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Front Air Dam on 1999 C5

 
Old 08-28-2017, 08:36 AM
  #21  
JF Ranch
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Originally Posted by lionelhutz View Post
I've seen a number of people post that they run no air dam and it didn't have any noticeable effect on the cooling. So, I wouldn't put a great deal of faith in it fixing your woes.

I do as already suggested and make sure the radiator and condenser are clean. The dealership might not checked the coolant and fans, but they might not have put it on a hoist and made sure the radiator fins were clean. They will look clean from the engine compartment fan side.

Also, what does harsh driving conditions means and what did you consider high coolant temperatures?
We live a couple hours from the Black Hills of South Dakota. Driving the Hills is an exhilarating experience, especially in our C5 Convertible. These narrow roads have steep grades and are very winding, with many hairpin curves. My ground speeds perhaps average 15-25 mph and no more than 5 mph on the hairpins.

When driving on 65-80 degree days, cooling temps have gotten as high as 230-235 in the Hills. As soon as we have resumed normal high way driving at 65-70 mph, the temp drops back to the 190-200 range.

This car has an automatic transmission. Gearing down in these conditions keeps the rpm higher and reduces the amount of braking, but this does not seem to have an effect on these temperatures. At 65, I consider myself a "cruiser" not a "racer" and am pretty easy on this machine.

Additionally, on a 100 degree day this summer, my temp got up to 220 on a normal highway, driving 65-70 mph. These temps seem quite high to me but it does cool as soon as the driving conditions change.
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Old 08-28-2017, 12:35 PM
  #22  
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Well, the stock high fan speed comes on at 236* so your low speed, high rpm temps are rather expected. I'm not sure where 228* came from because that is lower than the stock setting and higher than what most tuners would use.
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Old 10-06-2017, 10:16 PM
  #23  
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It's been over a month since we last visited. I've learned a lot since then.

But first I want to introduce myself a bit to you, so that you understand who you are dealing with. I am a cowboy. A fourth generation Nebraska cattle rancher to be exact. My great grandfather homesteaded here in 1885. I do not consider myself a mechanic. I know much more about cattle, horses, windmills and leather. I do routine maintenance & repairs on our ranch pickups, tractors & hay machinery, but do not tackle much more than that. Ranch work consumes my time. Much of the year we work 6-7 days per week, 10 hours or more each day and I do not have time for tinkering in the garage. I purchased this 1999, red Corvette Convertible (54,000 miles) a year ago as a result of a decades long dream. My first car was a 1969 Firebird 400, Hurst 4-speed, Tach on the hood. I've kicked myself a thousand times for selling that car. Undoubtedly this Corvette is a result of that self pity. I don't plan on doing any modification to this car, or much mechanic work myself. Both my wife and I love cruising in it and listening to great old '70's music, while driving to see our grandchildren.

Now back to the issue. The cooling system was checked by a very large GM Dealership last spring and found to be working properly, with both fans coming on at the correct temperatures (please see my initial post on this thread). I am disappointed that they did not notice the center air dam was missing, or explain it's function (I did not realize until I consulted this Forum, how important this piece is for directing air flow up into the radiator).

Still, it bothered me when in certain driving conditions, it will go to 230 degrees or higher. I have found this forum very informative and have learned a lot. Once I found the time to begin addressing the air dam issue, I got the car jacked up on stands, to determine what I needed to order for parts.

Once on jacks I could see a fair amount of stuff on the condenser. I learned from YouTube how to get to the radiator for cleaning. I used a long tube air blower to clean both the radiator and condenser. I did not get a huge amount of stuff out, but obviously they both needed cleaning. A much better job could be done if the radiator was removed. More disappointment in the "Dealership" for not checking this for me.

While working on all the above, I also noticed that both the upper and lower radiator hoses seem to be collapsed. 'Not sure if this is the proper term, but they are not hollow/round but flat in the middle. Another obvious problem that the "Dealership" should have recognized, offered to fix and charge me an exorbitant price for.

Now for a few more questions:
1. For the most part, the cooling system seems to be working fine at normal highway driving speeds, even though it appears that coolant flow is restricted with these radiator hoses. Could it be that they are opening up or inflating as the coolant temperature and pressure increases?
2. Assuming that these hoses should be replaced, please recommend what radiator hoses to get. Is there a reinforced kind with coils in side available? If so, where would you suggest I order them?
3. Should the radiator and condenser be removed and cleaned with a pressure washer, compressed air or other such method? Or, if these are original equipment, should one or both be replaced after 18 years and now 60,000 miles?

I appreciate the valuable advice from the many experts on this forum. Thanks for your help.

Last edited by JF Ranch; 10-06-2017 at 10:20 PM.
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Old 10-07-2017, 09:26 AM
  #24  
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JFRanch, nearly all of us have to or have had to work hard for our money just like you. Thus we like to hang onto that money when we can. There is a reason we've renamed them as "stealerships". Many have had similar experiences as yours. Our cars are fun, cool and just downright attractive but unless you take it somewhere that has an experienced Corvette mechanic, you'll be disappointed just about every time. Our cars are unique and are different from others in many ways and there are just things a regular mechanic will not know unless they do a lot of studying. I feel your disappointment. However, on the bright side, there are a bunch of folks here in CF that are in the same boat as you and we like to help each other. Even if you don't have the time to do it yourself due to your heavy work schedule, you can find the issue here and with that knowledge, take it somewhere and tell them what you'd like to have addressed. Good luck with your fixes and come here first!
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Old 10-07-2017, 09:34 AM
  #25  
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Originally Posted by 8VETTE7 View Post
If the hoses appear collapsed ( I am assuming the cooling system was cold when you were under the car) try opening the pressure cap on the surge tank and notice if the hoses return to a more normal shape.

If they do then the pressure cap is bad. The pressure cap works like a 2 way valve. As the coolant temp increases a vent in the cap is closed off so that pressure is built on the cooling system up to the rated pressure of the cap (usually 15 to 18lbs). Each pound of pressure raises the boil point of the coolant by about 3 degrees so that with a 50/50 mix of antifreeze and water the boil point is about 263 degrees for a 15 lb cap. As the coolant cools off the vent in the cap opens to allow atmospheric pressure in on top of the coolant. When the vent gets plugged up the system causes a vacuum to be created as the coolant cools and the air that was on top of the coolant in the surge tank gets sucked into the coolant and the side walls of the hoses also get sucked in. Air in the coolant is NOT good for effective cooling!!!!

Replace the pressure cap and then burp the coolant system to get the air trapped in the coolant out and then top the coolant off to the FULL COLD line on the front edge of the surge tank.

Try the car after this has been done to see if coolant temps are lowered while driving. If you have properly bled ALL the trapped air it should make a very noticeable difference!

As far as cleaning the radiator out of the car DO NOT use a pressure washer to try to clean the cooling fins of debris. Use either compressed air or the force of water from a garden hose. Hi pressure from a pressure washer will damage the cooling fins and can cut into the thin aluminum tubes that carry coolant. Blow or wash debris out of the fins from the back side of the radiator toward the front side of it as it was installed in the car. Going the other way just lodges debris deeper into the fins.
I went directly out to the garage to check the pressure cap. Yes! As I loosened the cap, the hoses swelled or opened up some. Perhaps not to a fully round shape, but definitely not flat or collapsed as before. Can the cap be unplugged? Or should a new cap be purchased?

Thanks too, for the advice on NOT using a pressure washer on the radiator. I am aware that high pressurized water can damage the fins, if directed at an angle. However, I have successfully used this method on tractor radiators by being very careful to keeping the nozzle straight in line with those fins. This more delicate aluminum radiator undoubtedly eliminates this method as an option, even if the radiator should be removed from the car. What is a typical life span for these radiators? Assuming this one is original equipment, it would be 18 years old.
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Old 10-07-2017, 09:37 AM
  #26  
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As long as its not leaking, the radiator life should be unlimited. They develop cracks and pinholes but those are usually from some outside stress problem. I would expect that the vast majority of C5 radiators still in use are the factory originals. Many have been replaced due high performance mods but as long as the car is stock, the original radiator should be fine.

Last edited by CactusCat; 10-07-2017 at 09:38 AM.
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Old 10-07-2017, 09:59 AM
  #27  
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Originally Posted by JF Ranch View Post
I went directly out to the garage to check the pressure cap. Yes! As I loosened the cap, the hoses swelled or opened up some. Perhaps not to a fully round shape, but definitely not flat or collapsed as before. Can the cap be unplugged? Or should a new cap be purchased?

Thanks too, for the advice on NOT using a pressure washer on the radiator. I am aware that high pressurized water can damage the fins, if directed at an angle. However, I have successfully used this method on tractor radiators by being very careful to keeping the nozzle straight in line with those fins. This more delicate aluminum radiator undoubtedly eliminates this method as an option, even if the radiator should be removed from the car. What is a typical life span for these radiators? Assuming this one is original equipment, it would be 18 years old.
The stock radiator has plastic side tanks, that over time and exposure to heat and cold will deteriorate and eventually leak. When it comes time to replace you can opt to just replace it with a stock unit or go with an all aluminum unit. The latter will be more expensive but can provide more efficient cooling and lower operating temperatures.
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Old 10-08-2017, 10:23 PM
  #28  
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After a long morning in the saddle today (Sunday), I got back home by mid afternoon for a late lunch and put the Vette back together.

I had changed engine oil, blew out the radiator/condenser and thanks to 8VETTE7, identified what turned out to be a bad/plugged surge tank cap, which is collapsing the radiator hoses.

As you all know, to clean the radiator (which indeed has plastic sides, so according to alxltd1 it must be original), I had to remove the air filter intake compartment. Those silly clamp straps came off and I could not get them back on. The front cover of the air filter is fastened at the bottom and I did not remove it. On YouTube videos, I saw where they can be taken out and put back in, but mine looked different and if I got it popped off, I did not know how I could possibly get it back on, so I left it in place. The metal bands came off with the air filter intake and since I could not get them back on, I used two heavy, 30" plastic zip ties to clamp the air filter intake & cover in place, instead of the original strap/clamps that were always coming loose anyway. This looks like a good solution to me. Perhaps very long cable clamps might even be better. You can let me know what you think about this.

Next, I an going to have a local body shop do some minor cosmetic work and also replace the air dam for me. I was prepared to replace the air dam myself, except the previous owner had bent one side of the skid plate/radiator support cradle and I do not trust myself to fix or replace that part. It will be going in to the body man later this week. So hopefully he can have it back to me in an couple of weeks, with enough time to test-run it in the Black Hills before cold weather sets in.

8VETTE7 advised me to "burp" the cooling system, after I get a new cap. I think I know how to do this and I've watched a vague YouTube video or two about that, but if you could explain the steps for this procedure, I'd appreciate it.

Thanks for all your help! You guys are the best. I will report back when I know more...
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Old 10-09-2017, 04:28 AM
  #29  
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the metal bands are a nuisance. i just put a piece of flat wood under them to get more preload. later i painted the wood black.

you read so much about burping, well, fortunately i never had to do any of these procedures, i just just fill her up and go (losening one of the top hoses).
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