Ok so I'm idling in Texas heat for about 20 minutes. It's about 95F outside and the AC is on. I drive on to the street and notice my temp guage is about 25% higher then it should be (another 1/4 higher then the halfway mark). Once i get to speed it instantly falls right back to the center where it is supposed to be. I didn't drive the car hard, but lower RPMs it seems to be driving fine.

I want to know; A) how much damage could've been done to my car (never rev'd it past 3K), and the liklihood of any permanent damage.

Also, I want to know what thermostat temps and fluid temps you guys recommend?

Thanks, hopefully the car will start again when I leave work, it was running fine when I shut it off, but still...

 

check/change your antifreeze first. it sounds like coolant isn't circulating properly. the key is you state it is ok once you get back to speed and the air is helping to cool things down.

 

If it dropped right back down, it seems to be some freak thing. Sometimes my temp gauge will just loose reading, I hit the dash and it will shoot up to the top and then eventually go back to normal, it could be the connector behind the guage, or it could be your temp sesor going bad, if there was something serious wrong, I would think it would have not dropped back down just by driving. When my water pump went out it would just keep getting hotter as I drove. As far as damage to the motor, dont worry, my car has been hot when the water pump went out, I mean top of the gauge hot and it has more mileage and it has been fine for a year now.

 

Something like that happened to me, and I ended up getting my radiator pressure tested, found a leak, had it replaced along with some leaky hose, and all good now.

 

It's odd that the temp rose but your situation is the worst for the cooling system. The ac while it does blow COLD air, it takes energy and actually generates heat to get that cold air.

Did you notice your fans coming on during that hot time or when you are parked? If not, maybe the fans aren't kicking in and helping the radiator cool when you aren't moving. (loose connector or blown fuse)

It could be low coolant level, thermostat not opening at the correct time, or maybe even your water pump giving up the ghost.

I don't think you did any damage though.

 

Thanks I had similar problems in my Acura Integra GSR

 

AC Fan turns on
Don't know about radiator fan
Coolant level is good
water pump is not leaking

 

You need to know if the radiator fans turn on, which shouldn't be hard to do just idling in 95 degree heat. Also feel the upper and lower radiator hoses, especially the upper one and make sure it's hot. Be careful while doing this, of course.

 

First I recommend getting an aftermarket temp gauge. Also when was the last time the cooling system was flushed? You might have some air bubbles trapped in the system. A few things you can do is get a Z32 radiator cap (has higher pressure) and re-bleed the air via the air valve. IF that doesn't work plan on flushing the system, removing the radiator and cleaning out the fins.

 

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It's not fin related because the second I got it rolling again it quickly came back down thus it's cooling fine with ari flow, it's when it idles that it has the problems.

 

Checking for a faulty water temp guage is easy. I believe you run the car up to operating temp, and the crack out the multimeter to backprobe the temp sensor connector. It's all in FSM.

 

I drove home with the AC on and it was hotter then before. It was fine, I had it idling at a couple lights for 2 minutes or so, drove it normally and no problem. I guess the car just can't take 15 minutes of parking lot driving, and 10 minutes of idling in 100F with AC and S/C loading on the engine (although many people think any car should be capable of this).

Most people will say that's never happened to me, but how many people with SC with AC on have sat and done this 30 minutes worth of stress before. Also, the second I got it rolling on the road within 30 seconds the temp was fully restored and the car drove fine.

 

Try Redline Water Wetter....8 bucks at Van's on 183 and Burnette. It'll help.

 

I have driven my car here in Austin with the same temperatures when I am at a stop I have not seen my temp gauge go up, and I have looked at it. But when I am at a stop I am not stopped for more than about 2 minutes.

 

The 2 fans up front are the radiator AND cooling fans. It's a combo circuit controlled by the ECU. Since the fans turn on with the AC, then the problem is not the fans, or the fan relay. The problem may lie in the cooling circuit, something may not be telling the ECU that the engine is hot, so check along the lines of a temp sensor, water pump, thermotstat, hoses, or radiator cap.

Do you smell some anti-freeze? Try replacing the radiator cap. It's a quick, easy fix.

HTH

DW

 

Also try a 50/50 mix of redline water wetter and distilled water. It will help keep the temps down. Can get expensive though if you do a radiator flush.

 

I do have water-wetter in my system now.

I do not smell or see any boil over.

Climax, I drive in the same heat all day long and stop for two minutes and no problems, but the 30 minutes is what killed me.

 

is it possible that your thermostat is not fulley opening? i've never heard of one do that, but i've had one stick closed on another car.

 

After having to replace my AC cooling fan on my now dead '96 GXE, I learned about both fans. When you said the AC fan turns on, are you talking about the blower motor for the interior, or the passenger side cooling fan behind the radiator? The passenger side cooling fan should be on at all times that the AC is on. It will also come on with the AC off to help the primary fan if the temp is getting too high. The driver's side fan should come on first when the temp starts rising normally. It should be on at all times when the AC is on (boils down to AC on=both fans on high). Not sure about the secondary fan (pass side), but the primary also has two speeds. It'll be on high whenever the AC is on, and whenever the secondary fan is also needed. Can't remember which is which, but for some reason one fan has 4 evenly spaced blades, and the other 5 unevenly spaced (my dealership can't explain why). I ran my '96 without the secondary fan plugged in for about a month in a Louisiana summer. No damage whatsoever, but the AC sucks when you are at a stop (really sucks in Louisiana heat, at a long light, and wearing a ballistic vest!). Fan cost somewhere around $120 at my dealership (probably really ripped off), that's why I had to wait. Other posts are right about checking things. I would recommend atleast a cooling system flush (not just drain/refill), depending on last time it was done. A Prestone kit (~$4.00) can be installed on your heater hose to backflush the system. Has worked great for me on several vehicles, including my wife's '88 Nissan pickup. Her truck warms up much quicker, and the gauge is where it should be now (was extremely low; stuck thermostat?). I've wondered about water wetter. Anyone have any personal experience or facts about it? Sorry so long, my Tylenol 3 is kicking pretty good. Hope some of this helps.

Dave

 

it is possible that everything is working properly and you were juss starting to overheat. Idling for long period of time and Hot weather plus AC on can cause many cars to start to overheat. I dont think you caused any damaged if it only went up some. Even sometimes when you hit way top H you dont cause damage but no guarantees.

 

On my 99, both radiator fans come on when the engine gets hot and they run at low speed until the temp drops and then they shut off again.

Switch the A/C on and the fans run all the time, on low speed.

Let the car sit and idle for a few minutes with the A/C on in 90+ degree weather and BOTH fans will kick up into what I call TURBO mode. You can hear them roar on high speed. That only happnes in really hot weather.

The temp gauge in my car never really seems to move, it just stays right in the middle area.

 

With the A/c on this morning (not very hot) just the poassenger side A/C fan was on, not the driver side fan. Is the driver side fan supposed to be on 100% of the time when the A/C is on or only when the engine is getting too warm?

 

Some of you guys are saying that one fan turns on, then the other. On my 98, both go turn on together. They seem to vary in 2 speeds. Maybe the 95/96 cooling system was a bit more sophisticated than the later 97, or 98-99 Maximas. You should check if both fans are supposed to go on together, and if they are, then maybe one fan has gone bad, or the harness to that fan etc.

DW

 

Is your main fan kicking in? If not check your temp sensors. My old Max had high/low speeds on the fan and either 1 or 2 fans running(depends on AC). I don't have the FSM for your car, but check/test all- relays/fuses/temp sensors/fans. You should be able to unplug or short the sensor and force the fans to go on.
Thermostats will slowly fail. Just replace it and your rad cap. And while your at it, flush your coolant. 50:50 water/antifreeze with a bottle of waterwetter should be good. Coolant is only good for about a year(regardless of what the bottle says). There is no coolant filtration and no way to remove suspended particles without changing regularly.

If temperature drops with vehicle movement, air(windchill) or water(gph) flow is the issue. To test waterpump, just rev engine while overheating in traffic. If the temperature drops with revving(all else equal), then water flow is inadequate. This could be caused by the pump/thermostat/or restrictions(clogging) of the system. If temp drops only after moving vehicle faster, then airflow(fan/ecu/thermo sensors) is the problem.

 

Re-read that did you mean that if temp doesn't go down with revving"

 

I agree with the fans.....check to make sure that BOTH are working


I think nissans have a habit of one fan dying yet the other works

and you can get a good "generic" replacement fan at pep boys....I had to replace both in my sentra when I had it

as long as the car was moving it was fine ...but once i slowed down or came to a stop....the gauge needles started to creep up

 

I'm in Lousyana and do the stop and go thing some times, Ive never had a problem.

 

If the temperature doesn't go done with revving, start with airflow debug(fans/fan switches...).
Because the problem occured in traffic(@idle or low RPMs/with no windchill), if temp goes down because of windchill(which it did once he started moving), check fans. Next time car runs that hot, rev it to 2.5-3.5k to get the coolant flowing. If temp drops, then deal with the coolant flow issues(clogged rad, defective thermo, worn pump, slipping belts).

Regardless, dump all basic preventive maintenance components. Buy coolant, OEM thermostat & cap, sensor, and yank those parts. If that doesn't work, then test fan motors. If fans work, test thermoswitches/sensors/fuses/relays/ecu/whatever. And, the last two things to replace is the waterpump and radiator. I never had to replace the Nissan radiator(except accidents) and usually dump the waterpump(never had one fail) during timing belt replacement. With regular maintenance(yearly coolant change), those components should last forever.
Online, the stat+cap+sensor < $50.

If fan is bad, please don't use a generic fan on the S/C'd V6. Either replace the motor(if option exists), visit salvage yard, or just purchase a new one online.

 

by generic i meant non oem

but i'm also pw'ing today so pay me no mind

 

I just came in here to see your sig

 

Oh yes, the sig

 

I agree with checking to see if both fans should come on together. My '96 and current '97, both fans are on high at any time the AC is on (even with engine cold). With AC off, my passenger side only comes on when the driver's side goes on high for extra cooling (idling in hot traffic). 98-99's may be different. Even when I had my passenger side fan disconnected on my '96 in a Louisiana summer, my temp gauge never went above normal (half-way), but the AC sucked (the dealership said it wouldn't hurt the car, just the AC wouldn't be cool. Imagine this, but they were right!). My guess would be that the driver's side should be on whenever the AC is on regardless. I agree with the basic maintenance items, too. Not too expensive, and can prevent many expensive problems. And I don't believe in extended drain antifreeze because as someone else said, there is no filtration for it that I know of. Rust and scale build up, and the cooling system loses efficiency. Hope you get it figured out.

Dave

 

No one has answered my simplest of questions:

DO BOTH FANS GO ON 100% OF THE TIME WHEN THE A/C IS ON, REGARDLESS OF ENGINE COOLANT TEMP???

 

no - not on mine at least (by the way I've got a great oil cooler set-up for sale if you're interested!)

 

On the 98 Maxima, yes, both. NEVER one or the other. Just turn on the AC. I think they have 2 speed settings, too.

DW

 

Put some Ice in the engine, eskimos in the back seat, and a polar bear in the trunk! PROBLEM SOLVED!

 

On my old '96 GXE and now on my '97 SE, both fans are on 100% of the time when the AC is on. This is regardless of engine coolant temp. Both are used for the AC. For engine cooling, the driver side is the primary and passenger is the secondary engine cooling fan. This means the driver side will come on a low speed (by relay) for normal engine cooling with AC off. When coolant reaches a pre-determined temp, the primary goes on high speed and the secondary turns on to assist. The motors are also inter-changeable (atleast they were on my '96), but the blades are different. I went for about a month in Louisiana heat without my secondary even plugged in, and had no problems with over-heating. The AC did suck when I wasn't moving. When my fan started going out, you could hear the bearings or whatever inside grinding like mad. Try unplugging each fan (for safety) and spinning the blades. You'll hear what I'm talking about if it is bad. I could also see that it "wobbled" as it spun. If your driver side is bad, I'd swap the fans around until you can get a new one. Remember to swap the blades, too. This way your primary fan will still function as the ECU sees fit. From your posts, I think that either your primary fan is out, or the relay/wiring/temp sensor. I'd check the fans first because of my experience with mine going out, and it only takes 10 seconds. (Plus it's free to check). Hope this all makes sense. PM or email if you need anything else (I can also look things up in my FSM for you since we both have '97s).

Dave