I have read multiple posts that it never needs changing, yet the advertising copy on ZipTy's site talks about seasonal drain and re-fill. Which is it?

Two, I read an article about Evans coolant, and it said it's hygroscopic (attracts water). I have a coolant overflow reservoir made from a syringe (Thanks, Trenchcoat85!), which is vented to the atmosphere. Should I still use the overflow, as the venting could allow the XF2 to draw in moisture, and contaminate the coolant?

you probably don't need the overflow tank. the thermal expansion is (guessing) only around 2-3%. the problem with regular water based coolants is that when the boiling point is reached, they turn into gas (steam) and expansion is orders of magnitude greater.

and if it is truly hygroscopic, it could take on atmospheric water- which you obviously understand.

how about a pic of your overflow tank before you remove it?

Howdy, Paw!

The XF2 instructions talk about topping up the expansion tank, so I was thinking of using a bladder/membrane at the far end of the tank, to allow expansion ad contraction, but without atmospheric air directly contacting the coolant in the tank. Either a plastic bag zip-tied to the tank, or a balloon. The bag wouldn't take as much pressure to move, whereas the pressure to inflate the balloon might hinder the process, unless I started with the balloon collapsed/recessed. I'm thinking of leaving the tank on, but disconnecting it, then run the coolant, and check the level periodically. If i don't lose anything, obviously, it's not leaking out the overflow tube, so I won't need the tank.

Don't know why the second pic is rotated.

Trenchcoat85:

Any thoughts about it needing draining/re-filling?

Related to the foregoing, I just installed a TrailTech temperature gauge and two sensors -- one on the left radiator, and the other on a left-hand cylinder mounting bolt. About 20 degrees hotter on the cylinder, but conditions were not identical. I want to see how the two different readings compare before and after the XF2. I'm going to install a switch, so I can compare virtually instantly, vs. having to stop, get off, then switch connectors.

I don't understand the seasonal drain/refill thing. maybe there is some corrosion from electrolysis?? I dunno.

I'd toss the overflow tank (nice job; watch for brush grabbing the line) and be satisfied with purging 40ml of air every time upon reaching reaching operating temperature, and sucking that back in on cool-down. I would think your coolant loss would be very minimal after the first 2-3 heat/cool-down cycles after topping off.

I think 20°F temperature difference would be about what I'd expect between the radiator (fan side) and the cylinder bolt. maybe a scoosh more?

Liquid water has many disadvantages, but it's hard to beat it for it's ability to hold and take away heat. I'm guessing Evan's big advantage would come into play at temps closer to "overheating" so I wouldn't be surprised if you see a minor & insignificant temperature increase during normal riding. Not to worry.

do you think you should reduce the pressure of the cap? maybe 0.8bar? does Evans say anything about that?

ps- that vent line out of your overflow tank is perfect. good job.

I don't know about the cap. Never thought about it. I haven't read everything on Evans' site. I was trying to find waterless coolant in Canada, and Evans came up. It appears that Evans' is propylene glycol, and XF2 is ethylene glycol. Tinken had posted about comparing the two, and found XF2 superior. Total price was cheaper from Slavens Racing, vs. ZipTy, so I ordered it from them. When I called to ask about the status of the order (you open an account AFTER placing an order, so the initial order isn't in the account), I was told it was back-ordered, but they could send me Evans instead. I think they think the two are interchangeable.

Thanks. I actually changed the tank vent line, because it got kinked. I'm now using a pen body (?) with a smoothie straw, vented into the rear body-work, so that it doesn't accumulate debris plugging it.