Hey guys, Bought my daughter a 92 camaro RS. It has a 305 and everything is stock. My problem is that when the car is in stop and go traffic, the water temp redlines. The fan will come on at about the redline mark and will cool it to about 230. within three minutes of idling it has redlined again. I have changed the thermostat, the fan switch on the passenger and driver sides. The gauge appears to act funny at times. It will jump 30 or so degrees in just a few seconds. So i took a after market gauge drop it in the radiator, let the in dash gauge redline. The after market gauge never read above 210. I also borrowed a laser temp gun from work. I shot the water neck, incoming and out going radiator hose, the block in many different areas and the rad itself. All the reading were between 180 and 240. I assumed it must be the gauge. My biggest concern though, as the gauge climbs into the red I get a little vavle chatter on accelleration. Witch teels me something getting to hot. I turned the timing a little thinking it was set to high. made no difference. I have tried all the inexpensive stuff I can think of. if you guys have any ideas it would be greatly appreciated.
Thanks, Randy

 

That's exactly what it's supposed to do.

The valves don't "chatter". What you're hearing is spark knock. It is normal to some extent, although it really shouldn't do it; you might want to check the actual timing setting correctly, with a light, and make sure it's not too far advanced, though. It may have carbon build-up in the cylinders, expecially if it's been poorly maintained before you got it. You can get rid of alot of that by running it at 2500-3000 RPM and pouring water into the intake, which will steam-clean the insides of the cylinders, and maybe reduce the tendency to knock.

People in general expect the cooling system to do something different from what it's designed to do. The fan turn-on point comes from the factory set at about 230°.... in other words, the factory didn't feel that the engine needed cooling until it reached that temp. That's about the pointer's width below the red mark on a stock gauge. This is normal, not an indication of any defect. The fan will come on at that temp, and cool the engine down, and will shut off at about 210°, which is about the middle of the gauge; should take no more than a minute to do that; then it will climb while the fan is off, until the temp reaches 230° (which should take about 2 minutes), at which point the fan will come on, etc. It should be able to sit there and do that indefintitely or at least until it runs out of gas. That's what it's designed to do.

The gauge "jumping" is from steam pockets around the gauge sending unit. If the cooling system pressure is not high enough, some water will evaporate; and since steam doesn't cool nearly as well as liquid water, parts of the engine where that happens, will get hotter until some liquid water comes along. Make sure you have a good radiator cap installed and a leak-free cooling system, that will eliminate this behavior, by keeping steam from forming.

If it bothers you, you can get a fan switch that turns on at a lower temp. Any stock replacement one will retain the 230° turn-on point. You could get one for a Buick GN with the turbo 3.8, that one turns on at about 210°; or from an aftermarket supplier such as Hayden or Hypertech.

But what you describe it doing is normal. The cooling system is not defective. It is not "overheating". It is working correctly.

 

Randy,

There are so meny different things that can be wrong.. First.. maybe the worst in term of money would that the radiator passages are compleatly or very badly blocked. and so could the coolant passages in the heads and intake.

One thing came to mind... does the heater work well?? i mean really hot air when you got a really hot engine??

have you had the radiator cap off while the engine is running?? if so did you see good presure from the hose that connects the radiator near the cap?? (big black one on upper left. looking into the engine bay.)

I think one thing could be the egr passages.. they are used to cool the heads but i've never heard of engines heating up too much for that..

i had the same kind of probles when my coolant was low and i got air in the system..

How did you fill the coolant? Is the water level filling the whole radiator??

just some small questions that might get us to the answer a bit faster.

-Crisis-

 

oh and one other thing.. my engine temp is 180-190 normally..

I would bet that you got air in the system and it's built up aroung the temp sensor..

 

Most people don't bother to do this, but I suspect its your fan switch relay.

I remember when I first got my car, it would never come close to touching redline before the fan kicked in. I changed the coolant temperature sensor, then the temperature in dash sender, and the passenger side switch. Nothing changed. I finally got the fan switch relay and its all back to normal. Won't come close to redline, fan turns on much sooner.

 

The timing being off can also cause an engine to run too hot.

 

I believe the car was maintain as well as it could be. The guy I got it from is a car fanatic. The spark knock I wuold love to make go away. It only spark knocks when the the temp gets way into the red. The radiator also appears to look brand new on the inside. I mean spankin new. I did replace the fan relay switch and i also replaced the radiaror cap. (forget to mention). One thing that does sound funny. The heater does'nt ever get just melt you away hot even the gauge is in the red. It is warm enough though. Yes it appears the rad is completely full and I fill it when the car is running. I pour it directly into the radiator. I use 100% prestone. Also kinda odd. I can hold the radiator hoses both upper and lower when the interior gauge say the temp is 250. Hey guys any thing you got I will listen too. Hopefully it is just air pockets around the temp sensor.
Thanks guys, Randy

 

fyi, the sensor in the passenger head is the fan switch and the one in your driver head is the temp sender(goes to the gage) and they should be different part numbers, if you replaced them with two of the same parts then that could be your problem. you should check the resistance between the temp sender and ground to compare the gage readings against sender readings. these are the resistance values you should get at certain temps:
edit: also, i bought a temp sender once that was defective out of the box, got a different one and all was well.

 

If you suspect it might be blocked coolant passages in the engine and or radiator you can try filling the cooling system with a 50/50 mix of viniger and water and let it sit for 48 hours. Then flush the cooling system out good and refill with a proper mix of water/antifreeze. The viniger will eat away the mineral deposites in the cooling system and open up the passages in the radiator and block.

 

Start the car with the radiator cap off and see if the coolant is circulating quickly. If you can hold the hoses without burning yourself, you've definitely got a circulation problem..be it some kind of clogging or a weak/worn water pump.

 

Ran038,

What you describe is exactly what my car [the ’89 IROC in the sig] is doing. At least for me, the problem is that my primary fan is not engaging (ever), and thus the engine temperature rises to a level such that the secondary fan is forced to come on. Of course, the secondary fan is “secondary” for a reason: under normal operating conditions, it should not need to come on, as the primary fan is generally responsible for keeping things cool.

So, much like with your car, the temp on my car will continue to rise until it barely hits the redline, then the secondary fan kicks in, and lowers it back to ~230 F, where it will then climb again.

If I were you, I would wait for your car to warm up and make sure that the primary fan is coming on. If you let the temperature climb enough, both fans should be on. Of course, if you check when it’s near the redline and only the secondary fan is on, you know you have a problem.

If you suspect that the primary fan/circuit is bad, you should try invoking the diagnostics mode on your car. As the engine codes are being displayed, you should notice that the primary fan is running.

You can check this thread if you would like to see if my situation is the same as yours. Personally, I have not found a solution as to why my primary is not kicking on.

Of course, yours might just simply be an issue of an inaccurate temperature gague (they are known to be inaccurate, to greater or lesser degrees), in which case you likely have nothing to worry about.

 

Thanks guys. Youv've been A lot of help. She gets her liscunse in June. Just trying to make sure she's in good shape, when she gets them. It May be a week or so til I attempt to solve the problem. When I do I let you guys know what fixed it. Best part is I'll need to drive it for a week or so to make sure everything is O.K....hehe...She does'nt care anyway.
Thanks, Randy

 

that's a nice first car to get. i hope it wont be more than she can handle (even though it's tbi lol). you should take her to a big open parking lot and just have her stomp on it a few times so she can get a feel for the power and handling, especially accelerating in a turn so she doesn't lose it and spin on the street (can you do that with an LO3? lol, i dunno, i havent driven one). you'd probably have fun too haha. good luck.