My previous thread about 2.2 cooling system, hoses & such, rounded up with a mention regarding filler neck 'T' being a fragile part. So I followed up in that direction.
I had to suspect the radiator/coolant system filler neck because I found the coolant level -low- when I'd remove the cap, and the recovery tank wasn't holding a cold -or- hot level. I'd add coolant, run the engine with the front end elevated (to burp air out of engine cavities) and monitor engine temperature at DIC .
When I'd come back after cool down, and remove the fill cap, the coolant would be -gone- again. I did this a half-dozen times, then came here and began researching.
I had realized, before ever discovering this problem, that Dorman markets a reproduction for this part, and I wondered why, the aftermarket doesn't tool-up and produce parts this particular unless there is a pronounced problem.
I read more than one post here where the OP discovered the coolant steaming off through a crack somewhere on these filler necks.
My car -never- indicated HOT, or threw any code, but when I discovered missing coolant I quit driving it until I could make effort to learn of, and fix, any cooling system problem.
I'd appreciate to learn -WHERE- the Engine Coolant Temperature sensor is located on the 2.2. The sensor MUST be functioning, but I'm cautious that it must be stressed, so installing a fresh AC-Delco replacement seems like -Best Practice- .
Also, is there a coolant temperature radiator fan switch ? And if the 2.2 is so outfitted, WHERE would -that- be located?
I have never witnessed the radiator fans operating, and I'm pretty certain that the fan SHOULD have run now & again during this episode.
The Dorman part arrived today with my R.A. -KYB- parts bonanza, and I'd like to wrap up the cooling system before this weekend.

 

The easy test for the cooling fan is to run with the AC on. The cooling fan is supposed to run whenever the compressor is on.

 

The switch is a transistor in the ECM.
This is the 21st century.

 

Just last week, I replaced the plastic one with an aluminum filler neck since the plastic ones apparently had a history of cracking. Easy to believe since the cap always needed to be removed with channel locks.

I ran into a problem too. It did not leak under pressure, but did puke the extra heated coolant into the overflow or recovery tank as designed. The issue is that it does not suck the coolant back into the radiator when it cools down. The culprit seems to be the connection of the small hose stub into the filler neck itself. It is not welded, but threaded and attempted to be sealed with teflon tape. With a leak in the small line setup, it will not suck the coolant back in.

No reason why it's still not drivable, I would just rather have no air in the pressurized coolant. The recovery system was first implemented in the Chevy Vega back in 1970 because of it's small coolant capacity. Before then all radiators ran with an air space in the top.
I would like to have it welded, but the only one I know that can TIG something this small in aluminum is 3 hours away. Perhaps epoxy in the threads would be a viable solution.
Last resort, I could always get the Dorman.

 

I installed one of these ,


no leaks or problems over last 5 years

 

JB Weld it.

 

Is the cap new and the correct pressure rating?
Is the coolant level in the tank at the full mark when cold. If it is too high things go wrong. You can't easily see the mark, it is near the indent.

 

I use plumbers Teflon paste sealant.

 

Looks identical to that but got mine from Amazon.
I'm going for the simplest first, new tape.
I didn't have the option, but I would have gotten the 90° one

 

I have a very similar one, but from an ebay seller. The problem is, even with Teflon tape, it still leaks. So you tighten it more. Then the cap won't go on because the nipple is threaded in so far. The nipple does have tapered threads, so that's good. I filed off a bit of the threaded part of the nipple, to allow the cap to be installed.

It seems better, but I'm going to have to keep checking the coolant level under the pressure cap periodically. I may need to file some more material off to be able to tighten the nipple more.

I agree that the 90 degree option would probably be better. The one that points straight, aligned with the big hose, the "ear" of the cap ends up right over the clamp for the small hose. This could cause an injury. Even the one with the slight offset would be better.