98 240sx : Water Temp Fluctuations

[rn240sx]

Im changing this topic cause it seems that nobody can expalin why my water temp are rising the way they should and im getting asked questions that have no irrelevance to this topic..

Im gonna expalin this in a simple fashion is hope's that someone can expain why...

A:While your driving on the hwy at speeds of 45+ mph and plenty of air is hitting the radiator, the water temps should stay stationary and NOT rise simply cause a continuous flow of air is hitting it and keeping the water temp stable... This is a FACT and i have personally seen this on my previous (two) 240's that i have owned...!! (180-185 deg is hot weather and 175-180 is cold weather)

B:Now, when u come to a stop light, no more air is passing thru that radiator so that simply means that the water temps will slowly start to rise... until the temp reaches the thermostat setting and then the fans kick over.. Another FACT..

In my case, i can be moving at speeds up to 90 mph and my water temps will NOT stay stationary as mentioned in part A..For some reason the temps will rise until the fans kick on, then the fans cool the water down, then the fans shut off, then the temp will start to RISE again and this cycle goes over and over.... They will not stay stationary while driving like it IS SUPPOSED to..!!

This is not normal and im trying to find out why. I have changed out the radiator, thermostat and water pump and nothing seems to change anything..

This has NOTHING to do with TOO many fans, Not enough fans, nor what size they are, nor what temp they are set to kick on to.

My fans kick on at 205 and they cool the water down each and every time, the motor does NOT overheat, i do have heat and it stays hot all the time. I can manually turn the fans on while driving and they WILL cool the water down to ~180 deg and HOLD the temp there until i shut them off, then the temps will rise up again while still driving..!!

Im not sure how much easier i can explain this, but this is not supposed to happen and i am out of options...

Modified by rn240sx at 11:22 PM 10/30/2005
Modified by rn240sx at 11:43 PM 10/30/2005

[NISTECH]

Replace your t-stat. I know it was fine in the other car but it has been sitting unused for some time. What I think is happening is its opening just not completely.

Edit: this was a response to reflect what was originally posted.

[rn240sx]

I replaced the thermostat, water pump and radiator cap and im still having this problem..!!

The only thing left is the heater core which i doubt will do this. I do have heat by the way so its not like its bad...

[NISTECH]

you have a flow restriction somewhere or a nice size air pocket. How hot does your heater blow sitting at a prolonged idle?

[NISTECH]

also did you buy a factory t-stat with a bleeder whole in its outer ring that absolutly needs to be positioned straight up?

[rn240sx]

I have heat and it works fine, ive sat at a stop light for well over 3 minutes and the heat remains normal...I purchased a new oem thermostat from autozone and when i installed it, i made sure that little nipple was aiming up...

Get this, for the past 3 days the temps have dropped into the 50's due to this hurricane that just hit us, and while it was 49 degree's for 2 mornings, the temps dropped down to 180 degree's while cruising on the street and hwy.. and stayed there until i came to a stop. like its supposed to.. and Now it was working normal like it did b4. THANK GOD..!!

After the cold weather came thru and passed, the mornings were now back up to the 70's and the afternoon's were back up to the mid 80s and the water temps started back up again. They wont stay stationary.

This is NOT making any sense to me.. Why is it that the cold weather keeps the temps stationary while crusing, but when the warmer weather comes thru, the water temps wont stay stationary...

Something is wrong somewhere...

[NISTECH]

For giggle check your mechanical fan and make sure it is blowing air back across the engine instead of forward through the radiator.

EDIT Was unaware car had dual electric fans as original post did not mention it.

[rn240sx]

I dont have a mech fan.. I have a dual set of 12 inch elec fans.. Kinda like the altima setup

[NISTECH]

What temp are they set up to come on at?

[rn240sx]

Not sure why this matters to this topic, but on the s13 and s14's they have a small 10 inch elec fan that kicks on when the a/c is on and when the water temp reaches 208 as a backup if the mech fan goes bad..

Ive got my 2 fans hard wired into that same circuit so when my a/c is on, my 12 inch fans kick on AND when the temp reaches 208, the fans also kick on..

It works just great and has been this way for over 4 yrs.

Again, im not sure what that has to do with the topic at hand, but u asked and i answered...

[NISTECH]

The topic at hand is your car has erratic engine temp fluctuations. My question was what type of control do you have over your coolant temp. Some how I felt it was very relevant.

[s13sr20chris]

too many fans.

ditch the little pusher and build ducting around the electric fans(similar to the stock fan shroud. maybe even put some vents in it that will open up at high speeds.

[rn240sx]

too many fans.

ditch the little pusher and build ducting around the electric fans(similar to the stock fan shroud. maybe even put some vents in it that will open up at high speeds.

Are u serious..??? Did u even read the initial post..??

[NISTECH]

Damn dude for someone asking for help from us you sure are getting pissy! You have completely modified your initial post to omit the fact you have just instaled this engine into another car after it sat for a long peiod of time. Being that it worked better for you over 4 yrs is the only thing irrelevant as you arent dealing with the same set up.

here is a FACT you arent considering , under load the car will get hotter faster, the more load [90mph on the freeway] the faster it will heat up. Even though air is blowing across the radiator from the speed in which your driving it is not enough flow to maintian a steady temp as you desire. The altima is set up to kick those fans on low speed at 190 degrees and run till it reaches ~176 degrees. They will come on high speed at ~205 degrees [which is what you are relying on right now.]

In all honesty reading through your NEW and improved first post I would say your cooling system is working about as expected with the set-up your running.

[rn240sx]

Damn dude for someone asking for help from us you sure are getting pissy!

Ahh yeah cause im getting asked questions that have no relevance to this topic

Quote »You have completely modified your initial post to omit the fact you have just instaled this engine into another car after it sat for a long peiod of time.[/quote]Yeah in hope's to re-word it so that u guys can better understand my problem and hope that i can get a better answer...

Quote »Being that it worked better for you over 4 yrs is the only thing irrelevant as you arent dealing with the same set up.[/quote]Who said i was NOT dealing with the SAME setup...?? Its been the same setup in all three 240's.....

Quote »here is a FACT you arent considering , under load the car will get hotter faster, the more load [90mph on the freeway] the faster it will heat up. Even though air is blowing across the radiator from the speed in which your driving it is not enough flow to maintian a steady temp as you desire. [/quote]

Explain how my last two 240's were able to maintain 180 degree water temps while steadily cruising at 55+mph.... Are you saying that its not possible..??? This 180 is not my desired temp... its the temp that was actually maintained in those last 240's...!

Quote »In all honesty reading through your NEW and improved first post I would say your cooling system is working about as expected with the set-up your running.[/quote]It is working, but not working like it should.. simply stated..!! The fans should not have to be RUNNING while on the hwy.. When ur on the hwy, there shuld be ENOUGH air flow to keep the temps down to where the fans dont have to physically working.... Been there, done that, seen it happen and thats the way it works... bottom line.!!

Im not sure how easier i can explain this.. My last two 240's i didnt run into this problem... simply stated.. Now that im on my 3rd 240, now im running into this water temp problem even after changing out everything that i can think of

[NISTECH]

Ahh yeah cause im getting asked questions that have no relevance to this topic

Yeah in hope's to re-word it so that u guys can better understand my problem and hope that i can get a better answer...

Who said i was NOT dealing with the SAME setup...?? Its been the same setup in all three 240's.....



Explain how my last two 240's were able to maintain 180 degree water temps while steadily cruising at 55+mph.... Are you saying that its not possible..??? This 180 is not my desired temp... its the temp that was actually maintained in those last 240's...!

It is working, but not working like it should.. simply stated..!! The fans should not have to be RUNNING while on the hwy.. When ur on the hwy, there shuld be ENOUGH air flow to keep the temps down to where the fans dont have to physically working.... Been there, done that, seen it happen and thats the way it works... bottom line.!!

Im not sure how easier i can explain this.. My last two 240's i didnt run into this problem... simply stated.. Now that im on my 3rd 240, now im running into this water temp problem even after changing out everything that i can think of

Oh Brother

[rn240sx]

Oh Brother

No more comments huh..?? No more suggestions huh..?? Oh well, lets find out what others have to say about this problem..

[NISTECH]

no dude nothing more from me as you seem to be the cooling system expert here. I am just some flunky that dont know crap about them.

[Rex]

No more comments huh..?? No more suggestions huh..?? Oh well, lets find out what others have to say about this problem..

Plain and simple - You're not listening .

Running non-stock fans? How much of the balance of the cooling system have you moidified or adjusted to properly use this new set up?

New OEM t-stat from autozone? Nope, OEM would be from Nissan, w/a Nissan part number. If your "autozone" t-stat has Nissan labeling on the package, I stand corrected.

And assuming that the increased air flow from a higher (maintained) road speed exactly matches the increased amount of air necessary to maintain the coolant temp you expect/have seen in the past is rediculous. Air temp, humidity, engine rich/lean, clogging cat, etc are all factors that can effect engine temp.

If you don't want his help, just say "No Thanks" and try elsewhere.

[Repo Man]

If you don't want his help, just say "No Thanks" and try elsewhere.

[Nismo_Freak]

I have heat and it works fine, ive sat at a stop light for well over 3 minutes and the heat remains normal...I purchased a new oem thermostat from autozone and when i installed it, i made sure that little nipple was aiming up...

Get this, for the past 3 days the temps have dropped into the 50's due to this hurricane that just hit us, and while it was 49 degree's for 2 mornings, the temps dropped down to 180 degree's while cruising on the street and hwy.. and stayed there until i came to a stop. like its supposed to.. and Now it was working normal like it did b4. THANK GOD..!!

After the cold weather came thru and passed, the mornings were now back up to the 70's and the afternoon's were back up to the mid 80s and the water temps started back up again. They wont stay stationary.

This is NOT making any sense to me.. Why is it that the cold weather keeps the temps stationary while crusing, but when the warmer weather comes thru, the water temps wont stay stationary...

Something is wrong somewhere...

Alright.

You have a turbocharged engine with a front mount, the front mount is not only heating the air before it reaches the radiator (only under acceleration) but it is restricting the amount of mass flow to the radiator.

The fans that you have on your radiator restrict airflow at speed. This is why the FAL 210 fans that sit flush against the radiator have been known to cause warm temps. You need to think about mass flow before and after the radiator. When the fans come on they assist in moving airflow, thus increasing mass flow through the radiator, but when they click off they restrict it.

It should also be obvious why cooler air = cooler temps. You are running above the thermostat's temp then it is wide open and the radiator is the last part of the cooling system to affect temps at this point.

What mixture of coolant to water are you running and have you checked the radiator for lime scale or other forms of build-up.

[rn240sx]

Nevermind guys, i posted on another forum and got an an answer, did what was recommended and it fixed the problem...

Now cruising at 55+ mph on the hwy got my water temp to stay solid at ~180 degree's as it did b4 with my other 240's... now its back to normal...

[maik21]

first.. you need to know if really the water is hot or not with you rise of them... maybe a fault......second... my father's car, sentra, has 2 fans... one of them , swith on when wather temp is hot-cold... and the other to ac or when the temp rise up too much....

if you r runing a fan clutch maybe you need to replace them for another... maybe the fan dont throw to much air and ...... the electric fan switch on to drop the temp. and its a circle!!

[NISTECH]

What was the fix? Remove the t-stat? or bypass the heater core by looping the heater hose?

[Rex]

I'm sorry, you weren't able to get the help you needed/wanted here.

The point I was trying to make was you "limited" the help, by not fully disclosing (never saw turbo & FMIC) mentioned anywhere, and deciding not to answer questions you felt weren't relevant.

[Nismo_Freak]

WE don't know your setup. YOU never said what it was. So how the hell are we supposed to know where to even start!? Thats like saying ... my car runs funny, but it's been running fine for the past year, whats wrong with it?

[C-Kwik]

It was SIMPLY stated. Ive had the SAME IDENTICAL setup in this 240 as WELL as the other 240's that i have EVER owned. I never had any cooling problems b4 until i bought this current 240sx. Then all of a sudden this cooling problem arises.. !! Its that obvious cause this problem did NOT exist in the last 240's i owned and all 3 cars had the same motor with the same setup.. NOTHING is different..!! I dont know how much clearer i can explain this..

But yet, they keep asking me these questions that mean nothing to me..

Robert, As frustrating as the problem may be, don't take it out on other forum members. And consider this is a forum. We do not have access to your vehicle and many of us will not know your set-up or history.

Regardless, if the set-up was identical, obviously something is different. Finding and eliminating this difference is the key. To do so, we have to approach it in a clean slate manner. Basically, eliminate each possibility until the cause shows itself.

So whether you think it is relevant or not is irrelevant. It seems that your mind was stuck on the airflow issue. Others trying to help you may have some ideas that you aren't thinking of and need answers to their questions to rule them out or go with it to help search for your answer. I'm sure, you have played with your car enough to know that it is a lot easier to diagnose issues with the car in front of you rather than over the internet. Anyone asking for help is likely out of ideas themselves. What's wrong with entertaining others at this point, regardless of how relavant it may seem in your mind. Asking for someone else's opinion is not about going down the same path as you did. It's about having a different look at the problem. If the questions mean nothing to you, it's probably better. If the cause of the problem is something you weren't thinking about, it could be more relavant they you realize. Or perhaps not. But it's one step closer to finding the solution. As much as you may want to jump straight to the solution, in many cases you can not. Ask any mechanic. Some problems are easy to find. Others require a lot of process of elimination to narrow down the problem. Given that this isn't an OEM set-up, those of us on here will want to know and understand your set-up better.

[s13sr20chris]

how about a link to the fix thread?