'93 240sx - Sporadic overheating

[Invictus]

Car Specs: 1993 240sx (purchased used in January '04)Location: Atlanta, GA

A couple months ago, I was driving home at around midnight (it was a pretty cool evening), when when i got out of my car in the driveway, i noticed a massive pool of liquid coming from under the front of the car. I got out a flashlight and saw that it was the coolant.

I took it to a shop where I had my timing chain replaced a few weeks prior (not sure if these are at all related), and he replaced the thermostat and said that should correct the problem. A few days later, the temperature began to rise again, to the point where I could hear the coolant boiling in the reservoir. I popped the hood and could immediately feel the intense heat. The next day, after the car cooled down, I popped off the radiator cap and let the car warm up. Not 2 minutes later did coolant start bubbling out of the top of the radiator.

On the way back to the mechanic, the car got really hot after about 10-15 minutes, but then dropped back into the normal range. The mechanic's initial thoughts coincided with what I've read here, about a blown head gasket. So they did a compression test and determined that the head gasket was fine. They also did a dye test, but couldn't find any leaks except for a hole in the radiator, which they patched. I picked up the car again, and it seemed to be running fine. I made one stop on the way home that took me about an hour, and then I started back home. Probably 10 minutes after I left the store, the needle was up near the H on the temp gauge. I babied the car until I got home, and then I popped the hood, to find coolant dripping onto the driveway, there was some on the underside of the hood (near the front), all over the top of the radiator, and the familiar boiling in the reservoir. What I hadn't seen before was the billowing of smoke coming from the top of the reservoir.

This morning I took the car back up there and I'm demanding that they do the job right this time. Again, the car got really hot about 10-15 minutes into the trip, but then settled down to mid-range.

The mechanic seems pretty stumped by this problem, especially since it's so sporadic. Sometimes it won't overheat, sometimes it won't. I read a few posts that talked about the A/C causing additional strain, but each time it has overheated, I've had the A/C off and the windows down. Is there anything else that could possibly be wrong that would cause this problem?

I appreciate any help that you can offer.

[DriftingXJDM]

well heres some help maybe is the car fully factory ? Maybe theres an aftermarket electric fan and not operating properly or the shroud for the fan is missing. Did they put the thermostat right??? and if your radiator leaking I say replace it don't try fixing it.

[Invictus]

As far as I know, everything is stock. I know they put a Nissan thermometer back in, but unfortunately I don't know enough about the mechanical workings of the car to tell if it has been installed right. I'm going to call them tomorrow morning to explain why the car is back in their lot (they are closed today, so I dropped off the car and put the key in the box). I'll be sure to bring up some of the things you mentioned to see if that'll help them find the source of the problem.

[574-240sx]

The coolant system is very hard to bleed on the KA24DE. It sometimes takes me a few tries. Also it seems like a sticky thermostat. It sounds like a bad headgasket almost too with the coolant almost instantly bubbling from the radiator. Nick

[Invictus]

I read a few guides about bleeding it, and I'll check to see if that's something they've done. I breathed a weighted sigh of relief when the mechanic told me that the compression test didn't turn up anything -- I know the head gasket problem is a serious job. Could it still be the cause even though this test succeeded?

[180fan]

If your compression test came up fine, check the color of your oil. If it looks like coffee with cream, you're in for a little bit of work with a new head gasket. If that doesn't show up anything and the oil's still oil, and the coolant is still just coolant, you're fine. Check the thermo. Get a new one, oem preferrably (never had one be bad at the start yet) and before tossing it in, toss it in boiling water to make sure it's working. When you also put together the elbow with the thermo, make sure you don't use too much rtv. A buddy of mine slapped on too much RTV and was keeping the thermo from doing its job. It took me and all the kings men to put humpty dumpty together again. Actually just me and about 30 minutes of poking around with me scratching my head till I noticed a bunch of RTV slapped around the thermo like a beard on a guy that hadn't shaven in 30 years.

[s13sr20chris]

is the fan spinning? does it always spin? did they put on a new water pump?

[DriftingXJDM]

or to find out if you have a blown head just take your rad cap off then start the vehicle if you see a gyser not sure how to spell then you have a blwon head...

[Invictus]

Thank you for all of your suggestions, fellas. I'll let you know what happens.

[Maverick7687]

My 240 is a 93 and I replaced the water pump and there where NO blades on the old one..just something to think about, Mav