Need help troubleshooting temp. reading

[Decibel]

Hi guys, my 92' Suzuki Swift has been having this "overheating problem" for some time. This is what the readings show me on diff road conditions.

 

Before problem surfaced - Constant reading slightly below 1/2 mark.

 

Now

 

E'way Cruising - 1/3 mark or slightly less

 

E'Way Crusing when raining - 1/4 mark or less

 

Normal driving - 1/3 to 1/2 mark

 

Start-stop traffic, ie; jam, slow traffic, hot weather - Bounces between 1/3 to 3/4, doesn't stay stuck at a high temp. reading. For example in 5 seconds, the needle may move from 1/2 to 3/4 or slightly higher, then drop and repeat...Sometimes, it even behaves like the rpm meter, going up and down as I accelerate and change gear..Wtf

 

 

My radiator system has been checked, it doesn't leak, nor have any blockages. My radiator fan works fine, it cuts in at ard half mark. The hoses aren't due for changing yet.Thermostat has long been removed by previous owner, not needed.

 

My mechanic is stumped, and tells me to ignore the reading as long as the needle doesn't stay above 1/2 mark for a long period. The car drives totally normally, I don't feel any difference even when the temp needle is fluctuating before my eyes as I drive.

 

 

Anyone have any idea what could be wrong? Kindly advise, cheers!

[Stationwagon]

Hi,

 

Looks like your problem is mostly more "underheating" rather than "overheating". haha. Anyway, it is right that if you drive, the temperature is much lower due to forced ventilation, as compared to when you're stopped.

 

As you read on, please remember that I'm NOT an expert in such things, so I'll just try to guess from theory. I think the temperature sensing circuit consists of the following items, and if any breaks down, it can affect readings:

 

1. Radiator and water condition: This you have already checked.

 

2. Sending Unit (thermcouple sensor, varistor, etc): If your sensor is coated with scale, or is faulty, this problem can occur. Sending units (fuel gauge, temp gauge, etc) are known to break down.

 

3. Battery (provides power to the circuit), I think should include a voltage stabiliser: If these provide unstable voltage/current for whatever reason, unstable readings are possible too. But since your readings have certain fixed trends, it doesn't seem to be like this is the problem.

 

4. Gauge (this is the one on your dashboard): Just like many other gauges in the dashboard (eg. fuel gauge), this is either a voltmeter or ammeter, more probably a voltmeter. Just like other equipment, this can break down too. Doesn't seem like this is the problem too, since your readings have certain fixed trends.

 

5. Wiring (to connect all the above together): I doubt that this is the problem in your case because wiring problems usually have the symptoms of total failure (connection broken), or intermittent readings (loose connection).

 

 

If you can't live with the present situation, I think the best way is to visit the Suzuki agent (Champion?). Or get the opinion of another workshop (sometimes this helps because different workshops have different experiences with different problems).

 

Of course if you are a DIY person, you can slowly change out parts one by one (solve the problem by isolation of components), measure the voltage across the components with a voltmeter, slowly going downstream from the sensor, etc. But this is only if you're very DIY oriented (I actually know some friends who are like that).

 

As for me, I'd rather do some overtime to get more money, then bring my car to the workshop.

Edited September 16, 2006 by Stationwagon

[Decibel]

Thanks bro, extremely helpful of you!

 

Given my description of the problem, do you think it is even possible for the temp to fluctuate so drastically in a few seconds? Btw i forgot to state that during idling, no fluctuations in temp. have been observed so far. It only occurs during driving.

Edited September 16, 2006 by Decibel

[Trex101]

My radiator system has been checked, it doesn't leak, nor have any blockages. My radiator fan works fine, it cuts in at ard half mark. The hoses aren't due for changing yet.Thermostat has long been removed by previous owner, not needed.

 

The problem is thermostat has been removed. Reinstall back the thermostat and your problem will be solved.

[Decibel]

But if this is so bro, how come the problem only surfaced a few months after I took over the car? The thermostat wasn't installed all along

[Stationwagon]

I once went to KL and had my radiator blown by some particle which flew through my front grille. All the coolant water shot out. Still, I managed to drive 4 hours down the NSH to Singapore and the temperature was normal. Once I stopped, however, the temperature went up to redline within seconds (maybe 15-30 secs, not sure).

 

So yeah, temperatures can fluctuate in seconds.....but you'd need an empty radiator to see that kind of drastic movement, I think (not too sure).

 

Sorry bro, as I've admitted before, I'm really no expert in such things.

 

From my amatuerish view, the first part I would zoom into would be the sending unit (a.k.a. the temperature sensor - its in the engine bay somewhere).

Edited September 16, 2006 by Stationwagon

[Stationwagon]

E'way Cruising - 1/3 mark or slightly less

 

E'Way Crusing when raining - 1/4 mark or less

 

Normal driving - 1/3 to 1/2 mark

 

Start-stop traffic, ie; jam, slow traffic, hot weather - Bounces between 1/3 to 3/4, doesn't stay stuck at a high temp. reading. For example in 5 seconds, the needle may move from 1/2 to 3/4 or slightly higher, then drop and repeat...Sometimes, it even behaves like the rpm meter, going up and down as I accelerate and change gear..Wtf

 

Actually, this is the correct temperature profile - cooler when moving, even cooler while moving in rain, hot when still. But the fluctuations are too much.

 

Since your thermostat has been removed, what controls your cooling fans? Are they permanently on?

[Trex101]

The function of a thermostat is to regulate the water temp in your radiator system, without the thermostat how to regulated? So more air flow more cooling, less air flow less cooling lor.

[Decibel]

Seems there is a seperate switch which turns the radiator fan on, guess its another thermostat of sorts. Gonna try and get that replaced too.

 

Well I hope the problem lies in one of these minor parts and not the engine itself. Will call up Champion, perhaps they will know whats wrong and be able to rectify it for me. Thanks again for your input

Edited September 16, 2006 by Decibel

[Mivec9]

My radiator system has been checked, it doesn't leak, nor have any blockages. My radiator fan works fine, it cuts in at ard half mark. The hoses aren't due for changing yet.Thermostat has long been removed by previous owner, not needed.

 

The problem is thermostat has been removed. Reinstall back the thermostat and your problem will be solved.

 

i would recommend putting the thermostat back as it regulate the correct temp for engine

[Stationwagon]

Bro,

 

The reason I asked if your fan is permanently on is: if it is on all the time, and your temperature still shows 3/4 when standing still.... there must be a clog somewhere in the system (not necessarily in the radiator itself). Seems like the cooling water is not moving much.

 

When you go to Champion, please remember to tell them all that you told us.

 

Good luck!

[Elfenstar]

damn... wish i saw this earlier. these symptoms are exactly the same as a thermostat stuck open (no problems earlier but problems now).

 

The fix is rougly the same as what trex said, but in this case get a new thermostat to put in. Should not be more than $40 for parts... add another 30mins for labour.

[Elfenstar]

E'way Cruising - 1/3 mark or slightly less

 

E'Way Crusing when raining - 1/4 mark or less

 

Normal driving - 1/3 to 1/2 mark

 

Start-stop traffic, ie; jam, slow traffic, hot weather - Bounces between 1/3 to 3/4, doesn't stay stuck at a high temp. reading. For example in 5 seconds, the needle may move from 1/2 to 3/4 or slightly higher, then drop and repeat...Sometimes, it even behaves like the rpm meter, going up and down as I accelerate and change gear..Wtf

 

Actually, this is the correct temperature profile - cooler when moving, even cooler while moving in rain, hot when still. But the fluctuations are too much.

 

Since your thermostat has been removed, what controls your cooling fans? Are they permanently on?

 

You're a lil lost on cars arent you??? Your coolant temp is supposed to be relatively stable. And considering the way factory gauges are designed, you're not supposed to see any fluctuations whatsoever once the car is warmed up.

 

If it gets too hot when in a thermo fan system, the fan will start so that the rad can get more airflow through the radiator. This is controlled by via a temp sensor. The thermostat will close if the temps start dropping too low and the fan shouldnt be on at all in these scenarios.

 

In a clutch fan sysytem the only control is the thermostat which opens and closes to allow coolant to flow.

 

this is the thermostat that he probably has thats stuck open causing the drop in temp when theres sufficient airflow.

[Sky8807]

Hi guys, my 92' Suzuki Swift has been having this "overheating problem" for some time. This is what the readings show me on diff road conditions.

 

Before problem surfaced - Constant reading slightly below 1/2 mark.

 

Now

 

E'way Cruising - 1/3 mark or slightly less

 

E'Way Crusing when raining - 1/4 mark or less

 

Normal driving - 1/3 to 1/2 mark

 

Start-stop traffic, ie; jam, slow traffic, hot weather - Bounces between 1/3 to 3/4, doesn't stay stuck at a high temp. reading. For example in 5 seconds, the needle may move from 1/2 to 3/4 or slightly higher, then drop and repeat...Sometimes, it even behaves like the rpm meter, going up and down as I accelerate and change gear..Wtf

 

 

My radiator system has been checked, it doesn't leak, nor have any blockages. My radiator fan works fine, it cuts in at ard half mark. The hoses aren't due for changing yet.Thermostat has long been removed by previous owner, not needed.

 

My mechanic is stumped, and tells me to ignore the reading as long as the needle doesn't stay above 1/2 mark for a long period. The car drives totally normally, I don't feel any difference even when the temp needle is fluctuating before my eyes as I drive.

 

 

Anyone have any idea what could be wrong? Kindly advise, cheers!

 

Possible could be the water pump not efficient when running slow. When cruise the circulation of water is okay. If everything is normal, this could indicate that the pump is not so good anymore

[Stationwagon]

Honestly? Yes, I'm a little lost on cars....which is why I told him that I'm not an expert, that I've never used my hands to repair this system before, that I was just amatuerisly guessing, and that he should go seek the agent.

Edited September 18, 2006 by Stationwagon

[Apollo]

i think since so many uncertainties, go for the cheapest option, which i believe is having a proper / decent thermostat to read off. then benchmark off there. too much guessing will not help.

[Decibel]

Hehe, was hoping you'd come in. Ok coming home from camp just now, same problem, temp at stable low during entire journey (e-way + length of mandai rd to yishun). Once i got to my neighborhood start-stop traffic however, needle's nonsense started.

 

Once I parked the car, the needle stopped misbehaving, even revving didn't cause the needle to move. Radiator fan ran for a couple of minutes after switching the car off.

 

 

 

So does this definitely sound like thermostat-related problem to you?

[Decibel]

Yep plan to do that asap. I can go to Lawrence Ong ya?