air pocket?

[sgull]

I recently drained quite a bit out of the cooling system from my '98 2.5L when I disconnected the coolant bypass hose at the engine block which runs up to into intake manifold so I could remove the intake manifold. I captured all the coolant that drained out, maybe a good gallon and a half I'd say.

Now after refilling the cooling system (after reinstalling the intake manifold), the coolant level is full in the radiator and in the overflow tank before I've replaced all of the coolant which originally came out. I'd say I've still got close to a third of a gallon remaining. When I refilled the coolant I made sure the heater valve was open, and I've run the engine and driven the truck around a few days now, topping off the coolant as it would take more.

But it seems to be remaining "full" now when I check the level, not going down anymore to accept the remaining amount of coolant which was in it previously. This leads me to believe there must be an air pocket within the coolant system that would need to be bled out. However, there seems to be no sign of abnormality otherwise; the heater is putting out good heat, the temperature gauge is acting normally, and the engine is running normally.

Is there some trick to making sure all the air gets bled out of the cooling system for this engine? Should I just wait it out with a few more days of driving around and figure the air will work itself out and top just top it off gradually off as it might finally accept the remaining coolant?

 

[adsm08]

I usually refill cooling systems through the heater hoses or with an air lift/radkit to avoid such issues. Anything with a thermostat below the heads is a real bugger to get all the air out.

Try blocking the bypass open and pouring some in through a heater hose. Might get some more air out.

 

[sgull]

I usually refill cooling systems through the heater hoses or with an air lift/radkit to avoid such issues.
Try blocking the bypass open and pouring some in through a heater hose. Might get some more air out.

In regard to trying to block the bypass open and pouring some in through a heater hose, can you elaborate/clarify how that would be done? What "bypass"? The heater bypass hose you mean?

Thanks

 

[sgull]

Really. I've never tried the method of filling the cooling system via a heater hose. Always just refilled it into the radiator but I guess that's not a good way anymore?

Could you describe how I can "block open" the bypass? By "bypass" do you mean the hose that's teed into the heater hose from the intake manifold? That hose? Block it?

 

[adsm08]

Just make sure the diverter in that stupid heater core bypass is open and allowing flow to the heater core. I find the best method of doing that is to throw it in the garbage and replace it with some barbs that won't bypass the heater core at all.


Filling through the heater hoses works on all engines to help get more air out of the system. The reason for that is because the heater core is the highest point in the system. Air wants to rise to the highest point. If you fill the rad, cap it, and then hold one of the heater hoses up in the air and pour coolant into it until water starts coming out the heater core. That pushes about 99% of the air up out of the block and out of the system.

 

[sgull]

Just make sure the diverter in that stupid heater core bypass is open and allowing flow to the heater core. I find the best method of doing that is to throw it in the garbage and replace it with some barbs that won't bypass the heater core at all. Filling through the heater hoses works on all engines to help get more air out of the system. The reason for that is because the heater core is the highest point in the system. Air wants to rise to the highest point. If you fill the rad, cap it, and then hold one of the heater hoses up in the air and pour coolant into it until water starts coming out the heater core. That pushes about 99% of the air up out of the block and out of the system.

I'm assuming the heater core bypass you're referring to is the small hose which is diverted with a tee off the heater outlet hose as shown in the photograph below. The diverter is just a tee and I don't know what you mean by making sure it is open. How would it be closed? Looks to me like it would always be open, allowing flow to the heater core.



Also, I'm not clear on holding one of the heater hoses up in the air and pouring coolant into it until water starts coming out of the heater core. Just disconnect one of the heater hoses (inlet hose I suppose?) at the firewall and hold it up in the air and pour coolant in it until coolant starts coming out the open inlet hose nipple of the heater core? Is that correct?

 

[adsm08]

I'm assuming the heater core bypass you're referring to is the small hose which is diverted with a tee off the heater outlet hose as shown in the photograph below. The diverter is just a tee and I don't know what you mean by making sure it is open. How would it be closed? Looks to me like it would always be open, allowing flow to the heater core.

On most 2.5L and 2.3 duratecs there was an H halve in between the heater core and the block that would bypass the heater core when the AC is on to improve cooling of the cabin. The piece in your picture there looks more like a T for a heated PCV valve. It is def not the bypass valve I am talking about.

This is the bypass valve I am talking about:

Also, I'm not clear on holding one of the heater hoses up in the air and pouring coolant into it until water starts coming out of the heater core. Just disconnect one of the heater hoses (inlet hose I suppose?) at the firewall and hold it up in the air and pour coolant in it until coolant starts coming out the open inlet hose nipple of the heater core? Is that correct?

Yeah, pretty much. Heater core doesn't care which way stuff flows through it, so it doesn't really matter much which hose you use. I'd go with the one without the T in it myself.

 

[sgull]

On most 2.5L and 2.3 duratecs there was an H halve in between the heater core and the block that would bypass the heater core when the AC is on to improve cooling of the cabin. The piece in your picture there looks more like a T for a heated PCV valve. It is def not the bypass valve I am talking about.

This is the bypass valve I am talking about:

Yeah, pretty much. Heater core doesn't care which way stuff flows through it, so it doesn't really matter much which hose you use. I'd go with the one without the T in it myself.

Okay, I don't know whether my 2.5L is a duratec or not but I do know it doesn't have one of those type valves on either of the heater hoses (my truck also is not equipped with AC). The small hose in my picture that tees off from the heater hose goes into the intake manifold.

I figure if I was to remove one of the heater hoses now to fill coolant into it as suggested, coolant would drain out of the heater core. Then I suppose I'd just start filling the disconnected hose with coolant until coolant started to flow fully and steadily from the heater core nipple from which the hose was removed? Then just quickly reconnect the hose and by doing that most if not all air trapped in the system would have been expelled?

 

[sgull]

I'd almost forgotten I have one of these type filling funnel things I've used in the past when working on my car: http://www.amazon.com/Lisle-24610-Spill-Free-Funnel/dp/B001A4EAV0/?tag=959media-20

I would think if I use it for my truck it should do the trick to expel any trapped air, since the high point in the system becomes the coolant within the funnel. At least that's the way I understand it works.

 

[adsm08]

That is not how a spill-free funnel works. A spill free seals itself to the rad cap so you don't spill. If you sit there and let it run with that thing hooked up it will usually get most of the air out, after a while, but you still have to drive it and wait for the bubble to get pushed out of the block and into the radiator.

The air pocket usually gets trapped in the block. Filling it through the heater hose pushes the air out the top of the block.

For the record, you are making this much harder than it needs to be by over thinking it.

Open heater hose, pour coolant, stop pouring when it starts making a mess.

 

[sgull]

So the spill-free funnel really doesn't work to expel all the trapped air in the cooling system out, as many of the reviewers claim it does? If there's an air pocket trapped in the block the spill-free funnel is useless in expelling such trapped air? If that's indeed the case, I'll go ahead then if there's no other way to get it out, and do as you suggest which is to open heater hose, pour coolant, stop pouring when it starts making a mess. Maybe a good idea in advance of doing that might be to drain some coolant out of the radiator to prevent a lot of coolant from running out of the heater core? Thanks, I don't mean to make this harder than it needs to be but I just wanna make sure I get the air that is apparently trapped in the system out. I guess filling the system through a heater hose is actually the proper method for this vehicle?

 

[sgull]

If I drain a few quarts or so out of the radiator should that empty the heater core so I don't get a lot of coolant running out of it when I disconnect the heater hose from it? Seems like it should if the heater core is apparently the high point in the system.

Also, another thought I had in regard to filling into the heater hose and waiting until it begins flowing out the heater core nipple from which the heater hose was removed: Wouldn't the closed thermostat prevent complete flow?

 

[adsm08]

The spill free does nothing to actually expel air. If it expelled it that means it is doing something to push it out. What it actually does is let you "over fill" the system so that as the air moves out to the radiator it come up, goes out the top, and is replaced by coolant right away. The same effect can be achieved by overfilling the overflow bottle and driving it with the rad cap on.

By filling with a spill free you initially trap more air in there because it won't vent as efficiently at first.

The only part of the cooling system closed off by the thermostat is the radiator. It plays no part in my method.

 

[sgull]

I see. Thanks for explaining. I'll proceed with doing the method as you suggest through the heater hose. Probably will use the heater hose without the tee/hose which goes to the intake manifold. By the way, should I do anything with that particular small hose that goes into the manifold while I do the procedure? Does that have any effect on contributing to trapped air?

 

[adsm08]

No need to worry about that little hose.