Genuine Radiator Vs. O.E Aftermarket: H-body

[TheLoyale]

Alright, I've been having an issue with radiators lately (Even a full Aluminum rad) The radiator seems to leak from the Cap flange (Even with a new Genuine Cap) I've noticed with it at running temp if gently wiggle the cap, coolant spews out. I've deducted that the flanges leak because on any/all after market radiators (Murry, Motorad, etc.) they are manufactured too thin, so even the genuine cap can not seal accordingly (Genuine cap does tighten down more snugly than a cheep cap)

My question is what does the cap flange look like on the Genuine rad? Does anyone have a photo they can provide? I am planning on swapping the rad for the 4th and hopefully final time with a genuine rad so this isn't a constant issue anymore.

Another thing I have noticed is, since coolant is seeping out, somehow the cooling system is creating a negative vacuum. Once the engine cools, the lower Rad hose sucks in on its self (And when you remove the rad cap, a little gurgling happens) If the cap is leaking under pressure, how can it create a negative vacuum?

I have spent a lot of time on this engine over the past couple of years, New WP, Coolant elbows, hoses, Upper Intake, removed lower intake to reseal and clean, even cleaned the valley where the Balance shaft is (So I've been all over this engine Haha) So far this is the one thing that is puzzling.

If anyone can give some insight on if its worth buying a Genuine radiator, feel free

-Tom

[MattStrike]

Sounds like something is plugging the overflow line. It's normal for there to be some thermal expansion to warrant coolant being drawn in and back out of the overflow tank every cycle.

As far as the cap leaking, I would say it sounds like it's not going on all the way. I've got aftermarket radiators on several of my cars and haven't noticed any issues leaking past the cap unless the cap was bad.

[TheLoyale]

I will check out the overflow line and probably replace it since its getting crumbly (Maybe it collapsed inside) As for the leaking Cap, the cap is fully tightened and fits snuggly, but it seems to leak. 3 Rads later and the same issue. Maybe I'm just having bad luck haha (I've never had an issue with radiators for any other vehicle, even for an '83 Subaru)

Guess sometime before Summer, I'll snag a Genuine rad and see if its made with more quality.

[MKMike]

The OE radiators (and condensers/heater cores/evaporators) are miles above the aftermarket ones.
I had to return 4 aftermarket condensers that had bent during shipping- not by any apparent mishandling.
Even the shipping carton of the OE parts is stronger.

Have you made sure the arrow on the radiator cap points towards the overflow outlet?
I would also be looking at replacing the lower hose, at the very least, unless that's one of the new ones.
The materials degrade over time and it's not worth being stuck on the side of the road because of a $15 hose.