I'm trying to fix a 1996 2.2L automatic, not the 2200 SFI.

It gets a small, recurrent air pocket in the upper radiator hose, just by the head and upper bleeder valve, after some driving. It doesn't seem to do this at idle unless it gets pretty hot. It doesn't seem to overheat, but an air pocket up there will be on the CTS, so I shut it off before it gets much of an air pocket.

I've tried bleeding it several times, replaced the thermostat, back flushed the radiator and run coolant flush. It doesn't seem to be losing any coolant, no oil in the coolant, and no sign of coolant in the oil. Upper rad hose eventually gets really warm, and the thermostat opens gradually in a pan of water, fully open at 180F.

I'm afraid it may be a bad head gasket and/or head that only leaks when it gets to the upper range of normal operating temp, and/or is driven up hills/accelerating. It's so damned inconsistent, but a small air pocket inevitably forms.

Any other thoughts? I don't want to waste someone else's money on a hydrocarbon test kit or gasket & bolt kit if there's anything else to check. Thanks.

I would do a compression test, That will let you know if youre H/G is failing, Also what color are the spark plugs?.

Well, if all else fails, you could always try one of those "head gasket in a bottle" fixes. I don't know how else you could be getting air in there and still not loosing coolant.

We tore into it without a compression test (NOT my idea, but it's too late now). Already tried a head gasket sealant that goes in the coolant: no joy ( and no surprise there). I couldn't find any obviously bad parts of the head gasket, head, or block. This is what it looks like:

First the head, cylinders 1 through 4

Cyl 1
Cyl 2
Cyl 3
Cyl 3 & 4
Cyl 4

Spark plugs:

Plug 1
Plug 2 - some deposits
Plug 3 - White deposits
Plug 4 - Blotchy on insulator - water spots?

Exhaust manifold at O2 sensor:

We tore into it without a compression test (NOT my idea, but it's too late now). Already tried a head gasket sealant that goes in the coolant: no joy ( and no surprise there). I couldn't find any obviously bad parts of the head gasket, head, or block. This is what it looks like:

First the head, cylinders 1 through 4

Cyl 1
Cyl 2
Cyl 3
Cyl 3 & 4
Cyl 4

Spark plugs:

Plug 1
Plug 2 - some deposits
Plug 3 - White deposits
Plug 4 - Blotchy on insulator - water spots?

Exhaust manifold at O2 sensor:

TTT, thanks

Looks like a head gasket has premature failure. Looks like the same thing with my dodge shadow did. Might want to get the Cyl head inspected for cracks around the valve area. Could have a hair line crack. In which will cause a future crack.

Good Luck.