Off-highway light interfering with vehicle cooling?

[Pskhaat]

So I'm in a desperate attempt to get my LC80 back to cooling...itself. AC and engine too. I've noticed that I and I assume many of us put those nice big bumpers on and winches and shovels and lights and custom license plates, &c.

All of them sit in front of a very crucial airflow of ram air across various condensers and radiators and tranny coolers. I am removing all front things except ARB and winch to try and get more airflow into this crucial area.

My AC works somewhat fine until the condenser gets heat soaked after the very first stop. Sure I'm bumping up the fan clutch a little and putting in a JDM pusher fan, but these should not be necessary, right? I am betting a little extra air flow will help cooling.

The questions: do your front aux. light interfere with cooling or airflow? where else other than the ARB-provided bottom and top tabs would one mount off-highway lights on the/an ARB?

 

[Cody1771]

hmmm roof rack? ive seen some people get an old set of swing out mirror stands that you see on old ford and chevy trucks, you know the tripod ones? pull the mirror off and attach the light. the tripods you can bolt just about anywhere you want... i was thinking of putting a pair on the front fenders

 

[R_Lefebvre]

What have you done to the rest of the cooling package? Have you changed/removed the radiator shrouding? All the stuff that used to be on the factory bumper makes a big difference, especially at low speeds.

 

[soonenough]

My knowledge of aerodynamics is limited, but I would think that if the lights introduced a little turbulence into the airflow just before it passes over the radiator, that could be a good thing. Turbulent flow over a heat exchanger is (as far as I know) always superior to laminar flow in terms of heat transfer.

If the lights were causing some of the air that would've otherwise flowed across the radiator to instead go over the hood or around the headlights, then that is a different and probably not desirable situation. Trying to figure out which scenario is actually happening would probably be difficult though.

 

[xcmountain80]

What kind of lights? Size matters though there have been no issues with my 4Runner (I know I know totally different vehicle but also huge radiator) and I'm running LF 240 Blitz. I have always wondered about all the other crap that gets tossed on the front end and shied away from it.

Aaron

 

[dust devil]

Too soon to make assumptions about the cause of overheating. Lights and winches can interfere with air flow, but on the trail they rarely do. At highway speeds, sure, maybe, but not at speeds under say 25 to 35mph.

Start with the basics. How old is your vehicle, and how many miles? Has your cooling system been flushed? Do you have an automatic transmission? Where to you live and drive and what is the average temperature and relative humidity outside when overheating most often occurs? Is your vehicle substantially heavier than it was when new? Have you changed to larger and heavier tires without regearing? Do you have other things hanging in the wind such as roof racks and spare tires? What thermostat do you have in the vehicle, and is there an optional one with a somewhat lower operating temperature that is still within the acceptable range for the engine? Have you verified that the temperature of the coolant going back in to the block is at least 30 degrees cooler than the coolant coming out when fully warmed up, and especially when you notice overheating?

Unless your cooling system is running at optimal level, you are not getting what the system can provide. Moving lights and winches to help out a crippled cooling system makes no sense. First verify the system. If that checks out and the overheating is at low speeds, check your fan and fan clutch. The clutch may be slipping and need replacement. If everything works fine at low speeds, but it overheats on the highway, move the lights.

 

[Sloan]

Have you had the radiator disassembled and serviced? I had a 1989 Nissan 4x4 that started running warmer and unfortunately this started crossing the Mojave and I had to do it with the heater on. I took it to a radiator shop here in LA and when they disassembled the radiator to hand core it I had only about 60% flow from scale and crud build up.

 

[dust devil]

My knowledge of aerodynamics is limited, but I would think that if the lights introduced a little turbulence into the airflow just before it passes over the radiator, that could be a good thing. Turbulent flow over a heat exchanger is (as far as I know) always superior to laminar flow in terms of heat transfer.

Surface turbulence on a heat exchanger is measured in very close proximity to the surface exchanging heat, and has little to do with the disturbed nature of the mass air entering the system. Lights don't cause surface turbulence on a radiator core, and would generally create little to no turbulence at vehicle speeds less than the air speed created by the fan drawing air into the radiator shell. If your fan is creating a 40mph breeze when the vehicle is static, it will take substantial vehicle speed to alter the result. At higher vehicle speeds, the air entering the system generally enters faster than the fan can provide, and the fan becomes redundant, which is why fan clutches were invented.

It is as speeds where the fan is no longer effective and the system relies on forced air flow that lights in the airstream become an issue, and at that point, turbulence behind lights is not a good thing. It is the same situation as in the discussion with snorkel heads and low pressure. If you create a low pressure system behind large lights and a winch at high speeds, the air flow that otherwise would be there to enter the radiator in what would be a high pressure area is partially deflected somewhere else, leaving behind in the radiator intake area a low pressure cell that reduces cooling efficiency.

 

[RonL]

I have a friend with a Lexus450, shock front bumper, no front lights and he has problems keep it cool at low speed(under 25mph). I think the FJ80 cooling system is not the best at low speeds. If the system is weak to begin with, anything up front will can it worse.

 

[Sloan]

Was it bad from the moment you put on the bumper and lights or has it gotten worse over time?

 

[Pskhaat]

To clarify and provide some info, the 1FZ-FE Toyota engine is notoriously a hot-running engine; I do not have overheating but absolutely anything to assist in cooling helps the 1FZ-FE greatly. Also not in my profile I live around Phoenix and do not have the pleasure of mild summer temperatures.

The main concern is AC! At <55mph the AC system might as well not be there. There is a perfect high-low delta at the compressor, no leaks, and 134a filled to spec. This leaves me to narrow this down to A) heat soak of the condenser/not enough air flow or B) evaporator inefficiencies. I'm installing a condenser pusher fan, but this should be rather unnecessary.

Fan clutch appears to be operating as expected but I'm planning on bumping up the oil in the clutch for a little more viscosity.

In my mind's eye, AC has become slowly worse over time (thus my A & B thoughts above), but I've always had the ARB on nearly since the vehicle was new.

 

[R_Lefebvre]

Any change it's just that the AC compressor is just too small? Some vehicles are designed that way. I had a WRX that just was not sized large enough. If the compressor size is way too small, it will even stop working altogether at higher temps, if it can't compress the fluid fast enough. It can't cross over the liquid/vapor phase. I'm a bit rusty on this stuff. I believe I was working on the Crown Vic program and something like this was going on with Vegas Taxis.

 

[flyingwil]

I did not notice a change adding the LF240's on the front of my bumper... It was a slight concern of mine as well, but when you come to think of it, when you're on the trail, how fast are you really going?

 

[bigreen505]

You might try adding Water Wetter to your coolant. It made a noticeable difference on the Pathfinder. Engine ran cooler, AC worked better.

 

[Cabrito]

I've noticed that I and I assume many of us put those nice big bumpers on and winches and shovels and lights and custom license plates, &c.

The questions: do your front aux. light interfere with cooling or airflow? where else other than the ARB-provided bottom and top tabs would one mount off-highway lights on the/an ARB?

I pretty much match your description except for these two items - No winch and mine is a FJ62 (older) - I did have some concerns before mounting the lights.
No cooling problems whatsoever.
For A/C - once the outside temp is over 95 the a/c does seem a little weak and won't really cool the inside any lower than about 82 degrees.
Problem with mounting big lights is there is no place that won't be in front of the head lights or turn signals.

-m