New type of radiator system?

Just bought a new Frontier. I pulled the cap off the reservoir and it had a LOT of pressure when it unsealed. Didn’t expect that but the reservoir cap looks like a regular radiator cap. Then I took the radiator cap off, no pressure, but it did not look like a radiator cap, it didn’t have the pressure relief valve built in, it was just to seal the radiator and nothing else.

First thing I though was that the caps got mixed up at the factory or dealership, but the label on top of the radiator cap said “Do not fit on overflow tank.”

The overflow tank was at the proper level but the top tank of the radiator was almost dry. Something doesn’t seem right.

My thought as it cools it sucks the fluid back into the radiator.

A number of makes have pressurized overflow tanks.

Volkswagen has used pressurized coolant reservoirs since 1975.

Pressurized reservoirs became common in the 1990’s with the low hood lines and long life coolant. With the low radiator height the reservoir is a better fill location so the “radiator cap” is not needed. My 1996 and 2000 Dodges do not have a radiator cap.

I am surprised that Nissan calls that an “overflow tank”, that term is from the 1970’s when cars need a reservoir to catch coolant that would otherwise spill onto the road.

My granddaughter’s93 Buick Regal had this type of system, the only way I could figure out to fill the radiator was to unbolt the resivoir and elevate it while I poured in the coolant.

OUR 95 Aurora was like that. When I changed coolant, I would fill the radiator through the upper hose first.

My 83 Saab 900 didn’t have a radiator cap. Only the burp bottle which was pressurized. I replaced the car in 2001 when I couldn’t find a replacement bottle which cracked in a national recycle yard network.

A little off-topic, but did you buy a 2021 with the new motor and transmission? I like my 2019 but an extra 49 HP and 4 gear ratios in the transmission would be great.

3.8 Dohc motor. Is it an offshoot of the Z motors?

It’s a 2020 but it has the new motor (3.8l) and 9 speed transmission. The first three gears come really fast, like within the first 15 or 20 mph. Shifts are like one to one and a half seconds apart. Then you don’t feel them anymore, it’s just like driving the CVT after that.

I don’t know. I heard it is a brand new design and since the Frontier has been a slow seller lately, they decided it would be a good place to test it out. Piss off fewer customers if anything goes wrong. The 9 speed will replace the CVT in the Rouge in 2022.

BTW, took it out on a little spin today, it did not overheat. The GM vehicles with the pressurized overflow tank have a large radiator hose size hose at the bottom of the tank and a bleed line coming into the top so that the radiator fills completely when the engine is running. I don’t see the big hose at the bottom of this one but there is a lot of stuff blocking the view, there seems to be a bleed line at the top but I was not able to trace it yet, too much stuff in the way.

When I go back to the dealer to get the plates, I’ll check with the service dept about the caps. Meanwhile I am reading the owners manual and putting a ceramic finish on it. That stuff is a PITA to apply, especially without a powered buffer. Doing it by hand.

it’s a slightly larger cousin of the pathfinder’s 3.5V6 and a new generation of the VQ engine that Nissan has used for just about everything.

Not new, thinking I have seen some decade old systems with the same setup.

Whew, Biden says the US will be all elec cars by 2035. Not far off. So long 3.5 vq motors.

Nissan has been using that setup for years now. The “cap” on the radiator is a fill point for when the cooling system is serviced. It shouldn’t be opened under normal circumstances.

Coolant tank, reservoir, degas bottle, surge tank, whatever you call it just about all cars use a pressurized tank integrated into the cooling system.

Our Volvo is 11 years old and gets waxed twice a year and still looks great . Don’t see the need for Ceramic on the vehicle . Just seems like something to argue with the insurance company in case of body damage.

never mind

Nope, just the federal fleet.

Pressurized cooling system reservoir in a 1964 Ford Galaxy;

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Gee that was our driver’s training car, but they never let us look under the hood. Our 61 Merc never had that though.

I remember working on those Fords at the gas station/garage. Kind of a pain, got in the way of working on the engine a bit.