Mechanics

MY IS OVERHEATING

1998 Nissan Sentra

Hi I am a young female and I constantly travel to work and school everyday. I travel about 85-95 miles a day. Well, I just got my 1998 nissan sentra from an auction. It has 119,865 miles on it. I just had my radiator rebuilt but my temperature guage keeps reading that my car is running hot. I don't smell fumes or see any smoke. I don't know what else to do and I am scared that one day I will be driving to school or work and something terrible will happen. Please Help Me. I don't know if my hose has a leak or what it may be. All suggestions are highly welcomed. Thank you in advance and have a good night : )
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Hmccray1
November 10, 2006.




Bleeding the system is easy. When warm, crack open the bleeders on the system by the hoses. Next, are you sure that the thermostat went in correctly? For instance, I am not sure if there is room on that model but in is possible on some cars to put the thermostat in backwards. And there is only ONE thermostat. There other sensors and make sure that the electrical was hooked back up properly to the sensors and the fans. Is the fan working, is there enough fluid in the vehicle, does the car heater work and get hot?
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Bruce Hunt
Nov 11, 2006.
Hmm I though I replied already, maybe I replied to the wrong thread or maybe I hitpreview and not submit : (.

First off thanks for the reply! I know my heater blows hot when I turn it on to cool down the engine after exiting the freeway. I know both electrical fan are working fine or else I would be in bigger trouble. The thermostat should of been in the right I used haynes manual as a references. Lastly I know how to bleed the system, I just didn't bleed it when I changed the water pump I though it would be fine, but now I have another problem the new radiator cap I purchased from stant fits my car but now it wont come off! The cap loosens but wont come off, the two hinges of the cap wont let go of the radiator. I dont mind destroying the cap I am thinking about prying it off with a screw driver. Start up car warm it up bleed it add coolant and slap on a new cap and hopefully get this thing over with! : X

Tiny
Bigaldizzler
Nov 12, 2006.
Well, I managed to take the radiator cap off. I changed the coolant and bleed the system but my temperature gauge is always going up and down not always constant. I dont know if I have bleed properly. Here is how I did it.

1.) Drain out all coolant in radiator by removing drain plug.
2.) Reinstall plug, and fill with new coolant with bleeder valve slightly open.
3.) Once I have finished pouring all coolant in I closed the bleeder valve. Then fill my coolant reservoir to cold max.
4.) I start the car with radiator cap off, and heat on max.
5.) I wait for car to warm up, then add if need.
6.) I turn car off and install new cap done.

Ok, so basically thats what I have done but I noticed that when I was warming the car up. It took probably 10 min the coolant would drop and rise out of the radiator, and once in a while I would see a big bubble of air shoot out the top of the radiator. I dont know if this is normal or not. During this period I choose to open the bleeder valve again, the coolant level in the radiator dropped and I proceed to add more coolant then I saw that coolant was coming out the valve I closed it. I waited another 1 or 2 min. And didn't see any bubbles coming out or anything so I just shut off engine and put on the raidator cap.

I took it for a drive to school about 5 miles away the next moring and while I am idling the temp rise when I am driving it would go down. Sometime when I am idling the temp would go pass 50% which was normal temp before any overheating happened.

Any suggestion as too what may be wrong? I notice one of my fan is not really really close to the radiator like the other fan.I bought a OEM " STYLE" radiator maybe I have a fitment issue. Its about an less than an inch way from the radiator

Tiny
Bigaldizzler
Nov 16, 2006.
The distance should be fine for the fan. The bleeding is something I do when I know the system is full of coolant and the overflow res is full too. Then when the system is warm I crack open a bleeder and let out the steam and air. I may have to crack it open and shut several times as the fluid exchanges around the system and lets the air get pushed around as well.

There are other things that you could watch for as well. For instance, the radiator hoses can look just fine but have a failure inside that restricts the flow of coolant. When you are idling and the engine temp starts to climb are you ever hearing the fan kick on?

Bruce Hunt
Nov 16, 2006.
Hey bruce nice to hear for ya again 8)

Hmm, I have new hoses and I also flushed the engine with garden hose I doubt I have any restrictions there, but I know I bent some of the radiator fins in accident does that cause restriction?

I will try bleeding it when the car warms up, and see how that goes! Thanks : P

Tiny
Bigaldizzler
Nov 16, 2006.
The fins will not cause any flow restrictions. They help dissipate the heat as it flows through the radiator. The radiator cap is very important to be replaced with a proper and exact replacement. The pounds of pressure is important and the ability to open and close to allow the use of the resevoir is critical.

Other than a blockage which we have covered, the fans to cool, the thermostat, bleeding and the radiator, the water pump is about it. Double check!

Bruce Hunt
Nov 17, 2006.
Hey bruce I doubled checked everything, the cap is 13psi like the OEM cap so it should be fine. I think I will take the car to my uncle who is a mechanic and let him bleed it in a few days as thanks giving week is around the corner and I will be getting off school.

I drove my car about 18 miles on the freeway I notice the temp. Gauge would be a little below 50% (50% was what the car use to be on when everything was fine regardless of local or freeway drive) It took maybe 20 minutes on the freeway for the temp. Gauge to move to the 50% mark then it would drop down. When I exit the freeway the temp would be below 50% but as I accelerate from the stop sign my temp gauge would raise to 70% and back down to a steady 40=50% when I got to my friends house I decide to check the the hoses, the upper house is warm and the lower hose is cold. I already replace the thermostat twice.I am getting so frustrate : cry: Anyways thanks bruce and happy thanks giving : D

Tiny
Bigaldizzler
Nov 20, 2006.
It sounds like a blown head gasket to me. The bubbles you noticed in the radiator is actually engine compression being released into the coolant system
Remove the radiator cap now (with engine cold) start car and observe for bubbles. Have someone rev the engine and continue to observe.
If you still see bubbles at idle or with the R.P.M.'S up you shoud know it a blown head gasket.
Also, there may be some crud mixed with the radiator fluid. This crud is actually oil gas exhaust all mixed, not mold as you were told.

Tiny
Doug29681
Dec 15, 2006.

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