I so appreciate this message board. I have spent several hundred dollars replacing cooling system components and having mechanics check out why my car was appearing to be overheating. I'm talking temperatures that flirted with the red zone and eventually going into the red. Someone suggested to me the other day after posting a message to "replace my radiator cap". I was skeptical, but figured what did I have to lose. They only cost around $3.50. Well I did it and am amazed to say that I think it's cured my problem. I was out driving today in mid 90 degree heat and ridiculous humidity with my A/C on max and it never got over 220. Thanks to everyone who responded to my post. This site is great.

 

I love you too

 

I tried that too. but mine still runs. what is the part number of the cap you used? thanks

 

it still runs hot. sorry this goes with other part of message.

 

I changed my cap about a week ago and had good results. Don't know the part number but it's a 15lb AC Delco cap - just like the one that was originally on it.

 

I replaced my original radiator cap with a Stant, part number 11231. It's rated at 16lbs. However, I think I may have celebrated a bit too soon. I'm so sick of this overheating deal. The first day I drove it after replacing the cap, it never got over 220. It was hot and humid and I was just amazed that something as cheap as the cap could make that much difference. The next day I drove in to work (11 miles). Again, never exceeded 220. Later that same day, did some running around in the city and it started climbing back up close to the red zone. I'm at wits end, trying to figure this deal out. One day it's fine, the next under identical circumstances, it's overheating. When I say overheating, it's just on the gauge. It's never boiled over or anything. Anybody have any other possible suggestions? I've tried troubleshooting everything this board has mentioned concerning overheating, short of replacing sensors.

 

Doesn't boil over you say?

Change the sensor. The part is cheap compared to the 'hundreds' you've already spent. So why not give it a shot...


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1985 Camaro SC - 2.8L, auto.

http://www.xenodrgn.f2s.com/Frontright.jpg

 

Also try changing your thermostat to a 160 degree one. Sounds like you do some city type stop and go driving. The lower thermo will make your car run at a lower temp during the stop and go summer weather. I hope I am saying it right, but I know my car never overheats and we just finished 9 straight days of 90 degree and above weather. Now I don't drive my car in the winter so I don't know about such a low t-stat in December but you need to drive now and worry about Dec. in Dec.
I bet when you went to work the driving was more constant like driving on the highway so your engine was cooler. When it came time to do the city driving because you have a higher thermo stat(probably a 200 degree) the temperature of the engine was hotter. Expect the temp to rise some anyway during stop and go but not in the redzone. Try the lower thermo and you wil be happy.

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86 Camaro Black SS Coupe, T Tops, Flowmaster, Custom Paint, Dunlop Road Kings S/R tires, Wheel Country Directional Chrome Wheels,new charcoal & gray interior including seats and door panels, new carpet and headliner, complete front end suspension rebuild, new Valve seals, and more mods to come
http://www.angelfire.com/sports/niterider/86camaro.html
Morgan_Andre@hotmail.com

 

I was getting that problem a lot until I replaced the little air dam thats under the radiator, it did the trick. I don't know if that's the problem, but it sure helped me out.
88 Iroc Mostly Stock

 

my car does the same thing it is something you just have to deal with and be careful with. i say go with dual fans if u don't have them that would make ur car run cooler.

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86 Z28:
L98 350
aluminum heads
T-5
235/60R15 BFgoodriches
dual 3"flowmaster exhaust
20% tint
hatch wing
2 12"kicker solos
300 watt Sony xplod amp
Sony xplod deck
K&N air filter
http://www.geocities.com/xmikex.rm/mike.html

 

This will not solve the problem. There is a common misconception regarding the purpose and function of a thermostat. It is to keep heat in the engine, not cool it off. The 'stat traps water in the engine so that it warms up quicker, then slowly allows cool water to come in and maintain the desired temperature. If the cooling system will not keep up with the heat the engine's producing, it doesn't matter what thermostat you install, it will overheat. A lower thermostat will only lower operating temperatures if the cooling system can keep the water temperature that low. If not, the 'stat will stay wide open and the engine will never cool down because the radiator can't remove the heat fast enough.

Cars normally run cooler on the highway because much more air is moving across the radiator and removing more heat. In "traffic" less air moves across, removing less heat, perhaps to the point that the radiator can't keep up. That's when you see the temperature begin to rise... Powerful electric fans, if properly controlled, will help this condition dramatically. However, little will make up for a undersized or clogged up radiator, poorly performing water pump, missing air dam, or other fundamental defects within the cooling system.



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'87 IROC 5.7l TPI - original owner!

 

clewis,

To help narrow down the possible problems, when does the coolant get too hot?

1. On the highway?

2. In the city?

3. Both highway/city?

4. Is the A/C running?

5. How many fans do you have?

6. Is the fan(s) running when the temperature is too hot?

7. Do you have the stock coolant fan switch if it is equipped with one?

8. Did this always happen? If not, how hot did the car typically get before?

9. Was anything recently done to the vehicle that could affect the problem?

Make sure that you drive it long enough so it gets hot enough for a good test.

[This message has been edited by Stuart Moss (edited August 10, 2001).]

 

I had overheating problems identical to the ones described in this post. To make a long story short, the problem turned out to be a lot of leaves, feathers, cig. buts etc. lodged between the radiator and the A/C condenser. After removing the radiator and cleaning out all that stuff, the car never exceeds 220F. It seems these F- bodies are designed so that a lot of leaves from the street can get sucked up between the radiator and condenser and restrict the air flow through the radiator which is imperative for proper cooling performance

 

I agree with the leaves...my 92 Z28 was doing the exact same thing - overheating big time in stop and go traffic, even to the point of boiling over in the resevoir! When I pulled the radiator out, I found 10 years worth of rotting leaves, cigarette butts, and candy wrappers. Cleaned it out and the car runs no hotter than about 220-230. And it has been 100 up here in Jersey the past few days, and I've had the A/C on.

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=====================
1992 25th Anniversary z28 Convertible

 

Well, we've been through the runs too hot thing also. And sometimes we run into that problem from time to time after all the changes we made.

Here's what we did and the results we got.

1) Changed from a one row rad to a 3 row rad.

2) Changed to a 180° stat.

3) Use Havoline Anti freeze and watter wetter.

The result....
No matter how hot it is (we get up to 110° here) the car will stay on the 1/4 mark while driving on the highway and city.
In traffic during the middle of the day it will get into to 220 area until we get moving again. Then it drops back down the the 1/4 mark.

The car ran much cooler than the above described until we had a short in the fanswitch and it fried that puppy. We bought a stock replacement from GM and never ran that cool again.
By ran that cool again I mean.....
Prior to the fanswitch burning up the car ran in the 1/4 mark all the time and in any weather and driving conditions.
Don't know what happened but it's just not the same.

I'm going to replace the stock fanswitch with one from Jegs.
But I've been hearing that it won't work unless you get a computer chip along with it. Don't know how true that is, but I'm going to give it a try.

Also our single fan will not come on unless you have the A/C running.
Again this happened when the fanswitch fried.
We had a major melt down when this thing fried and it took along a fuseable link with it.

I'm guessing it's either a sensor or one of those relays on the drivers side. There are two of them there and I don't know which is for the fan. Guess I'll replace both since they don't cost that much.

So all in all....
even with a cooling system that works only half the time I'd say we're pretty lucky compaired to some on here.

Again we run mainly on the 1/4 mark and get up into the 220 range from time to time.
Plus we have to run with the A/C on at all times in order for the fan to work. If not we overheat.

That's my story and I'm stickin to it!

 

When I'm running the car at speed on the highway, it normally does okay. It hovers right around the 220 mark. When I come off the highway and get into slower traffic or stop and go traffic, it almost always starts to creep up sometimes into the red. It does it whether or not the A/C is on or not. I only have one fan, and it runs all the time when the A/C is on. When I'm not running A/C it comes on around 230 something I think. It is the stock coolant fan switch. No, it has not always run like this. I've done several things to it over the last few years. In fall of 98, I replaced the AC Delco radiator because the upper tank cracked and it leaked profusely. I replaced it with a 3 core from AutoZone. I replaced both upper and lower hoses at the same time. A month or two after replacing the radiator, I was detailing under the hood when I noticed that the coolant recovery tank was empty. I opened the radiator and there was no coolant to be found. When I pulled my dipstick, I found my coolant. Had the car picked up and taken to the shop, where the mechanic suspected a blown head gasket. He took the heads off and the gaskets looked fine so he had the heads magnafluxed and could not find a crack or any warping, but recommended I replace them anyway which I had him do. This happened in December 98 when the temperatures were pretty cool. Moved from Tennessee to Missouri shortly after repair and did not notice a problem with overheating until that following spring. Since then have replaced the thermostat, had the radiator pulled, flow tested, cleaned out and put back it, the entire cooling system pressure tested, checked the flow of the water pump, checked for carbon monoxide in the coolant (suspecting cracked head gasket)and my mechanic cannot see any reason whatsoever why it should be doing this. I have also replaced the A/C condensor and when they installed it, they placed some folded pieces of rubber hose to serve as a spacer and cushion between the radiator and condensor. Since both the radiator and condensor have been removed and placed back into car, whatever debris may have been there is no more. I've also checked it recently based upon the advice from other posts and it is still clean and free of debris. Recently replaced the radiator cap and initially thought it had solved my problem, but not so. I really don't want to install another fan or make any other type of modifications on this car. If only I could figure out why this problem exists, perhaps it could be fixed. The last advice I got from my mechanic is to just drive it and keep an eye on it. If it is a real problem, it will worsen over time and then maybe they can accurately diagnose and fix the problem.

 

So wait... is it still eating coolant? If it is, there's your answer. Head gasket or cracked block.

If not... umm, well... hrm. You aid it wasn't boiling over... I still say replace the sensor and related components... it's a sure way you're not getting a false reading.

Otherwise... good luck man.


(It's a good excuse to wanna build a new motor. "But honey, the engine I have in it now can't move the car fast enough to keep its self cool, so I have to build a bigger faster one." )

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1985 Camaro SC - 2.8L, auto.

http://www.xenodrgn.f2s.com/Frontright.jpg

 

Clewis:

Is it really overheating? Have you tried replacing the gauge sensor, in case the motor temp is fine but the gauge just reads high?

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"So many Mustangs, so little time..."
ICON Motorsports

 

That's just it, I don't think it's really overheating since it never boils over and I'm not loosing coolant. I think I'll try and replace the coolant temperature sensor and see it that cures it. It sure can't hurt it.

 

Wow. I don't think I ever go above 200° on the highway, even when it's >95°F. Although my car is stock. Since you have an aftermarket radiator, we're not making a fair comparison.

I too am beginning to think the sensor/gauge may be off.

Here's a thought if you can't test the gauge sensor for resistance.

Remove the sensor but keep the wire connected to it. You'll have to have the base of the sensor connected to ground with another wire to complete the circuit you lost when you removed it from the engine block.

Now, boil water and put the sensor in this water. It should read ~ 212°F (at sea level), minus a little for the amount of cooling that takes place from the time it is boiling on the stove until you can run to the car to put the sensor in it. If you have a couple quarts of water, it should retain enough heat to get a good enough reading.

Of course, if you have a thermometer, checking the sensor/gauge would be a lot easier. Sears has a nice (accurate) digital one for $20.

 

I hover around the 1/4 mark on the highway but 20-30 min into stop and go traffic and it starts to climb to the red zone (mine has boiled over). I have checked the fans and checked for debris, and i am not leaking coolant...

Anyone have any ideas?

 

Clewis and Carter,

I posted in another thread about my situation with a cooling problem. It turned out that all though the water pump was circulating fluid it was not doing it well enough to keep the car cool enough in town. Highway driving was no problem. I replaced the pump, thermostat (195), and hoses. Put new fresh coolant and now the car runs cool all the time. Actually the fan will come on if it sits long enough and cool the car enough to switch back off while sitting still. Something that never happend with the old pump.

Just my experience.

Phil

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89 IROC 5.0 TBI
Soon to be a 5.0 TPI, with a disk rear.

 

Clewis, make sure that you replace the Coolant Temp Gauge Sending Unit and not the Coolant Temperature Sensor as you stated in an earlier post. The sending unit for the gauge is located on the drivers side of the block between the #1 and #3 cylinders. Just a friendly reminder.
bsa

[This message has been edited by irocbsa (edited August 14, 2001).]

 

Thanks for the correction.

 

Sounds like it could be the sensor or the gauge. Also have you checked the timing? I did a recurve kit on my distributor and set the base timing differently and now when I get on it it stays cool.

 

I was reading through another post and someone had put the head gaskets on backwards and blocked a cooling port. Dont know if it applies to you but thought I would mention it since the probelm started after you had some work done on the heads.

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My 85 Iroc

 

Hold on, back up a minute. I read EVERYTHING here very intently. When all exle fails look for WHAT'S DIFFERENT FROM BEFORE!!! Engine ran fine before (nice and cool), head gasket blew, was repaired, and now it runs hot. What's changed? The ENGINE has changed. Start thinking about that and I think you'll find your answer.

Does it still run like a scalded cat?? Or is it maybe a little slower than before? If your mechanic replaced the heads then he had to pull the distributor and intake, right? Well, what if he didn't set the ignition timing correctly when he put it back together? Stock setting is 6* BTDC but only if you disconnect the timing wire. Set it with the timing wire still connected and you'll be way retarded from wher it should be- THAT'S A GOOD WAY TO OVERHEAT AN ENGINE.

How about a plugged cat? Run with retarded timing for a while or on an engine with hard mechanical problems (like a blown head gasket) and you'll eventually melt the cat down and plug the exhaust. Plugged up exhaust is a GOOD EWAY TO OVERHEAT AN ENGINE.

See where I'm going with this? I haven't covered all the bases by any means but I think you're looking in the worng places. If the problem WAS the cooling system you would have fixed it by now.

 

I took the car to another shop from the original one that put on the heads. (Moved from Tennessee to Missouri). I had them set the timing as I could turn the distributor by hand. It had not been tightened down. I have also had the catalytic converter replaced a while back also. It does still run pretty good, although it may not be quite as fast as is was before. I guess I just considered that as normal on an engine with some age on it. Aside from some valve stem seal work done while it was under warranty, the head work is to only other engine work that's been done on it. In reality, I think it was my intake gasket that went because when he took the heads off, he indicated the gaskets looked fine, and even the heads checked out okay, but he advised we replace them anyway and I did. It seems to me that there are alot of us out there that have the same problem with the cars running at a high temperature. Like I said before, it hasn't boiled over or anything and even when the gauge has read in the red, I've gotten out and looked at the coolant recovery tank and it shows a normal hot reading level of coolant. :confused

 

My temp guage was showing higher temp numbers that what were real. I tried a cheap temp guage and the temp. was 190* on the new guage.

[This message has been edited by gmanuel (edited August 15, 2001).]

[This message has been edited by gmanuel (edited August 15, 2001).]

 

I had just gotten my car back form being rebuilt.Then drove it home in like 10 to 15 min,my car boiled over.But the bad thing about it is that I didnt have the front nose on the car either.I am certian that my fan doesnt work,cause i turned the ac on and the fan didnt come on,I have also replaced the relay which is on the far left side of the bracket on the driver side.I also know I have to get a new radiator cap too,the old one only turns 1/9 of the way and around.The pressure will not be sufficient to pump the coolant around will it because of that,am I correct or not.My car also idles really high that will cause the motor to boil over too.If you can help me on that it will help me alot,I've got to take it to the shop to get exhaust put on,and tuned up.

[This message has been edited by 85SportCoupeto89RS (edited August 15, 2001).]

 

hey 85 sport...

You've got more than one problem but.....

My fan motor just bit the dust this past weekend and I had the exact same results as you did.
Drive 15 minutes and boil over!!!!!

See my post which might be a few pages back regarding "if you are having cooling problems....read this"

Just because you don't have the front clip on there does not mean you are getting nothing but air to the rad.