Coolant Tank Cap Broke

[BluePonyGT]

Seriously? I was going to take a peek inside the tank a few days ago and the two halves of the cap separated leaving the lower part stuck in the tank. Terrible design.

So I ordered a new cap, and have it in hand. How the hell do I get the other half out of the tank w/o destroying the tank itself?

Anyone have any tricks?

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[BluePonyGT]

Never mind. I got it. The trick seems to be to separate the spring center section from the bottom part. Put the silver plunger piece back in so you can block debris from getting in the tank, then gently pry the rest out slowly without putting too much pressure on the tank at the same time. A set of right angle needle nose pliers and a screwdriver did it.

terrible design. Have a new one handy. The old one gets destroyed.

 

[jblue]

Never mind. I got it. The trick seems to be to separate the spring center section from the bottom part. Put the silver plunger piece back in so you can block debris from getting in the tank, then gently pry the rest out slowly without putting too much pressure on the tank at the same time. A set of right angle needle nose pliers and a screwdriver did it.

terrible design. Have a new one handy. The old one gets destroyed.

Is the new cap a different style compared to the old one?

 

[Farkel]

You're not alone -
https://www.mustang6g.com/forums/threads/coolant-cap-problem.136979/#post-3563898

 

[ice445]

The reason this happens is because the o rings get dry and stick really hard to the plastic. I noticed my cap was taking a stupid amount of force to twist off, so I lubed the upper and lower o rings with silicone grease. It goes on 900% easier now. Do it with the new one every once in a while and I can guarantee it will never break.

 

[BluePonyGT]

Is the new cap a different style compared to the old one?

Nope. Same.
So yeah now that I know this a small amount of silicone lube will do the trick for sure.

 

[jblue]

Nope. Same.
So yeah now that I know this a small amount of silicone lube will do the trick for sure.

Ok, thanks for the info. I have already lubed mine even though it is not a year old yet.

 

[Cobra Jet]

Ford needs to issue a TSB on this and get a revised cap design…

I’ve seen this issue on here many times since the S550’s inception and I can’t imagine how many more owners it affects that don’t even post here or go online…

it’s an inferior part made of craptastic inferior plastic, it’s not because the o-ring is not lubed. The plastic is degrading and becoming brittle due to under hood heat cycles…. And it wouldn’t be breaking down as quickly IF it were made of better materials that can resist the heat.

 

[ice445]

Ford needs to issue a TSB on this and get a revised cap design…

I’ve seen this issue on here many times since the S550’s inception and I can’t imagine how many more owners it affects that don’t even post here or go online…

it’s an inferior part made of craptastic inferior plastic, it’s not because the o-ring is not lubed. The plastic is degrading and becoming brittle due to under hood heat cycles…. And it wouldn’t be breaking down as quickly IF it were made of better materials that can resist the heat.

It's a combination of both my guy. How is that cheap plastic supposed to resist the massive amount of force you need to remove it when the o-rings are dry and seized? It was an absolute night and day difference for me after lubrication, and it's not like I overdid anything. Just a light wipe.

 

[BluePonyGT]

I think the point is if you have to use an o-ring to seal this cap at all its because of how it's designed. If it weren't for this inverted two-piece plunger design you wouldn't need o-rings once the pressure in the tank is more than the spring plunger will keep back against the inside of the housing. The heat does make the plastic hard and brittle over time, which makes it hard to remove without breaking.

Use different material, ditch the inverted design so you don't need o-rings, and use a fastener to put it together rather than weak clips that snap over a ring at the top.

 

[Strokerswild]

Garbage design, much like the plastic coolant hose T-connector...

 

[Zathras]

Is there no better aftermarket equivalent, like Stant caps? The part linked below is described as a "radiator cap" so I'm not sure it fits the overflow tank.

https://www.carparts.com/details/Fo...p/2018/GT_Premium/8_Cyl_5-dot-0L/ST10262.html

Edit: this Stant cap seems to get poor reviews on Amazon (customers complaining that it falls apart, and/or doesn't hold pressure)

 

[Vlad Soare]

It would be awesome if we could find a replacement. I know there are many aftermarket coolant tanks, which presumably don't suffer from this issue, but for people who have no need or desire to replace the entire tank, me included, a better designed cap to fit the OEM tank would be great.
Mine was still easy to remove, but I've lubricated it anyway, just in case.

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