Blocking radiators with large lights -- a non-issue?

[Right Turn Clyde]

No luck finding past threads on this question, so hoping someone may have experience. The question is whether anyone has experienced radiator cooling efficiency losses after mounting 1pr or more of large driving lights in front of the grill,

I am looking at a pair of 240mm lights that will be mounted there. That isn't too unusual, I know. However, I'm also likely to mount a 2nd set, which in the 9" diam range.

Blue clutch, PHH etc have been done (since then temp doesn't much budge). Are there reasons to think cooling will be reduced to a noticeable level?

RTC

 

[ALX4X4]

I've got 2 IPF HID's, 2 light bars solenoid box and insect mesh, winch and bull bar 6.0LS manual can tow 2.5tonnes with AC and cruise set at 100kph on in 40+DegC all day and still crawl in lo range with AC in same temp never overheats, standard radiator and belt drive fan.

 

[Corbet]

I've never noticed an issue. You might in a place like Phoenix. But in Logan you should be fine. If you fan clutch is healthy it will find air to pull.

 

[SUMMIT CRUISERS]

My son's @SUMMIT CRUISERS Jr has 240 lightforces. Not an issue as long as your fan clutch is healthy as Corbet mentioned.

 

[rc51kid]

Yep. Not a issue if your coolant System is healthy.

 

[Hornd]

You bought round lights; Right?

Just run the calculation to see what it is with and without,

It's as easy as calculating the drag coefficient with and without the lights and subtracting to determine the difference the lights make.
https://en.wikipedia.org/wiki/Drag_coefficient
Drag coefficient - Wikipedia


I think your worrying about and issue that does not exist.
Think of Ambient temp variation, and when not moving, how little air moves thru radiator.
The system was designed to compensate for these variables, so blocking 10-20% is not going to do harm (It's not helping either).

Adding a supercharger......

 

[Hyup]

I installed 9" LED spots on ARB bumper. Blue fan clutch keeps it around 185-190 in most conditions around NorCal. Recently in some low range crawling in 90+ heat in Moab had my coolant temp as measured by Torque app spike to 220 +. I stopped to take lights off and engine temps immediately dropped to 200. I had temp problems previous to the larger lights which prompted the blue fan clutch, but the immediate drop after yanking the lights indicated to me that there is a threshold for this setup - at least for my rig.

 

[mikedamageinc]

I had a pair of large Hella lights from PO that pretty much blocked the radiator. I noticed lower highway temps after removing them but it still climbs when it is hot so I'm planning to change from the current 6k fluid to 10k in the fan clutch.

 

[greentruck]

Yep. Not a issue if your coolant System is healthy.

Yeah, it's not just the fan clutch that could be the culprit. When I started running into cooling issues was when I mounted the ARB and winch. Threw the plate on dead center above the fairlead, but mounted high enough so was square in front of the radiator. Noticed it made a difference then, so moved it to a clip-on the fairlead. The cooling issue was periodic for the next few years, steadily but slowly getting worse. Eventually concluded the radiator was gunked up and swapping that out solved that.

With even the youngest of the 80s now 20 years old, if your radiator hasn't been replaced, you might run into cooling issues. If your lights block the flow into the radiator enough to cause temp rise, then you might start analyzing what the cooling system may need to bring it up to snuff -- fan clutch, radiator, etc.

 

[1973Guppie]

it can be an issue but is completely dependent on the particular rig, it's system cooling quality and components. I had an fj40 with a v8 that had cooling issues under heavy load on the freeway. I light bar up front blocking the radiator made a huge difference. I have not seen the same thing on my 80 but I try to keep the area in front of the truck clear. In fact I plan to move my light bar from the front bumper up to the roof eventually for this reason. I would suggest running a specified route and with and without the light bar in similar outside temps to see if there is a difference.

 

[inkpot]

Stock blue fan clutches are rather whimpy so we juice them up to at least 30,000 CST to insure premium cooling performance in the desert heat.

 

[thedoughboy]

^x2 on the 30,000 CST.

 

[DirtScaresMe]

Random / useless thoughts:

Regarding the drag coefficients, I'll dust off my physics minor and suggest maybe it doesn't matter. Unless the air is being truly deflected away from the radiator entirely, the same volume is still arriving on the radiator albeit in different forces. I guess you could get into some serious metallurgy/thermodynamics argument about the benefits of reduced airflow in certain area-inches of the radiator and increased in other area-inches, where the light deflects wind from but then forces it in.

I think at speeds where that would be noticeable, if at all, there's so much air ripping through the front that it's effectively meaningless.

Then again, I read on here about how running the AC while towing can overheat the engine, because the heat from the transmission coiler and AC condenser are going back on the coolant radiator.

 

[Right Turn Clyde]

Appreciate all the input. Running a Short Bus and XP9.5 the air flow now is pretty free. I am looking at light arrangement in an inverted U shape to keep the direct frontal core open.

This is both intentional and (it seems) necessary due to just fitting the big reflectors in that space. From mock-up's it appears the upper pair of lamps will extend up into the view line for the driver. A little annoying but will keep below them more open.

 

[george_tlc]

With compact high powered and reasonably focused LED lights, I can't see the use for the massive diameter/housing lights of yesteryear.

6000 lumens each:

cheers,
george.

 

[jcardona1]

I've ran various front bumper setups over the years with different types of lights as well. Front grill has always been blocked and I never experienced cooling issues. My thoughts are this:

- If the truck is moving at highway speeds, air will be forced through the grill and around the lights at such high forces that it won't matter what you have in front. No issue.

- At very slow speeds or sitting idle, air is not being forced through the grill; you are relying on the fan to pull air through the radiator. Again, lights sitting in front of the grill do not impede the fan from pulling air in. No issue.

Caveat: Ambient outside temps. When it's been 113º here, it doesn't matter if I'm going down the highway at 70mph or sitting in traffic - the truck will always run hotter than normal and even my AC has trouble blowing cold air. It makes a difference if there's a 40º difference in the outside air temps.

Never overheated when I had lights like this:

Or how it is now like this. My winch sits up higher than before too, had to cut some of the grill out to make it fit.

 

[4G63 POWER]

Fyrlyts here with no issues.

 

[super40]

i put my warn winch controls box in front with an immediate increase in engine temp. low speed not a problem. the problem occurs when on the hwy. over 70- 75mph.