kitt_2000

82' firebird 305 computer controlled carbureted and computer controlled timing. AIR DAM IS INSTALLED. NEW 8 vane hi flow water pump, 180f thermostat, upper and lower hoses, heater hoses, stock radiator, heavy duty lockup thermostic fan clutch with 7 blade stock fan, new coolant, redline water wetter, NEW radiator cap, new air filter, new fuel filter. coolant is half gallon green coolant the rest is water. coolant was completely flushed. NEW a/c condensor, removed heater hose and coolant shot out OVER 10 feet with engine running. removed upper radiator hose and shoots out hot water when the tstat opens. timing was checked and set to 6btc with 4 wire distributer disconnected. no computer codes. engine is not running lean. checked it with scanner running 44 percent dutycycle to the metering rods. shows in closed loop. fan shroud is installed. ok now ive listed all the knowns that I can. heres what happens. gauge shows it gets hot driving 5 miles or so runs around 180f but rises temp to around 200f. NOTE at 200f THERE IS ENGINE PINGING!!!! but if i turn the a/c on it climbs a little quicker to around 220-230f and keeps climbing. with ignition pinging!!!never comes down if the a/c is turned off. heater hoses run like this, intake manifold to heater core, heater core to radiator. it used to run to the water pump but kept being told to move it to radiator. I cant figure this out and all i keep hearing on the forums is the same thing.. is the air dam installed yes it is, timing checked yes it has the right way, and yes it was rechecked. everything as far as the cooling has been checked. fan clutch pulls serious air and does not stop with a rubber hose to stop it. I cant figure this out and is really driving me nuts. engine is bone stock. no tricks. no fancy parts. all factory. are 305 engines known to have poor cooling? and i know there are fanatics out there that say 220-240f isnt hot but that is rediculous. it really is. theres no reason this engine should run that hot ever. especially if you put a set temperature tstat in there. so come on guys. what else am i not checking? is there something like head gasket design that can cause this? ok well im completely lost and i mean really lost. I just cant see buying a 3 core radiator for a car that is bone stock.

green92

Well that sucks. Ok I assume you know that they cars naturally run hot. Gm designed them to run around 220 supposively for fuel mileage reasons. At least I've been told that. I've owned my car since 97 and have fought with the 220 plus temps for the longest. Stock motor except for headers but bout six years ago I went with a radiator built by a former employee of a radiator manufacturer. It helped tremendously but on those 100 degree and 98% humidity days car would still creep to 220 even with a 160 stat. Along with the radiator I added two 10 inch fans in front of the condensor (about 3 years ago). Not one issue since when I know it's going to be hot outside I use one or both of the fans and it never breaks past that 160-180 range. Sounds like you have checked everything and all I could see changing would be the fan clutch for a electric fan. I say that cause its one less thing the engine has to turn even though its on the pump it does cause drag. But if you don't want to do that have you looked at putting the fan straight to the pump with one of those spacer deals? That way the fan is constantly turnning at engine speed and moving air. At least that may give you some insight on if its pulling enough air. I'm just throwing ideas at ya this is a hard one to figure out.

86White_T/A305

Thats a big list of new parts lol.My stock 305 non ccc would run about 210*,bone stock..poorly maintained everything when I got this car.You are boiling over easily it seems,keep in mind just because you get coolant spraying out when you disconnect the lines does not mean the cooling system is properly burped.Might make it quite worse with air pockets.This also happens alot with ls1 motors and i fought that battle of needing to burp the coolant lines 3 times over the course of a week before it got all bubbles out.Their are some good tools to do this at the rad cap that fills coolant but lets the air pockets out letting the car sit and run for 30-40 mins with heater on and light revs.

naf

iTrader: (7)

How are you determining the temperature of the motor? Do not rely on the stock temp gage.

If it's not boiling over, it's not overheating. If it begins to boil over, first replace the radiator cap but it sounds like your motor's not.

When you removed the hoses with the coolant hot, it was under pressure. Of course it's going to shoot out. Don't do that again.

The heater hoses should run to the water pump and the intake manifold.

Pinging is usually caused by timing. The next thing I'd check on an LG4 would be EGR function.

Confirm your temperatures by an alternate means.

landell76

Just went through what seems the same issue with mine. Entire cooling system was new. I beat myself to death trying to figure it out.It would get to temp and then just keep on climbing. In the end all I had to do was park it on a very steep hill chock the wheels and lift the front end to burp it. After burping it took almost a gallon of coolant. Gremlins!!! Car now runs 190 hottest in Missouri summer humidity.
Give it a try.

kitt_2000

well i tried burping it thinking that was the problem but it never burped. I even used a radkit which puts a vaccum on the entire cooling system. still overheats. I thought that because i have a knight rider front bumper this may be causing over heat but then relized it overheats just sitting at idle over a period of minutes after it has been warmed up. weird part is ive been putting serious miles on the car over 600 miles a week. i get 25.4 miles to the gallon no kidding. Im still not sure if timing is playing a part in all of my overheating but makes no sense i have checked it and rechecked it. still hear that ignition pinging under a hard acceleration. I keep trying guys and dont think the burping is the problem i gave that idea my best shot. is there any other way to test base timing other than disconnecting the ccc 4 wire connector on the distributer? I heard there was a way to use the datalink connector and paper clip somehow. maybe that will be the right way to test base timing? anyone know how to do this or which pins to pin with paper clip? keep the ideas coming thanks !!

TTOP350

iTrader: (8)

These cars run 200-240degs from the factory.

Is your lower rad hose new or older? Is it sucking shut when you drive it?

Buy a lazer temp gun, stock gauge sucks (esp on Camaros).
I run a 160 tstat in every F car I have. 195s are for emissions.

Do you have underdrive pulleys on it?
Try a stock clutch for the fan or yours may be defective, esp since you said it over heats at idle.
Maybe that is the problem, the temp setting in the clutch fan is set to stock type temps and its letting car get to warm b4 it kicks in.

Just tossing spit ***** at ya. Good luck

naf

iTrader: (7)

Timing is not causing it to boil over, IF you're actually getting over 20 MPG.

First replace your radiator cap. It is a wear item and an old cap will allow the system to boil over at lower pressures.

If it's still boiling over, pressure test your system.

You shouldn't need to 'burp' the system unless you've recently lost a lot of fluid, which can happen when it boils over. Drilling a small hole in the tstat to allow air to pass will help prevent vapor pockets within the system next time.

If it pressure tests OK but is still boiling over, verify coolant and air flow-through the radiator. If you haven't recently removed the radiator upper hold down, swung the radiator back some and cleaned between the condenser and radiator, it's time.

You can only check the timing with a light. Plugging a scanner into the ALDL will not only disable some ECM commanded timing functions, but the ECM doesn't KNOW what the base timing is anyway. It only adds timing to whatever it's set at.

If timing is within 0-6 degrees base and you have pinging at low speed cruise with throttle tip in, I'd do what someone above recommended and check EGR function. You've got an 82? Shouldn't have a KS and should have the lower compression motor.

kitt_2000

Thanks naf, but as stated above coolant cap was replaced and coolant was burped and it was pressure tested great to 22 psi for over half hour no leaks and held the pressure great. Do you know what pins to short to check timing through the ALDL?

naf

iTrader: (7)

If it pressure tested to 22 psi, it must be getting pretty hot to still boil over.

As stated above you can't check base timing thru the ALDL. The computer doesn't 'know' what base timing is, it only adds to it. You have to disconnect the four wire connector to the dist and put a timing light on it.

Airflow or coolant flow.

mmadden55

Ok couple of things, you may have a bum thermostat new it may be but working it may not. Sometimes they are bad new. I am assuming your radiator is not blocked. Get a 180 and drill some holes 1/8" with a drill bit, three is good,to pass steam and water when it is closed so you are always getting some circulation and it will pass your air bubbles through.

I would recomend going to an electric fan.

One other thing since you replaced you water pump recently is there any chance you put your fan blade back on reversed?

kitt_2000

I thought you can pin a and b to check base timing? I've tried both ways and still have it set at 6 btc. I can't figure this out.. It's nuts and makes no sense. What do you think if some of the coolant passages were plugged?

naf

iTrader: (7)

Nope.

joshc

iTrader: (1)

It sounds like you replaced just about everything except the radiator.
That would make me suspect the rad is partially plugged internally, or the external fins are packed with dirt and debris.
Take the rad out and make sure the rad and condenser fins are not plugged, blocking air flow. If they are plugged, blow them out with compressed air. (careful! not full pressure or it will fold the fins right over)
It could also be plugged internally, it doesn't take much to plug the small tubes. Rust and scale builds up over time.
If you have an older style rad with copper or brass tanks, a radiator shop can boil it out, plastic tank rads are pretty much throw aways.
The cost of boiling out a rad, its almost just as cheap to buy a new one.
If the rad is out of the car, you should be able to put a garden hose in the upper hose inlet and the water should run through about as fast as it will come out of the hose.

kitt_2000

i just replaced it a week ago. it started leaking coolant around the transmission cooler nuts on the radiator tank. so i replaced the radiator. also i replaced the condensor about 6 weeks ago and caused the trans cooler to leak on the radiator. so now i know radiator and condensor are brand new. it still gets really hot. runs around 230-240f. i even checked it with a laser temp gun. i do notice the a/c blows ice cold out at 37f until the engine has warmed up to 220f then the a/c doesnt blow cold anymore. will only blow cold on the freeway as long as im above 70 mph. also it will only get to 220f on the freeway. but as soon as i pull of the freeway not even to the off ramp light the temp will skyrocket to 230f and usually holds that temp as long as i turn the a/c back off. so with all said and done, and everything replaced. including the thermostat twice. im still getting way to hot. radiator isnt boiling over yet but there sure is a ton of pressure in there. coolant hoses seem to be always under pressure. but when it cools down i check the coolant level seems fine. at this point im almost thinking of having the block and heads boiled maybe there are coolant passages clogged up or something. im really anoyed. thanks for your help guys i really appreciate it. let me know if im forgeting anything else...

naf

iTrader: (7)

This is an airflow issue.

Your title referenced overheating, which may have confused me.

There's supposed to be pressure within the system. The pressure keeps the coolant from boiling at higher than standard (atmospheric) boiling points. There are two things that can cause it to boil over:

1) Actual overheating-where the coolant temperature exceeds the boiling point of the coolant under system pressures.

2) Failure of the system to maintain adequate pressures.

Sounds like you have neither issue

dennis.warren

I posted this in another forum, then I saw this one. I have been having this trouble for years with my 88 IROC 5.0 TBI. Over the years I have done everything told to me by Chevrolet and my mechanics and nothing has made this problem stop for me. My temp gauge in the car runs nicely at 210 220 while driving. In any stop situation it runs all the way up to the top of the redline 260! The fan (single) comes on and the temp heads back down to 230 240. If the car is sitting idling in the garage, I have the same performance. When A/C is on, the fan runs, so I know my relays are ok. Here is where it's at with repairs/replacements - New ECM - New A/C Compressor, just went bad and replaced it - New water pump, the old one was fine - New T-Stat 190 degree - New temp sensor, the one in the in the manifold - New Radiator - and everything that goes along with all these things such as hoses, clamps and the like. The temp gauge still reads this way no matter what I do. Today I had the temp sensor in the block replaced. No Change. I can't see that there is anything left to consider other than the programming of the new ECM. I thought it could maybe wiring somewhere, but mechanics keep telling me that it's ok. Relays and the like.
So, I am getting ready to pull the computer and have it reprogrammed or maybe just get another new one. If anyone knows what I am missing or what I can do to test the engine temp outside of that gauge, I will do it! I am all out of ideas.
Thank you for reading and any suggestions!

kitt_2000

ironic isnt it !! I see this same problem in almost all the posts on here. and all i hear is it "normal" lol. I know that it cant be normal. Im a diesel mechanic for ford and know that when ford diesel engine gets to 230f engine oil starts to boil. At 240f the pcm starts to derate the engine greatly and goes into a terible limp mode. so when i hear other fellas say 220f is normal i just dont agree with that. Ive looked at all these forums for the answer to hit me in the face but nothing is found. and if they ever did find the problem to their overheat they never never told us about it or updated their forum. i used redline water wetter helped but didnt fix the problem nor did running more water and hardly any coolant. so i wish i can help you but im in the same boat. i guess we're both on this quest to find the mystery overheat !! HELP....

kitt_2000

hey guys.. i just wanted to be clear.. my car isnt boiling over. im not sure why they think its boiling but its not.. just running hot 230+f

dennis.warren

The thing is my car appears to over heat. There are never any traditional overheat problems. Performance is unaffected, nothing leaks, no ping. Nothing! Just that damn gauge says the car is way too hot. I think with mine it's a question of is that ECM supposed to kick that fan on or not? If all the other sensors are a combo of mechanical fail safes and they are all working correctly, isn't that all that is left?

kitt_2000

You should use a laptop and read what the PCM is reading for temperature. I'm sure there is a coolant temp pid in the computer.

naf

iTrader: (7)

That 'damn' gage is no real indication of the actual state of nature at the end of it's sensor. When it was new it didn't read correctly. Your vehicle seems to otherwise be running fine. Maybe swap the temp guage for one that works?

The factory installed temp switches don't turn on the fan until +220 degrees. Apparently they didn't think that was 'too hot'.

If you have the dual fan system, the ECM controls only one of the fans. The temp switch controls the second. If you're unhappy with the ECM commanded turn on temp, why not swap to a lower rated temp switch? Or just reprogram the ECM...

dennis.warren

She is a single fan. That is what I am working on - What am driving at is where that gauge gets the temp indication from? Like all the other parts in this car, that gauge has also been replaced along with the boards behind it. All the sensors and the ECM. Everything folks are saying here makes sense. There is no clear indication to me, though where that gauge is getting this from. There has to be a way to make it accurate. If I was to put another sort of temp gauge in the car, for instance, where is that gauge going to be getting the reading?? If the ECM supplies this info to the dashboard instruments, is the ECM needing some help? It is new and I pulled it out of the car last night. I was going to have it reprogrammed tomorrow. This ECM does not have an EPROM that can be removed, so it has to be removed and reprogrammed. I really appreciate all the comments - Maybe I'm finally getting there!

naf

iTrader: (7)

The ECM is involved in no way shape or form with the readings on the dashboard instruments. The dash temp gage uses a temp sender that is installed in the left (driver) side cylinder head between #1 and #3. The gage relies on a single wire that varies resistance to ground (cylinder head) with temperature (coolant).

An aftermarket gage can be either mechanical (a closed tube filled with a fluid that varies pressure on the gage with temp change) or electrical, which would work similar to the stock system except likely more accurate.

After market temp senders can be installed at, or in, any fitting that exposes the sensor to coolant. Often installed in the water neck they 'may' run a few degrees cooler than the cylinder head boss.

FYI, your single fan is controlled by a fan switch installed in the same boss on the opposite cylinder head, hence between #6 and #8. At idle in the driveway the motor should slowly heat up until the fan comes on, cool down till the fan turns off, then repeat until it runs out of fuel. EDIT: There may be some 5.0 TPI motors with single fan controlled by ECM. I'd have to check.

A lower temp fan on/off switch can be purchased for around $30+ if you're uncomfortable with your current factory settings. Combined with an efficient cooling system AND a well tuned motor you should seldom see temps (actual not 'gage') above 220.

dennis.warren

Thank you naf! Replaced the sensor on the driver side a couple days ago. There was nothing on the passenger side, which is where I was expecting it to be. Nothing there at all. Supposedly by the oil dipstick. This is a new motor, though. I replaced it back in 2005. Might not be there on this one. Anyway - The car runs real nice. It is just this gauge that is totally wrong in a BAD red line way! ;-) I guess I am going to replace the t-stat down to a lower temp and replace the fan switch to a lower rating, too. I am also going to get the chip reprogrammed, even though it does nothing for the temp sensors or my terribly inaccurate dashboard temp gauge. I guess I need to see if there is such a thing as a replacement gauge for the dashboard. I would like to find something that at least resembles how the car is now and just install it in the factor ones place. Is there such a thing?

naf

iTrader: (7)

A repop of the original gage is available from Rock Auto. I cannot attest to it's accuracy though.

dennis.warren

I will check it out! Thank you!!

naf

iTrader: (7)

If your 5.0 has the primary fan controlled by the ECM, it is simple enough to provide alternate control with a temp switch. The ECM provides a ground to the fan relay as does the switch. You can tap into this lead and wire it to a secondary switch. You can even retain the ECM control, where the switch merely overrides control of the relay, providing a secondary ground circuit - if the switch fails or wiring to the switch (lead falls off) the ECM would still command fan on at its setpoint. This would be similar to the AC override of the fan, where the AC head switch (or AC pressure switch in later models) provided a ground to the relay when AC was turned on.

naf

iTrader: (7)

You can pick up an infrared thermometer for around $20ish these days. Point it at the water neck and you can expect to see temps maybe 10 degrees cooler than the temperature where the gage sensor is.

Your 5.0 fan is probably set to turn on at 230ish from the factory.

dennis.warren

This fan is not controller by the ECM. 88 was an odd year for this stuff. 89 ECM is controlling that. My big beef is that crappy gauge. Mechanically, the car runs so well. Very happy with all the work on it - it's the little stuff. That gauge is kicking me ;-) To keep her all together with the stock looks and performance is why I really don't want anything other than what's there. I think I will need an exception to that factory temp gauge. Which I am working on.

RS Chris

To the OP, like naf said it sounds like an airflow problem. Could be your mechanical fan just isn't cutting it for cooling. Its my be time to upgrade to a dual electric setup from an IROC or and LS1 car. I did this on my 91 RS with a stock 305 TBI motor and 224,000 plus miles. It has a 180 t-stat with dual fans from an IROC and even sitting in traffic in Texas heat at 100 plus outside temperature with the AC on high it won't go over 200 degrees.

Also, what is the mileage of your motor? Does the water in the rad look dirty or rusty? I had to flush my rad about twice a week for almost a month just using straight water to try and get as much of the junk out of the block as possible. It isn't 100% clean but definitely helped. That may be something to consider.

dennis.warren

Thanks RS Chris - but it isn't the airflow. This motor has about 8500 miles on her, 7 years after the installation. She is also a single electric fan. We get this kind of heat in the summer months, also. It was 98 here, yesterday. This motor is super clean inside and out.

RS Chris

I was actually refering to kitt_2000.

Your problem sounds like naf suggested and you have also talked about that it could just be the stock gauge is off. You said when the fan comes on the temp drops so it would seem to working fine as far as bringing the temps down. And no performance lost or knocking so...I would say your on the right track witht the lower temp thermostat and fan switch.

I did have a similar problem years ago with the stock gauge occasionally reading high, like 260. I would pull over turn the car off then back on and the gauge would read around 195-200. Haven't had the problem in some time but it does show that your not alone in your problem. Did the gauge read that high with the old motor, or was it after the swap that it did this?

dennis.warren

Sorry about that ;-) Yes, I think that it did, but it's been so long with that old motor, hard to be sure. This one gets to 260 according to the gauge. Kinda nerve racking to look at when you're driving it.

jimdutro

iTrader: (1)

I checked my coolant temp with a laser and a radiator cap with built-in thermometer, the stock temp gauge reads 20 degrees hotter than the laser and cap. Don`t trust your stock gauge.