covering the radiator opening for heat

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I have a '15 Fit (DI; non Turbo).

Would it be beneficial to cover the open with a piece of cardboard to help the engine heat up quicker, maybe make it run hotter, to mitigate the dilution problem? Back in the day this was common but I can't remember the last time I saw this trick. This will be the first winter with this car.

So far it heats (interior) up at least as quickly as anything else I drive. Also- it has an idiot cold temp light, no gauge, so who knows, I could be baking the motor by blocking the airflow without even knowing it.

And yes, the motor oil reeks of fuel right off it seems. (I drained the oil when the mm read 90% to get the unknown oil out).
 
The thermostat controls the warm up and min operating temp. Covering the radiator could possibly burn up the ac compressor when the defroster is on.

In the old days you saw winter fronts on semi trucks but that is a different story
 
Early Saabs and some Volvos had a radiator blind. Some large trucks too. I don't think a modern vehicle like your Honda would need this. If your thermostat and cooling system is in good order even winter in Maine won't faze it.
 
I would think that unless it's really cold that a winter front would do more damage than good. The thermostat should keep the engine at operating temp. Granted I'm sure in extreme cold weather it wouldn't hurt.

The only way I would consider such a setup is if I had a OBDII reader displaying engine coolant temperature and if during very cold weather the engine temp wasn't reaching operating temperature.
 
Covering half your rad in the winter makes sense, just make sure if the fan comes on it can get good airflow.

Instead of driving around with your thermostat one percent open, it might be 30% open, and your average underhood temps slightly warmer too. You'll get more of a heat soak when you turn it off.

My saturn s-series were cold blooded despite religious t-stat maintenance. The cabin would cool off during fuel cut-off going down a half-mile hill.
 
The thermostat controls the warm up and min operating temp. Covering the radiator could possibly burn up the ac compressor when the defroster is on.

In the old days you saw winter fronts on semi trucks but that is a different story
The EcoDiesel RAM's come with a grill cover, I assume other small diesels do too.
 
In the winter of 1989 I drove a Mazda B2000 about 400 miles of a 500 mile trip with the front of the radiator totally covered with cardboard just to have heat in the cab of the truck. We were travelling from the Charlotte, NC area to my parents house in Elkton, KY. When we got to our destination actual temperature was -28F with a wind chill of -56F. Most cars have more air circulation through the grill than is needed. I used to block all or a large portions of the grill on my work cars so they'd warm up faster on cold mornings. Did this for several years and never had any issues.
 
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Yes diesels are different. They do not have a throttle and suck in so much cool air that they can't warm up .
Certainly, just pointing out that blocking off the grill is an option (rather than totally blocking the rad) and is OE on diesels, which also have A/C. These little Honda engines seem to have serious fuel dilution issues when it's cold out.
 
2017 Honda CR-Vs and newer have shutters on the front. Snow can jam them and that can cause overheating.

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About 15 years ago I got a call from a brother who was stranded on the side of a highway with his kids in the car and the car overheated. It was a warm winter day and he forgot about the carboard he had added infront of the AC condenser behind the front grill.
 
2017 Honda CR-Vs and newer have shutters on the front. Snow can jam them and that can cause overheating.

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About 15 years ago I got a call from a brother who was stranded on the side of a highway with his kids in the car and the car overheated. It was a warm winter day and he forgot about the carboard he had added infront of the AC condenser behind the front grill.
Our RAM has the automatic grille shutters, we've had no issues with them, but there's a pretty good gap between them and the rad/condenser so I'm not sure it would cause any issues even if they were to jam.
 
And FWIW, modern programming on the shutters seems to anticipate some of the cold weather or snow clogging issues. The shutters on my F150 are actually cracked 1/3rd open all the time once ambient air temps drop to 35F or colder... Otherwise in cruise mode with no a/c, they are often around 11% open even in very warm weather...

As far as the compressor goes, the logic is actually the opposite of a poster above - the compressor controls the shutters opening. When the compressor runs, the shutters are opened more. The shutters do not control the compressor - at least in both the Fords I own.
 
30+ years ago when I lived way up North we covered the grill - they sold them at the auto stores custom fit to your pickup back then. If you didn't the underhood temperature stayed too cold and you would freeze up the carburetor due to the venturi affect. Either that or the bimetalic spring choke would never open, but smart people replaced that with a manual choke anyway.

I don't see any good reason to do so with a modern vehicle - since most have some sort of bypassed fan like a clutch fan or electric, along with no choke and fuel injection. If you do decide to anyway, as mentioned don't close it all the way - or better yet keep your cover on the front of the grill which blocks direct flow into the rad at highway speed but leaves lots of internal space for circulation if the fan kicks in.
 
The grill shutters on modern cars have nothing to do with engine warm up etc…the cooling system handles that. They are there to reduce the wind resistance of the vehicle and improve fuel efficiency.
 
The grill shutters on modern cars have nothing to do with engine warm up etc…the cooling system handles that. They are there to reduce the wind resistance of the vehicle and improve fuel efficiency.
They also block airflow through the rad while moving, reducing warm-up time. This is VERY apparently on our RAM, which warms up MUCH quicker than my Jeep, that has more cubes but no shutters.
 
Back in the day it was common for engines to run at 175-185F. Now it’s common to run at 210 F so there is plenty of hot water in the heater core. No need to have to use an old school radiator cover.
 
The little 1.5 L tdfi Honda engines have a lot of complaints about not having enough cabin heat in the winter, and there was a post here on BITOG last winter of someone having theirs overheat because it would not open due to snow and or ice.


So, at least for that engine it is part of the engine and cabin heating / cooling system.
 
The bottom of the radiator on most cars cools the automatic transmission…

If you have a manual tranny, this is unused…

A pool noodle in the bottom grill opening slot helps MPG, and does not affect radiator cooling….
 
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