Car seems to almost over heat when I ...

[DRFT]

Turn on the AC for about 10 mins. Is there a way to fix this when my AC is on? I need the AC because its get really hot here in Sac. Do I need a new thermostat?

[yellow_jacket]

Or your radiator could be plugged

[S13Nissan240SX]

I've had a similar problem for a long time. Mine will last longer then 10 minutes, but I will start running after a while of driving in the heat. My daily commute is probably about 25 miles through city traffic and by the time I get home in the afternoon, I can see my temperature needle start creeping up. It usually only does it at stop lights. Once I start moving it goes down pretty easily. The problem is, it's not my thermostat and my radiator is pretty clean. I agree, however, those are the first places you'll want to look.

Giving my car a good radiator flush at the start of the summer has really helped in the past. I'll be doing mine in a couple weeks. This usually helps keep the temp down. You might want to try it.

If you come across anything else that helps please let me know. I live in Tucson, Az and it's breaking 100 degrees here every day.

Thanks,
Matt

[DRFT]

Well I also noticed thatmy coolant is low. would that be another reason why it causes the temperature to rise?

[Pudula]

Air in the radiator could most definately cause that.

-Ryan

[elevator]

Thermostat
Air in radiator
Needing a good flush

Any of these could be the culprit......I'd be willing to bet the theromostat would fix it though. Replace that and you could be killing all three birds with one stone. A new thermostat at the beginning of summer is a good idea anyway.

[S13Nissan240SX]

Another thing you might want to consider is to buy a new radiator cap. If it's not holding the pressure you could be letting air in the system that way. It's only a couple bucks at checker so you might as well.

Good luck,
Matt

[Bill Roberts]

Ditto S-13, you took the words right out of my mouth.

It is all about these things....if you have all of this, you will run cool.

A system that flows freely (most important)
A system that will pressurize. NEW CAP, clean cap receptical/filler rims. (water boils at a higher temperature under pressure)
A well Bled system (no Air) , open the bleeder valve on the intake.
Cooling fins unobstucted by bugs, sand and debris.
Correct OIL level in the engine.
If automatic, clean tranny fluid including the tourque converter and filter.
A 40/60 mix of clean water (distilled is best) and antifreeze.
A working non leaking radiator. (DUH)
A leak proof waterpump, tight bushings.
Electric fan that works properly.
Clutch fan that works properly (optional with electric fans X2)
New thermostat and gasket.
Good flowing heater core in case it is a bad heater exchange valve causing the water to try to flow through a clogged heater core, wasting the flow rate. Flushing keeps that core clean. You should actually use your heater a few times during summer if you live where it does not get cold to keep the valve seats working properly.

Look for a kinked hose as well...disturbing flow.

Now, if the water jackets in your head and block are not flowing and your radiator needs rodding out, you will burn it up every time.

I wish someone would design a mist system for the front of the radiator that you could turn on from time to time with a 3 gallon tank. That would really help if everything else is right.

Hope this helps...

[fast240rb25]

On some of the 240's there is a temperature gauge in the lower radiator hose between the radiator and the motor, check if you have one & it may be bad also, That should be a safety backup if the coolant gets too hot it is supposed to kick the electric fan on to help, also if the problem is only when the A/C is on, check and make sure that the electric fan kicks when you turn on the A/C, you could have a bad fuse or relay.

Hope this helps!!

[240 2NR]

I'd stick with 50/50 water/ antifreeze or better. Anntifreeze is really only good for lowering the freeze point and inhibeting corrosion. Provided you use distilled water and keep the system clean you could probably just use water if freezing is not an issue. My guess is you probably just need to change your coolant and be sure to purge all the air. If it was the cap or thermo, he symptoms would have been apparent earlier IMO if they actually did fail. Not to say they may not be suspect.

[Bill Roberts]

Antifreeze raises the boiling point by at least 30F degrees under a specific mean 13PSI above atmosphere.


You will get a higher boiling point with the additive.


Actually all of the different types of antifreeeze does this.


Jay Leno...where are you dude????


LOL.....


Strait water will never increase your boiling point like antifreeze/mix will.


My 40/60 is 40 anti/60 distilled H20

YMMV of course

[Phlip]

Also check that coolant tank on the driver's side of your engine bay, mine was a little low after I got a water pump and the temp would creep up at odd times sitting at lights at idle and waht have you... I bled the air out of my system and made sure that was properly filled and the problem cleared right up...

[S13Nissan240SX]

Originally posted by Bill Roberts
A well Bled system (no Air) , open the bleeder valve on the intake...

Bill,
I've got a couple questions for you. I open the bleeder valve when I flush my radiator but then I tighten it up for every day driving. Do I want to keep it open or make sure it's really snug?

Thanks,
Matt

[Bill Roberts]

When driving, it needs to be tightened down. you will lose pressure if the bleeder valve is open and it can run hot. Remember, the pressure allows the water to run hotter without evaporating due to being at a sub boil. Right before water boils, you see all the steam coming off. This is pure evaporation. Yep, I cannot see any advantage of leaving the bleeder valve open.

[S13Nissan240SX]

Cool, that's what I thought. Just making sure.

Thanks,
Matt