Help me diagnose my car.... its a mild overheating problem.

[The Stigenator]

This problem cropped up sometime late last year. I had posted about it here... It was the car's coolant temprature that went up to half and then didnt go down. It stayed at 1/2 (which is not normal for my car under normal diriving conditions). Anyway back then I had noticed an increase in power too. I had given it for a serivice to Toyota and they found the problem with the "radiator cap" not pressurizing at higher tempratures. I also noticed after the service that the car was idling a lot higher than usual.. but the water temprature was its supposed to be and I really didnt care for the additional idle.

Now forward 4000 miles later and I gave my car for an oil change to jiffy lube. Today while waiting in line at the drive thru the water temprature went up to 1/2. But it was rather quickly. It never goes up in 5 minutes of driving. The needle came back down after I started driving again. When I got home I let it idle and noticed it was idling a lot higher than before jiffy lube looked at it. One thing is that car is running very smooth (engine) and the power deliever is smooth and ever so present. Infact it accelrates so fast that is frightning.

So here is the deal.. I have come up with possible areas that this idling problem could come from.
1. Oxygen sensor is bust
2. PCV valve possibly closed
3. Cat converter has something to do with it (well I know that needs replacedment soon).
4. Radiator cap needs replacement - will change that today.

The car is a 1994 Toyota Tercel with 126100 Miles or so. Its an EFI (Electronic Fuel Injection) model. Its been in good care for the most part, regular service and all. Though the cat converter does need work (I barely passed CA smog last time).. sometiwht with HydroCarbon and CarbonmonOxide being too high.

If I want to replace teh O2 sensor and the PCV valve myself.. how hard will that be? I will probably drop by Autozone to see if they got what I want. They also allow you to borrow the tools for a deposit.. its something simple as replacing my

Can you confirm if I am going the right direction.

 

[Vegito]

PCV should be easy

O2, get the right one, some of them have 3 wire, some has 2.. also if it's mounted on the exhaust pipes... good luck getting it off...

you might have to hammer it off 🙁 wd-40 soak all day..

also it might be ur water pump not working right or the themostat broken...

maybe the belts are loose, check belt tensioner...

I think it's more of a themostat w/ belts...

have you ever change the belt in the life of the car ?

 

[etech]

I'd replace the temperature sensor first. They can fail and give bad readings. The thermostat would also be higher on my list than the other parts you mention. Get the temp reading normally and then see if you have any other problems.

The location of the temp sensor-
UNDER HOOD, DRIVER SIDE, UPPER ENGINE AREA, END OF CYLINDER HEAD, MOUNTED IN TOP OF WATER OUTLET

Check the electical connection boot also to make sure the contacts are not corroded.

 

[The Stigenator]

I just checked the bill from toyota.. they tested the thermostat.. they said its fine.. no need replaceemnt. It was replaced about some 15,000 miles back. The fan for the radiator cooling is an electric fan and not connected by a fan belt. The fan works cause it does kick down teh theromsatat when it does go up. The water pump was checked by toyota (I had asked them to do so since it had gone bad twice in two years - last time replaced was Jan 2001) and its not leaking or anything.
As for the rest of the belts, I just checked them, they seem taut. The timing belt was changed at 75,000 miles, will be changed in 10,000 miles again, prior to that it was changed as a precautionary at 35,000 miles (before my brother gave me the car).

I found my Haynes repair manual and I am going to look thru it now. I will look into the thermostat. If its something I can replace I will do so myself. Its no harm doing so. The PCV valve is right up front. The O2 Sensor I think is also up front, somewhere near teh EGR.

TGG

 

[Kadarin]

Sorry to interject, but a Toyota Tercel that "accelerates so fast it's frightening"?! Heh.. god forbid you get behind the wheel of a Camaro or Mustang or something with some balls.

Anyway, please continue... (check the timing, could be advanced a bit too far)

 

[The Stigenator]

You know come to think of it, the car might be due for what toyota calls a "major overhaul". The car was in at toyota just past 100,000 miles in the beginning of 2001. Now at 2002, Its at 126,000+ miles. I think back then it went in for a service around 101,000 miles. which would mean that the car is soon due for its 30,000 mile major service..

 

[The Stigenator]

<< Sorry to interject, but a Toyota Tercel that "accelerates so fast it's frightening"?! Heh.. god forbid you get behind the wheel of a Camaro or Mustang or something with some balls. Anyway, please continue... (check the timing, could be advanced a bit too far) >>


well I am burning out a bit too much.... If I take this car to the So.Cal meet this weekend I will try and make sure we got some proof of the car burning out. It normally does burn out, but this is too much and too easy.

 

[Scarpozzi]

1. I still think I'd swap the thermostat.... I wouldn't believe Toyota. How did they test it? My point is....you're looking at a needle (which isn't that accurate to begin with...a change in humidity can make those readings do different things). If you swap it out, you'll at least know it's good.
2. The oxygen sensor may solve the idle problem, but it may not be a problem unless it's idling EXTREMELY fast.
3. Check to make sure your A/C compressor isn't kicking on when it's not supposed to. This would make it sound like it's idling faster than it actually is.

Now for a little anecdote. I used to have an 89 pontiac sunbird....it had a terrible thermostat in it. It wouldn't show much change at all....until it overheated. And really, that's all most of the guages can really tell you. They're either COLD, HOT, or In Between. As long as it's in between, you've got water in your radiator, and your water pump is doing its job, you should be just fine. I don't think it really matters HOW FAST it heats up because you're talking about an internal combustion engine. Every time the crank turns, that's 4 or so explosions....it's bound to generate heat pretty quickly. Oxygen sensors sometimes will cause "check engine" lights to come on, so you may wanna ask your dealer to do a computer analysis on your car. This will let you know if the computer senses anything...usually will cost you a couple of bucks, but can save you some time. 😉

 

[TekViper]

have someone rev the engine while u look under the hood, or rev it yourself by playing with the throttle under the hood. see if any of the radiator hoses collapses from the extra rpms. read about this in the latest hot rod mag, and ive found out this is a common problem with old hoses. even tho its only a 94, still worth a check.

 

[The Stigenator]

I am going down to check on the termostat and try and adjust teh idle.. damn haynes manual doesnt have a good diagram on how to find that screw.. its there.. just got to match the drawing and find it.. would have been easier if it was a picture.

 

[thomsbrain]

Your idle probably just needs to be adjusted. Incedentally, a high idle can make car feel smoother at idle, and if it's an automatic, it will feel more "powerful" when you start from a stop. But it's not a good thing. It's like you're always brake-torquing the car whenever you stop, which is hard on the engine and on your brakes. Get it lowered to spec. It may say on a sticker under the hood what the idle should be.
Overheating while you are sitting still might be due to a dead/blocked radiator fan or a blown fan fuse.
Also keep in mind that most cars idle slower when warm than when cold.

 

[The Stigenator]

okay I adjusted the idle a bit after it warmed up. This is without a timing light or a RPM meter. Did it the way I always did in India with our car there and how I do it on my bike. The thermostat is a big pain in the butt to take out, i will have to take out the air intake tube going to the air filter to access it. On top its connected directly to the electric fan atleast it looks like it. Too much of work for the moment, since I have to go out. Lets see how this holds up. The radiator coolant looks good, its bright green and upto spec.

Will let ya know how it holds up. By the way is a manual tranny car, and this car has no AC in it.. thank my brother for that. In his infamous knowledge when he bought this car initially he didnt buy it with an AC.. now I am having to dread summers with this beast. Hopefully by summer I will have my 2002 Jetta VR6