89 formula TPI

I can't keep seem to keep my stock LB9 running cool. After a while of normal driving it likes to hang around 230 and then the fans are constantly fighting to keep it cool. The other day after I shut it off I heard what I thought was the antifreeze boiling. Temp gun confirms my guage is accurate

Do u guys have the same problem?

TTOP350

iTrader: (8)

The 2nd fan comes on around 239* so thats normal. You may have heard the rad cap burp into the overflow tank. It happens sometimes.

BrianI

I have a custom chip that turns my fans on at 195 deg and have a 180 deg t-stat. Gauge never reaches halfway on my 88 GTA. From the factory, these cars run too hot for my taste.

89 formula TPI

Can u explain a little what u meant by burp into the coolant tank? Relieved to think it was burping and not boiling off. That makes more sense too since the temp guage showed 235 and I don't think a 50/50 antifreeze water mix would boil that low.

-=Z28=-

iTrader: (3)

If you are ever idling at a light on a hot summer day and the gauge climbs to high for your liking, crank your heat on high and fan speed high. It WILL help cool. In fact you will watch your gauge drop.. I knew this guy who's fans didn't work at all and drove around with the heat on high for years... I remember my buddy was going to buy it, so we took it on a drive. We were like MAN, its hot in here, so we turned the heat off and it overheated... All in all got it home fine after a phone call saying to have the heat on.. I still cant believe that it worked for years. That Camaro started my 3rd gen itch back in 96'... heh. By 98 I had mine!!

TTOP350

iTrader: (8)

Water gets hot and it expands. When it expands, it creates some psi. Your cap will hold X amount of PSI, when the cooling system gets a bit over that X PSI, it will let some out into the overflow tank. It will let more out sooner if the cap is weaker than its supposed to be.
When the system cools off, the coolant will be pulled back into the rad from the tank.

TylerSteez

iTrader: (3)

Went through overheating hell with my car. Last year I took it for a thirty minute drive and the car went past 240 and when I went to turn it off it kept running with the key out of the ignition. I was dumbfounded when I saw that.

I replaced every part of the cooling system and put a 170 stat in. In town driving it will hang around 160-170 but on the highway for a little while it'll reach around 180-190. Satisfies me

89 formula TPI

TTOP350 that's helpful info ty.

Tyler- so it was the lower thermostat that finally did help u? I've not read up on it but I understand there are conflicting arguments on whether or not that works or if it's better for the car.

apie2546

As soon as I bought my car I replaced the entire cooling system and eventually gaskets. I also put in a lower temp thermostat. The most I've seen my car peg is half without ac. When my ac did work, sitting in traffic did stress it. This is in a trans am

TylerSteez

iTrader: (3)

Not sure if it was the cause for over heating since I replaced the rad and water pump but it is the reason it runs cooler. People don't agree with it because our cars came with a 195 degree stat and it supposedly runs more efficient around that temp but I personally haven't noticed a difference at all and have peace of mind not worrying about my car creeping up past 210 ever again. Nothing scarier than glancing over and seeing the temp gauge at around 240. Luckily I fixed the gauge a couple months earlier other wise I might not have noticed until it was too late

89 formula TPI

Does it really run cooler though? i guess what i don't understand is why opening earlier would help it run cooler. The 195 may open 25 degrees later but it does open and at that point it should stay cool on it's own. i feel like the 170 will just make it take longer to overheat but it eventually will.

TylerSteez

iTrader: (3)

By opening at 170 it allows the cold coolant from the radiator to run through the system and cool off the motor and just keeps repeating the cycle, same as a 195 just at a lower temp

89 formula TPI

I agree with that. But it won't prevent an overheating problem. if the car is going to overheat it still will whether the thermostat opens at 1770 or 195.

Besides a new radiator is there anything else to do to actually help the motor run cooler?

apie2546

When I eventually get AC running I am putting in the dual 4th gen cooling fans. Much more efficient and easy to do. Don't feel like turning off AC at every stop light

blacksunshine'91

iTrader: (10)

Mine stays pretty steady at around 210*. If its worth adding, I have a 170* t-stat.

TylerSteez

iTrader: (3)

oh of course not, I read your question wrong. an overheating car is gonna overheat no matter the stat you have in.

radiator,water pump, hoses (lower hose can get sucked close and cause resistance) air dam if yours is messed up. i feel like im forgetting one

TylerSteez

iTrader: (3)

I wouldn't bother putting a lower degree stat in if your car is running fine, no point in fixing what isn't broken. I was just having problems with overheating due to a bad water pump or radiator, I also moved to Florida so after replacing the pump and radiator I wanted to keep the car as cool as I could due to the Florida heat especially since I knew I had a cooling issue. maybe Ill switch back to a 195 some day.

89 formula TPI

Sorry if I wasn't clear Tyler. Yes I do have an overheatinG problem. in stop and go traffic the fans will keep it between 210 and 235 until I get some airflow to the radiator but I don't like relying on them Or knowing it's running that hot.

Is the 4th gen dual fan set up a direct replacement? I imagine you'd have to do some hacking of the wire set up with respect to fan switches?

Water pump is an idea but I feel like as long as it's spinning it's working no? Or do better ones spin faster and push more water?

BrianI

Connections are the same between a dual fan 3rd gen and a 4th gen. I had to modify the housing on the 4th gen fans to fit my Iroc.
What temp does your fans come on at?

89 formula TPI

Good to know about the 4th gen rad setup. Surprised it's a direct fit but that's great.

My first fan comes on around 230 and the second around 240 I believe. They usually bring it down to 210 and shut off. If I'm idling or in traffic they kick back on shortly and the process repeats.

What are your guys thoughts on the water pump? I feel like it either works or doesnt...assuming all the fins are on it

BrianI

I would get the fans to come on earlier before I changed anything else. If it only gets hotter in stop and go traffic, I would think it's fan/airflow related.

89 formula TPI

That's pretty hairy to do without a manual switch right? How would u program it to do that?

I was thinking of leaving the first fan alone which comes on around 230 and maybe putting a manual switch for the secondary which comes on way too late around 240. this way if I forget to engage the secondary the primary will still be temp operated. what's the best switch and how would u run it?

BrianI

Get a prom reprogrammed so the computer will handle it. I wouldn't want to worry about it. I ran a wire to the ground on my Iroc so it runs with the key on and had a chip programmed for my GTA. The chip is a much better way to do it. Just my experience

89 formula TPI

I'd rather not mess around with the chip only because I like having the control over the secondary. I am sure they sell a simple fan switch for these cars other guys have run. How do u rout it through the firewall though? I feel like thats a real PITA. I am only so experienced with electronics, do I need to worry about getting the right type of switch/wire with respect to resistance voltage etc?

Thanks for all your help btw

TylerSteez

iTrader: (3)

My fan comes on as soon as the key is turned thanks to the previous owner. I've been wanting to fix it since I don't trust a single thing he's done to the car (especially wiring) but it hasn't failed me yet.

89 formula TPI

I literally just fixed that on my car! My secondary fan was grounded right before the relay..he basically just crossed the two wires and my fan would engage as long as the key was in. I bet yours is done the same way. A wiring diagram was what helped me trace everything. My primary is still controlled by the coolant temp sensor And engages around 230

I'd like to have it so the secondary can be turned on via a switch

TylerSteez

iTrader: (3)

I took a quick look at what he did but he twisted a bunch of wires together and did a sloppy job so I'll have to really analyze it to see but I'm sure it's the way you described. The reason I'm hesitant is because I'd prefer to have my fan come on earlier at around 180-190 so I'd have to get a tune or wire in one of those adjustable thermometers for the fan which I'm not ready for yet

89 formula TPI

Yeah I don't see any real harm except prolonged fan use. The sensor for the secondary is under the passenger side exhaust manifold. It engages it way too late so I'd leave it the way it is for now like u said. I think it's also influenced by the AC pressure switch and won't engage if there's not enough pressure (aka your system needs a recharge) but it's supposed to come on when u flip on AC

FRMULA88

220-240 is perfectly normal on any daily driven street car.. some newer cars run hotter than that.

A hotter engine is more efficient, it can run leaner AFRs and creates less pollution.
all good things for a vehicle that was meant to provide daily transportation for 100,000+ miles.

Even a race engine is in 180-220 range.

My drag car can get up to 220 on a pass. Once off WOT it cools back down to 180 on the return road to the pits, perfectly normal
and it runs 10s all day long.

Lowering the engine's operating temp does little to improve performance and can actually create other problems.

If your car is boiling over it's not the t-stat is too hot. You have failed components in the cooling system or a dirty system.

Usually 1 or both cooling fan is inoperable, the radiator cap is not holding the rated pressure anymore, the bottom air dam is missing or the lower radiator hose is missing internal spring and getting sucked shut.
some simple tests / diagnostics and flushing the system will solve most of the issues without ever needing to change the t-stat.

The only time to change the t-stat is if it failed (stuck open or stuck closed) stuck open the car will take very long to warm up & you will have heater issues in cold weather.
Stuck closed, the car will overheat very quickly since the coolant cannot leave the block. You can test most t-stat's by boiling them in a pot of water.. to see if they open.
it is always best to install the t-stat used by the OEM. since this was the best choice for performance, economy, and pollution control.

TylerSteez

iTrader: (3)

I replaced the entire cooling system on my car but still once it would hit a little above 210, the car wouldn't shut off when I took the key out of the ignition (dieseling). I got tired of popping the hood to shut it off so the lower degree stat keeps it from reaching that temp and I haven't had a problem since. I'm not doubting anything you said and I agree with the majority of it but for me it was well worth it. It runs around 180-190 which is fine for me, like you said I don't do any real racing so I'm not too worried about optimum performance. my little 305 has high miles but I've tuned it up to run and idle smooth, the only thing I'm overly concerned about is the rebuilt trans I put in lol

FRMULA88

On the dual fan system the secondary fan will also come on when the A/C is turned on regardless if A/C system is charged or not..

The single fan system will cycle on and off, but will run constantly when the A/C is on.

This is great way to test if the fan(s) are functional..

FRMULA88

Dieseling on shut down typically means you have; too much ignition timing, plugs with incorrect heat range, the A/F is too rich, not enough octane fuel (or a combination of all) that the engine wants to keep running because the sparks plugs are still hot and fuel is getting to the chambers.

All of these issues (too much timing, poorly calibrated carb, too hot a plug) will also increase engine temp so yes the natural inclination would be to lower coolant temp..

another possible cause of dieseling could be injectors leaking at shut down until fuel pressure drops.. or improper float bowl settling / worn out or debris stuck in needle & seat on a carb. letting fuel drip into the manifold

TylerSteez

iTrader: (3)

Yea Im pretty sure it's just old tired injectors leaking into the hot cylinders. they're still holding up fine driving wise so Id rather spend the money on ones for a 350 that will eventually replace the 305. Thanks for the information

89 formula TPI

I agree that the lower thermostat will not prevent overheating. I wanted to change it out mainly because my car does take a long time to heat up and it's cheap enough to do so.

I hear arguments on both sides regarding the running temp on these cars. GM built them to run hot so they would have lower emissions to meet the strict requirements back then but I don't think I agree that running that hot is best for these engines. more heat translates to more wear on internal components but too cool is also bad. i would like to keep this thing running at 190 all the time which it does when i'm cruising on the highway. Not fluctuating between 230 and 210 because my fans are constantly flicking on and off.

also, the AC pressure switch closes and engages the secondary fan. if there is not enough pressure in the system to close it, it won't engage the fan. so turning your AC on will not always engage the secondary fan. here it is per the manual anyway


The Auxiliary Coolant Fan (V8 VIN F and V8
VIN 8) is controlled by the Fan Pressure Switch
and the Auxiliary Coolant Fan Switch. If one of
these switches closes, the Auxiliary Coolant
Fan Relay is energized and the Auxiliary
Coolant Fan is turned on. When a switch is
closed, terminal Dl1 of ECM connector C2 is
grounded. This tells the ECM that the Auxiliary
Coolant Fan should be on.

FRMULA88

The fans are supposed to cycle on and off.. even a clutch driven mechanical fan cycles..

more wear caused by heat is a bit far fetched because the the engine oil will always be hotter than the coolant since it exposed to more heat because it is in direct contact with the piston and cylinder walls. if the oil is not hot enough it cannot burn off condensation and other impurities caused by combustion which will lead to sludge build up

By using good engine oil / filter and changing them at the recommended intervals this is not an issue.

An engine that runs too cool can also have other long term problems for example on a fresh build the piston rings may not seat correctly which can create to excessive blow by.
It can also create too rich an AFR due to incomplete / inefficient combustion which can lead to; spark plug fouling, cylinder wash down, improper ring seating, and fuel contamination of the engine oil.

I accept the fact that the millions of dollars and tens of thousands of hours spent by the OEMs researching and developing every system on the vehicle, (Not to mention the millions of vehicles they have manufactured) is worth more than the opinions of a few shade tree mechanics.

89 formula TPI

I'd rather not run my car 20 degrees over the temp water boils at. GM needed to make compromises between hp, heat, and emissions. I'll risk sludge/condensation at 190 rather then let it swing between 210 and 240. I guess that's where we differ. Curious what other people's opinions are on this

apie2546

Since these cars were very prone to overheating, thanks to engineering and the companies that built millions of cars, I decided to change things. Go drive a 59 Chevy and use the brakes, you'll want them upgraded, or be terrified lol. The engineers do a good job making cars, but it doesn't mean its perfect forever. The lower t stat just keeps it cooler a little longer on my car which is very nice, because no ac = engine heat in my lap at op temp. And gives my car a fighting chance in big cities

FRMULA88

That is because you do not understand how a pressurized cooling system works!

Once you do then you will begin to understand why a 210-240 operating temp is perfectly normal on any modern car with a pressurized cooling system.

These are not flat head fords gentlemen, there is a BIG difference between an engine with low / no pressure cooling system versus one in a any car built from the 1950's onward !

My '72 cutlass supreme has 4 wheel drum brakes, it stops just fine and goes down the highway at 70-80 MPH all day no problem.. But I also learned to drive in an era where you paid attention to traffic and allowed for stopping distance! The best thing is there is no temp gage to geek out over either ! :lol it has a mechanical fan, and 190 degree stat, original radiator, etc all OEM from 1972

my drag car has 4 wheel discs brakes, but is stopping from 130+ MPH in less than 1/8 of an mile.. BIG DIFFERENCE in application.

FRMULA88

They are prone to overheating because they have been abused and not maintained. OR most shade trees think the stock cooling system is still adequate when you double or triple the HP on these cars.

I had my '88 since 1993, and never had issues with it overheating in stock form except when the cooling fan gave up, or the lower air dam gave up it's life to speed bump.. LOL replace the worn out / damaged parts and good as new.

When I transformed it to a street/strip car and increased the power of the engine the first that got replaced before the new 383 engine went in was the radiator/cooling fans.
The system was overkill for the 383 in 2000, but that was OK since 13 years later it still work great on my 421 !
The only upgrade I did when I went to the 421 was swapping the OEM twin fans for aftermarket higher output twin fans (about twice the CFM of the stock fans) this keeps the 680 HP motor well within normal operating temps at WOT... and can run the number all day at the track without overheating.

Granted this is no longer a LB8/L98, so I will stay out of this topic since I don't know what I am talking about.

TTOP350

iTrader: (8)

My (tpi) 400 mini ram stroker runs 160-165 with the stock twin fan setup and stock rad. Granted, the car has no A/C but still.