JulieGTA

91 GTA, (5.7 350) 110k, had it about a year.
Basically the (yes stock) gauges seemed to work ok, the car stayed in what I considered the 'normal' range and when the temp went up, the car got 'lazy.' Usually caused by idling, slow traffice for long periods of time, and once the car got moving again it would return to 'normal' temp and acting normal.

A few weeks ago, the car started running unusually warm all the time, staying at it's 'hot' temperature (still well under the 220 mark) and having the related laziness. It started the very same day I put a flowmaster exhaust on it, and even though my gut tells me it's causing the problem, it also doesn't make any sense. Around the same time I was also having trouble with a new alternator but it seemed straight forward and unrelated, and fixed it. All the electrical checks out ok.

A friend with a 92 trans am assured me that my car's problem was due to a bad fuel filter, because I was having poor performance as well as high temps, and I had hopes, but changing it didn't make one bit of difference. (This person's car regularly runs in the 220's even with a new thermostat he specially installed, but he claims it runs perfectly well.) (Meanwhile, my dad says a thermostat is a bad idea because then the car will run TOO cold. I disagree!) I also had a mechanic check the computer codes & the car thouroughly but nothing came up and they could not find anything wrong.

The car has been getting steadily hotter. Now it gets to 220 after driving it 10 minutes and pretty much stays there, but under stress it goes a little higher. Not to mention, anybody in any kind of car can breeze by me now.
Am I forgetting anything? The air dam is ok, and nothing leaks. (I replaced the radiator with a stock one last year, when the old one leaked too bad, but it never gave any trouble.) I can't think of anything else except flushing out the coolant and making sure the fans work ok, one of them seemed to have shorted out a while ago and I had a new motor put on it, but I don't think the one fan is going to make such a huge difference anyway, because even when it was bad it still wasn't running this hot.
Any suggestions? Up until now all its problems have been pretty obvious but this is weird. Maybe my car is just suffering from old age and abuse, but I refuse to believe it! Maybe I have cruddy oil. I changed it around the same time the heat problem started...Maybe I'm going insane.

Danno

Welcome to the boards. The normal operating range for these cars is about what you describe. On highway with good airflow from the dam and a 195 stat they typically run on the first line bet 100 and 220. Most GM's are designed that way. In traffic idleing the primary fan should turn at about 225 degrees, seconday if so equipped at about 238. Check or replace the fan relays, they are a major source of intermittent cooling problems. Exhaust, well only if for some reason it's running extremely lean. Your dad is correct, no matter what you read the best operating temp for an electronically managed engine is the stock 195. I run an 89 iroc/zz-4 block, everything stock and with a 195 it gets close to 25mpg on the highway. You might want to try a new stat. You can get by with a 180 if you want and you do a lot of stop and go because the average temp will still be higher. You might want to try a new O2 sensor. Even though you have no SES code it might be getting lazy. Many times I have worked on cars with poor mileage or just poor performance and changing the O2 solved the problem. As they get old they slow down in reaction time. How about base timing, poss distributor is loose and moved? With EST wire disconnected you should see about 8 deg BTDC. Thats one thing to really check. Aa always the usual things, coolant mix and condition yada yada yada. Keep us posted, LOL there is a way using the ALDL connector to place the ECM in the field service mode that will let you check to see if its running rich or lean. Wont waste any more space, pm me if you want to know how.

MdFormula350

well my car runs basically runs 220...

i am using the stock factory dual fans.
new rad, new cap, new pump, new thermostat... 50/50 mixture coolant..

anyway i ran at the track a while track and my car started gettiing hot, anyway even with the driver fan on at 225 it still was only keep the temp under where the other fan would not come on (like high 220s to mid 230s, any way my car did not run lazy and ran 14.5XXX..


now since i wired in a manual switch so the pass. side fan can come on at any time i never run past 220 now and i seen to run a tad quicker like 14.3's to 14's...
so i seems you may have something else wrong..

JulieGTA

Thanks for the tips!
It's going to be a long weekend trying to solve the puzzle. Could be running lean? It's getting really excellent mileage now with the flowmaster, which makes me suspicious, but reluctant to part with it. Then again I've put alot of abuse on the car in the past year and it could be anything. Definitely overall slower reactions, stays at 220 so at least one fan is working right. After looking at some other posts I tried turning on the AC to see if that might get the passenger side fan moving and affect the temperature but I didn't notice any changes. (the heater's always been disconnected because it's too hard to fix the core.) But I keep forgetting to look at the fans when I stop the car and its still warm. Anyway I'll be working on it this weekend and I'll post any new developments or if I get stuck. I'll be sure to let everyone know.

86BirdSE

I'm running a 160* stat from Napa, and I'm not having any drivability issues in the cool Notheast. I'm averaging about 19-20 MPG on a 305 CC Q-Jet with Mobil 93 octane., and Pennzoil 10W40 oil on Purolator Pure one filters. The car ran at 220 constantly and pinged (yes, pinged on the 93!!) before the 160 stat and new 16lb cap, and now I don't ping anymore It had a 180 and 7lb cap previously. I cvleaned the carb, and it still pinged, but not nearly as bad as before. I know it needs a tune-up, and that's a project for the upcomming weekend, just need a good set of wires yet...

...but I noticed the temp climbed a ton and a bit over the 220 mark sitting in traffic yesterday, and I didn't *seem* to hear the fans kick on. Highway speeds and most anything above 40 with the heater "1/2" on the water temp is now a hair below the first "long" mark (which I'm assuming is 195) and the temp climbs rapidly.

Call me crazy :lala: but I'm getting more of the 20 MPG than the 18 since the thermostat swap, and a mere top off of just water. I need new hupper and lower hoses, and I'm waiting on the fresh coolant /distilled water until I get those too.

Just my observations in the 2 short months I've had my "chief."

3.1EyeCandy

iTrader: (3)

old thread I know....but my car was doing this and I found out that the T-stat was stuck open. This will cause your symptoms as well. I'm no mechanic and I'm not sure what the deal with that is...but try replacing your t-stat with a factory replacement. Fixed my problem.

JulieGTA

It was the thermostat. Yep probably stuck open. My second cousin, a mechanic, was visiting for Thanksgiving and he helped me put it in, (and also showed me how to check the pump too, in case that goes bad.) Apparently, the new thermostat works, because the gauge (which works) shows that the temperatures are back to normal, and nice and cool because I got a 180 thermostat. It no longer smells really hot either. However my car has been continually running down, losing power and misfiring due to some other vague long term problem and it's barely driveable anymore! I had the spark plugs changed Saturday (I admit it, it was too hard to attempt myself) and either they bungled it or it didn't help, because it's really going nasty now. SOS! I'll try to post in the appropriate place. Also my oxygen sensor looks new but I bought one anyway. I was going to change it today but the old one looks fine and still new, and I really think its more serious than that. Anyway hopefully when its working again I will be able to enjoy my new cool temps, just like old times.

I wasn't able to get the news in until now because my two computers were taking turns getting fried and getting viruses, and then the message board reset my password and stuff.

Thanks everyone for the tips!

3.1EyeCandy

iTrader: (3)

strange. I just replied because I knew the answer...and wala! you replied back

About your car seeming like it's running down...
1) Check to make sure your Catalytic converter isn't clogged. Many 'cats will rattle if you hit them with something when they're clogged.
2) Try the TPI board. they'll give you all the help you can handle.

305sbc

iTrader: (3)

I second this advice. A clogged CAT can make the engine run hot too. If you're misfiring badly now, that could explain the cooler temps. Be sure to check everything including the CAT.
& keep us posted.