Jason92Z

Ok, is it just me, or is this normal? I have a 160* thermostat, both fans on switches, 3 row copper/brass radiator, air dam in tact, new waterpump, and newly flushed system. I replaced all of this stuff yesterday. Here is my problem...

I have been watching my temp rise over the past few weeks and without the AC on. I would be on the freeway and on a 95* day without the AC on, the car would climb to about 195/200ish on the freeway. And with the AC on, 220* on the freeway. This was with a small leak from the waterpump and the 180* thermostat.

So yesterday, instead of make the cruise (which I WOULD have overheated for) I decided to change to a 160* thermostat, new waterpump, flushed the system, radiator flush, pressure wash the radiator and make sure there were no obstructions, and make sure air damn was good. After which, I took the car for a test drive. (9pm and 70*) I drive the car and it stays at 165* and one time spiked to 185* (figured it was an air pocket). Knowing that the cool temps dont do me any good and wanting to compare it with the 103* it is here inland, I took the casr for an hour drive consisting of surface streets and freeway.

I drive the car with the AC on at 1pm and its a good 105* outside at the time. The car hits 160* and the thermo opens. I see the car hover there for 5min or so in traffic and then begins to rise. By the time I got to the freeway, it hits 190* and begins to slowly rise when ON the freeway. I stayed on the freeway for 20min and when I get off 15mi later, the temp is at 215* WITH BOTH FANS ON AT 75MPH!!! This just doesnt seem normal to me. I then get off the freeway and do surface streets again and the car climbs to 220* in no time, again, with both fans on. I pull into a gas station and look under the hood, no leaks, and no boiling in the overflow. It is however nice and toasty under the hood, but thats normal for these high temps inland.

I get back on the freeway and head home again with the AC on and the car cools to about 210* and stays there the rest of the trip. Does this seem odd to anyone else? I know for a fact that other people with a similar setup are running 180-195* with AC on in traffic. Why am I getting so hot? The radiator is only 1 yr old and has been rodded out just as a precaution. There is no trash in between the radiator and the AC condenser. There is a small tranny cooler in front of the AC condenser on the passanger side, and there are a few mashed down fins on the condenser, but doesnt look like enough to block much flow to the radiator.

Anyone have any suggestions for me? Im pretty stumped, everything on the cooling system has been replaced and this continues to happen, and without an AC here in the Inland Empire (to keep from these hot running temps) is really misurable. Help?

Bens3rdGen

I couldn't tell from your post, but since you overhauled the cooling system how does the car run with the AC off? If it runs real cool with the AC off and then real hot with it on you might want to look at your AC system. There are quite a few problems that can make your high side AC pressure (condensor side) go up.
Check your compressor, check your freon level, and check that you have good flow through your condensor. If you need help diagnosing your AC system, lemme know.

Russ-So Cal

What temp. gauge are you going by? Get it to 220* on the gauge and then CRACK the radiator cap with the engine running.
DON'T REMOVE THE CAP UNTIL YOU KNOW ALL PRESSURE IS RELEASED. On my old 89 Rs with the 3.1 six, I had it idling in my driveway with the radiator cap off, and the G.M. temp gauge reading 240* no evidence of boiling, no antifreeze in the cooling system. Plainly, the stock G.M. gauge is worse than useless.

Jon92TA

Try leaving the fans off on the freeway, they me be causing an obstruction of airflow at that speed.

I'm using a 180* stat and a Jet 200* on - 185* off fan switch and it seems perfect for my stock 305 Auto. w/ dual fans.

Jason92Z

I know nothing about the AC system or how the AC system can effect temps other than it puts a strain on the motor. The AC system was serviced about 3 yrs ago and at the time, everything was fine. The condenser, I wouldnt know what do check for flow. One thing I changed was when I first got the car about 3yrs ago, I removed all the plastic ducting under the airbox, and I wondered if that would cause an air flow problem to the radiator, so today I bought some sheet metal, and spent a few hours rigging up a decent "ram" box to direct all air from under the car into the condenser.

How does the temp run with the AC off? Pretty much the same. When I was on my way to HomeDepo to get the materials to make the flow box, I had the AC off and temps reached 195-205* while moving. So the AC isnt effecting it much.

The guage that I have to monitor my temps is an Autometer Electric. My dash guage took a dump a while back and when I replaced the sending unit, I got the same thing you stated, temps were reading 20-30* over what the laser thermometer said at the thermostat neck.

I will let you all know how the flow box I made does in the hot temps tomarrow. I got my fingers crossed.

Kevin91Z

iTrader: (1)

During normal cool weather my cars runs at or just under the first line on the temp gauge all the time. In traffic and/or in hot weather it'll get up to the second line and sit there. If I get any hotter than that then I know the coolant level is low. So I would say my car runs about the same as yours in this hot weather in traffic.

2.73's Suck

keep the fans off when your going faster than about 40 mph, I tried it both ways with my car and it did run cooler with the fans off on the highway.

BretD 88GTA

That 160° thermostat isn't doing much for you. You're just making the the thermostat work harder. To properly run a 160 thermostat you need a new chip in the ECM set-up for the 160 stat. The primary fan is run by the ECM.

In this heat, once that stat opens, it's probably staying open. This causes the water to circulate constantly and doesn't allow it to pause in the radiator were it can cool down before passing back thru the block. Even with your manual switches on the fans, the air is just too hot right now. That's why you're now seeing higher temps after the stat switch.

These cars are designed from the factory to run at 195°+ and come with 195° stats and a secondary fan switch set for 235° IIRC. You can install a new secondary fan switch set for like 185° and can run a 180° stat without trouble or messing with the ECM.

With it hot like this, a 200 to 220° reading on the factory temp guage is fairly normal. My car will typically run at the 1/4 mark on the gauge, but on a hot day in traffic the gauge will climb to 1/2 way (220°). I hope this helps you out.

Jason92Z

Thanks to everyone who shed some light on some things. Yesterday I drove the car with the AC off and with it on and the temps stayed about 10-15* cooler with it off. I think thats normal. And since Kevin and Bret both said that their cars will reach the 210* mark in traffic (and since its WAY hotter our here compared to OC and LA) I suppose that I am running normal. I will take what Bret said into consideration and put my 180* thernostat back in and see what happens.

Now I only need to fix the problem with the fuel tank pressure. Kevin has seen it, when I remove the cap after driving it a while, the pressure in the tank gets VERY high, and in the hot weather can smell gas. I believe Kevin you had mentioned something about the valve in the carbon canister possibly having something to do with the pressure build up? Anyone want to shed some light on that?

I always remove the cap slowly so that I dont get fuel shot out, but this just isnt right. Oh, and this problem is also temp related, the hotter it is outside and the hotter the car gets (200* and above) the stronger the gas smell is... TIA!!!

BretD 88GTA

In addition to the carbon canister, there is also a small plastic valve located underneath the car next to the fuel tank. You might want to inspect it also while you're checking. It's fairly cheap to replace, but you will most likley have to go to a dealer to get a new one. Good luck!

Jason92Z

Car is still pissing me off and I am at my wits end!!!! The car got to 210-220* today in traffic, but once moving, it WONT COOL DOWN! I finally saw it get to 230* and with both fans on! Once I got moving, it only froze where the needle was, not cool down. Im getting to the point to where I just want to drive the car into a brick wall and let it explode if it wants to be hot that badly!!!

I know that my gauge is accurate because I have lights in the car to tell me when the fans are on, and the first fan turns on right at about 220* like its supposed to. (I only let it turn on that late to see if the gauge was acurate, I turn the switch on at about 195* on the street) I am now thinking that even though the radiator is only a year old, thats its just a piece of garbage.

Russ-So Cal

How does the copper/brass radiator compare with aluminum? Everything I've read suggests that aluminum is much more efficient. If you change from the stock aluminum to copper/brass, I think it needs to be 25%-30% bigger to equal an aluminum radiator. Also because aluminum radiators use wide flat tubes instead of two or three passes of round tubes, the airflow is more efficient in an aluminum radiator.

james_85Z28

Maybe you should take your car to a real mechanic and have them look it over to see if you missed something

BrandenCali

Get a new Rad. A Modine or something Alum. With the nice fins air should blow through nicely. Or Maybe the fans are not turning fast enough. I know dealing with a Hot car is a pita I had that problem till I had Kevin and Don fix all my problems and I bought a New GM terminal that goes from the positive the alt starter and 2 wires for the fan system. Kevin set the chip Im running a 160 thermo and the car runs cool in the heat, along with The new Modine I have in the car that is a year old or so and a new water pump. But now my temp gauge broke but Im not stressing b/c I know the cars cooling is all fixed.

Could it be possible you have a intake leak or some leak some where sucking in Hot air?

KiLLJ0Y

i had ALL the same problems you did... i did everything you did as well.. new everything.. still running hot..

you know what my problem was???

frickin air trapped inside the engine.. when changing all these things did you happen to run the engine for 1-2 minutes with the radiator cap off??

after 3 weeks of kicking and fussing and taking my car to 3 different people.. i went to Orange County Radiator.. told them my problems..

he walked over.. took the cap off.. let it run about 2-3 minutes with the cap off..

no my car NEVER gets above 160* while driving.. and about 200* sitting idle.. and i also have a 160* stat.. hi-flow water pump.. new radiator, water wetter, 50/50 mixture, 16lb radiator cap..

i even got a new auto meter temp guage..and you know the stock one.. was 8* off..reading high

rezinn

I'm not normally one to argue with experts, but I believe copper is a better metal to use than aluminum due to its greater thermal conductivity. When first measuring thermal conductivity, the scale was based on %s in relation to copper, which was 100%. I believe aluminum was something like 60%. So, I think copper would be better suited to transfer heat efficiently.

The construction of the radiator is probably the #1 determinant to how well it performs, though.

Jason92Z

Thanks to everyones suggestions (Except James') I think that the culprit really is the radiator. I ran it with the cap off last night, and didnt really help today. The car got to 210* while on the freeway with the AC off, and when the car gets to those temps, it simply wont come down. I looked inside the radiator fill neck and the rows are just so tiny. They are VERY thin and flat, but look MAYBE 2mm thick and 1/4 in wide. Doesnt that seem small? I also noticed that some of the fins on my condenser are smashed, but only a little bit, not nearly enough to hinder flow to the rad in my opinion. I will remove the radiator this weekend and have it flow tested again and possibly just get an better constructed radiator to put back in there.

Does anyone have a particular radiator they like? Prices?

james_85Z28

"Maybe you should take your car to a real mechanic and have them look it over to see if you missed something "

You may not like it but as you said you're at your wits end to find a solution to the problem. A radiator shop has all the experience and diagnostic tools to troubleshoot your car for free or for a nominal fee. Throwing parts at a car is a gamble if you haven't done your due diligence to methodically approach the problem at hand. It seems like your parts are pretty new and therefore replacing them again without knowing they are bad, isn't the best course of action in this case, especially a $130+ part.

Rather than just throw parts at it you can't afford you should take it to a radiator shop or mechanic. Most radiator shops (at least a couple I know of) will test the coolant and pressure test the system free of charge. My friend had a problem for months and it turned out to be a cracked head that vaporized the coolant by the exhaust port. My sister had a crack in her aluminum engine block. Sh*t happens.

You mention it runs hot but how accurate your gage is (all senders do start to flake) and what, besides the gage showing hot, are the symptoms that your car is displaying leading you to believe it is running hot? Or are you just relying on the autometer gage?

Have your pressure tested the system? You haven't mentioned if you have or not. Leaks in some locations are hard to find/spot and even a pinhole leak will evaporate and not leave a trace on the ground.

Has your car boiled over at all? You haven't mentioned if it has or not. What happens if you let it idle with the AC on? How much coolant (not water) is there in your system. Too much coolant will prohibit the efficiency of the heat exchanger.

How new/fresh/full is your oil? If it has overheated your oil isn't doing what it need to afterwards and needs to be replaced. Are you burning oil? How do your plugs look? What's your base timing? Too much or not enough timing will make it run hot for different reasons.

Have you noticed a loss of coolant at all? If so how much and how quickly? You haven't mentioned if you have lost any coolant, are filling the radiator/reserve up daily, or have had it boil over.

How many miles are on your 305? Engines with lots of miles run hotter because the tolerances have opened up. When mine got up there in miles if anything wasn't perfect the motor would suffer a nuclear meltdown. If the oil was old or a quart low it would overheat. If I had too high a coolant/water ratio it would overheat (less than 3/4 gallon of coolant in the system and the rest water). If I didn't cycle the engine a couple times to get the air out of the system before driving it a distance it would overheat.

How have you checked the calibrationof your you autometer temp gage? Where is the gage plugged into, what port, where? In the head, manifold block? There can be 20-30*+ between the intake manifold and the cylnder head temps. How is the wiring to the gage?

Our cars need pressure in the system to not overheat. Even at idle if there is no cap it will eventually run too hot.


FWIW, my ~400 HP engine relies on a stock $20 Kragen water pump and a $150 PepBoys radiator. Nothing special. And it has never overheated since I put the old combo in a couple years ago.

Like I said, take it to a shop that's been dealing with these types of problems for 30+ years. How is that not good advice?

EDIT: spelling/grammar....probably missed some as well

BrandenCali

Seems like good advice..

12secSS

:sillylol: @ James response
Jason, James has a point

Jason92Z

Yes, I know he does. However, see it from my point of view. I work M-F and have no other transportation to work, and cant leave the car with someone. Second, on saturdays, I CAN take my car to a radiator specialist and I HAVE already. I was simply told that I need a new radiator, etc, that mine was old, etc.. Which is funny... the radiator was rodded out and is only 10mo old as it is. So, looks like I will be figuring this one out on my own.

James, I have done everything you mentioned. I had the radiator pressure tested, but not the cooling system or block. Timing is set to stock, car hasnt boiled over, temp senser was checked to be accurate within 2* with a laser thermomoter AND checked with stock fan switch (let car get to 220* according to the gauge, which is also when the fan turned on), the fill is fresh (mentioned that in my original post), the mix is little less than one bottle of coolant, the rest distilled water, car was ran without the cap for about 15min to allow air out of the system, level never dropped, i havent had to put collant in the system at all, never gets low, the engine has about 60k since the rebuild. I think that answers all of the questions you asked.

Anything else that I missed? No time to leave the car anywhere, and dont trust the radiator techs in my area anyways. The most reputable guy in the area charged my mother over $500 for replacing the radiator in her 1997 T-Bird (which turned out to be a used radiator, not even new) and the problem ended up being just a bad fan switch. My mouth about hit the floor when she told me this after the fact (year ago)

Russ-So Cal

You don't want bigger passages in your radiator. Surface area is what does the cooling. The smaller the passages, the more it will cool. Just make sure it flows properly.

Fcarguy

Jason, I have the exact same problem as you and I have also got a new water pump, recently replaced leaky intake gasket, 160* stat, low temp fan switch, flushed system , etc.. It always seems to run hotter in the summer time. I suspect a faulty guage or sender. Its gotten as high as 240* on me w/ AC on but no boiling coolant, resevoir is normal. I stoppped worring about it. A friend of mine had the same problem on his VW Corrado VR6. He replaced water pump, flushed system, new fan- nothing helped. Turned out to be a bad sender-(the one thing he didnt replace). Anyways, eventually I would like to get a Be Cool radiator but at $550-600 its a bit pricey but they guarranty a 20* drop over stock radiator. Maybe I ll get it for Xmas

Kevin91Z

iTrader: (1)

Try Dyno Don's shop first, he has better prices than that.

Jason92Z

Don can get Be Cool Radiators?

Dyno Don

iTrader: (7)

Yes, I can. I can get just about anything for our cars.

Fcarguy

Dyno Don, what type of shop do you have?

Jason92Z

Auto repair shop! DUH! lol...