I mean
Realistically, there's one of 2 things going on
1. The fluid in there doesn't like cold temps. Would be unusual, but not unheard of. Power steering honestly isn't that sensitive of a system. I'm a big proponent of synthetic fluids.
2. Level is either too high or too low. A bubble or two in the p/s system is normal because it churns around at fairly high speed. But it should absolutely not be foaming.
- Too low will cause it to draw in air
- Too high will not allow it to purge air. I genuinely couldn't tell you why because it doesn't really make sense to me. Only that it is. Like, the reservoir is just a column of fluid sitting above the pump inlet.... Best I can figure is that too high of a fluid level won't allow the air bubbles to settle to the surface and pop before the fluid cycles again, but that's a shot in the dark. Just something I've observed when bleeding the system in the past.
If you want to change it, the best way I've found to do this and get fresh fluid in the system is to:
- Evacuate fluid from the reservoir. A fluid extractor like a mityvac is a big help here. It's one of those tools that I've just taken to buy-once-cry-once because the darn things are so helpful
- Remove the return line to the reservoir and either attach the mityvac to it, or a drain hose
- Jack up the front wheels and with the engine off, turn the front wheels from lock-to-lock a bunch of times. This will help force the rest of the fluid out. If you have the fluid extractor hooked up, you'll get a good 90-95% of fluid out of the system
From there, you can fill it.
- Usual method is to reconnect the return line, fill the reservoir about half way, turn the wheels lock to lock, fill, turn, etc, until the reservoir level no longer changes. Then start the engine for a second or 2, check fluid level again, start engine again, turn from side to side, then turn everything off and go take a coffee/pizza break while you wait for the air and bubbles to settle out before doing your final check.
- Alternate method is to roll up and ear plug and plug the return hole in the reservoir. Fill up w/ fluid, then turn on the fluid extractor to draw fluid through the system before turning the key. Hook it all back up and finish the bleed as above.
Anecdotally, I've found the p/s system on my rig tends to prefer a slightly thicker fluid like royal purple. Though this may have been when my p/s pump was old and worn with a couple mm of end play in the shaft, YMMV(~150k miles)
Note: These systems take power steering fluid, not ATF. I have no idea what happens if fluids are mixed up here or why one or the other. Just reporting what the spec is.
