Mr.ChevyStroker

So I literally just bought my 1991 RS. 5 speed 305 tbi. Didnt notice the first day but it was most likely happening the day I got it. (Monday) but I was driving kinda hard yesterday when I notoced it and heard this percolating sound from under the hood so I popped otopen and the overflow tank was bubbling. Took the lid off of it and steam started coming out. The gauge on the inside read 220. But was running and driving fine. So I did a flush and clean and put a 160* thermostat in there. Warmed it up and drove and was till around 220* on the gauge. Is this normal tempurature?!?! I wanna know just incase. Maybe theres a blockage somewhere or something. Any thoughts? Ill also post some pictures once I get off my phone.

85Special

Go back to a 195 therm... The 160 won't help. Go to hawks third gen or summit and get an hd cooling temp switch. There will be a brass plug between the back 2 cylinders on the passenger side. remove the plug and install the switch. Stock the fan in third gen camaros doesn't come on till the engine is 210-220ish find the lead from the computer that activates your fan relay... Green/white lead if memory serves and run it to the switch. It will bypass comp control of the fan and bring your temps down. Be sure to cap the wire from the computer.

85Special

Oh the thick wire bundle is the one your after that runs on the passenger side from firewall to the front of the car. When you clip the wire be sure to cap the lead on the firewall end and use the lead from the front of the car to run to the switch. Get a Haynes or chiton manual they have good wiring diagrams.

J-money

when i first got my 1992 rs 5.0 it done similar to yours. It did it a while when my dad drove it before me. I had my fan straight wired to run all the time and a 160 thermostat and it still would overheat like yours whenever I drove in town or up long dirt roads.
Eventually changed the radiator (it was clogged apparently) and flushed the system.
Havent had any problems with it overheating since then.

Mr.ChevyStroker

Okay, so summit or hawks what would be cheaper? And two brass plugs between cylinder 7 and 9, and its a switch, green/white wire from passenger side, wire it to that and it should not get so hot like that? along with a 195 thermostat. Also when it starts it throws a code. INFL REST. right next to my serive engine light that comes and goes from time to time. Any Idea about that??

Mr.ChevyStroker

Nevermind about INFL REST, its an airbag code, haha. But what is the name for the switch for replacement of the brass plugs? I been lookin and havent found it yet

Mr.ChevyStroker

Unless this is it? http://www.summitracing.com/parts/der-16749/overview/

jazzdadss

Sounds Like it may just need a new radiator cap?
My 89 TPI Iroc factory settings did NOT turn the fans on until it saw 232 and would shut them down at 215.

You have to remember that your cooling system acts like a pressure cooker. As long as it holds pressure, it takes a lot more heat to boil over. If it wont hold pressure the boiling point becomes much lower.
If it was boiling over into the overflow bottle at 220 I would say your system is not holding pressure.
That would be the first thing I would check and put a 195 t-stat back in it.

Mr.ChevyStroker

Okay thats what a buddy of mine said as well. Should I get a higher pressure cap or thw same 15 pound one?

jazzdadss

Just a factory replacement, Needs nothing special.

Mr.ChevyStroker

I went to the local part store and they got me the correct cap. OE is 16 pounds not 15.. And i got the one with the release on it to help it. On the drive home it didn't do the bubbling after going a little hard, so I am hoping it fixxed it and I am gonna do the 195 stat tonight or tomorrow then it should be okay! :fingerscrossed:

Keoman

iTrader: (3)

I'd hate to see you go out and buy a bunch of parts for no reason. More often than not on this forum people seem to skip the basics. With that said, thirdgen's are designed to run hot.
Please have a read before buying anything else.

https://www.thirdgen.org/overheating

https://www.thirdgen.org/forums/cool...tml?styleid=40

Mr.ChevyStroker

Okay, So I only have one electric fan, it kicks on when it gets around 220ish, that area, i still have the air dam, but im not sure if it is bent or not. The cap that was on there was a old looking 15 pound one, I got a proper OE one from the parts store that was a 16 pound one with a pressure release gauge on it. And tomorrow Im gonna check to the water pump tomorrow, and replace the 160 degree thermostat with a proper 195 one. That should fix it! Also, i did run a diagnostic testing ma-bob on it and it gave me the idle and air fuel ration... It was leaned out quite a bit i believe. and i guess Ill check it tomorrow as well. According to the hood tag is says timing is suppose to be a 0 degrees. Should i advance it or retard it more? helping over heating issue a little and a little gain performance like reaction time along with the leanness that should hopefully fix it

deadbird

Tbi fan is not ecm controlled. Tbi fan switch turns on at 238°F. Turning a/c on, regardless of working, should run he fan. Lower temp fan switch, sw505 (215°F on) or similar, is only solution aside from manual fan control or, aftermarket controller (ie: hayden) . Running warm is part of the design in slow traffic.

Mr.ChevyStroker

Okay, well We did a block test on it today and redrained the coolant, and it frothed out into the block tester... So It may be the radiator? We are gonna pressure test it on monday in school. Im hoping it isnt a headgasket

85Special

http://www.hawksthirdgenparts.com/pr...an-Switch.html

Still a good idea to go to a cooler switch. Best to replace the head gasket but for a temporary fix blue devil head gasket repair works well.

Mr.ChevyStroker

Itl have the intructions hopwfully haha

85Special

I didn't see that you were TBI. TPI has computer control over the fan relay. It maybe just an "out with the old in with the new" swap. Dunno... easy way to tell is if you have a connector between the last 2 cylinders on the passenger side below the exhaust in line with the spark plugs that looks like the connector to the knock sensor. If so it's a strait swap.

Mr.ChevyStroker

Im confusing myself. Whats a straight swap?

deadbird

The fan switch is screwed into the cyl head as 85Special stated. If you choose to get a new, cooler on temperature fan switch, it will replace the OE fan switch (straight swap, no modifications needed).

85Special

gt4373

What Is Your Water/Antifreeze Ratio,A 50/50 Mix Should Not Boil At 220.

Mr.ChevyStroker

When I got it? Im not sure. Drained it, did a flush and clear with some radiator cleanin stuff, filled it 50/50, (this is now with the 160* in it, still got warm at idling no movement.
Got the proper 16lbs cap with a release, and havent changed the fluid after the second try, did a block test, it was frothing over a lot... but Even driving 110+ miles from yesterday to my Fathers ( grama went into ICU) and another 110+ today, it never got above the hash above 100, like the second hash before 220... So i think it might be fixxed with the proper cap. I may changed the thermostat to a OE 195 and do the fan switch...
From what I saw (which was not a lot from any angle above the car) it would be easier to crawl under there and swap in that switch thingy that you dudes were talking about. Ill find out tomorrow. Gonna let it warm up and see if it still gets really hot just sitting

deadbird

It will always get hot sitting. No airflow (fan or driving) through the radiator and you're just circulating hot water that keeps getting hotter as the motor runs. When the gauge reaches the ¾ mark, 240°F, the fan should run. Thermostat temperature will not change the problem while sitting still.

The exhaust manifold and heat shield hides the fan witch quite well. Fan switch location...

Mr.ChevyStroker

well i think The cap actaully fixxed it, but after it warms up, and it hits the fits time at the (230ish mark) fan engages, then i turned it off, open the release valve on the cap, and some coolant went into the overflow holder, then after 3 or 4 minutes took the cap off and it was frothing, like bubbly, but not over flowing... So there has to be a leak some where, or my cylinders are eating coolant... ;/ Good picture btw's deadbird!

Uhltheman411

Hello everyone, I'm pretty new to the site but have used it a lot to work on my bird. Got a pretty big problem with my 1988 firebid formula 350 5 speed tho that is driving me crazy. RUNNING HOT! Sprung a leak in my last radiator cause of it. I've read a lot on here about it running hot and all and the temps which the fans kick on. So I know a little bit about this. So I went on eBay and bought a nice new 3 row aluminum race radiator. Installed it same was I read on here which worked fine and also bought 2 new 12" fans which are installed. Also put a new 195 thermostat in. So that said and done everything was put back together. Started the car and it warmed up fine drove it and stayed nice around 200 degrees. Parked it in the garage and let it run and it went right up to 235ish. I know both of my fans are kicking on. One at 226 and the other about 240ish. So I turn the car off and let it sit fans running and it starts boiling out of the radiator cap, pretty good 2. So now it's cool I take the cap off which is brand new with the radiator. Notice that the spring is fairly easy to depress. Must not be the right poundage. Went to parts store got a new cap, 16lbs OEM. Install and run the car, it heats up to 235ish again sitting, still with the fans working right and defiantly know the thermostat is good. So I turned it off again and go to the cap and nothing is coming out and overflow is rising. Look down at the fins by the cap and notice fluid really coming out. Must have sprung a leak or the radiator is bad. Was not doing this before the 16lbs cap. System was leak free besides the cap letting it out. Pretty bummed out at this point considering the money I've spent so far. Gonna try to get the radiator replaced and start over again. Plus I'm going to by a new fan cooling switch and a chip. So this is where I'm. Does anyone know why the radiator sprung a leak? Was the 16lbs to much? Also I've had this engine replaced years ago by some garage. Was a 305 tpi now it's a 350 with the same tpi. Is it a problem that the motor was changed to a bigger block and it still thinks it a 305? Called hyper tech today for a chip and the asked my model and trans so I told them 88 formula 350 manual and he said they don't make a chip for that. Gotta get a custom chip cause 88's didn't come 350 5 speed only 305. So my trans must have been changed out anyways called a guy that makes custom chip and he needs to know what injectors I have and I don't know if those were changed with the motor so I need to know how to locate the number on them. Any clues how to find this number? Some PLEASe HELP!