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Why do trucks cover their front grill?

S

steppinthrax

Diamond Member
I notice on the road large trucks often have some sort of "fabric material" that covers or obscures some of their front grill. I notice a white van, where someone simply taped a piece of cardboard onto the front.
 
Could be for several reasons.

1: Bad cooling system that is over cooling.
2: Older diesel motor and large cooling system will over cool even when working correct.

Those are the 2 most common. Many newer diesels have dual thermostats and/or electric grills to keep from over cooling.
 
To warm them up quicker in the winter. Manufacturers are beginning to integrade active shutters into the grill to assist with this automatically. The upside for them are lower emissions and ability to reach maximum MPG more quickly.
 
Jimzz said:
Could be for several reasons.

1: Bad cooling system that is over cooling.
2: Older diesel motor and large cooling system will over cool even when working correct.

Those are the 2 most common. Many newer diesels have dual thermostats and/or electric grills to keep from over cooling.
Click to expand...

This one definitely.

You used to see this a LOT on older diesels, especially during the winter up North. In sub-zero temps, the engine would over-cool itself and this helped restrict the airflow into the engine when the air temp was VERY cold.
 
I have a Cruze Diesel that takes forever to heat up in the winter. My dad suggested I do this as it should help but I chose not to. Active shutters would have been nice, but i wouldn't expect a feature like that on a mid-range car.
 
To answer your question, the trucks don't cover the grill. The people that operate the trucks do that.

Now you know.
 
cbrunny said:
I have a Cruze Diesel that takes forever to heat up in the winter. My dad suggested I do this as it should help but I chose not to. Active shutters would have been nice, but i wouldn't expect a feature like that on a mid-range car.
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Do you have an engine/oil heater? Diesels run cooler and being in Canada a engine/oil heater goes a long way. Just plug in when you park for the night and unplug in the morning.
 
cbrunny said:
I have a Cruze Diesel that takes forever to heat up in the winter. My dad suggested I do this as it should help but I chose not to. Active shutters would have been nice, but i wouldn't expect a feature like that on a mid-range car.
Click to expand...

I wouldn't expect a feature like that on any car. Nor would I ever recommend covering the grill of your car. Doing so, even on the coldest day, might cause it to overheat.
 
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Jimzz said:
Do you have an engine/oil heater? Diesels run cooler and being in Canada a engine/oil heater goes a long way. Just plug in when you park for the night and unplug in the morning.
Click to expand...

No I don't. I wish I did. Could have had a block heater for $100 as part of factory install but they didn't have one on the lot and I didn't think it'd really be an issue given that I have a garage where it is parked most of the time. My concern at the time was more about just getting it going rather than heating it up fast.

Also, I park outside at work, which means the block would be cold at the end of the day.

Thankfully I only had one day where this was an issue, and it was a morning when it was -26C. When it warmed to -21C it started but took some effort. Then took forever to warm up.
 
Hey depending on where he lives in Canada this is exactly what he should do
But don't completely cover it leave about a pie plate hole in the middle of the cardboard.
I was told by a Honda dealer to do this to my brand new Civic because that small andengine can't keep up with the xtreme cold. diesels are similar because of their efficiency

I see the issue is starting, this won't help with starting at all, block heater is what you need,
 
What you do is dependent on the vehicle. If the car is equipped with inlet and outlet temp sensors and the engine is big enough to keep ambient block cooling from lowering the temp to far, cardboard won't have an effect.

Even small gas engines (think Honda ~1.6 to 2.4 liters etc) can have a hard time keeping engine temp when idling due to ambient block cooling in -40F. Blocking the radiator doesn't do a whole lot at that point except improve the warm up time and highway holding temp but can cause overheating.

The big rigs do it to prevent snow build up (rare), keep inlet temps up (more common.) Blasting the front cylinders with 10F coolant driving down the road isn't conducive to efficiency and long engine life. This is why most of the newer engines include a tstat on the inlet side to effectively seal the radiator off if the inlet temps are low enough. They use the heater core and sometimes a bypass pipe to keep coolant moving a bit.
 
AdamK47 said:
To answer your question, the trucks don't cover the grill. The people that operate the trucks do that.

Now you know.
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lfJIQIE.jpg
 
IIRC, VW TDI owners used to have trouble keeping their engines warm while idling. The temps would actually drop in the winter if they stopped the vehicle and left it idling to "keep it warm". They would block the radiator with cardboard.
 
JulesMaximus said:
I wouldn't expect a feature like that on any car. Nor would I ever recommend covering the grill of your car. Doing so, even on the coldest day, might cause it to overheat.
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The Focus has Active Grill Shutters, and I would expect other manufacturers to include them on most of their vehicles as they try to squeeze out every last drop of MPG. Of course they open back up once the car warms up.
 
Car grilles are designed with worst-case scenarios in mind. Even in a Florida winter, I have my upper grille blocked and my lower grille 75% blocked, and my radiator fan rarely comes on. When the weather changes, I plug in my bluetooth dongle and look at the coolant temperatures, and adjust as needed.

Pulling a 1000lb trailer in the winter, I found I can leave my upper block in place but I have to reduce the lower block down to 0-25%.

Why cover the grille? Two reasons:

1. Warmup time is significantly shorter. Warm cars get much better gas mileage, and short trip mpg is vastly improved with a grille block. Not to mention, I like it when heat comes from the vents.

2. Car grilles have a big aerodynamic penalty. You've probably noticed today that big grilles are in style with some manufacturers (e.g. Toyota) but most of it is fake. It's worth a few mpg on the highway to direct no more air than is necessary around the smooth outside of the car, rather than through the turbulent engine bay, but the amount of air necessary varies with load and outside temperature.

I wish I could buy a set of aftermarket active shutters.

2015-Toyota-Camry-Hybrid-Front-View.jpg
 
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Yuriman said:
1. Warmup time is significantly shorter.
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Blocking the radiator should not have any effect whatsoever on warmup time for a properly functioning engine (assuming non-extreme conditions).

The engine's thermostat causes coolant to bypass the radiator completely until operating temperature is reached. There is zero flow through the radiator until the thermostat opens, so whether the radiator is blocked or open the car will still warm up just as fast.

In very extreme conditions (Rocky Mountain or Alaskan winter), the block may radiate so much heat that it can't reach operating temperature and in these very isolated cases, blocking off some of the grill can help keep underhood temperatures up, but you're not going to see these conditions in the vast majority of areas.

ZV
 
cbrunny said:
I have a Cruze Diesel that takes forever to heat up in the winter. My dad suggested I do this as it should help but I chose not to. Active shutters would have been nice, but i wouldn't expect a feature like that on a mid-range car.
Click to expand...

I have them on my Ford Focus...


Brian
 
I block off the grill on my 04 jetta tdi with pipe insulators. Only part open is the VW symbol and my water temp usually hangs around 160f and if I'm really lucky it gets up to 170f in the winter. And yes idling does nothing other than let my heated seats warm up.
 
thedarkwolf said:
I block off the grill on my 04 jetta tdi with pipe insulators. Only part open is the VW symbol and my water temp usually hangs around 160f and if I'm really lucky it gets up to 170f in the winter. And yes idling does nothing other than let my heated seats warm up.
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I do the same on my 2012 Jetta TDI and the difference in time to heat up is fantastic. Temps have been around 0F on Chicago a lot lately, and having heat in the car is sort of necessary.
 
cbrunny said:
I have a Cruze Diesel that takes forever to heat up in the winter. My dad suggested I do this as it should help but I chose not to. Active shutters would have been nice, but i wouldn't expect a feature like that on a mid-range car.
Click to expand...

Your Cruze does have active shutters, but they are only on the lower section of the bumper and only close at highway speed to decrease drag and increase efficiency.

Despite the engine taking forever to heat up, you've been taking advantage of the electric auxiliary heater for the cabin, right?

I've heard of some guys on the Cruzetalk forums using cardboard or something to block the top section of the grill to improve warm-up, and some of them leave it in all the time (when it's below 0).
 
Interesting tidbit. Starting in about 87 I think, the Porsche 928 had an automatic electrical shutter system to control inlet air to the radiator. It's usually broke and painful to find spares for, but it's there.
 
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