Cooling problem in my 96' 240sx.... help!!!!

[johndavid400]

OK, so I have been noticing a slight leak from my car in the garage over the last week. It is just about a tablespoon or two of coolant that leaks out after each night. Today, the 'check engine' light came on, and then it started heating up (the temp. gauge went almost to the red). So I check the coolant level and it is about 2" from the top, but completely covering the radiator fins inside the radiator, so I head over to get the code checked at autozone and it says "check coolant level". Now while I was driving through town, it would start to heat up, but as soon as I hit the interstate and began going 60-70mph, the temp gauge went way down to the normal operating range.

I was thinking that the problem has to do with one of two things. Either the water pump or the thermostat (since when I briefly looked, I saw no cracked or leaking hoses... and it hasn't been below 40 degrees this month). I thought it might be the water pump or maybe just the gasket on the water pump. Since when I start pushing higher RPM's, it starts pumping the coolant and the temp goes down. I do not have the time right now to go outside and get under the car to check everything (I am 1.5 hrs away from my house, visiting a friend and have no jack or tools with me), but does this sound like a probable cause, given the symptoms? When I get home Sunday, I am going to do a full inspection and replace whatever is necessary, so what do you guys think it might be?

Also, Is the water pump on this car driven by the timing chain or the fan belt pulleys? On some of my other cars, it was on the timing belt, but my Chilton manual says that it is on the fan belt pulleys on the Altima but it didn't say for the 240sx (I know they are the same engine, so I'm guessing that is the same also).

Any help is GREATLY appreciated! thanks in advance

[TheOne]

fan belt driven.as for the rest, sometimes gettin on the highway will lower your engine temps(it did on my mother's dodge caravan.....it would go lower than normal operating temps on highway)

[johndavid400]

well, for the last year and a half of owning the car, the temp has always stayed EXACTLY slightly below the center, I mean ,once the engine warmed up, it would never budge a bit and now it gets all the way up to the red line but cools off once I get on the interstate.... so something is definitely wrong (plus the check engine light came 5 mins before this happened... that light has never come on since I have owned the car)

[eddiec]

i'm not positive about nissan's design but some pumps have a weep hole that will leak telling you its about to die. i think GM are the worst for this as i had to replace the pump on my gf's j-body this week.

i also had an overheating issue on my 240 several months ago and it turned out to be the thermostat.

[johndavid400]

hmmm.... well, I guess I should just go all out. It has 115k miles, so it probably wouldn't hurt to just replace the water pump and thermostat. Heck, I haven't had to put a penny into this car since I got it a year ago.... so I don't mind fixing whatever is wrong.

[midnightsliding]

yeah my stcok water pump had a weep whole. and so did the replacement.

[hachibroku]

i had the same problem on my ca18 the harder i drove it the cooler it got the water pump was shot. you should check that out.

[Sliding_S14]

Id check the thermostat, easy to get too on a ka24de and the price is cheap. but keep in mind just cause you baught it from a store dosent mean its not broken. went through 4 in a week till finally got one that worked. check out where the water's coming from when my thermostat went out on my 96 you could see a slight water trail from the thermo down the head and down the block. it wasnt dropping directly down from the thermostat since the leak was so slow it made its own path down by the oil pan.

[johndavid400]

Ok, I replaced the thermostat and the water pump and put a thin layer of silicon on both sides of the new gaskets before installing them to prevent leaking. It appears to be working well now, I haven't seen any leaking and it is running cool. The only other thing that I think could possibly be wrong would be the lower coolant hose might be cracked or just leaking.... though I examined it and saw no leaking yet, but I just finished an hour ago so I won't know until tomorrow if it is leaking at all. I drove it around the block a few times to let it warm up and it stayed pretty cool, didn't heat up more than normally does and I drove pretty slowish so that it wouldn't be pumping a whole lot of water while I was testing it. But the CHECK ENGINE light is still on! how do I get this off? Is it supposed to automatically go off and I just haven't fixed the problem yet, or do I have to manually reset it by doing the diagnostic test on the ECU?

Thanks for your help guys

[hpdrumakk]

codes are stored in the ecu's memory for 50 cranks of the ignition... (pretty sure thats the #) so if the problem isnt seen again for 50 cranks the ecu drops the code from its memory and the light goes off.... so yah unless u want to see the light on forever just do the diagnostic on the ecu and reset it....