20(kmax)00

Hi all!

I've been reading up about overheating problems with the 5th gen Max and so far I haven't found someone with the exact same symptoms as me. So here's the deal: my car drives fine normally and the temp gauge stays around halfway exactly all the time, except last weekend I was going up a very steep gravel hill (going mountain biking) and the temperature just kept creeping up until I got to the top. I had to stop a few times, left the engine on and the temperature came down withing 5-10 minutes (both fans on, no load), then when I started moving again the temp came right back up. Going down the hill was fine, and driving home was fine on flat-ish ground.

My rad fans both seem to be running fine (I replaced them about 1-1/2 years ago). The coolant levels seem to be good. The coolant seems to bubble a bit in the tank, not sure if that's normal. The coolant looks ok (no signs of rust).

I see in the forums that some recommended options are flushing the cooling system, cleaning out the rad, changing the thermostat and getting a new rad. For the system flush, is it better to do it myself or just go to the garage? I'm not very experienced with this stuff. I will also check the temperatures of the hoses next time I go for a drive (to see if one is significantly cooler than the other, i.e. low flow).

Anyhow, any help would be appreciated! Thanks!

EuroDriver

iTrader: (21)

It can be a number of things (i.e., thermostat, water pump, clogged cats), but if you have bubbling in the coolant reservoir, it can be something more serious - like a blown head gasket.

20(kmax)00

I checked the temperatures with an infrared thermometer after a short-ish drive in traffic. The temp going in the top was 180F and coming out the bottom was 160F. Does that make sense or is that too much/too little of a drop?

My cats should be good, I have an aftermarket y-pipe installed so no cats there, and the main cat was replaced about 2 months ago. Blown head gasket sounds bad :S

Is there any problem with getting a garage to do the cooling system flush for me? Will they know to put the heater on high and drain from all the plugs and stuff? Or does everyone just do this themselves? I'm learning that sometimes the garages cut corners and don't get it just right (a now defunct shop installed my brake pad shims wrong, not a huge issue but contributed to premature wear maybe).

Thanks again!
~K

EuroDriver

iTrader: (21)

It doesn't seem like a huge temp difference - 180F is still within normal range. There's a good possibility your thermostat is on the way out. When they start sticking, they restrict the coolant flow, making the coolant overheat in the engine. When they get stuck open, the car takes forever to warm up.

I'd start by making sure you don't have any air pockets in the cooling system (remove the temp sensors briefly - if there's no water coming out, loosen the radiator cap very briefly - when water squirts, retighten the sensors). If that doesn't work, replace the thermostat. Get it from Nissan - I've read the aftermarket ones cause problems.

If that still doesn't solve it, I'd replace the radiator. If it's clogged, it's most likely a waste of time to have it flushed.

If you want to start by checking for a head gasket problem, I believe they sell a kit that consists of strips (think of pH strips) that you dip in the radiator coolant and if there's emission gases in the coolant, it will change color. I don't know if it's worth buying the kit, or if it's cheaper to have a shop check it for you.

Good luck and keep us posted.

20(kmax)00

I've been reading up in the service manual a bit and checking for parts and such and I have a couple questions:

-The manual says to only use Nissan L2N coolant or equivalent. What is equivalent to this and what do most people use in their Maxes? (In the manual it says to mix this coolant up to 50/50 with distilled water)

-Both the thermostat and the water control valve seem to be similar. I was thinking of taking them both out to test. Is there any reason that the thermostat would be more likely the culprit? Should I just test both of them?

Thanks!
~K

ShocknAwe

iTrader: (3)

Thermostats do fail so it is quite likely

2brosgixxer

^^^This. Try bleeding your system before you put too much more into it. I believe in start small and work toward the bigger/more expensive.

20(kmax)00

Yeah, makes sense to start small! I'll try that to start. It may be a few days before I get to it since the car runs fine for now and I don't want to start messing with it until the weekend. I'll keep ya posted.

Any tips on type of coolant to use?

Thanks for your help everyone!

microfight

I have a 2001 maxima with 290k + miles on it. And mine started over heating in traffic after the RPMs were high do to what i think was a RSS issue. I replaced that yesterday and read codes today P0100,P0430,P0720. I just cleared them and the car is running like it used to idling at around 800rpms in drive. But yesterday it over heated again in traffic right after i replaced the sensor. But today the car runs great. How long will it take for the car to adjust toe the sensor?

noahrexion

If you're flushing the system yourself you can just go grab some Prestone Conentrate coolant off the shelf and a gallon of distilled water. Considerably cheaper than OEM and definitely cheaper than what any place would charge you for product.

They are both anti-freeze/anti-corrosive without any borates. I don't know of any standard off the shelf product that isn't actually - but I do like Prestone personally. They've got lots more options than what you normally see on the shelf at your local Autozone too.

Definitely bleed the system first; purged air can always complicate things.
Thermostat would be my next test (though water control valve essentially does the same thing). If the coolant is still in good shape then leave it while you do all of this. If you're concerned about it after you've solved the issue then have it flushed afterwards.

Your temp tests are fine; your radiator is cooling just as it should. You can look inside your cap and tell a lot about the passages from the few that you can see through it (corroded, plugged?).

Start small!

EuroDriver

iTrader: (21)

When you pull your thermostat, look for scrape marks on the walls of the plunger base. If the walls are scored, it's likely sticking, or soon to start sticking. Replace it. And again, buy original Nissan.