Question: can the cooling system self bleed small amounts of air into the overflow tank? 

Kinja'd!!! by "DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
Published 03/03/2017 at 20:48

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Unrelated car pic. So i can git dem clicks!

Kinja'd!!!


Replies (10)

Kinja'd!!! "" (bignslow)
03/03/2017 at 20:52, STARS: 1

Yes, if there is any air left in the system after normal bleeding it will slowly bleed off.

Kinja'd!!! "gogmorgo - rowing gears in a Grand Cherokee" (gogmorgo)
03/03/2017 at 20:53, STARS: 3

Usually they do to a certain degree, if they’ve been drained then refilled. If you’re asking about a falling level in your own recently refilled overflow tank, keep an eye out for drips under the engine bay, but otherwise as long as the level hits a certain point and quits dropping (make sure you’ve still got enough in there) then you’ll be fine. So long as you’re not overheating.

Kinja'd!!! "RamblinRover Luxury-Yacht" (ramblininexile)
03/03/2017 at 20:54, STARS: 1

It depends. Not if you have high points in the cooling system above the radiator/overflow tank, which a bunch of vehicles do, such as some GM trucks and U-body vans.

Kinja'd!!! "Dr. Zoidberg - RIP Oppo" (thetomselleck)
03/03/2017 at 20:54, STARS: 0

[Click]

Kinja'd!!! "DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
03/03/2017 at 20:55, STARS: 0

Time to talk to google about getting ads on my posts!

Kinja'd!!! "My X-type is too a real Jaguar" (TomSlick)
03/03/2017 at 20:57, STARS: 0

Yes burping my old X-Type was a pain in the ass.

Kinja'd!!! "DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
03/03/2017 at 20:58, STARS: 0

It should be good then. It’s definitely higher than the bleed screw. Although oddly enough the bleed screw is lower than the radiator cap. 

Kinja'd!!! "DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
03/03/2017 at 21:01, STARS: 0

No leaks thankfully. Just sometimes the temp gauge likes to fluctuate a little. My best guess is I replaced the temp gauge a few months ago and didn’t put any additional RTV on the threads, so I think some air is getting by through there. Although it was fine for a few months before doing this.

I also replaced the thermostat at the same time so I doubt it’s doing anything weird. Although who knows. And I properly bleed it afterwards.

Kinja'd!!! "gogmorgo - rowing gears in a Grand Cherokee" (gogmorgo)
03/03/2017 at 22:21, STARS: 0

Sometimes tstat scone bad out of the package. But I don’t know how frequent that is.

My Jeep’s temperature fluctuates a bit too. But I’ve changed every part of the cooling system, including the engine, except for the heater core and blower motor, and it still does it. The up/down cycle isn’t approaching overheating, is unaffected by exterior temp, and doesn’t coincide with a/c use or the electric fan coming on, or increase in load, or anything that would make sense. I’m starting to think it’s just a byproduct of 26-year old, 525,000km wires.

Kinja'd!!! "The Stig's former college room mate" (das-stig)
03/04/2017 at 10:45, STARS: 2

Yes. If it’s higher than the fill cap. Or pressurized.

That’s how I used to bleed GM V6's after water pump swaps. Bolt it together, run it down the block until the gauge (or gage, because 90's GM) is pegged- it wasn’t actually overheating, just trapped air- then lightly crack the cap loose. The overflow would gurgle as all the trapped air purges by the sudden pressure release. Once the gurgle stops, fill to spec with coolant and good to go!

Definitely not the OSHA approved method, but much faster than those stupid little bleeder screws. especially when they were broken off, because brass screw in aluminum water neck works so well.