diitto

Hi... I own a 2012 GS 6MT Convertible. I was checking stuff tonight and see that I need to add a dribble of fluid to the radiator reserve tank. I got the cap off once before (the car will soon be 2 years old) and all I recall about getting it off that time was it was profoundly hard. I have unscrewed the cap (car is cold). It has unthreaded, I think, as far as it goes. As I continue to turn counterclockwise now, it offers resistance over part of the rotation, then gets real easy, then offers resistance again on the next rotation, then easy again and so forth. And as I am turning I am lifting hard enough that the plastic tank tried to rise up as I pull. But for the life of me, it won't pop free. If I recall from the last time (long ago), it has a really tight O-ring and it's really just the resistance of that O-ring that is preventing me from removing it. I recall last time even putting a very large screwdriver blade in the gap between the cap and the top of the tank to try to pop it off but I only tried that for a moment and realized I was gonna mess something up if I continued. I did get it off the last time with GREAT difficulty and so far this time, I have had no success..

What am I doing wrong??? Do I just have to pull up even harder than I'm pulling now??? And should I pull up while the cap is offering NO resistance during the rotation??? That would seem to be the time to pull. But maybe I'm wrong...

Any help??? thanks... bob...

owc6

It's a childproof cap. PUSH down while turning.


lisa

diitto

I tried that... Still doesn't work. Something is wrong. The manual simply says

"Keep turning the pressure cap slowly, and remove it."

You may be correct but the manual certainly doesn't say anything about push and turn. Nonetheless, I tried that several times and no go.

I finally got it off tonight but there is clearly something wrong. As I unscrew it, it is quite hard to turn and I believe that is due to the two O'rings and how tight they seat into their respective seating surfaces. There is one smaller O'ring that seats down inside an inner hole and then a higher, larger O'ring that seats in the main "mouth" of the surge tank.

I pushed and turned, lifted and turned, wiggled. Everything I could imagine. Finally, after fighting with it for a good half hour (which is exactly what I went through the only other time I ever tried to remove it), it finally popped off.

The upper thread on the tank appears to be partially stripped. See pictures..

Then, after adding a tiny few ounces of 50/50 mix of Dex-cool and distilled water, I had almost as hard a time getting the cap to go back on. I had to push down very, very hard while turning and eventually it caught and I was able to crank it down all the way.

I'm taking the car in this Friday for other reasons but this is now going to be added to the list.

I just went back and tried again to unscrew the cap while doing a "push and turn". Again, no go... Beats me... Any other ideas???

thanks... bob...

darr3239

I know what you are talking about. Just turn it about 2 or 3 complete turns and forcibly start wobbling it and it will come off. Kind of weird how they made it. You do have to push it down hard to put it back on. Maybe a new cap would help?

weathermaker

It looks like the radiator threads are damaged at this point. I think you will need a new cap and radiator to fix it right.

mickey5

the top 2 threads look crossed. You can clean them up with a knife blade swiss file or let the dealer replace the tank if its under warranty.

diitto

When I get the cap where it is completely loose, thread wise, or at least so I think, it is still being held firm from coming off vertically by, I think, one or both of the O'rings that are on the cap itself.

I worked hard for nearly a half hour to finally get it to come off. As I said, this is only the second time I've taken it off, the first time being the first month I had the car (new). I looked last night and I posted a question back then as well and had many similar responses.

The car is going in to the dealer on Friday for some other stuff and I am adding this to the list.

I wonder if it would be easier to remove if the water was at least warm?? Both times I've removed the cap, the car has been stone cold. I wonder if it's designed to come off more easily when those O'rings are warm to hot?? Or maybe that makes it even harder yet although I can't imagine it being any harder.

I will take these pictures with me to show them the threads. I don't believe I did anything wrong to cause those plastic threads to deform but we will see what they have to say. The dealer, at least the one I like to go to, is 60 miles from my home so the water is going to be good and hot when I get there. But it will be there long enough that hopefully the water will cool somewhat and I am going to ask them to remove the cap while I watch. That should tell me something, either that I don't know what I'm doing or that there is something wrong with this reserve tank or the cap.

thanks for the help.

bob..

dcarter0001

The threads look like someone tried to use a screwdriver. LOL

diitto

I have an appointment to take the car in to a nearby Chevy dealer to have them address a few things, including this nearly impossbile to remove reserve tank cap. Both of the previous times I've attempted to remove it, the car was stone cold. So today, just so I can say I tried this as well, I took the car out and got it up to operating temperature. I then brought it home and after waiting a few minutes, I slowly (with a rag over the cap), unscrewed the cap. I got to the place where I heard it vent some hot air and even a tiny bit of liquid came out of the overflow tube. Once vented I went ahead and unscrewed it to the point where it was completely felt very free to turn, like as if it was completely uncoupled from the threads.

But I then lifted and wiggled and no go. Considering that the last time i had it off, I had a terrible time getting it to start threading again (had to push and turn and just keep doing that until it finally caught the threads), I was not willing to try any further to get it off today. I just wanted to see if maybe being hot somehow made the cap easier to remove. But no.

So it's off to the Chevy dealer early next week to learn more... Just reporting... bob..

Dr Dalnet

My 2013 GS had a similar problem - I unscrewed the cap and it came off leaving the pressure relief portion still in the tank.. Had to destroy the pressure part to remove and install a new cap.. VERY poor design..

diitto

Oh wow... Very interesting. I'm curious. First, what did you have to do to get the part that remained stuck in the reserve tank to come out??? And second, can you say what you think was holding that stuck part in and making it, well, be stuck??? I would assume it has to be one of the two O'rings.

When mine came out either of the two times I got it to come loose, as it came out it was so violent that I thought the cap might have broken and left a part behind as it did in your's. Yes, this is a truly bad design.

I'd really be interested in hearing your answers to the two questions above. thanks. bob

Cherokee Nation

My 08 is a bitch to get off.Ordered a new on from gmparts house,hope that cures it....

Dr Dalnet

My take was the O'rings were too dry and stuck to the sides.. I used a needle nose pliers to break out the pieces.. Used silicone grease on the new cap to hopefully prevent it from happening again..

diitto

Hi... Thanks for your response. Someone else suggested to me that I might try some silicone grease on the O'rings. But can anyone say if having such grease near and perhaps at times in contact with the Dex-Cool (and water) coolant is a problem??? If not, I will likely try the same.

Did you attempt to remove the cap after you put silicone grease on the O'rings? If so, did it come off much easier???

Holler back... thanks.. bob..

mickey5

After reading this thread I went to the garage to check my '13 base coupe with 950 miles. Never took off the cap before. It was stuck on! Applying max hand torque finally broke it loose with an audible CRACK. The O ring was dry to the touch. Applied some antifreeze solution to it from the tank and that helped putting it back some but will coat with lube next.

diitto

That was my experience as well with my 12 GS the first month I had it. I was just checking stuff on a new car when I came to find out that cap was almost unremovable. I am taking my car in Tuesday for an oil change but this is also on the list. Seems like a really poor design that has been around for quite some time as one guy reported is 08 was also hard to remove. I will report what I hear from the dealer.

thanks... bob...

Powershift

Just removed the cap on my 2011 GS to add some coolant. Cap removed easily. Turned it counterclockwise about four turns until the threads were free. Pulled up gently and the cap came right off

To install, I had to push down on the cap a bit to get the threads to engage. After that, I just turned it clockwise until it was tight and the cap began to "click".

No issue either way.

Larry

diitto

Hi Larry... Thanks for that input. It's good to know that at least some caps can be removed easily. My turns, releases from the threads but that's where the war begins. Having read some other posts, I am now pretty convinced that on my car, the O'rings are sticking hard to the wall of the reserve tank and the cap only comes free after great effort. When I have pulled up on my cap, I end up pulling and wiggling so hard that the top of the reserve tank (all plastci of course) distorts upward because I am pulling so hard... I have an appointment at my Chevy dealer tomorrow at 10:30 and I will report what I find out... thanks... bob..

darr3239

My son, a Nissan lead tech, said clear silicone grease would work, but since don't have any he agreed that spraying the gasket with silicone spray should work also. It sounds like the gasket is causing most of the problems guys are mentioning.

Powershift

The cap o-rings are EPR (or EPDM….essentially same) rubber. This compound is fine for water and AF solutions, but not for any greases or petroleum products. Some of these chemicals will cause the EPR o-rings to swell up considerably. Perhaps sometime in the past someone added something to the coolant or on the o-rings. I am not certain how EPR will react to silicone, but if I remember correctly, in the past I tired silicone grease on my old 1967 Corvette radiator cap rubber and it swelled up and distorted. No issue since I needed a new cap anyway.

Best thing may be to buy a new cap and also "chase" the threads on the reserve tank to clean them up.

Larry

LATE EDIT: I did some checking on chemical compatibility and it seems that silicone will not harm EPR. Maybe my memory from years ago is bad, or maybe I used Vaseline rather than silicone dielectric grease