Recently I replace Water Pump/Thermostat and now I'm having temp issues. She's not overheating to the point that will blow something but moving up one bar on my digital dash cluster. Nothing is leaking, I believe thermostat opened up and put new belt on water pump. Could it be the belt tension or maybe the temp sensor? The thermostat is Duralast from Autozone and so is water pump(WP is brand new). The fan seems to go on, she's good at idle but on long stretch of open road at 60mph she jumps up one notch/bar on temp gauge. What would cause this 2 happen? I used Prestone Extended Life coolant with poland spring distilled water and totally flushed out old coolant. Any suggestions/help would be greatly appreciated, I know everything in installed correctly , radiator looks good, hoses look good, thermostat housing looks good. I believe this is all info on whats going on with my Biotch.!

 

I guess nobodies got any ideas or don't wanna help or too busy, that's kool anyway. I'm gonna replace tempsensor and the switch one at a time to see but need to do soon cause I'm doing WP/thermostat on Wifey's Sentra so I need my Max just incase I run into problems and need to go to the store!!!

 

"summer"



any codes from the ECU? if it's still in the normal range then don't worry about it. if it starts getting really high or still does it during the winter then maybe take another look at it.

 

It doesn't look like summer thing, about 30 degrees above normal but maybe the fan switch connection, I sprayed fan switch w/electrode cleaner to see since it was moved around a little during WP/therma. job. I will watch cause at first it got so hot it was boiling but then thermastat opened up then next day temp went up 2 bars, so I turned heat on 2 lower. Today ran it around a little and 1 straight away at 60 but it was raining hard so I'll try again tomorrow. I might just replace temp sensor and fan switch cause there cheap enough, plus it's worth not ruining her engine. Thanks 4 reply.

 

take it out at midnight-2am when its cooler maybe and see if it does it

 

Can you start it, let it warm up to the normal temp and then park it somewhere, bring engine speed to 1k rpm and watch the temp. Fans behind the radiator should kick in if they were not already on. If temp starts to climb and gets to the last third of the scale then you surely have a problem and this is either thermostat or WP, sorry. Fans should be adequate to cool the engine down when car is not moving, even in hot weather. This is of course if thermostat managed to open and provided circulation to the radiator and WP works as it is supposed to. I'd start with thermostat as it is simpler to get to.

Once I lost about half of coolant and the rest was still enough to cool the engine down on hot summer day. It couldn't keep up when I lost about 2/3 (one of the hoses broke) and I noticed the temp started to climb. By that time my radiator was almost dry.

 

If there is no air in that system you have a self-created problem - either the WP or the TS isn't working properly. No way the TS should only open when its "boiling".

WRT "boiling" ............... that you know because of what symptoms?

 

Check the thermostat, the temperature sensor(like $7 at parts stores) or the radiator pressure cap itself. I had a similar issue, when I first bought my max, only it was the opposite, it was running cool instead of hott. I really noticed it during the winter months when my heat would come on and go off. I thought it was the temp guage sending unit, So I replaced it, and still had the same problem. On really cold mornings it would take at least 30 minutes for it warm up, But as soon as I replaced the thermost problem was solved. If you replace your radiator cap, make sure its one from nissan, and not an aftermarket parts store like AutoZone, Ive had problems with a stant radiator cap from Autozone.

 

I know sometimes a thermostat can get stuck new, so some guys boil b4 installing 2 make sure it works, I didn't do that(forgot). I heard it bubbling/building up pressure, then the upper hose was sucked of coolant that was building up pressure cause thermostat wouldn't open and I had to add a little more water next morning to make up 4 water that is now in engine. Just remember I installed new WP/Thermo.. They were done right, no leaks, yesterday I cleaned fan switch and temp. sensor and took 4 ride seemed fine, will take 4 long ride again and see, thanks.

 

I am getting the idea you never bled the thing?

Not really following what you said there at all .................

 

What I was trying to say was at first after installs were done she got real hot cause thermostat wouldn't open, they get stuck sometimes when new. Then the thermostat opened up sucking in all coolant that built up in upper hose, while it was building up pressure I could hear it like it was kinda bubbling and I shut engine off and left inside heater on. After that I thought all was well, next morning on kinda long ride the temp went up 2 bars but went back down cause I put inside heat on high. She was only now running above normal temp about 20 degrees, and as U said she needed to be bled again. I probably tightened bleeder valve up 2 quick. So far she looks good, I ran her and opened bleeder valve up for a little while, then did that again later and she ran at normal temp just a little while ago. Thanks though, cause I wasn't checking that again as I thought it was good.

 

It doesn't sound like it was boiling. To me, the remaining air that was still there was getting cleared up as the thermostat opened up thus the coolant going down.

You don't want to know when it's boiling. Been there.

 

trapped air can in certain circumstances cause temp readings to be too high, as the air pocket will allow steam rather than hot water to go past the temp sensor.. and steam is able to reach much hotter temps than water as a liquid. just like ice can be way way below 32* as long as it's all frozen, steam can go way way above 212* as long as it's all steam.

so find THE steepest hill you can find, park facing up it, and let the car cool down, then pop off the radiator cap and start the car (with the heater running as well) and let the air all work its way out (squeeze the hoses a few times as well) then once it starts to overflow throw the cap on and let it run till the fan cycles on and off once. after that, make sure you have plenty of coolant in the overflow tank, then drive the car home and keep checking the overflow tank every 30min until it's all the way cooled down (just in case it sucked back in more coolant than you had in the tank when it cooled down)

 

Nope...............

Superheated steam (what you are mentioning there) can only be created by keeping the steam under pressure - with a car engine and cooling system there is no way to create such a condition because the radiator cap is by design releasing pressure at around 0.9Bar abs - as a result the highest the steam temp in an under-filled cooling system in a vehicle can reach is exactly the same as the boiling point of the water in that system (probably around 119C if its filled with water only - if you add antifreeze that temp will be slightly higher up to a max of around 155C for certain 100% antifreeze only combos) ................... yes the steam contains a lot of additional latent energy because of the phase change of the water, but its temperature is not responsible for the high readings on the temp guage.

The reason for the high temp reading in an overheating and under-filled cooling system (on the 3rd gen's design anyway) is that the temp sensor is in contact with the overheating source of the heat (ie the head) and that overheating condition is propagated to the temp sensor (brass/copper manufacturing materials of the sensor is known to be some of the best and cheapest heat conductors) ................. the metal is overheating because the air bubbles in the water in contact with the metal surfaces are effectively insulating the metal from the water and thus removal of heat/cooling.

 

actually keeping it under pressure keeps it liquid rather than allowing it to become steam. hence when your hose bursts open it all comes out as steam when pressure is released and it can expand from liquid to gas or are you saying that keeping it under high pressure allows it to reach higher temps as a liquid, and therefore keeps that same higher temp upon converting to steam in a lower pressure (like when your hose busts)?




but i see your point, in a controlled environment like a closed radiator system, not all temperatures and pressures are possible especially since the liquid in question (antifreeze) boils higher and freezes lower than normal water, which distorts the phase diagram quite a bit. dunno if antifreeze even has a triple point.

 

Correct - but the real reason why when the coolant escapes as gas/steam once the pipe burst is because you are suddenly lowering the boiling point of the coolant from around the overheated 119C as I said before to only around 96C - thus all the liquid will immediately boil in the cooling system soon as a pipe burst on an overheated engine

As for the diagram - that is the wrong area you are looking at - you are actually starting to work in an area of around 1.9 atmospheres because that is the dictated release pressure of your radcap (std on the 3rd gen anyway).

What you were proposing is located at the right side of this diagram, but the avg car cooling system is only EVER operating in the area defined between R and partly on the way to T in that diagram.

Yes - I am saying that - the boiling point of the coolant is directly proportional to the pressure its under - with a radcap of 0.9Bar your water boiling point is around 119C as long as the system has no air in it and the radcap has not started to release - once your pipe burst with the system at that temp, you drop the pressure of all the water to atmosphere immediately and as a result your boiling point immediately falls by around 20C to 96C with the result that any and all water in that system immediately boils. This is the reason why you often see radcaps of 1Bar+ on performance motors with cooling problems - it raises the boiling point of the coolant by a few degrees granting a bigger safety margin before the water in the cooling system starts to boil.

Lots of technical stuff I know, but this also explains why you mostly have temp meters calibrated to 120C like I said before - up to that temp your cooling system undoubtedly contains SOME water that may still be present to effect some rudimentary degree of cooling, but once your cooling system reaches 120C anywhere on Earth, your std 0.9Bar radcap WILL release pressure and as a result guarantee ALL your water to boil off almost immediately if you continue to pump more heat into the system.

Also - just for giggles and to confirm me not lying about the way the temp sensor operates - you can drain all the liquid out of the engine/cooling system and your temp sender unit will still quite faithfully cause your temp meter to report the engine temp .................. absolutely no need for either water or steam to be present around the sensor at all.

 

lol sorry i think i'd rather concede the point without a trial than run my car without any coolant in it at all.

 

Oh cmon man - where's your sense of adventure?

 

i already fcuked up my z's engine by overheating it... don't really feel like ******* up another engine.

 

- fortunately taking a lot of heat to do that cooling down the engine as a result. That's the first reason I wouldn't do that experiment with CTS without coolant in the system.

Well this is fair under stationary conditions. In reality you would probably damage your engine before CTS would get hot - it is installed on aluminum alloy pipe which is not good heat conductor on its own without coolant inside. This would be my second reason against such experiment. The third and most important is IMHO absence of coolant would create high temp zones inside the engine so it would be damaged much sooner compared to the case with burst hose. I just hope nobody takes this discussion to heart and try to actually perform this experiment .

 

Very valid points there, but the suggestion was done in jest and yes, it really should not be attempted in real life ........................ but then the issue under discussion was the steam actually not heating the temp sensor causing high temp indications and I was only describing the real working of the temp sensor and the behavior of the water in a cooling system.

Nope - its taking a lot of energy/heat out of the cooling system by releasing the steam to atmosphere, but its not taking ANY heat away from the engine other than that contained in the water itself - remember the water was already way above the atmospheric boiling point when the pipe goes, and as a result the latent energy in the water is simply converted to steam along the line in that graph I posted earlier - the engine was only ever "cooled" before the pipe burst by having the water under pressure absorb the heat.

As for aluminum alone being a bad heat conductor ............. I think you need to seriously rethink that theory because aluminum is around 250+ times better at conducting heat than water

 

Install a Stant brand thermostat.......normally overheating occurs at idle, while moving at 60 mph the airflow alone keeps things cool.....remove and see if it overheats then.....maybe you have a flow problem,......possibly a blocked radiator....

 

You're correct except the end result - by the time water cools itself back to 100C due to boiling there would be a lot of it left in liquid form: heat capacity over 20C is 80kJ/kg while evaporation energy is 2270 kJ/kg so it would take approx 4% of water to evaporate to cool the rest down to 100C. That water will be at 100C which is cooler than surrounding engine at 120C hence it still will be able to provide some cooling capacity compared to completely dry case.

Again - it depends. In this case water is moving through the system and that makes this comparison invalid as there's always supply of the fresh coolant at the tip of the sensor compared to the case of still water where it can only conduct by convection which is very slow as you pointed out. What I actually meant that aluminum would become a limiting factor in the absence of moving water: by the time sensor would reach 'normal' temperature from cold engine it might be already too late as those pockets around cylinder heads will be already overheated like hell.

It is slightly similar to the idea of 'heat pipes' used to cool modern CPUs - their equivalent heat conductivity is much higher than copper due to evaporation/condensation processes constantly going on inside. The static heat conductivity of the liquid used inside those pipes is irrelevant.

 

I think we basically agree on the temp sensor not possibly being influenced by steam at any temp higher than boiling point of water.

We seem to also agree on the thermodynamics of the whole thing - in my case I am pretty sure because of experience with many such happenings that you do lose a lot of (close to all) actual steam suspended cooling liquid should a pipe rupture while you lean more to-wards the ideal and simple energy content of remaining undisturbed liquid situation only.

Either way - lets just say that steam and air is a no-no in any vehicle's cooling system

 

My coolant system definatly had to be rebled, she was only running a little hot on long stretch of road not idle at all. The air pockets are a direct result of the engine rising above normal operating temperature's. In this case my engine was running above normal not temp sensor being dooped. I will keep bleeding coolant system until she's perfect. Today was very hot/humid here in NY, I took for long ride all around w/full car stopping and going, not until hours later on highway did she jump up in temp a little and I pulled over, at idle for 2 minutes she went back down. I believe there's a little more air in system unless I adjusted the belt wrong but I believe it's still some air. Yesterday it was fine all day but it was only 80 out and not humid. As far as I know on a open stretch of road inproper bleeding/purging of coolant system would cause this effect, that is of course that all else in that system is functioning correctly. I will bleed again while running with bleeder valve and squeeze all hosing, if this does work so that she is running properly I will drain system and refill again. Thank my dudes, really appreciate the looking out on this topic, Shiloh. I left out this, if this does not work I'm replacing the Duralast thermostat with OEM from Nissan.

 

Sure, I was just keeping discussion up as you expressed some interesting points .

 

From your description it sounds like you have circulation problem - car cools down as soon as you decrease engine load. My bet would be thermostat as WP is supposedly run faster at higher rpms so if it provides adequate flow at low rpms I don't see why it wouldn't do the same at higher end. I'd go and buy OEM thermostat, replace it and be done with that. As I stated before half the coolant was enough to cool my Max on hot summer day, I can't imagine you have less and haven't noticed that. OTOH thermostat stuck in closed position would easily lead to your symptoms in my opinion.

 

I am with Max_5gen on the circulation issue .................

and
No - the air pockets are a direct result of you not filling and bleeding it properly.................. and wanting to drain and start right over is not going to solve the problem either because exactly what is it that you intend doing differently this time that you cannot do with the system already filled? In my experience with all hoses intact and no leaks anywhere (especially on a properly filled overflow bottle's hose and with a decent radcap) any small pockets of air is anyway soon completely removed with the engine going though 2 or 3 hot/cold cycles.

 

Yes I wasn't bleeding and filling, I'm man enough 2 admit when I fuycked up!!! Yeah I really don't want 2 do thermostat again but I'm not willing 2 ruin my Biitch 4 a couple of dollars on a thermostat. I'm going today to get/order thermostat from Nissan by me and will redo when I get it. I do have 2 admit that at first when I rebled system a few times I really thought she was good until yesterday running all over the place in Hot/Humid weather, but I was wrong. On another Nissan note, my wife has a 93 Nissan Sentra w/220 thousand miles(runs great), I just did WP/Thermostat on her and I'm happy 2 say she's looking/running cool/good, the temp is good. The install was a little less time consuming/easier, less things in the way, the duralast thermostat is agreeing with the engine fortunately. Thanks my dudes for all the feedback, really, Shiloh.

 

Another Sentra runner then ............... that spaghetti mess at the back of the thermostat housing sure is a pain - hope you replaced those too while you were at it - personally I would rather do the Maxima's than the Sentra's stat

 

Yeah the Max's stat is easy is comparison but the Sentra's WP is easier.

 

well it sounds like you got a bad thermoustat. its probably not opening all the way.
ive had the problem before.

 

Yeah its' boiled down to stat, got Nissan stat yesterday(25bucks), got other plans 4 her though.