Bleeding air, coolant system, w/ expansion tank

[Lee Ann]

Hi All,

Allow me to begin by saying that I thought Eric had produced a video about bleeding the air from a coolant system that includes an expansion tank. For the life of me, I cannot find it. Did I dream it?…I mean, for about the last month, I have been thinking constantly about cars so maybe I did dream it? 🙂

I have seen a couple different methods for this bleeding air procedure. My Haynes Manual just simply states, as part of the cooling system service (drain, flush and fill) procedure, to let the car run a couple minutes after stage 3, filling. Turn off. Add more coolant. Turn on and allow to come up to operating temp. Check for leaks.

I have seen videos/read articles where the car is jacked up (on the side where the expansion tank lives) to make it easier for the air to escape from the system and then out the expansion tank. This jacking up of the vehicle would be done after the car is at operating temp or during? And you would loosen the cap slowly (cuz the engine is hot) during the jacking point, too? This procedure seems potentially dangerous.

And of course, employing the spill proof funnel on vehicles with an actual radiator cap-running it at 2500 rpm until the fans turn on. Or using the bleeder valve during fill stage (I don’t think my car has one cuz I haven’t come across it yet).

So to say the least, there is a lot of information out there and some of it doesn’t seem so safe.

Btw the vehicle I am working on is a 1997 Saturn SC2, I4-LL0, DOHC, 1.9L 4 cyl., MFI, 5 speed manual. Thanks for any comments/suggestions you may offer.

Topic

[dave1645]

I use this method if you have an old radiator cap , remove the lower valve assembly this is the small valve on the very bottom of the cap this allows the coolant to free flow back and forth to the expansion tank
install this cap on your car run the engine at 2000 rpms for a couple on fan cycles keeping an eye on you r expansion tank level don’t let it run dry. this work great for both my jeeps then of course put your regular cap back on

[Lee Ann]

Thanks for your amazingly quick response. Appreciate it so much.

Here’s the catch though-my fan will only kick on when I turn the AC on. I have been told this is a common problem (a pattern failure?) with GM vehicles.

NOTE: Until I learned of this AC trick, I was under the impression that my cooling fan was malfunctioning and had been diagnosing it as such. However, I found myself at a stand-still because I could not get the fan connector disconnected (I think the tab had been broken off by the previous owner). That is when I ran it up to my mechanic for his advice (on this and other issues, namely diagnosis of a suspension noise). Since I had recently replaced the upper radiator hose and didn’t bleed the system yet (because of all the different info available), I figured I would back track now and just do it.

But yes, I will look at the expansion tank cap and see what I can see. Again, thanks for your response.

[Lee Ann]

I do see what you are saying, now, but unfortunately, I don’t have a radiator cap that would fit the expansion tank. I did recently buy a 2000 Honda Civic that has a “true” radiator cap, but it won’t fit my Saturn expansion tank. But thanks, that seems like a great idea! 🙂

[college man]

I think this is the video your looking for. 🙂
pick it up around 11 minutes in.

[Author]

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