1990 Q45 original radiator style

[Ryantzer]

My recently purchased '90 Q45 has an aluminum radiator with plastic tanks. A '94 Q in a wrecking yard that I was pulling parts from had an all-metal radiator. Has one of these been replaced with an aftermarket radiator, or was this a model year difference? I'm thinking of grabbing the one out of the '94 if it's OEM as it can be rodded out by a radiator shop where the plastic tank radiator can't. Anybody have any insight?

[Q451990]

The 90 came with plastic end tanks. I'm guessing the 94 that you saw in junk yard was an aftermarket one. As far as I know all OEM Nissan radiators have plastic end tanks.

[BCC93QT]

1990 to 1992 are different. 93 to 95 are the same as far as my experience. .. Could be wrong but im currently replacing a 95 radiator with a 93. Its identical. The 1990 has some weird extra negatives so I've figured out.... the 1990 should NOT have a plastic jump off. But the ends yes.

[Ryantzer]

I'm aware of the additional transmission fluid cooler loop in the later models, but am just wondering if they were all aluminum/plastic construction.

[BCC93QT]

I wish I could answer that for you. I have owned now 5 G50 Q45. Never had to resort to an aftermarket. No they were not all *plastic* the radiators for the 1990-1992 I feel were way too efficient. Driving in hilltowns in winter I could never be satisfied with the heat or defroster over 50 mph. My experience. A 1993+ radiator is not a direct fit without modification. For the 1990 at least.

[Ryantzer]

There's no such thing as a radiator that's "too efficient". If your system wasn't building enough heat then there was likely a thermostat problem - the thermostat should remain closed and prevent any coolant flow through the radiator until the engine approaches operating temperature. If the thermostat is closed then it doesn't matter how efficient the radiator is because no coolant is flowing through it. I'm guessing your thermostat was either not closing properly or was the wrong temperature.

[3Q Jay]

All the 90-96 factory construction were aluminum single row with plastic end tanks.
I have an aftermarket CSF 2652 in the '95.
I got hyped up about it being a 2-row.
It is copper/brass.
I have to run G-05 exclusively to remain compatible with all metallurgy in the cooling system ( i could use basic 'green' but i won't).
The core thickness is slightly more on the 2-row than the aluminum single row. HOWEVER. I'm not convinced that the total surface area is more, especially given the fact that there are noticeably fewer stacks in the 2- row than the OE aluminum (note also that not all aluminum single row are created equal in terms of number of stacks).
My data logging using the ECU temp sensor says that the CSF has LESS reserve capacity than the OE Nissan radiator. I'm sure you could spend really big bucks for a custom Griffin or the like.

[BCC93QT]

There's no such thing as a radiator that's "too efficient". If your system wasn't building enough heat then there was likely a thermostat problem - the thermostat should remain closed and prevent any coolant flow through the radiator until the engine approaches operating temperature. If the thermostat is closed then it doesn't matter how efficient the radiator is because no coolant is flowing through it. I'm guessing your thermostat was either not closing properly or was the wrong temperature.

None of my G50s had any coolant issues. I live in a mountainous region. Try a mountainous decent of a few miles without touching the throttle. I guarantee your temp will plummet... causing less heat as I said

[Ryantzer]

I don’t think you quite understand how the cooling system is supposed to work. The only time your engine should be below operating temperature is when it’s first started and is warming up, or if you’re in a location with extreme cold. At any time the engine is below operating temp the thermostat will be closed, preventing coolant from flowing through the radiator. Coolant will flow only through the engine and heater core until it’s warm enough to need cooling again and the thermostat will open again. If your engine temp drops below normal after warming up and you’re not in below zero temps, there is something wrong with your thermostat.

[BCC93QT]

Definitely know a hell of a lot about coolant systems. As well as the one on the G50. And I dont think you are understand what I'm trying to say. You seem be just trying to make it sound you are some sort of superior. Good luck. I'm out

[Ryantzer]

I completely understand what you’re trying to say, but I don’t think it’s possible when the cooling system is functioning properly. I’m pretty confident in my automotive knowledge, which stems from having worked on vehicles for 36+ years, 20+ of those years at jobs in automotive fields, 10 of those years at a Nissan/ Infiniti/Pontiac/Buick/GMC dealership, and 2 of those years as a Nissan Service Advisor. That said, I don’t profess to know everything, and am always open to learning new things. Can you explain how the engine temp would drop below operating temp if the thermostat is working correctly?

[BCC93QT]

Engine temp WILL drop when descending from 620 meters to 311 meters. 3 miles long at 55 to 65 mph... guaranteed. That's a significant amount of increased airflow at a high speed. How can it maintain normal engine temp at that rate

[Ryantzer]

The engine temp will not drop. The radiator temp will drop, and the thermostat will close to keep the engine portion of the cooling system at operating temperature. That is the reason the thermostat exists.

[BCC93QT]

Okay. This is going no where other other than typical "I'm right you're wrong" ego fulfillment. It's really irrelevant. All the best with your replacement

[Q451990]

I have to admit this spirited discussion brings back fond memories of this forum's peak years.

I'd say the engine should maintain the minimum normal temp in above frozen tundra ambient temperature conditions - provided the rubber thermostat seal hasn't deteriorated. I can see how cruising several miles down a mountain could cause the engine temperature to drop. Probably not much below the bottom of the normal range, but that level of airflow through the engine bay with an engine basically idling is a unique situation.

[dnudelman]

All the distractions and ego aside, if you are pulling parts in a pick and pull, take everything you can including the radiator. You can always make it work. The car will be crushed in a few days and then you'll be REALLY sorry. Parts for these cars are very expensive or UNOBTAINIUM now so build up a stock of as many used parts as you can afford. Front spindles with hub are good, anything electric, switches, door window actuators. Maybe a MAF sensor. Heck, a front bumper cover came in handy for me. The seats in your car are very unique. You might want to consider them also.

Sorry that is 116 in phoenix right now, maybe you can pull parts early in the AM. I have a set of headlights for your car that you can have. If you want them now, just pay shipping or if you can wait, remind me in September, we drive down to Glendale in October and I can put them in the back of the minivan.

[Ryantzer]

The engine temp will not drop. The radiator temp will drop, and the thermostat will close to keep the engine portion of the cooling system at operating temperature.

I need to apologize. After doing some research I found that the Nissan ECU completely shuts off fuel to the engine on deceleration, so under certain circumstances it could conceivably be possible to reduce the engine temperature on a long downgrade. It would have to be long enough though, that the airflow through the radiator drops the cooling system down below operating temperature so the thermostat closes, and then the cold airflow through the engine compartment continues long enough to draw a bunch of heat out of the engine (where it's not being replenished because there's no combustion going on), to the point where it's below normal operating temp. Basically you'd have to remove all the heat in the radiator, coolant, engine block, heads, etc, in order to get the temp down below normal, which would take a very long time. It could happen though, so I was wrong.

[3Q Jay]

The engine temp will not drop. The radiator temp will drop, and the thermostat will close to keep the engine portion of the cooling system at operating temperature.

I need to apologize. After doing some research I found that the Nissan ECU completely shuts off fuel to the engine on deceleration, so under certain circumstances it could conceivably be possible to reduce the engine temperature on a long downgrade. It would have to be long enough though, that the airflow through the radiator drops the cooling system down below operating temperature so the thermostat closes, and then the cold airflow through the engine compartment continues long enough to draw a bunch of heat out of the engine (where it's not being replenished because there's no combustion going on), to the point where it's below normal operating temp. Basically you'd have to remove all the heat in the radiator, coolant, engine block, heads, etc, in order to get the temp down below normal, which would take a very long time. It could happen though, so I was wrong.

....one sign of a scientist is a person who has a theory, then gathers additional facts and data and objectively looks to see if the hypothesis is validated or needs to be tweaked.
I mean this in a positive way--thank you for taking the time to post back up. It's also refreshing these days to see someone who can check their ego for the sake of having a fruitful discussion.
fwiw, i have seen when descending a fairly long grade at closed throttle in the G50, exactly this phenomenon: forget the almost worthless dash temp indicator. The data logged ECU temp went from 194F at the summit, down to 180F, where it hovered for a long time. then, it eventually dropped down all the way to the mid 150s, by the time I got back on the gas. this was in December in New Mexico, the ambient air was about 34F.

[Q451990]

After doing some research I found that the Nissan ECU completely shuts off fuel to the engine on deceleration.

Where'd you see this? I'm assuming it's still sending enough fuel to keep the engine running, since it doesn't shut off completely - but I'm interested to see what you saw.

[Ryantzer]

In the factory service manual in the engine management section, under the description of how the engine management functions. It says fuel is shut off completely on deceleration.