All, I have been having some engine temp concerns. Oddly enough to me my highest temps have been while on the highway, not in stop and go traffic. All temps mentioned in this post are from my ultragauge. So with ambient temps in the 80’s and low 90’s, in town with ac on, I’m seeing 190-196. Same ambient temps on the highway avg 55-60 mph, and I see similar but slightly higher temps, up to 197 or so. However if I go up slight inclines for a while, they creep up even higher. In this scenario 199-203 isn’t rare and I have seen 206-208 a few times. So, I feel like my normal temps are higher than I would like. I’m not sure what to think about temps being higher on the highway. Usually with overheating issues I think slow or stop and go traffic. The only things I have done yet are to check coolant level, which is full, and blow out debris from radiator fins with the compressor. Any thoughts or items to check?
Highway temp trouble (1 Viewer)
- Thread starter Nightbrew
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94SRUNNER
GOLD Star
When did you last flush and fill the coolant system? How about age/mileage on the radiator, radiator cap, thermostat, etc...?
- Thread starter
- #4
Unknown. I bought this rig late last year. Everything appears to be oem. The radiator top does not show any browning. I do see varying levels of coolant in the overflow bottle. The timing belt, and I assume the water pump based on looks, were replaced about 20k ago. I will also note that the coolant is the regular green color, but there are signs of Toyota red/pink crusties around and on radiator hoses.
Trunk Monkey
Moderator
Bubble in the system can be the easiest culprit, then t-stat maybe. If you're unsure of the history, maybe time to start baselining. Also heater t's while you're messing with the coolant system.
- Thread starter
- #6
I will see if I can get a burp out of it. Haven’t tried since the fluid is full on flat ground. If I end up tearing into this I will get the T’s while I’m in there. They “look” pretty fresh, but again no idea of age.
Doesn’t really sound like too much of a problem to me. Those temps are within the design perimeters, a hotter engine burns cleaner.
- Thread starter
- #9
Hmmm. Seems like I remember some posts saying temps stay in the 180’s even in adverse conditions. I just figured 200+ is leaving the “everything is working great” area of temps.
Over 200 is a little high but on long climbs out west ive seen temps climb 6 to 8deg or a little more, (only to watch them quickly lower on the way down the other side of the hill). For reference, a healthy cooling system: new rad, new water pump, new thermostat and rad cap, new coolant will show and fluctuate around 186-190 during normal city hwy operation( not climbing mountain passes) no matter if its 30deg ambient air or 80deg ambient air temp.
1. First thing in the morning (cold engine) remove radiator cap and make sure fliud is at the top of filler neck. Also have a look at condition of fluid- can you see the radiator core? Check cap spring for corrosion.
2. At the lower end of radiator, there’s a gap between the A/C condensor and front of radiator. Check that the front lower portion of radiator is clear of grass, mud/dirt build up. Inspect front of condenser for mud dirt etc that might restrict air flow.
3. If cooling system was not well cared for the lower portion of the inside tank may have some build up and restricting coolant flow- might be time for new radiator.
Other thoughts, Thermostat may not be functioning 100%, waterpump cavitating at higher Rpm’s. System not maintaining correct pressure (cap).
1. First thing in the morning (cold engine) remove radiator cap and make sure fliud is at the top of filler neck. Also have a look at condition of fluid- can you see the radiator core? Check cap spring for corrosion.
2. At the lower end of radiator, there’s a gap between the A/C condensor and front of radiator. Check that the front lower portion of radiator is clear of grass, mud/dirt build up. Inspect front of condenser for mud dirt etc that might restrict air flow.
3. If cooling system was not well cared for the lower portion of the inside tank may have some build up and restricting coolant flow- might be time for new radiator.
Other thoughts, Thermostat may not be functioning 100%, waterpump cavitating at higher Rpm’s. System not maintaining correct pressure (cap).
- Thread starter
- #11
Coolant has always been to the top of the filler neck. I can see the core when I look down from the top. I don’t have a coolant tester , but it appears to be relatively new/clean, as I see no discoloration. Maybe I should buy one of those testers. For kicks I pulled it up in ramps this morning with the spill free funnel. Front and rear heat turned all the way up, shook rig around, never saw a single bubble.
A couple of days ago I blew out all the debris on the lower portion of the radiator, with compressed air. I couldn’t believe how much junk came out. Also shocked at how much dirt/sand came out from the upper portion of the radiator. To anyone has hasn’t checked for this debris, it is probably worth a look.
I guess I could throw a new cap and/or thermostat to make sure that is operating correctly.
My original radiator was performing similarly to your temps prior to me replacing all the items I listed for healthy cooling system. You might just replace one thing at a time to see if that action makes any difference. Radiator cap, then thermostat etc. You could pull your radiator, and do a thorough cleaning of the outside fins to get as much debris out as possible, and then a basic distilled water flush of the radiator, reinstall with some fresh coolant and see what happens. Water crossings through crud filled puddles and driving through tall grass will take its toll- this is a regular maintenance area if you drive off pavement.
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- Thread starter
- #13
I don’t want to waste money, but with unknown age of items, I will probably replace if I pull stuff. Any trick to cleaning out the heater core? The 80 series had a heater control valve, and I’m not seeing it on the hundy.
Based on your location, I suspect tons of bugs trapped in the ac condenser fins. When I lived in Louisiana, I used to wash off the condenser fins before summer comes.
100 got no control valve. Just disconnect both hoses going into the heater core at the fire wall. USE a pick if the hoses are tight to loosen it from the T joint, don't use pliers to make it loose. Also replace the heater T joints with OEM part if you haven't done so.
100 got no control valve. Just disconnect both hoses going into the heater core at the fire wall. USE a pick if the hoses are tight to loosen it from the T joint, don't use pliers to make it loose. Also replace the heater T joints with OEM part if you haven't done so.
- Thread starter
- #15
The condenser fins had bugs but nothing more than what I have noticed from other vehicles.
I had TB/WP done in 11/18 when I bought my truck, as well as a new radiator. I was seeing temp spikes last summer at idle, so also replaced with new OEM t-stat and fan clutch, since everything else was new.
This season, I replaced the radiator as mine developed a leak. Temps kinda high, still. Replaced with another OEM t-stat and radiator cap. Now, with a completely new cooling system, I get up to 198 as a peak when running 70-80MPH, front and rear AC blasting. Idle is a champ and temps stay at or under 190. I'm also confused as to why the temps are rising at speed, but that mine cools well with no air flow tells me it's not totally unhealthy. Regular highway driving runs between 188-193, when it's not spiking.
This season, I replaced the radiator as mine developed a leak. Temps kinda high, still. Replaced with another OEM t-stat and radiator cap. Now, with a completely new cooling system, I get up to 198 as a peak when running 70-80MPH, front and rear AC blasting. Idle is a champ and temps stay at or under 190. I'm also confused as to why the temps are rising at speed, but that mine cools well with no air flow tells me it's not totally unhealthy. Regular highway driving runs between 188-193, when it's not spiking.
- Thread starter
- #17
Well it seems like I’m not that much higher than what you are running, until I go up a slight grade. Maybe this issue isn’t an issue. Guess it just depends on who’s opinion I want to listen to at the moment. Decisions, decisions.
I'll check my Temp's and report back. I did a Radiator around 2 years ago. But with normal Antifreez. Not the Toyo Red stuff. I am going to use Torque pro to get my temps. Will that matter Torque pro vs Ultragauge?
Although this Timmy the toolman is for a 4runner temp fix. At least the first part might show you how to look and check if your fan clutch is working properly. The 4runner fix was to change the Coolant temp sensor/Radiator cap. Ours might be something totally different.
BTW Timmy needs to get the best...how many thing he needs to get a LC.?
Although this Timmy the toolman is for a 4runner temp fix. At least the first part might show you how to look and check if your fan clutch is working properly. The 4runner fix was to change the Coolant temp sensor/Radiator cap. Ours might be something totally different.
BTW Timmy needs to get the best...how many thing he needs to get a LC.?
I wouldn't be concerned with those temps, but if you really are:
replace heater tees, drain (via block drains) and flush your whole system a few times with distilled water, replace t-stat, and replace coolant with Toyota red or Zerex Asian. If **I was** going to all this trouble, I'd also pull the radiator and really get the fins cleaned out.
replace heater tees, drain (via block drains) and flush your whole system a few times with distilled water, replace t-stat, and replace coolant with Toyota red or Zerex Asian. If **I was** going to all this trouble, I'd also pull the radiator and really get the fins cleaned out.
Waterpump cavitating was my first thought. When I bought my FJ60 back in the mid 1990's I replaced every hose, coolant, thermostat, and an aftermarket cap. Took off on a road trip across Texas in July so temps were around 100F and it started running hot at interstate speed but would run fine slower. Tried another cap that made no difference and eventually made it to Santa Fe and bought a cap from a Toyota dealer. Never ran hot again.
