97 240sx overheats when not moving

[SlidnSideways]

The car is an auto 97 240sx like the title says. I first realized this problem 2 days ago. I was stopped at a red light and just happened to look at my temp gauge. It was slowly creeping up and right when the light turned green it had already maxed out the gauge completely to the H. I atleast wanted to get out of the middle of the road so I drove through the light and off to the side of the road but noticed the temp going down as I was moving. Since then the problem has happened a couple more times.

Last night I left it run and kept a good eye on the temp. As it started to climb I shut off the car and noticed a faint grinding noise coming from the engine bay for a few seconds after I turned it off. It only happens when I left the car heat up a bit and then shut it off.

Any ideas? I searched and found only one topic about this for a 300z. I noticed one of the suggestions was a bad water pump... Could this maybe be what the grinding is? I havnt noticed any leaks around the seal. Oh and my fan seems to be working fine also.

Thankyou!

[3Q Jay]

maintenance history and recent work are always good input when asking for a remote diagnosis. what is the condition specifically of the cooling system/radiator passages/thermostat?

grinding after shutting engine off does not compute---unless it is for just a few seconds immediately after shutdown (only while clutch driven fan is still spinning--clue).

do the cardbaord test and report back.

are all the foam seals around the radiator to force flow still in place? how about your splash pan? when was the last time you blew out all the bugs and road grime from the radiator fins?

you are running recommended 30% G-05 coolant, 70% distilled H20, and 12oz WW, right?

[SlidnSideways]

Im not sure what you are refering to when you ask about the condition of the cooling system. the mileage on the car is about 88k. Im not sure what mixture is in the car at the moment as I just bought it a couple months ago. Im planning on flushing out my system this weekend and applying the appropriate mixture.

The grinding noise, as I stated before, is for a very short period of time right after the engine is shut off (about 2 to 3 seconds) and only occurs if I let the car sit still and heat up past normal temps. Any other time I shut off the car when its not heated past normal there is no grind.

Im thinking bugs and grime in the radiator fins may not be the problem because that doesnt really come into account until after im moving correct? I may be wrong so please correct me if thats the case.

Im not sure what the cardboard test is but Ill search for that after this post.

Another question though... could this be a thermostat prob maybe? I mean the heat went from the highest it could go on the temp gauge to right back to normal almost as soon as I started moving. Im not sure but is it possible for the engine to cool down that fast after being so hot? Maybe the gauge is just misreading?

Ill let everyone know how the flush works incase anybody else has the problem later. If there are any other suggestions please let me know.

[driftingmy240sx]

is radiator coolant full? if ther is an air pocket it may be playing tricks on the sensor for your gauge. if the car is overheating while sitting still can you rev the engine in nuetral and get it to cool down?

[sleepyS14]

the clutch in your cooling fan may be slipping causing it not to function as well. hence why the temp gauge would go down while you were moving. cooling fan cools the engine and brings air through the radiator while the car is not moving so that the coolant can be cooled and continue not to overheat the engine. when the car is moving.. air is obviously pushed through the front of the radiator and cooling the coolant more so than the cooling fan. if the clutch on the cooling fan were to slip.. then that would mean that the engine is spinning the fan but the fan itself is not spinning .. basically the effect of those gangster SPINNER RIMZ.. and how the wheels spin but the spinners dont .. or dont spin until they stopped. thats the best example of a slipping clutch fan i can think of. so basically when your at stop.. your radiator / engine isnt getting the cooling required that you would usually get from driving at normal / highway speeds. its a thought and an easy fix . my $0.02. also might want to check your coolant levels.. might be running low..

gl

[SlidnSideways]

Problem solved everyone thankyou for your suggestions. The car was a bit low on coolant but was still within the min to max range. I ended up just taking the car to get its oil changed and cooling system flushed instead of doing it myself. The problems are gone though. Right after the service I took the car to the nearest parkinglot and allowed it ample time while sitting still to overheat but it didnt budge past about the halfway mark. Im guessing either it was a tab low on coolant or there could have been some minor blockage? Either way... problem fixed... THANX NICO!!

--Tim--

[0wn3r]

it was low coolant...and a flush at that point always helps.