What is the normal water-temperature range for our trucks?

[stioc]

I had the coolant boil over this past weekend on my trip to Death Valley - (pics: http://www.expeditionportal.com/forum/threads/100650-Five-SoCal-trucks-in-Death-Valley)

 

After the boiling over I nursed the truck the rest of the weekend i.e. everytime the temps went north of 197F I cranked up the heater full blast, it sucked for us in the warm weather but it never spit the coolant out again. I do believe that perhaps my radiator cap is not holding the pressure which makes the coolant boil over sooner. I'll probably start by replacing the cap and then see if may be the fan-clutch needs replacing too- they're usually pricey.

 

Going up the steep grades in warm temps I've seen the ScanGuage show up to 202F. I'm assuming the clutch fan engages at a certain RPM and is a single speed? Anyone know what the 'normal' operating range is? I guess I'm trying to find out at what temp should I start to worry that the car may overheat?

 

[Towncivilian]

I have not seen higher than 195F here in Florida. All original cooling system except for the coolant of course - had a flush done @ Nissan around 70k miles, then a drain & fill around 115k miles with Nissan Green coolant. Everything else stock except for the hose between the radiator cap and the overflow bottle (it was weeping), and the cooling fan blade which had many cracks in it (don't know how to explain that one).

 

See this TSB, it'll help you inspect your radiator cap properly. Replace with an OEM one if necessary.

Edited April 2, 2013 by Towncivilian

[Trogdor636]

the cooling fan blade which had many cracks in it (don't know how to explain that one)

 

The WD21 blades do the same thing. I've never seen an original that doesn't look pretty bad.

[XPLORx4]

The "normal" range is between 175°F and 224°F. When the temp hits 224°F the temperature needle starts to rapidly move away from the middle of the gauge and towards "hot".

[Towncivilian]

Thanks for that info! I was wondering what the upper range of "normal" was on the gauge. It starts showing normal at approximately 152F.

Edited April 2, 2013 by Towncivilian

[devonianwalk]

That range must be pretty universal. I had the option of going with a 160F or a 180F thermostat for my Miata last year (I went with the 160F).

[stioc]

Thanks for the info! Is it published somewhere in the FSM? and s it the same for both the VG and VQ engines? I ask because I read somewhere the VQ engines use a reverse coolant flow or something and uses a water-flow valve...whatever that is.

 

Any ideas why I may have boiled over the coolant? It was a long steep and dusty uphill grade and I didn't turn off O/D. Additionally I had recently installed 6" aux lights on the bumper right in front of the grill. It never happened again once I watched it and used the cabin heater to keep it under control...so I'm wondering if the lights would make that much of a difference or perhaps a stuck thermostat or a bad radiator cap?

[devonianwalk]

... or perhaps a stuck thermostat or a bad radiator cap?

 

My experience with the Miata was that every thing was going fine. Then one day I'm shooting down the interstate and noticed the temp sharply go up. I kept my foot off of the gas and it slowly went down. I consulted with my mechanic buddy that suggested I replace the $16 part. He was right. I was $16 poorer ... but happy?

[Precise1]

Any ideas why I may have boiled over the coolant?

How old was the coolant and what percentage mix? Is there any scale on the inside of the radiator? Do you see flow when it is hot and running? Is there dirt/bent fins that could obstruct flow on either the condensor or radiator? How hot was the tranny and do you have an aftermarket tranny cooler? If not and it is plumbed through the radiator, you are actually adding heat to the radiator from the tranny.

 

The fan clutch really only matters at about 30mph or less, the rest of the time it is airflow from the vehicle speed that cools. Obviously test/replace the cap and go from there. Also, your thermostat might be failing or partially obstructed.

 

B

[shoesandsocks]

i read a way long time ago on the Nissan path about that happening the guy had a 99 with light blocking the grille and he said he put a cooling additive i think he used the hyper lube one and he never had a problem again.

 

In the drift car i use pure distilled water with water wetter in phoenix in the height of July and i never get the gauge above half.

 

I would try some water wetter i run it in my pathy and it is amazing i stay between 1/4 to a a lil under half considering how hot it is outside.

 

http://www.turbomagazine.com/features/0703_turp_cooling_system_additives/viewall.html

[Towncivilian]

The water control valve is a smaller thermostat at the rear of the engine near the firewall. It opens at 210F. The main thermostat is fully open at 176F.

[XPLORx4]

The temperature gauge is not very accurate; its response is not linear. It doesn't move from the bottom of the gauge until around 100°, then moves really quickly from about 100° to 155°, plateaus at the center of the gauge from about 155° to 224°, then moves again very quickly from about 225° to 254°, by which point your radiator has exploded and/or the engine computer has shut off the engine.

[stioc]

I have a ScanGauge like you xplorx4 so if the water temp sensor is accurate enough then the readings should be accurate too.

 

So I find it interesting...the water control valve opens at 210F? if so then I shouldn't be alarmed by the temps reaching 200-210ish? I know I've seen the ScanGauge reporting 208F on a very warm day (102F ambient) before. I'm still perplexed why the coolant boiled over just that one time? maybe the cap wasn't seated properly when I did the pre-trip inspection. The coolant is about 3 years old, I'll change it soon. I've ordered a new OEM cap already. I may leave off the aux lights but that sucks...I like them there lol. I may just replace the radiator, radiator hoses and the main thermostat, I've heard it's a PITA job on the VQ like most other things

[XPLORx4]

I have a ScanGauge like you xplorx4 so if the water temp sensor is accurate enough then the readings should be accurate too.

 

On the VG33, the ECT sensor and the coolant temperature sensor for the gauge are different. The ECT sensor reports a voltage or resistance level to the PCM, which converts it to a temperature value (and this is what the ScanGauge reports). I don't know if the ECT sensor and the gauge sensor have different responses or if the temp gauge has a nonlinear response to its input.

 

Bottom line, the temperature gauge is not a good way to evaluate engine coolant temperature.

[Slumpert]

If the system cools well enough though the heater core, you looking at thermostat or crazy clogged up radiator as my best guess.

 

Provided the coolant is not leaking out somewhere.

[theexbrit]

I had exactly the same problem on my Sierra trip last year. Middle of the California heatwave, going up a long, steep hill in 102f weather, low revs so water pump turning slowly, slow speed so not much air coming thru the rad. Boiled up a couple of times had to use the old heater trick same as you. Turns out my electric fan temp sensor was in the wrong place (couldn't be bothered to fit it into the hose somewhere so I used the other sensor provided that fits between the rad fans. Should have know better) so I placed it down in the water, set it 186f, nary a problem now my son!

 

I thought my radiator might have been some of the problem as it was the original rad, so I replaced it with a new Koyo, it helped but the resetting of the 'leccy fan probe made all the difference. I know you don't have electric fans but the slow turning of the water pump, the uphill load on the engine & the slow turning speed of the fan are the culprits. I tried to find one of those "reverse water pump" thingy's that pump more water at low speed & less when you're on the highway with the wind whistling thru your rad, but they don't seem to make 'em for the R50. I've heard of an electric water pump but never seen one. If you're going to be doing a lot of slow hill climbs in hot weather you might want to invest in some 'leccy fans, set correctly they'll at least make sure you have tons of air blowing thru your rad & over your engine at low speeds. Heat travels to cold, so no matter how hot the outside weather is your engine will always be hotter, even the hot outside air blowing thru the rad is still cooler than the system in your car. As I said, since I moved the probe & set the fans to come on at 186f I've never had another problem. 'Leccy fans will bump up your gas mileage quite a bit also!

Edited April 4, 2013 by theexbrit

[stioc]

I've ordered a Koyo rad, OEM cap, OEM thermostat. I may also get a new fan-clutch too.

 

I've done the electric fan conversion in a street car in the past but I'm a bit concerned about doing it on an offroad truck. Mainly from over-taxing the alternator perspective where it'll see lots of crawl-speed miles in hot conditions. I feel the stock setup should be ok as long as everything's working properly.

[Precise1]

I feel the stock setup should be ok as long as everything's working properly.

I agree. My experience is that the stock Nissan cooling system is more than sufficient, regardless of outside temperatures, if it is in proper working order. I have not owned or driven a VQ though, my info is based on Z24i, VG30 and VG33.

 

You might want to look into an aftermarket tranny cooler as well...

 

B

[theexbrit]

I hear what you're saying, but I've had my fans on for about a year now & they've worked great. 3300cfm & a draw of about 12 amps. I've gained maybe 3-4hp & get 18mpg or so highway (& that's with all the "El Cheapo" crap hanging off my truck, lights, rack, shovel, gas can, spare tire, etc). imho the reduction of stress on the water pump alone, is worth it. That said, they are very noisy & if the alternator fails for some reason..... uh oh.But I carry the stock fan with me so I'd just bolt that back on & head for the road

 

Electric fans are like a lot of other things, some love 'em, some hate 'em, it's just personal preference I guess.

[XPLORx4]

You carry the stock fan and its shroud with you?

 

if the alternator fails for some reason..... uh oh.But I carry the stock fan with me so I'd just bolt that back on & head for the road

Do you carry your stock fan and shroud with you on every trip?

 

On my last trip to Death Valley (March 2007), I had an electric fan installed - a Flex-a-lite #295 27" dual fan rated at up to 4600cfm. I had also installed a cut-off switch to cut power to the fan - such as for water crossings.

 

The first day of that trip, I was in Mengel Pass and my alternator failed. Not wanting to inconvenience the group (and cut short an adventure that hadn't even started yet), I limped along with only my battery (making sure to turn off as many electrical loads as possible), getting frequent "recharge" sessions from another rig every time we stopped for a few minutes, all the way to Furnace Creek, where I called Autozone in Pahrump,NV and ordered a new alternator.

 

If I hadn't had the electric fan, the battery would have been able to last much longer, needing only to power the ignition system, PCM, and gauge cluster.

 

Since then, I've sworn never to go back to ONLY an electric fan to supply all cooling needs. I do plan to install an auxiliary pusher fan in front of the A/C condenser later this month to help move more air at low speeds. I'll probably tie it to the A/C compressor, with a separate three-position switch to manually turn it on/auto/off.

[theexbrit]

I rigged the stock shroud to take the electric fans so it's still there, I'd just need to remove the electric fans & bolt on the stock one. That is the only downfall with electric fans, a 2 battery system would help but it's still a sob if/when the alternator goes.

 

Maybe I'll carry a spare alternator with me :laugh:

[Tungsten]

I don't know about the VQ powered trucks but the VG powered trucks can get up pretty high. Somewhere between 170 F and 205 F is perfectly normal. With my E-fan the temp stays at around 170 F even if it is 95 F out. Race motor VGs are run at 205 F and that makes a difference you can feel. I can swap the thermostat and program my fan controller to operate the motor at race temps but that's not very good for the hoses and in case of a fan failure there wouldn't be any cushion room for an emergency.

[stioc]

Good discussion guys, BTW I found this info in the FSM today so I'll post it here in case someone needs it in the future:

 

THERMOSTAT:

Valve opening temperature 76.5°C (170°F)

Valve lift More than 8.6 mm/90°C (0.339 in/194°F)

 

WATER CONTROL VALVE

Valve opening temperature 95°C (203°F)

Valve lift More than 8.0 mm/108°C (0.315 in/226°F)

Cap relief pressure (kPa (kg/cm2, psi)

Standard 78 - 98 (0.8 - 1.0, 11 - 14)

Limit 59 - 98 (0.6 - 1.0, 9 - 14)

 

 

 

So how big of a job is it to replace the cooling system parts on this engine? That Water Control Valve is really buried in there it seems I may do everything except that i.e. new radiator, thermostat, fan clutch and waterpump. I've started collecting the parts and I plan to do it all at once in the next few months before the height of summer.

[XPLORx4]

I doubt you need to invest that much in new cooling system components, since you didn't ever really run hot.

 

Your original post said you observed temps getting as high as 202? That's still absolutely normal as far as engine coolant temp goes. I have had my engine run as hot as 220 without any coolant loss.

 

You said you observed coolant dripping during your DV trip. Did you see where it was dripping from? Was it coming out of the coolant expansion tank? After the engine was cool, was the expansion tank empty and the coolant level in the radiator low?

 

Maybe you overfilled the expansion tank or it's cracked?

Edited April 5, 2013 by XPLORx4

[Tungsten]

If you can drive fast and the engine doesn't get hot until you stop then it usually means a bad fan clutch or e-fan not working. High temps even while driving usually mean a clogged radiator. For this reason you want to keep track of your coolant. I change mine every 2 years because it's cheaper than buying a new radiator. Coolant, over time, will break down from heat and form brown sludge and can even clog the radiator. Ever look at the bottom of an old overflow bottle? That crud could be sitting inside the tiny cores of the radiator.

 

Water pump failures and thermostat failures can happen too. However, thermostats typically fail in the fully open position so you won't see any warm up. If one fails in the closed position you can overheat pretty quickly. Water pumps typically give a clear sign of failure as the bearing starts to make noise but its pumping function does not go away unless the impeller falls out.

 

Air can also build up in the cooling system and make the cooling system less effective. You can try purging the system of air but typically they are self purging anyway after a few warm up cycles.