sight tubes are by far one of the ugliest things possible to put in your engine bay...if you want one ill add it but im going to charge extra not for the labor but for the eyesore.

opening the lid and peeking in is part of regular maintenance. Do you have a sight tube for your oil in your engine? Transmission fluid/gear oil? Blinker fluid?

Now if I can come up with a way to have a "sight" window on the tank not a piece of tubing hanging off the side then I'm all for it!


On the note of being pressurized, I have been giving this a TON of thoughts from an engineering standpoint and I do not see any reason at all why this is even necessary. There are no known issues with a "normally non pressurized" coolant overflow reservoir.

you do realize that it's a little more of a pain in the *** to check fluid levels in a metal tank than a clear plastic one, right? So if there's an easy solution out there that customers want that offends your sense of aesthetics, you might have to get over yourself and do it unless you can come up with a better idea. I for one won't be purchasing a tank I can't look at and tell fluid levels.

Nissan gave it a ton of thought too, and made a conscious decision to change to a pressurized system. I'd defer to them on something like that.

I hear ya on the little more of a pain in the *** to check! I do respect that but the tubes out the site have been discussed by everyone in the shop and we have all agreed that its not a route we want to see our products take. That being said though. I might have a neat idea for an actual "window" and we can talk about that right now.

Does the window have to be positioned on the side of the tank? Notice the oem tank is plastic and the "gauge" is on the backside of the container which is difficult to see since you have to look from inside the engine bay towards the front of the car to see the min/max lines. I see a feasible way to add a sight glass or a sealed window to the top of the tank without too much fuss.

The window or and even the SIGHT TUBE poses a real issue in regards to a pressurized tank. The sight tubes absolutely cannot withstand the pressure of a coolant system.

On the topic of a pressurized tank, I along with millions of people probably feel the same way about things big companies do in terms of engineering or product manufacturing. Just because they put some thought into it doesn't mean it was the right idea to move forward on. We dont know the true reason they changed the design of the tank, I am all for doing some testing to figure out what the true pressure reaches inside the oem car with oem pressurized coolant reservoir and then coming up with a solution from there.

There has to be a concise reason why the tank design changes from a non pressurized, to a pressurized. The reason might not be a good one but there is a reason for sure! Lets work together to figure out what that reason is and if it has a direct impact on the performance of the car in any way.

They wouldn't have made a change and spent money if there wasn't a clear reason why. These cars run hot already. If I had to guess, they wanted to increase cooling performance since they were stressing the system more adding the oil cooler the 2012s+ got.

To be fair and coming from an angle that most wouldnt think of...just because there was a clear reason, doesnt mean the reason was the right reason. That being said. Whats your take on how a pressurized tank increases the cooling performance?

What is the stock psi the coolant cap can take on the older style vs the new style? Is the new cap rated at a higher psi? What are the psi differences between the different types?

Since I've got a 2011 with the nonpressurized system, I'm just spitballing. My guess was that they needed to increase the system pressure, but that became an issue with a nonpressurized overflow tank thus the pressurized tank. It's a (slightly) more complicated and expensive system, so I would assume they would need a solid reason to change it.

I would think that this is definitely related to the oil cooler lines on the 2012+ models. Probably needed a consistent flow at a certain pressure to guarantee cooling...

Agreed.

It's most likely "OE Overkill", but it would be silly to take a step backwards.

I can see a reason for needing a higher pressure and thats what the cap on the actual coolant system (taking the reservoir out of the equation) is for.The whole purpose of the tank is that when the system heats up and the main cap releases pressure, the coolant has to have a place to go, hence the reservoir. When the system cools the coolant is "sucked" back into the system.

So raising the pressure of the main system (with or without a reservoir) has no effect whatsoever on how big, what style (pressurized or non) of reservoir tank being used.

That is my take thus far on a performance standpoint, I dont think that it matters. NOW! this is my take on a possible reason WHY 'they may have changed and to me seems the most logical right now.

With a non pressurized you are relying on the main coolant system to overlow at certain pressures into the vented tank. As the system cools the system sucks the coolant back into the radiator. Perhaps Nissan found that there was not enough "suck" force to get the required coolant back into the system and thats why they changed to the pressurized system?

The pressurized system would always have some degree of pressure which would force the coolant back into the system as the system cooled instead of relying on what vacuum forces the cooling system had to offer at the time of cooldown.

That is the ONLY good explanation I have at this point in time.

Would you say you agree or disagree? What are your thoughts?

to add to my statements above. The reason for a pressure cap on the new style tank is purely for safety. If the pressures get too high, it needs a way to vent that pressure to prevent over pressure.

Could be. I've only seen pics of the 2012 setup, so I'm just thinking out loud. You might be right. Maybe there was too much of a pressure differential between the unpressurized part of the system and the pressurized part. Hell, maybe they just got a really good deal on a large quantity of pressurized tanks from their supplier. :rofl2:

chuck now you're thinkin! Big business does funny things..hell maybe the guy that signed off on that new tank, his cousin owns the facility that makes them and needed more money to pay for stippers and blow for the year? Maybe they found a way to manufacture the new tank which no doubt is a better engineered product, cheaper and decided it was more bang for the buck. those would be the reasons i would lean towards over a performance standpoint.

moving forward the thing to look into is this, with a pressurized reservoir, is it needed or does the non pressurized one work just fine. if the non pressurized one doesnt work the same if not better then I will go the pressurized route. If there is no gain at all to be seen or no problem at all...then a non pressurized one is most cost effective in this product over a pressurized. best bang for the buck.

With a metal tank, what's the issue? The window? I mean, the only difference between a pressurized and nonpressurized metal nonwindowed tank would be a gasket on the cap, right?

wrong. same reason you dont use a car window in a submarine. the pressure differences.

inside the tank the pressure will be greater than outside the tank. You need to engineer something that can take the pressures without failure. So 1) plastic needs to be able to not melt and deform or 2) glass needs to be thick enough to not break.

I think we just said the same thing. :confused:

If there is no window, what would the difference between a pressurized and nonpressurized metal tank?