hi folks
this might be an obvious one, but i couldn't find a definitive answer from the other threads i found.

i spend a lot of my summer in the cape breton highlands area of canada, routinely driving up several 1200ft mountains on both paved and gravel roads. it is really really awesome bombing around up here, however the vehicle will consistently reach temps approaching the red line as i get to the top of the mountains. by the time i get to the top of i can coast and the temp goes right back down in about 1-2 minutes. ambient temps have been 80-85. just me in the vehicle, usually with about 200lbs of gear (suitcases, camera equipment, normal stuff). a/c off. i am wondering if this is normal, or if others climb mountains and have the gauge dead center, maybe even with their a/c engaged? i think something else might be amiss because the ac gets really weak when i'm idling even tho i have a brand new ac compressor. so maybe an air flow issue?

i have recently replaced the radiator fan clutch, thermostat and water pump as part of larger maintenance including the timing belt and some other stuff. new pink antifreeze too. mods to the vehicle are 3" lift and rock sliders. tires are p rated 265/70/17.

two things i haven't replaced are the ac condenser and radiator. i was doing a lot of offroading/mudding last year in which i fried my ecu and did a number on most of the pullies/bearings in front of engine. replaced all that stuff and lesson learned. i got a ton of mud in the truck during that time had to wash a lot of mud out of the ac condenser and rad. i am wondering if both those should be replaced (i think they are both original to the vehicle). the fins look mostly ok (some are bent). i was wondering if mud is caked between the condenser and rad. any easy ways to diagnose my radiator or ac condenser before i replace them? is this normal? i feel the truck would overheat if i had a few passengers or i was towing (i don't do either).

any info would be appreciated. i'll keep the thread updated as i move through different approaches to the problem.

thanks!

The cost of a new radiator is relatively cheap, i would replace it. Sounds like you just about covered everything else.

Use a bright flashlight at night and see how much light shines through the radiator and AC condenser, it should show a good bit of light coming through when using the light.

I would say almost certainly that you need a radiator. I suspect your coolant flow is restricted. New radiator, flush the rest of the system and I bet your problem will be gone.

I've flogged my truck up mountain passes at 100km/hr with trailers in the dead heat of summer and I've never seen the coolant temp gauge move.

Something is wrong for sure.

importman hit it square: new rad, flush the system until you get clean water out, then new coolant.

There's a prestone rad flush product I've always used whenever I get a new-to-me vehicle. You put it in and drive around for a while and then rinse it out. If the water coming out during flushing is hideous, I use tap water for a while to try to get it clean. Then switch to distilled water at some point. I end up filling up every container I can find with coolant/water/gunk and taking it to recycling.

It's an ugly, time consuming process, but worth it in the end.

Yup, radiator time. After 15 years you probably have enough scaling built up inside to reduce cooling enough to cause the issue. Seen it in a lot of vehicles - cools fine all winter but come summer it starts to overheat.

As long as your AC blows cold, no need to replace the condenser; or, at the very least do the radiator first then check AC output.

If you're running bigger tires (which it looks like you're running 32's) then you should be monitoring your transmission temperature as well.

Do you have a winch and or lights blocking your front grille? My engine and trans temps are noticeably higher ever since I put lights and a winch in front.

Tires: if you are running E rated heavy tires rather than c rated then you're trying to push heavier tires up those hills and your truck will have to work harder.

BUMP

My V8 started spewing coolant everywhere after I got out to take pictures after a particularly difficult climb. The dash temp gauge was dead center the entire time.

Fixes already posted in the thread.

Flush the system thoroughly and use new Toyota red/pink coolant or Zerex Asian formula. Make sure the heater is on full hot when you do a flush to get the heater core flushed as well.

Replace water pump with timing belt every time. If you don't know when that was done last, start there. Do the flush first so crap doesn't get in the new water pump.

Replace the radiator if you don't know the history of it. Again, flush first and use new upper and lower hoses.

Check your fan clutch and replace it if questionable.

Check your radiator cap. If it's not sealing it will allow the coolant to boil out. I replaced mine earlier this summer. I kept smelling anti-freeze and couldn't find where it was going and it was because the cap wasn't holding pressure. A lot of people don't know this but the reason the system has to be pressurized is because pressurizing raises the boiling point of the coolant. And coolant that is boiling cannot cool your engine.

thanks folks. fan clutch timing belt and water pump all done within the last month. i am going to have the radiator, ac condenser and rad cap done next week. that should cover all the bases.

no winch or front lights, it's a clear path through the grill. ran a flashlight through it last night, light did get through the rad. but i think it's bad and i think the rad and ac condenser are original on the vehicle. i think one thing that probably happens with these trucks is they get sold at relatively low mileage before the first big scheduled maintenance and then they pass through a few owners and the big maintenance jobs just never get done.

do i need to take the truck in for an ac/recharge when the ac condenser is replaced?

Yes. If you are having a shop replace the AC condenser, they should be able to do that. It's part of the job since the system needs to be purged and then refilled when done.

An overheat is something you don't want. I have a 2005 V6 4runner with 150,000 miles and am in the Bahamas (low temp annually 75 degrees / 90 degrees summer).

I've never had an overheat and don't do any special maintenance for the coolant. Original radiator and WP. Replaced radiator cap one time.

4runners hold 2.2 gallons of coolant, and changing it might be smart every 5 years on older car.

Those mountains will "stress" an older (any) car/truck. I'd ask around for advice. I wonder if they have a better/oversized radiator for people in those "rockies".

Keep an eye on it.

I was in Denver where my daughter works for big broker. She drives a 2015 Camry I bought her for graduation - now 6 years old (50,000 miles). As far as I know it has never had an overheat.

Camry runs and starts up like new car. Glad I got her a 4 cylinder Camry. Don't need a 6.

Change the oil and filter every 4000 miles - should help with temps too.

Getting to the "red line" might be normal where you drive.

Good call!

I just want to add to this to replace the rad cap with a Toyota cap, not a parts store special. Toyota rad caps are really expensive by comparison but there's a lot to them. I think they're well made in the way the metal is cut, stamped, and put together.

A parts-store special will get you through a bind, but they don't appear to work the same way as a Toyota cap does. And I'd suspect there's legitimate reasons the Toyota is 3-4 times the price.

Yes, which is why I suggested only replacing the radiator if the AC is blowing cold.

Too many times I've seen an AC system leak after getting cracked open for the first time.