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Car Forum / Nissan / Nissan Cars / September 2007'01 Pathfinder overheat problem
In May, my '01 Pathfinder overheated in VERY slow traffic towing my boat on a 71F day. I pulled off, kept topping up the overflow tank with water as it sucked it back in, and it got me 60 miles home. A week or two later I changed the coolant, refilling with 50:50 Nissan Long-Life and distilled water. It's been pretty much OK since, with once instance of filling up the overflow after towing the boat home. This past week I drove up to Vancouver BC and back (2000 miles round trip). On the way home yesterday, I stopped in Willows, CA for gas. Ambient temp had been about 100F for the last 120 miles or so, and I'd been running the AC. No boat trailer. I'd been keeping a close eye on the temp gauge, and it was fine. At the gas station, I smelled coolant, and it had filled the overflow bottle and spit out maybe six ounces on the frame and ground. With the hood up, it started sucking the coolant back out of the overflow, but stopped when it was down a couple of inches. I gassed up, and headed home with a weather eye on the temp gauge and the AC off. Ambient temps ranged from 99F to 108F. After about two hours, I made a quick stop, and checked the overflow -- it was about where it was when I left Willows, and I continued another hour to home. About a mile from home I stopped at a stop sign and I watched the temp gauge go from normal (centered) to the first hot mark (there are two) in about three seconds. I flipped the heater on full blast, and it swung right back down as fast as it went up, and I made it home. It seems to me that the heater shouldn't have had that quick an effect on the gauge. I left the hood up overnight, and most but not all the coolant sucked back in. Coolant level was down about 3/4" in radiator. I see two scenarios: 1. Occasionally sticking thermostat. This would explain the rapid swing up back down, I think. 2. Fan clutch or belt slipping so the fan isn't doing it's job at low speed. Any thoughts?  SignatureChuck Tribolet http://www.almaden.ibm.com/cs/people/triblet/ Silicon Valley: STILL the best day job in the world. > In May, my '01 Pathfinder overheated in VERY slow traffic > towing my boat on a 71F day. I pulled off, kept topping up [quoted text clipped - 41 lines] > > Any thoughts? Another possibility is a partially plugged radiator from the fluid not being changed for a long time or the use of the wrong coolant. It's not wrong coolant, it's never had anything but Nissan factory coolant in it. When I changed the coolant, the old coolant was PERFECTLY clean. I love aluminum engines. >> In May, my '01 Pathfinder overheated in VERY slow traffic >> towing my boat on a 71F day. I pulled off, kept topping up [quoted text clipped - 44 lines] > Another possibility is a partially plugged radiator from the fluid not being changed for a long time or the use of the wrong > coolant. > In May, my '01 Pathfinder overheated in VERY slow traffic > towing my boat on a 71F day. I pulled off, kept topping up [quoted text clipped - 46 lines] > > Silicon Valley: STILL the best day job in the world. The rapid drop in temperature when first turning the heater on is to be expected even in warm ambient temperatures. All the hoses leading to and from the heater, the heater core itself, the heater box etc. all initially soak up heat and thus produce an initial rapid cooling. You see the same effect when turning the heater on on a cold day if you let the engine warm up first. The drop can be dramatic. It sure sounds like a blockage in the cooling system and not necessarily in the radiator. Have you done periodic cooling system flushes? By flush I mean a power flush and not just drain and refill. The generic recommendation is to do a flush every two to three years and/or 20-30K miles specifically to keep the cooling system open and clean. I might be worth doing it now if it's never been done. Good luck. Al last time I did a flush on my Nissan, I ended up chasing leaks for 2 months. >> In May, my '01 Pathfinder overheated in VERY slow traffic >> towing my boat on a 71F day. I pulled off, kept topping up [quoted text clipped - 15 lines] >system open and clean. I might be worth doing it now if it's never >been done. Good luck. Al > The rapid drop in temperature when first turning the heater on is to > be expected even in warm ambient temperatures. All the hoses > leading > to and from the heater, the heater core itself, the heater box etc. > all initially soak up heat and thus produce an initial rapid > cooling. This line of reasoning may have been true for a 1969 Plymouth Fury, but it doesn't apply to a '01 Pathfinder. There is no water control valve in the heater circuit. Hot water is always circulating through the heater hoses and heater core even if the heater is "off." Therefore "all the hoses leading to and from the heater, the heater core itself, the heater box etc." are already "hot" and there is no "initial rapid cooling" when the heater is first turned on. Turning "on" the heater just changes the air path so that the cabin air is directed through the heater core rather than around it. This does provide additional cooling capacity since you are now moving air through the heater core and carrying away heat, but the line about initial rapid cooling is a total fantasy. No one has mentioned the two most likely causes of the problem - a bad thermostat and a bad fan clutch. My money is on the fan clutch. From the description, the problem always occurs at low speed or when stopped, precisely when you need the fan to pull large amounts of air through the radiator. When a fan clutch goes bad, it doesn't stop turning the fan, it just allows the fan to turn much slower, and move a lot less air. This is not obvious from looking at the fan. If it was my truck, I'd spend the $100 or so a new fan clutch costs. Ed > You see the same effect when turning the heater on on a cold day if > you let the engine warm up first. The drop can be dramatic. [quoted text clipped - 5 lines] > system open and clean. I might be worth doing it now if it's never > been done. Good luck. Al I mentioned thermostat in the original post. The fan doesn't have a clutch per se, but it does have a viscous coupling. That's worth a shot. Any way to check it? And a lot less messy than a thermostat. >> The rapid drop in temperature when first turning the heater on is to >> be expected even in warm ambient temperatures. All the hoses leading [quoted text clipped - 26 lines] >> system open and clean. I might be worth doing it now if it's never >> been done. Good luck. Al >I mentioned thermostat in the original post. > > The fan doesn't have a clutch per se, but it does have a viscous > coupling. > That's worth a shot. Any way to check it? > And a lot less messy than a thermostat. The "viscous coupling" is the fan clutch. It has a clock spring that responds to the air temperature. When the air is hot, it moves an iinternal element that increases the resistance between the input shaft and the fan which should result in the fan turning at near the same speed as the input shaft. When the auir is cooler, the fan is allowed to freewheel. I have had very poor luck diagnosing bad fan clutches - you need special equipment I do not have. You cannot look at them and tell if they are turning the fan at the correct speed. On the other hand, two out of two times I thought the fan clutch was bad, it was! Here is how Ford says to test a fan clutch (good luck): Fan Clutch Mechanical Fan Clutch Test Spin the fan blade by hand. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows: Minimum Speed Fan Clutch Requirement Test Use a suitable marker to mark the water pump pulley, one of the fan blade bolts, and the crankshaft pulley. Connect a tachometer to the engine. Install a throttle adjusting tool. Connect a digital photoelectric tachometer. WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation. Failure to follow these instructions can result in personal injury. Start the engine and run it at approximately 1,500 rpm until the normal operating temperature has been achieved. Adjust the engine speed to 2,300 rpm. Adjust the strobe light to 3,000 rpm and aim it at the water pump pulley. Adjust the engine speed until the light flash and the water pump pulley mark are synchronized. Aim the strobe light at the fan blade retaining bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade retaining bolt (fan blade appears to stand still). The fan blade speed must not be greater than 1.500 rpm at 3,000 water pump rpm. Turn the engine off. If the fan blade speed was greater than 1,500 rpm , install a new fan clutch. Maximum Speed Fan Clutch Requirement Test Carry out Steps 1 through 5 of the Minimum Speed Fan Clutch Requirement Test. NOTE: The engine temperature should be above 96°C (205°F) for maximum fan speed. Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille. This will raise the temperature of the air striking the fan clutch and should cause the fan to operate at maximum speed. Place the climate control function selector switch in the MAX A/C position and the blower motor switch in the HI position. Adjust the strobe light to 3,000 rpm. WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation. Failure to follow these instructions can result in personal injury. Start the engine and adjust the engine speed until the strobe light flash and the water pump pulley mark are synchronized. Aim the strobe light at the fan blade retaining bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade retaining bolt (fan blade appears to stand still). If the fan blade speed is less than 2,300 rpm, install a new fan clutch. Visctronic Fan Clutch Test WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation. Failure to follow these instructions can result in personal injury. Start the engine. Using the diagnostic tool, set the visctronic drive fan duty cycle PID to 100 percent. If after several minutes the fan speed increases, the minimum and maximum fan speeds must be checked. Refer to minimum and maximum speed visctronic drive fan clutch requirement tests. If sent here from Powertrain Management, install a new visctronic drive fan clutch. If after several minutes the fan speed does not increase, refer to Powertrain Management for further diagnosis. Minimum Speed Visctronic Fan Clutch Requirement Test WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation. Failure to follow these instructions can result in personal injury. Start the engine. Using the diagnostic tool, set the visctronic drive fan duty cycle PID to 0 percent. Adjust the engine speed to 1,500 rpm until normal operating temperature is reached. Increase the engine speed to 3,000 rpm for two minutes while reading the fan speed PID on the diagnostic tool. If the fan speed is above 1500 rpm , install a new visctronic drive fan clutch. Maximum Speed Visctronic Fan Clutch Requirement Test WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation. Failure to follow these instructions can result in personal injury. Start the engine. Using the diagnostic tool, set the visctronic drive fan duty cycle PID to 100 percent. Adjust the engine speed to 1,500 rpm until normal operating temperature is reached. Increase the engine speed to 3,000 rpm for two minutes while reading the fan speed PID on the diagnostic tool. If the fan speed is less than 2,300 rpm , install a new visctronic fan clutch. If DTC P0480 or DTC P0528 are present, refer to the Powertrain Management. Ed >>> The rapid drop in temperature when first turning the heater on is >>> to [quoted text clipped - 42 lines] >>> never >>> been done. Good luck. Al I mentioned thermostat in the original post. The fan doesn't have a clutch per se, but it does have a viscous coupling. That's worth a shot. Any way to check it? And a lot less messy than a thermostat. >> The rapid drop in temperature when first turning the heater on is to >> be expected even in warm ambient temperatures. All the hoses leading [quoted text clipped - 26 lines] >> system open and clean. I might be worth doing it now if it's never >> been done. Good luck. Al On 9/2/07 7:46 PM, in article 13dmmac5adf8c3d@corp.supernews.com, "Chuck Tribolet" <triblet@garlic.com> wrote: > In May, my '01 Pathfinder overheated in VERY slow traffic > towing my boat on a 71F day. I pulled off, kept topping up [quoted text clipped - 41 lines] > > Any thoughts? The '02 Pathfinder hasn't done this (yet), but I had those same symptoms with the 240SX last spring. The problem turned out to be a combination of an air bubble in the system and a bad radiator cap that wasn't holding pressure. Replaced the cap and "burped" it a couple of times and the problem has not recurred. I forgot to mention that the first thing I did after the May overheat was replace the radiator cap. And it was definately burped after the coolant change. > On 9/2/07 7:46 PM, in article 13dmmac5adf8c3d@corp.supernews.com, "Chuck > Tribolet" <triblet@garlic.com> wrote: [quoted text clipped - 50 lines] > pressure. Replaced the cap and "burped" it a couple of times and the problem > has not recurred. If you let your Pathfinder overheat in the driveway you should be able to tell IF the cooling fan begins turning when the temperature gets too high. I think your Nissan - (probably like my old pickup???) - has a fan clutch that will engage when the motor temperature gets too high and this make the fan rotate. You could put some newspapers over your radiator to make the temperature get hot quick. Then you ought to see the cooling fan start spinning after the block heats up. My engine (2.4 liter 4 cyl.) has also overheated a few times so I'll need to do this same test also. If that's not it - maybe you have a slipping fan/water-pump belt. If your belt is slipping you could use some belt dressing to give it adhesion (non skid effect) on the pulley. Using dressing also lets the fan/altenator/pump work without having to overtighten the belt, which can wear out the bearings. > In May, my '01 Pathfinder overheated in VERY slow traffic > towing my boat on a 71F day. I pulled off, kept topping up [quoted text clipped - 41 lines] > > Any thoughts? > If you let your Pathfinder overheat in the driveway you should be able to > tell IF the cooling fan begins turning when the temperature gets too high. I [quoted text clipped - 60 lines] > > > Silicon Valley: STILL the best day job in the world. Aren't clutch fans always spinning? And when the thermocouple inside the clutch heats up, forcing the clutch to get a tighter hold, thereby making the fan spin more? Fans that turn on and off on a car are electric fans. CD My fan spins a good bit even when the engine is cold. The latest problem is that I've popped the hood so much to check this that the cable has stretched.and the hood doesn't want to pop most of the time (slaming a door shut will pop it open perhaps half the time). >> If you let your Pathfinder overheat in the driveway you should be able to >> tell IF the cooling fan begins turning when the temperature gets too high. I [quoted text clipped - 68 lines] > > CD > My fan spins a good bit even when the engine is cold. > [quoted text clipped - 74 lines] >> >>CD The worst case scenario would be a blown head gasket. You don't want to go there just yet. Replace the thermostat and see what happens. Then replace the radiator if the car still acts up. The way your temp rapidly changes would rule out the clutch fan. A clutch fan problem would be more gradual. Hopefully it's the thermostat. CD The hood cable problem succumed to some 3-in-one oil on the latch. I picked up a new fan coupling at the dealer today. Damn., that thing is heavy. But it spins a lot more stiffly than one on the truck, so I'm guessing this is at least part of the problem. And it would explain why my freeway gas mileage got better (less power going to sping the fan). I chose the fan coupling because it looks like the easiest install, and I wasn't comfortable with how easily the fan spun. I'll get it installed by and by. >> My fan spins a good bit even when the engine is cold. >> [quoted text clipped - 83 lines] > > CD I installed the new fan coupling Thursday. It was easier than I expected. But it didn't fix the problem -- I had an overheat today. We were towing the boat back from Monterey in about 70F and got caught in a ten minute traffic jam (ten minutes for us, till we got to my secret back road). The temp was fine in the jam, but as we came off the traffic light onto the back road, the temp needle went up to about the 3/4 mark and back down again. About four miles later, at (the first) stop sign, the needle went up higher, and back down again, and then a half mile later up and stayed. I pulled over, put the hood up, and the overflow bottle was overflowing. Let it cool off good, pulled the vent plug, topped up with coolant, put the vent plug back, cap on, and got home with no further incident. I'm thinking next step is thermostat. And flush since I gotta drain the coolant. What flush to use? \ > The hood cable problem succumed to some 3-in-one oil on the latch. > [quoted text clipped - 93 lines] >> >> CD on 9/16/2007 11:58 PM Chuck Tribolet said the following: > I installed the new fan coupling Thursday. It was easier than I expected. But it didn't fix > the problem -- I had an overheat today. [quoted text clipped - 120 lines] >>> CD >>> Excuse me for suggesting a most simple cause, but did you check the front of the radiator for a blockage, like a plastic bag sucked up on the road? SignatureBill In Hamptonburgh, NY To email, remove the double zeroes after @ No problem, it's a question that needed to be asked. But yes, I 've checked it multiple times, and also between the AC condenser and the radiator. > on 9/16/2007 11:58 PM Chuck Tribolet said the following: >> I installed the new fan coupling Thursday. It was easier than I expected. But it didn't fix [quoted text clipped - 105 lines] > Excuse me for suggesting a most simple cause, but did you check the front of the radiator for a blockage, like a plastic bag > sucked up on the road? Last week I pulled the radiator to give it a good fresh water flush and check the front (which is behind the AC condensor). I was impressed with how easy it was to pull the rad: eight bolts to drop the cardboard pan (which I had to do anyway for an oil change), unclip the lower shroud, pull the hoses off, two bolts for the upper shroud, two bolts for the rad. The inside of the rad looked like the bottom of a beer can: CLEAN. No obvious crud came out when I flushed it. There was a little dirt on the front of the rad, but nothing major. I changed out the thermostat at the same time. The old thermostat looked clean except for some crud on the piece that actually seals things off when cold. The temp gauge still sits in the same place when running. Changing out the thermostat was easier with the rad out, but would have been doable with it in, I think. Got back and forth to Monterey twice with the boat on this weekend with no problems, but no stop and go traffic either, so the jury is still out. > No problem, it's a question that needed to be asked. > [quoted text clipped - 109 lines] >> Excuse me for suggesting a most simple cause, but did you check the front of the radiator for a blockage, like a plastic bag >> sucked up on the road?
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