240sx overheating rebuilt KA and ready to throw away

[nisjay]

I am ready to throw this car in the trash, it keeps overheating. This is what I did so far:

Flushed radiator, new cap, new water pump, new thermostat, sensor is good, new head gasket, got the air out by opening the bleeder valve and put coolant in until it came out of the valve then closed it, let it warm up then shut it off and put more fluid in. and still overheats. I have an electric fan so it is on all the time so thats not a problem.

It was good for 2 days then it started overheating again. so drained it and filled again but it is still overheating. The car is running lean so I wonder if that might have something to do with it. WTF?

It seems to idle fine but when I drive it, it overheats right away

[nisjay]

today I found out that my radiator is cold along with the bottom hose when the top hose is really hot. does that mean the thermostat is not opening?

[Vegascorbin]

A lean engine will run hot. You need to fix that before you damage things.

It sounds like you either have a bad thermostat or it is not installed properly. When you install a new one there should be a small hole in it.

The small hole goes at the top. If not it will over heat.

Check those and let us know how it goes.

[nisjay]

its installed right

I also put the thermostat in a pot with hot water to make sure it opens and it did. I also tried electrical taping half of a water bottle to the radiator and run the car to try to let some bubbles out but it kept over flowing so tomorrow I am going to jack the car up and electrical tape half of a 2 liter bottle to the radiator and just let it run for awhile and see if there is more air in the system. I will let yous know what happened. if that don't work I guess I'll get a new radiator, its my only other option.

it doesn't seem like coolant is going through the system, my overflow was full

[NISSAN240SX12]

make sure that not some crappy autozone thermostate or any other third party junk. buy from the dealer. makes a big difference using oem. goodluck

[greencar]

I had this problem too, My aluminum. radiator that I put in was too efficient. The cooler than ambient temp on one side of the term, to the hotter water temp on the other side would not allow the thermostat to open.

My remedy was to drill a 3/8in hole in the thermostat. It takes a little longer to warm-up, but it works.

-Dan

[Wc240]

if its an egay radiator, drain it and take of the lower hose. pour water in the top and make sure it flows thru. may sound dumb, but 3 cars ive worked on with this problem, and it was the radiator sh###y construction. next time you blead it, get the front elevated( like on a incline drive way)what temp did the thermo open? coulda gave you a wrong temp, happens alot also, you could try running no thermo. still over heats its probly your radiator/fan setup

[480sx]

Wow 240 tech you guys fail pretty bad on this one.

Fresh Ka, coolant flushed twice. Whats the number one cause of Ka overheating after radiator swaps or coolant flushes/drains?

OP - You most likely have air trapped in your system. Follow this guideline if you ever do this again.

zerothread?id=393654

At this point, you probably still have to go through the PITA of bleeding the ka's system once air is trapped in it.

That consists of basically, letting the car run with the front end elevated and the rad cap off as well as the bleeder screw out. You can park it on a hill, or use a jack. Let it run 5-10 min until it starts to bubble and surge out, then cap it, and go for a drive and see if it overheats. If it does, do the same thing again. Repeat until it doesnt overheat.

[nisjay]

ya I've already tried bleeding it like that about 5 times. it seems like its getting blocked. I did get a 10 dollar OE thermo from national auto 2 different times and both open at about 175 degrees when I put them in a pot with a pot of water but they open really slowly.

[nisjay]

well I got an extra thermostat to spare. where do you drill the whole? at the bottom of the thermo?
Modified by nisjay at 7:46 AM 6/16/2009

[nisjay]

ok I tried the hole in the thermostat thing, and I bleed it again. Its fine at idle but when I drive and my turbo kicks in it overheats again, I am only boosting like 2 to 3 pounds. I can't figure this out, I have tried everything expect getting a bigger radiator. I guess that is the next step. if anyone knows what might be happening let me know.

[480sx]

Throwing parts at the problem might fix it, but it surely will burn a hole in your pocket. An overheating issue is fairly simply man, there is only a handful of things it can be. Take out your thermostat first off. Then disconnect your upper rad hose from the radiator and start the car. See if the thing shoots out coolant, when/if it does, turn it off after you have established that it can consistently chuck out some water. Obviously, dont run it long, and run it cold.

What your looking for here is the basic first step in engine cooling, the movement of coolant through and out of the motor.

Another thing, it still very well could just be simply air trapped in the system. The Ka's are freaken notoriously difficult to bleed after you get a good amount of air in them.

[nisjay]

I'll try taking out the thermostat and taking off the hose and running it like you said. If nothing comes out then its got to be the water pump because I flushed the whole system for blockage and it seemed fine. I'll do that tomorrow and let you know.

[unahanaretsu]

Bleed your entire system and try again.

[nisjay]

it turns out its the crappy thermostat from national auto. I took it out and my engine goes to normal operating temp and stays there, even on a cool day. so screw a t-stat, in the summer anyway. In the winter I'll go to nissan and get a thermo from there. hopefully it don't start overheating again in a couple of days. Thanks for all the help everbody

[480sx]

Well, you can run it that way. Its better for the motor however if you have a T-stat in. Go buy a OEM T-stat, they are like 30ish bucks and will last a long time.

You want your engine at operating temperatures as fast as possible. Without a T-stat, it takes a long time for your oil temp and coolant temp to build up to full operating temps. It has most to do with the health of the oil really, oil likes to be between 185-210 for the most part for it to be most effective. You will also get better fuel economy overall if you have a tstat.

Glad you got it fixed.