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OT Overheating problem?

car is a 1990 Nissan 240SX. Radiator has been flushed and is clean, new coolant. Head gasket etc is ok. The temp gage stays in the middle of the gage 99.9% of the time, car does not have A/C. Coolant does appear to be circulating as if you remove the radiator cap, and rev it up it will cause coolant to gush out the fill neck. What [prompted this problem is it is hard to start, or refuses to start when it gets hot. Downloading the ECU gives me a fault code of 13 which is temp control circuit. No other faults show up. But I have a hard time believing its running to hot as there is never any loss of coolant, and there is never an overabundance of coolant in the overflow resivoir. This thing has me stumped.

ANy ideas on what a fix may be would be appreciated. I hotwired the fan that is normally used to augment the engine fan with AC as its electric, and the other fan is engine driven, but since the compressor is shot, and AC does not work, I simply wired it to a switch to aide in supplying additional air flow thru the radiator, but it does not seem like it made any difference as the temp gage still stays in the middle. As far as I can tell the temp gage reads right. The engine fan is a clutch type driven by belt, and there is resistance to the viscious fluid in it, but I sure don't have any clue if its really working like it should be, and thats about all I can think of.

I know there is someone here that knows whats wrong, as this group has never failed at least to my knowledge to get at the root of a problem.

Regards Roy

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Contents: foundry and general metal working and lots of related projects. Regards Roy aka Chipmaker // Foxeye Opinions are strictly those of my wife....I have had no input whatsoever. Remove capital A from chipmAkr for correct email address

Reply to
Roy Hauer
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A bit of research on Google says a fault code of 13 is an "Engine Coolant Temperature Sensor" failure.

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If it thinks the engine is cold when it's really hot it would probably feed it too much fuel making it hard to start. Check and/or replace the sensor. I couldn't find a test procedure but you can probably check the voltage to ground (while it's connected) when it's cold and see if it changes when the engine warms up. Since it's registering a fault code it may actually be completely open or shorted.

Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

Reply to
Keith Marshall

Roy- I wonder if there are two temp sensors. One for your gauge and one for the computer. If that is the case then maybe the one for the computer is faulty. It may then give the wrong fuel mixture when hot so the engine is hard to start. Maybe it thinks the engine is still cold so it "chokes" it and the extra rich mixture causes hard starting. Or I could just be talikn' outa my ass. Cheers, Eric

Reply to
Eric R Snow

I don't see in your post where it's actually overheating; you state that it runs mid gauge 99% of the time. The code

13 is coolant temp sensor circuit. This is used by the ECU >
Reply to
JR North

Yes there are two sensors, one feeds the gage itself, and the other goes somewhere deep inside a bundle of wires, but it is installed in the coolant by way of the intake manifold. There is also another on the bottom radiator hose, so I need to cypher which one is what. I can buy the fuel mix, as when it does finally start it belches black smoke, and its consuming fuel a lt more than it should.

Appreciate the feedback

-- Visit my website:

formatting link
foundry and general metal working and lots of related projects. Regards Roy aka Chipmaker // Foxeye Opinions are strictly those of my wife....I have had no input whatsoever. Remove capital A from chipmAkr for correct email address

Reply to
Roy Hauer

Yes it sounds like a sensor that is feeding information to the EFI.

The one that controls the dash gage is probably a separate circuit so just unplug sensors and see which one kills the dash gage. Then ignore that one from there on in.

The error code probably has implicit in it which sensor is bad. Either they will tell you in the error code section, or you could figure out which one is getting checked by reading the literature. Sounds like reading the EFI section of the manual is what's needed.

I replaced the dash gage sensor on my truck this winter, because it never got off the peg. I tested the old one and sure enough it read some resistance, and that changed when I stuck it by a light bulb to warm it. Oddly changing the sensor did not fix the gage. Changing the thermostat (stuck open!) did though, and also restored the missing heat. I thought it had just been a really cold winter. Well it was. Now I have a spare toy gage sensor!

I would simply ohm out the two remaining sensors, in place. One of them is probably shorted or open.

Jim

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Reply to
jim rozen

Replace the engine temperature sensor for the EFI system. Better yet, check the voltage at the sensor and at the ECU to be sure you do not have a connectin or ground problem before replacing the sensor. If the sensor tells the computer it is cold when it is hot, the engine will go pig rich when attempting to start. If it saya it is real hot when it is not, it could be too lean to start.

Reply to
clare

I've got a 240sx. I've got a display that plugs into the ecu diagnostic port that gives the readings for all the sensors as you drive. The temp gage on the dash reads the same from 135 degrees to 195 degrees.

Reply to
S Austin

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