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The Complex C4 Corvette Cooling System Explained
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- čas přidán 6. 08. 2024
- Today I'm taking a close look at the cooling system on the high mileage 1996 Aqua Metallic LT-4 coupe. Watch as I show potential failure points of the system, and describe the individual components and how they work together to keep the Corvette cooling system properly balanced so it doesn't overheat.
To see more of my C4 Corvette How To Videos -
• C4 Corvette Trivia and...
To see more of my Maintaining Vintage Automobile Videos -
• Maintaining Vintage Da...
#corvettetrivia #c4corvette #corvettelt4 #vettesource
Very excellent info. really like this channel, glad I found it tonight. Thank you.
Thanks again Dalton, I'll be sure to keep at it👍.
Thanks for the video Brian. You're the man!
Glad to do it, buddy👍
Awesome video, very well done and great info.
Sub!
Thanks Barney. Appreciate the feedback👍.
Wasn't sure about needing a new radiator cap, but one is going to be delivered today and I am happy now after your info that I ordered it. I noticed the older one had crap around the spring etc so it has to go!
Update old one was stuck on so tight I had to use channel locks. So new one is great
Very useful info 👍🏻👍🏻
Thanks buddy👍
super useful info thanks man
Glad you enjoyed it👍
Great information. I got nervous first time I saw my temp run up , but it came right back down. No EGR on LT4 either, which I'm sure is in another video. Thanks for the C4 content .Roger that on the "scalded ape."
Thanks Paul. I'll be making a follow up video soon showing the operation of the electric fans and the on/off temperature ranges.
LT4 don't have EGR? i know my LT1 has one
Thats correct, they deleted it from the LT-4 due to overlap of the intake and exhaust vavle timing makes the EGR valve ineffective and unnecessary.
Got a 96, appreciate the info. First thing I bought was a set of factory manuals.
Hey Tom, glad to do it. The service manuals are like having the keys to the kingdom. Then all you have to do is invest in the special tools to read the electronics😁.
Long time car guy, just can’t deal with muscle car prices, these things are a great alternative, actually better engineered in many ways and that makes them a bargain at current prices. Big leap forward from the muscle car era but not ridiculously complex as the latter generations. Just my opinion.
I agree. The vintage muscle has become almost unattainable for the average guy due to "collectors" treating them like an asset/commodity class. As cool as it is to see spotless restored vintage cars, it kinds takes the fun out of it when it's nothing more than a static display.
It's also easy to look at them with rose colored glasses if you've never actually driven one. Once you get home with your best girl and she's soaked in sweat and smells like raw fuel, and then grills her calf on the sidepipes it changes people's minds in a hurry😁.
The C4's and mid 80's performance cars were a great compromise like.you mentioned, and can be easily used as daily drivers/road trippers.
Of course I'm a hopeless case, and still love the old vintage iron😁.
Brian this video is the only one that I have seen that shows and mentions the one way valve in the heater hose I mean I cant find any info on it even in the haynes manuels or any other web sites it just does not show up I really would like more explanation and where to find more info on it I really would appreciate it and thanks in advance I just replaced mine along with the thermostat and rad cap
Hey Randy, I believe it's function is to retain the heated coolant in the heater core so it doesn't flow back the other direction, but I'm not sure. I'll have to check my factory service manual this evening and get back to you with further information.
Replacing the weatherstripping on the targa top, the strips that run down the sides of the top are held in by a hex screw. Mine are rusted to nothing... any idea where I can find replacements after I drill these ones out?
I probably have them in stock. You can reach me by email vettesource@hotmail.com or on FB @ facebook.com/vettesource
Thanks Brian-great video! I have a ‘96 LT4 as well. Thinking about doing the throttle body coolant bypass mod. It looks like I can just take the hose off the drivers side throttle body and attach to the passenger side next to the fuel rail (where the elbow hose is)-does that sound correct?
Hey B, glad you enjoyed it. Yep, you're correct about how to perform the bypass. However, be aware that the bypass doesn't really do much for HP gains, and creates another potential coolant leak point. Thanks for the comments👍.
@@VetteSource Thanks Brian-I’ll give it a shot and will let you know if I feel a difference…It’ll probably be all in my mind!
so i got a low coolant light and checked everything seemed to be how it should but i noticed the overflow doesn’t send coolant back into the radiator and it stays full basically all the time… i never noticed it until i got that light and checked but like i said i thought everything was okay until i was driving one day turned the car off after it being completely normal but when i started it after that it started not letting me go over 2500rpm in gear and sometimes in neutral, i ran my codes nothing came up but the low coolant light is still on, i have not driven it since other than to see how it’s running after trying a few things
That is an unusual set of symptoms. So the black expansion tank mounted up near the RH firewall is full of coolant? Also, the RPM problem on the surface sounds like a different issue. When you get to 2500 RPMs does the car cut out or stutter?
Sounds like maybe optispark if ur not able to rev over 2500 rpm I don’t see why ur coolant would make that happen but most the time it’s a leak from the water pump or radiator that leaks on opti and ruins it over time maybe give it a check?
Good idea, thanks for chiming in for him👍
I put a 1994 c4 lt1 in my truck now there is plenty of room to work on the engine I’m planning on running the cooling exactly like the manufacturer
Yep, if you have the room, keeping the factory cooling system components in place will keep it running at peak performance.
,,,,,New subscriber here,,,,,,,,I was lucky to find a near mint unabused LT-1 in a 1996 Z28 Convertible , 6 speed stick............The guy I got it from said it pops out of reverse gear [ It has the 6 speed Borg Warner ] ....I think this may be a common problem ???,,,,,,anyway vettes used the same gearbox . I wasted alot of time on forums. I believe you can help with an answer . As I park the car , I need to hold tightly on the stick so it won't pop out of gear.. thanks for being here.......................
Hey Thomas, glad to have you. Sounds like a nice car you found there. The Borg Warner T56 6 speed is what you have in your car, which is different from the Corvette ZF6, which was only available in the Corvettes during 1989-1996.
From what i remember, the popping out of reverse gear is a problem with the synchronizer or the slider on the main shaft. Regardless, it will most likely need to be opened up to figure out what's going on since I don't believe there is any external adjustment possible.
Let me know if you need anything else👍.
@@VetteSource As a certified auto tech ; now I need to find a factory type repair manual ; before I remove the unit from my car.......Any recommendations about finding such a manual ??? and thanks.....
Great video and useful info, thank you. I just had a lower coolant line off the tank start leaking. How much would replacement of all coolant lines run, would you happen to know a ballpark figure?
Hey Mike, thanks for the feedback. Glad it was helpful. I believe GM may have discontinued these hoses, but I'm pretty sure Dayco or Gates offers replacements. I would check first on rockauto, or your local AutoZone or O'Reilly. Figure you can get those smaller hoses for around $25-$40. Let me know if you need anything else👍.
@@VetteSource Gates is just as good i would do gates
Rockauto.com or oreilly is good. Oreilly delivers fast. for the hoses make sure to use some wd40 or grease to make the hoses pop in easier Goodluckn
@@VetteSource thank you I appreciate the info!
@@alexl9334 thank you, good info!
I believe that lt4 still has the factory plug wires on it. When people change them or have them changed they don't usually put the red plug wires back on them most the time you'll see black plug wires on them. That's what makes me think those plug wires have never been changed. But I may be wrong. Also the polo green 96 lt4 that I bought at the high end of 70,000 miles on it still had the original plug wires and plugs. I thought how could someone let that car go that long without changing them but they did
Yep, I believe you're correct. The gentleman that had it before purchased it with around 60K miles, and then just drove it for the last 6 years or so. Once I start cleaning up the engine bay I will take a closer look at the wires to see about replacing them, but man it runs good right now.
My LT1 has got a second bleed screw on the throttle body where the coolant hose goes in from the top hose. I've only owned it for 7 years but I found that a few days ago.
Yea, the 2nd bleed valve gets overlooked quite often. In fact, I think I remember that that bleeder isn't even mentioned in the Owners Manual when describing the bleed procedure. It's only talked about in the Factory Service Manual.
@@VetteSourcewe’re you buy the service Manual
I would look on eBay or Amazon.
I’ve found some fluid in my inner tire rim on the passenger side, 95 LT1 can’t find the leak though to save my life. Any ideas?
Y first thought would be a minor leak from a brake caliper. Take a flashlight and look around the pads/rotor area to check for any wetness.
@@VetteSource should say it was radiator fluid, nice and green.
Oh, ok. Well for starters, that's all kinds of wrong. You should have orange DexCool in your car. Sounds like somebody mixed the old green stuff in, which definitely causes problems in a DexCool system. I would be willing to bet you have a pinhole leak located around the expansion tank or the expansion line that runs to the overflow tank in the front right wheelwell.
Question, I bought a 95 corvette and was able to fix most of it but the coolant pipe that leads under the headlight kept hitting the passenger light. I bent that thing every way possible and slush with jt but couldn't get it. Ultimately created a hole in it. Was wondering if I should try and patch it buy a new one or look for a more flexible counterpart. Hmmm
I would look for a good used unit. The C4 coolant system operates at a higher than normal pressure, and a flexible line most likely won't last long before blowing out.
@VetteSource Figured haha, it's been sitting for a month killing me while I work on it. Patience is key, I guess. Thanks.
No problem, anytime👍.
Watching now... By the way what's the temperature there? It's a stifling 40f here... Will drop to 30 tonight.... I'm sure the heat will be unbearable where you're at soon enough
Yep, we're getting there. Low 80's and humid today even with the rain. Be in the upper 90's again in a few weeks. Time.to make sure the air conditioning is working properly.
Have you done a tire video? I’m a new corvette owner and want to replace the 12 year old tires. I don’t want summer only tires
Not yet, but that's a good idea👍. I'll see what I can do for source material.
Been trying to replace the CCM/BCM in a 1993 corvette, i been trying to remove it from the driver side, i can pull it out about half way but i just can pull it out completely any help or tips i would appreciate it
Hey buddy, that is a tricky part
to remove from the car. I'm assuming you removed the metal retaining plate on the driverside. It won't come all the way out unless you disconnect it from the electrical connectors first. What I usually do is angle it up just enough so I can access the connector metal retaining tab with a long flat tip screwdriver. There is just enough room to pull the connectors out and away from the CCM and that should give you enough room to wiggle it out and around the large wire bundle that is in the way. Let me know if you need any more information👍.
@@VetteSource yea i was to a point that i disconnected the first connector closest to me, then i could only pull it out half way, i jiggle every which way, i could not reach the second connector to undo and if i was able to undo the second one don't know if i could put the new back on / the wires are not long enough to pull out the side? i was play with this for about 3hr's in 90 degree heat i was not happy I'm so close and still couldn't remove it yet
Yea, I hear you. It takes an amazing amount of patience. I believe they did it on purpose since the odometer mileage is stored in it. If it's being really difficult, I end up taking the passenger side mount bracket off so I can get some movement the other direction.
@@VetteSource can i sent you picture? , does the right side have a flap like the driver side does?
Sure, send it over to vettesource@hotmail.com
I’m having a hell of a time doing all of this for some reason…
I did a complete flush, I filled it back up and kept the dexcool in it…
I keep overheating. I’m going to tell you that I didn’t feel the need to change the thermostat because the person I bought it from mentioned they had already done that but now I’m thinking they didn’t.
For the bleed screw, is it engine cool fill until a stream comes out then close it and fill the reservoir until it fills then run it up to temperature and then check to see if it needs more coolant???
I keep hearing that I have to have the engine at temperature, unscrew the screw and then add coolant until it’s filled, if I bring this thing up to temperature and open that bleeder screw I’m afraid it’ll all come spewing out.
What’s the CORRECT set of instructions on refilling this thing???
Hey Atom, you're on the right track. Sometimes, these LT series engines are difficult to "burp" and require being run up to temperature several times and loosening the bleed screw to get it right.
Just out of curiosity, how high is the temperature getting?
@@VetteSource 240, 250 one time it was pushing 260. Since then I’ve had it overheat again but I filled it cool until it ran out of the bleeder, closed the bleeder and filled it up, filled the expansion tank to the COOL mark…
Turned it on and let it get to 180 and as it burped I filled it back up at the reservoir, I got it up to 197-198 back and forth and kept filling it, added coolant to the expansion tank at that point to just above the HOT mark and I feel like that might have done it because it hasn’t skyrocketed like it was but it’s also been a lot cooler out now because of the rain around here…
I ALSO jacked up the passenger side a bunch and filled it with it was tilted let it back down and made sure it was filled and then sealed it up.
One thing I didn’t notice was the radiator cap (which is the correct one for the car) has a tear in the upper rubber seal…
Ah yes, a failed seal on the radiator cap can cause havoc with these cars since they run right at the ragged edge of overheating as it is. Any comprise of the closed system can cause temperature flares.
How do you reset change oil light?
Turn the key to the "run" position.
Press the ENG/MET button once, then once more within 5 seconds.
Then press the gauges button within 5 seconds and hold until the "Change Oil" light flashes and then goes out.
Hello, my daughter and I picked up a 91 convertible from a guy and he said it may need a water pump. 🤦🏻♂️ I can’t tell exactly where the fluid is leaking from. How ever I did notice the bypassed the heater core completely and where the check valve would be, has a splice and no valve. I was out of town and my daughter overheated. She stopped at a shop and they filled the coolant so she could get home. The car is sitting until I get this fixed. As of now the car is cold and upper tank is completely empty and the lower tank is over full(I’m guessing bc of the bleeder valve). That shop also said it may be the radiator and not the water pump. Any advise?
Congratulations on the purchase👍. First things, bypassing any component of the C4 cooling system is a bad idea, as its designed to run higher pressures and removing part of the circuit can cause problems like you describe.
To start, you will need to determine exactly where it is leaking from, as this is the weak spot that the higher pressure found its way through. Once you do that, it would be a good idea to change out the leaking component, water pump, radiator hoses, and thermostat to make sure you're good for the summer months.
Also, as much of a pain as it is to change the heater core, I would install a new one since it is part of the circuit and needed to ensure proper cooling.
Let me know how it's going.
@@VetteSource thank you for the advise and quick reply!! I will get on that first thing in the morning. Thanks agin
No problem👍
@@VetteSourcehey bud this is Orrin we spoke a while ago I have a 1986 Chevy Corvette my coolant fan is pushing the air forward of the radiator can I switch the wires and reverse this fan.?¿???
Hey Orrin, off the top of my head, I don't think that will work, but I don't have the schematic in front of me. Have you checked to make sure the fan blade wasn't installed in the wrong direction on the motor shaft?
I wired a fan relay up to mine with a temperature sensor that kicks the fans on at 185 degrees. It behaves a lot better in Acts a lot happier in that range. LOL. Also it just makes me very paranoid about the car overheating when the ECM doesn't kick on the cooling fans until the car reaches 225 - 230 degrees not because of the coolant blowing out because of the raised boiling point but giving the oil the viscosity of water. Even synthetic oil it still thins out
Yep, even though that's exactly the temperature the engineers wanted the car to run at, it's always nerve wracking to see them get to the edge of overheating, especially when it's Houston in August and 110 degrees outside.
@@VetteSource I bet.. it just barely reaches triple digits here but when it did & I had to drive it on those days before the fan mod that Corvette had me thinking about asking my physician if Xanax is right for me.. Lol
Oh yea, all the stress inducing things about Corvette ownership they never mention in the brochure😁
They definitely have a stronger seat of the pants feel when they're warmed up and running at the factory intended temperature, but it sure doesn't leave any room for error.
The other day the upper radiator hose blew out on this one when I was running at speed down the freeway in 100 degree weather a few miles from the house. I managed to make it back home with the valves just starting to clatter and the oil temp at near 300 degrees, but that old SBC took it like a champ and fired right back up with no apparent issues once it cooled down.
@Sara Lora I know my car, I know how it reacts... I do not know your car, I do not know how it reacts... You do not know my car, so you do not know how it reacts... So please do not tell me about my car... Okay? I have ( not a mechanic ) Replaced 2 optispark distributors, water pump, fuel injectors, TPS, fuel filter, alternator, ICM, oxygen sensors, spark plugs, spark plug wires and shit i can't even remember because It's a 26 year old car.. Nothing wrong with being cautious and if you look online at a Super Chevy article for Hypertech's Power Programmer III for the C4 LT4 they got the best 1/4 mile times when they lowered the temperature for the fans to come on at 185 degrees.. I won't be a PANSY if you promise not to be a ____!
Question. I test drove one today and temp gauge seemed to read correctly and didn't show it hot. However the coolant boiled out of the upper tank. Guy told me previous to that happening that he just had it flushed by the dealer. Any thoughts?
Kyle,
Coolant boil over on the C4 pressurized system could be as simple as the dealer not following the proper air bleed procedure when refilling.
Even though I think that's the most likely culprit, you'll want to check for small leaks around the hose fittings and connections. There's a slight possibility there could be a head gasket failure, but that wouldn't be my first guess since it was recently serviced.
@@VetteSource Great thank you for the response. That was my first assumption as well. I checked oil it seemed to be clean as well. There was quite a bit of oil or something on the under side of the car. But I didn't see any dripping. If it wasn't a manual I would probably look elsewhere but I haven't found any other manuals
Yep, manual transmission is a good choice. Is it a 96 or another year?
@@VetteSource 92
Ok, 1st year of the LT1 with a six speed and the updated interior and body panels. Good car, and very dependable even as a daily driver.
How about the lines at the rear of the engine?
You're referring to the coolant crossover tube that runs behind the cylinder heads?
My '94 will turn a fan on if I push the a/c(auto) button. I have a 25 minute run to work and often hit the drive-thru window. Knowing my car is going to heat up while waiting I like to turn a fan on. Don't neglect the front air dam. It is plastic, certainly abused by the road, and worth replacing. It is where the cold air starts in to cool so a vital front of the process point.
Good observation and advice👍. If you want to keep the engine temperature a bit cooler, you can always keep the A/C on, which will cause the secondary fan to turn on.
I do the same on my '94. I pay attention to the temperature reading more than any other gauge. Speaking of hoses
My lt1 tends to stay at 199-201 when I’m moving no matter what the outside temp is. Sitting in traffic it will slowly climb to around 215-220. I’ll turn the fans on around 210 tho because I’m paranoid lol
Completely understandable. The factory temp settings on all the C4's make most people nervous.
VetteSource When I’m moving I’m normally between 185-200 and when I’m in traffic around 215-220 like you on the digital gauge. The analog gauge however consistently reads 25 degrees higher which looks really scary when it’s almost pegged at the top. I think the digital gauge is right because in the time I’ve owned it I haven’t had any over heating problems. Is it normal for the analog gauge to be off?
Mine usually looks a little off but never comes close to the 260 mark which I believe is the peg? Might wanna check that out
Yep, it's very common. The Aqua LT-4 has the same issue. The analog gauge is almost pegged at the warning area while the digital reads lower. I am going to do another video showing the operation and comparing while hooked up to a scan tool as well.
Yep, I'm going to show different readings by cross referencing the analog and digital gauges while monitoring with a scan tool.
can you flush it at home as well as a shop?
Yes, you can. Best if you have a way to capture the water runoff.
Ok🤦🏻♂️, I bought a mess, my 85 has a aluminum intake with aluminum heads and a four barrel carburetor, my pressure tank has been bypassed and the radiator has the cap on it! I also have a blown head gasket now! It has a aluminum water pump, and the distributor on top and not behind the water pump. Now I have no clue on which way to go to fix this problem? Can anyone help me?
Hey Randy, is your car an 85 or a 95?
@@VetteSource 85 and is supposed to be fuel injection. Wondering now if it is supposed to have the reverse cooling system like described in other year models? And does it mean that I could possibly have the wrong water pump? Also I didn’t think a carburetor intake would work on a injection motor because of the head to intake angle? And thank you for responding too!
No problem Randy. Your 85 will have the Gen 1 SBC, so no reverse flow cooling system or straight center head bolts. Sounds like the motor was upgraded at some point in the past with aluminum heads and the aftermarket intake, carb, and water pump. This happens quite often when owners don't understand the TPI system.
The good thing is that taking it back to original fuel injection isn't that expensive, it's just a matter of whether or not you feel like diving into the project. With a blown head gasket, you might even look into the possibility of locating a complete junkyard engine from another 85 Corvette.
Let me know if you need any more guidance, I might be able to point you in the right direction.
@@VetteSource thank you for the information and my brother has a TPI motor out of a Z-28, so are they the same?
Almost exactly the same. You will need to change the fuel rails as the Corvette rails come in from the passenger sides and not the driverside like the F bodies. Also make sure it has the 350 and not the 305 injectors.
Where is bleeder valve on 92???
Should be in the exact same spot. I will double check my 92 tomorrow to verify.
@@VetteSource thanks i just changed my thermostat and my CTS on the water pump. Been trying to figure out how to bleed without drenching the Optispark!
I hear ya. Thankfully the stream of antifreeze that comes out of the bleeder screw is quite small, and can easily be captured with a rag before it gets down to the optispark
The L98 is so much better to work on....😃😎😏
Oh yea, kinda like the difference between a 2000 piece jigsaw puzzle versus a 3000 piece😁. Both fun, but maddening at the same time.
If you had told me ahead of time that you wanted to do a video I'd have held up on the rain. Hahahaha
Good one😁, I'll check in beforehand next time👍
Your bay needs some cleaning
Yep, I mentioned the reason why in another video on this car.