Overheating Issue with Pic


It’s one of those ordinary overheating issues but I done some research and started the troubleshooting process but I need the help from the community.

I found two problems to my overheating issue.

  1. During idle, temperature needle spikes to H but slowly moved back to the middle when moving.
  2. Lost of coolant(about half a gallon). There are no leaks or puddles on the ground and I lose coolant when the engine is on or when the car is in motion.

Problem #1) So far, I have tested the fan by hooking it up to the car battery and it turns on. So that eliminated the fan as being bad. So my next guess is the coolant fan switch but when reading through my Haynes manual, I couldn’t find the location of it. After reading through some posts in this forum, I noticed that there were two locations. For 90-91, it was behind the engine block. For a 92-93, it was under the distributor. I have a 93. So I looked under the distributor and noticed two sensors. I was wondering if the sensor that I circled is the coolant fan switch:

Problem #2) This one has been bugging me for awhile. I was losing a lot of coolant and don’t know where. I’m losing about half a gallon of coolant on each time I go out for a drive. There are no leaks or puddles on the ground and it only happens when I do a long drive for say 30 minutes or so. But I have some observations.

  • Through the exhaust tailpipe, I don’t see any white smoke so it’s not a head gasket problem
  • Engine oil still looks dark brown and doesn’t look milky white.
  • Only when the car is moving is when I lose coolant
  • As of now, I don’t drive the Integra except once a week for 10 minutes, but I noticed something interesting. Before I take the Integra out for a drive, I would check the coolant. Right before the drive, the radiator and reservoir is filled to the max line or to the top. I go for a drive and come back within 10 minutes. I let it cool down, and recheck the coolant levels. The levels are the same as before!
  • Another observation is that there was one incident when I did a long distance driving that I didn’t lose any coolant at all. All I did was checked the coolant levels, and went off to drive.

Now my hypothesis. Problem #1 can be related to Problem #2. I noticed that I been taking off the radiator cap and putting it back on whenever I check the coolant level. Sometime, I will lose coolant after a drive, sometime I won’t. Maybe the radiator cap is malfunctioning and the seals are worn out. That could explain why the coolant is leaking out of the radiator cap(bad seals). Also because the coolant system can’t hold pressure due to bad seals, it could cause the engine to overheat. Another also, because I’m losing coolant(half a gallon), the coolant switch sensor is not reading the right temperature and is not causing the fan to turn on when I’m at idle.

So what do the community think? Could it be my radiator cap that’s causing coolant to leak when only moving and cause the engine to overheat?

Also, Yes I’m sorry for the prolong details but I think this might be important, the thermostat gasket seems to be replaced awhile ago. So I don’t think the thermostat is leaking nor the waterpump nor the hoses. If either of the parts I mentioned were defected, I would have seen a puddle on the ground but I don’t. I’m losing coolant only when the engine is on.

Thanks for reading through my post and hopefully, we all can find a solution to my overheating issue.


Personally, I would swap in a new thermostat and radiator cap. Both are cheap items that can possibly resolve your issues. You don’t mention bleeding the system, which could also account for your situation. Do you use the bleeder screw to accomplish this? One scenerio, if the system isn’t bled, the fluid in the resevoir will be sucked into the radiator and make it appear as if you are loosing coolant. Just a thought. Prepare yourself for my long-windedness.

As for the head gasket, it could have a pressure induced leak that will only leak coolant into the cylinders under certain conditions, like under acceleration during higher cylinder pressures. This could account for your coolant loss. On the other hand, you could have a small hose under your throttle body that has a tiny undetectable leak that leaches out coolant, that lowers the level enough to have air in the system which could cause the fan switch to not register the coolant temp to operate the fan.

There are so many possibilities when it comes to the coolant system. There are also many sensors involved with the coolant system. You have the Engine Coolant Temp Switch-- that operates the fan (this should be to the left of the connector you have circled, either under the thermostat towards the firewall, or on the back of the block on earlier year integras), the Engine Coolant Temp Sensor-- that feeds the ECU (I believe this is the one circled in your pic), Engine Coolant Temp Gauge sensor (also in your pic just below the question mark), for the indash gauge, and the Engine Oil Temp Sensor (back of block) that can operate the condensor fan if the oil reaches like 220* or something like that.

You might just have an air bubble if the system wasn’t bleed properly. But if not, and your loosing coolant, then you are either leaking it or burning it. Do you have a driveway that allows you to look for leaks easily?

Sorry about the novel, I have no life. Good luck and possibly this proplem can be easily resolved. I didn’t even bring up a bad waterpump and clogged radiator.

Everything you described happened to me. Mine was a bad waterpump. So how many miles on motor and do you know when the last time the waterpump and timing belt were changed? If not, I would recomend getting them done if you plan on keeping the car for awhile, including the tensioner, thermostat, and I think I replaced some other seals while I was in there too.



  • Just ramble on! I’ll take any information that you have. Ah, when I say I’m losing coolant, I meant from the radiator + the reservoir. I usually have to add half-gallon of coolant back into the radiator and reservoir to top it off. I haven’t bleed the system but will give that a try.
  • Also, if the headgasket was a problem, well, I can say that when I accelerate hard, I don’t see any smoke at all. Also if there was a coolant leak in one of the cylinders, I would see some smoke or even feel some engine hesitation but I don’t.
  • I’m going to recheck all the hoses and replaced any that are worn and damaged.


  • I bought the car with 130K miles on it. I believe it has 144K. I assume the timing belt was recently changed. On the cylinder head valve cover(one of those) and there is a big yellow writing which say “96” which I think means the head came off a 1996 B18A1 engine. So that could mean that not long ago, the timing belt broke off and the valves got damage and a new(used) head was installed along with a new timing belt. That’s just my guess but I will look into changing the waterpump and timing belt.

Also, the radiator is brand looks new. So I’m hoping that there aren’t any leaks from it. I now have some ideas on how to approach the overheating issues. I will check for hose damages and will look into buying a new theromostat, gasket for the thermostat housing, and radiator cap. Oh and bleed the coolant system. If none of these helps, then I shall change the timing belt along with replacing the waterpump. So I have a long list of things to do. Hopefully, I can finish it all by finals but I need to study!!! ARG! Guess I’ll leave the car in garage until winter break, then I’ll have several weeks to work on it.

I don’t think its the headgasket. You’d know. My friends 240sx blew it, and there was white smoke everywhere, and it ran like SHIT. You would know. I don’t think it is the water pump either. Mine leaks, but only when I am parked, not in motion, cause I guess the bearings seal up. Maybe it’s a small leak that evaporates before you can find it, I think someone else had a problem like that on here.

One more simple thing to check would be to pull your spark plugs and see what they look like to make sure coolant isnt getting into the motor. I think white on the plugs would be burning coolant.


Yeah. It’s only strange that it usually happens on long drives for say 30 minutes or so. And when I come back home and pop the hood, I don’t notice any “wet” areas in the engine bay. I don’t know how a 30 minute drive could evaporate half a gallon of coolant. Must be some crazy small leak.

I’ll do some work on the car during thanksgiving break.


I know you said you tested the fan to make sure it works, but while your car is just sitting there idling and that needle is shooting over to the H those fans should be screaming. Have you popped the hood to see if they are on at all. Judging by the fact that the gauge drops when you start moving my guess would be no.

yeah that has been discussed plenty of times…it happens to me occasionally, it’s the idle fan

btw, I’m just wondering…you said it’s been over at H…do you just sit there and let it stay hot until you can move? That really scares me, you can cause really serious damage overheating an engine. If you are at a light or something, pull the ebrake, go to neutral and rev it a little bit. The fan will turn on.