My car likes to overheat only when it is above 85 degrees. Does anyone have any hints as to what it might be?

i can think of 4 things off the top of my head:-check your coolant level-make sure you're running 50/50 coolant/water-thermostat might be bad-clog in the system

More info on my overheating problem. I took it into a shop and they said that I had a blown head casket. Yet when ever it is not 80+ in temp outside it will not overheat. I drove it home yesterday from the shop with them telling me that it would overheat no matter what because of the blown gasket. Yet it did not even get hot on the way home which was a 30 mile drive. Has anyone ever heard of something like this happening? I don't think it is a blown head gasket yet I don't know of what else it could be. I have noticed that when it does start to overheat that the transmission also starts to act up by not shifting properly. Is this something that is associated with overheating?

blown head gasket - symptoms are loss of power, white smoke out of exhaust, oil and coolant "disappearing". shops like to to rip you off. i think replacing a head gasket runs around $2k? not sure because i'd do it myslef.

did they check for it with a testing kit or just "figure out" that was it?

is your coolant running low?
Modified by allensteiner at 7:44 AM 5/31/2008

Here is the thing with my car. I know they did not take apart the car to find out what they told me but I am pretty sure they are just ripping me off because I have drove it since it overheated two weeks ago and it has yet to overheat again. So I am thinking that the head gasket is not blown and they were just ripping me off. I have never noticed any fluids leaking onto the pavement when I am parked for periods of time. It just seems weird to me that it overheats occasionaly and only when it is above 80 degrees or so. It seems very weird to me. Could it be a bad thermostat that only acts up if the tempeture outside is to hot? I am at a lose and really don't want to take it in somewhere for fear of them ripping me off again. I am not that car savvy so I don't know what to do.

If the coolant isnt a 50/50 mix that could aslo be why. So I would check that and fluid levals and all that. Have you checked any of that yet? its really easy to do!

Is your radiator fan coming on at all?

Yah the fan is coming on.

Well then I would recommend taking a look in the radiator and see how much crud has accumulated. It's possible that it's somewhat blocked off and that the crud is insulating the coolant keeping it hot.

It would run VERY poorly with a fully blown head gasket.

It could be PARTIALLY torn. You would probably need to check the engine compression to be sure I think.

Check to see if oil is in the antifreeze or antifreeze is in the oil.

Looks and see if you get a lot of exhaust bubbles comingup when you open your radiator cap and look down

Might want to multimeter your engine temperature sensor

4puresky wrote:Yah the fan is coming on.

get a head gasket test kit and you'll know for sure if that's it. maybe a sticky thermostat? you can take it to a lube shop for a reverse coolant flush.

Make sure the fan belt is not slipping

NutriaforBreakfast wrote:Make sure the fan belt is not slipping

??? electric fans have belts ???

So I took a very close look at the radiator last night and found that there is a two inch cut on the plastic portion of the top of the radiator. This cut is allowing fluid to escape. My question is would using JB weld on it fix the crack and will it last. Also could this be the root problem to my engine overheating? The fluid is very green so I'm guessing there is no other fluid coming out. Also while investigating the radiator I noticed that only one fan is working. Is both electric fans suppose to be on or is it just one until it needs the second? This is another one of my concerns. Thanks everyone for their input on this. It has helped me save a ton of money.

One should come on with the AC and the other when the car is hot. Don't bother with JB welding it, it will just let you down when you are in the worst spot possible. It's very possible that this is what is causing your overheating as the radiator won't hold pressure and boil at a lower temp.

So should I replace the whole radiator then with a new one or should I try to find a used one from a junk yard?

you can get a new radiator for fairly cheap i would go that route unless you can find one on a car that looks to be in good condition at the yard.

i've had the same thing happen with my radiator but jb weld won't work. as a temporary fix i bought some epoxy that when hardens resembles plastic and is supposed to withstand a few hundred F - working pretty well.new radiators are expensive from a parts store but you can buy one off ebay for about $80 shipped. i don't know about the quality of the ebay ones...but half price

I would get another radiator and mount a seperate transmissioncooler for the fluid. I do remember someone telling me its toughgetting a copper radiator due to the metal being short. I thinka copper radiator is better than an aluminum radiator?

I think you can order "heavy duty" radiators too but usually theseare for RV's or trucks.

i think aluminum has better heat exchange - cools faster.

go to radiators.com igot mine from them

unless you're looking to pay cheap get the ebay one or to be sure of quality don't buy online - got to a parts store, by the time you paid the shipping the parts store's will be the same or less.

Alright so I am going to put in a new radiator. I was wondering if their is anyone that has done it that can help me with what to do? How many hoses need to be unhooked, the best way to drain fluid, etc. Any input would be helpful. Thanks.

very simple. drain the radiator - cap off, drain valve open. disconnect top and bottom rad hoses and and the reservoir hose, remove the fans - 4 bolts i think - and remove the 2 tranny cooler lines from bottom of radiator. then take out the old one, slap the new one in and put all back together.

you can look it up in the fsm - i don't know a link but you can download the whole thing in a pdf from here: http://pdftown.com/Nissan-Maxi....html

Thanks allensteiner. You have been a great help. I'll update when I am done. Hopefully everything goes well. Lets hope this fixes my problem