Cooling problems maybe on my C4

[Bob Yates]

My 86 vert is my dailey driver and if you could see my waist size you could tell I spend a lot of time idling in fast food lines. While I'm making my mouth water thinking about all those carbs I'm getting ready to injest I spy my temp gauge. It goes up to 225 degrees and my fan kicks on and cools it down to 205 degrees. I always manage to get behind some one who is ordering food for the eastern half of the United States,so my fan keeps doing it's thingy. I like many of you get Corvette catalogs. I'm always looking for items to make it better. One of those items was an Auxiliary Fan Kit....A must for cooling it reads. This fan kicks on at 200 degrees and off at 185 degrees. I run a 180 degree thremostat and keep the raditor intake air area clear of junk so that area is clean. I purchased one of these kits. I have two problems. Here's the first...the fan switch that came with the kit kicked on at 190 degrees. The fan started but the temperature kept going it's merry way til the main fan kicked in at it's normal 225 degrees and cooled down to it's normal 205 degrees. I called the vendor's customer dept. and talked to a tech. He said he would send me a new fan switch and he did. I installed it as per instructions and this one comes on at 186 degrees. I called back and told him of the out come. His responds was he finds it hard to believe that two switch would be bad . HEY jack believe it. I've got'em. I told him I was more interested in second problem. Why isn't the temperature going down when the auxilary fan kicks on. He told me to check the flow of air going thru the radiator. It's coming thru but not with a lot of force. Has anyone had this problem? If so were you able to correct it. Maybe I need a new water pump? I only have 57,000 ticks on the clock. The car did a lot of setting in it's day. Thanks to any an all for help. .... Bob Yates

 

[Edmond]

Bob,

From what I understand, there isn't much you can do besides have the fans come on early when you're sitting there. There isn't any air getting up there to cool the radiator and it'll heat up until you get moving.

One thing that could help is Water Wetter. It seems like Water Wetter will keep the temps from rising too fast and at the same time, it will help cool the coolant pretty quick when you do get going. I used 2 bottles in my system last summer and even on the hottest days, I didn't see coolant temps over 186. I'm running the stock thermostat with a chip that turns the fans on at 198

 

[SurfnSun]

When was the last time you changed your thermostat? I had the same problem on my 85, it would hit 225 and then cool down. Turned out the stat was old and wasn't opening up until 225 or so. I put a 160 and early fan switches...car never got hot again.

Make sure youre 50/50 coolant/water and throw in some WaterWetter too.

 

[Alfonso Gomez]

This is what I did a couple of years ago after I had replaced the radiator, which was busted:
1. The radiator shop flushed the cooling system and verified that there were no leaks.
2. I cleaned the space between the radiator and the AC condenser. It was incredibly full of pieces of newapaper, leaves and other assorted junk. This has to be done about every 6 to 9 months. It is a PITA but has to be done.
3. I installed a 160 degree thermostat.
4. I purchased from MidAmerica or some other company a manual fan switch. This switch enables you to manually :duh switch on either the auxiliary fan or both fans.
5. Watter Wetter and a 50-50 solution of Prestone coolant.

I live in Puerto Rico and the traffic jams and heat are legendary but I rarely see 215 degrees with the AC on and standing still.

Hint: when driving, if you run over a plastic bag or a newspaper, look in you rearview mirror. If you don't see the bag or newspaper fly behind your car, it probably got sucked up to the area in front of the radiator. Stop and check it. :L It has happened to me a couple of times.

 

[warren s]

Fan overide switch !
Clean radiator and check for debris clogging up fins.

 

[Bonnell]

Hi Alfonso,

How do you go about cleaning your radiator? My '88 stays cool until I sit still and then it will sometimes go past 235 (summer driving) until I turn off my A/C or start moving again. Maybe a cleaning is in order.

Thanks,

J Bonnell

 

[Bob Yates]

A big thanks to everyone for their post. To clear up a few points, I replaced my thermostat last summer and use a 50/50 mix. In one of my early post. I told how to make a screen grille to keep paper and junk out of the air intake area for the raditor. So this area on my car is clear of debris. I can't see between my raditor and A/C condensor but when my main cooling fan comes on the temp goes down so I assume it is clear. It's when my auxiliary fan comes on that the temp keeps climbing and has no cooling down effect. If I put a manual switch in and control the fan that way it still won't cool my temp down so I've gained nothing there. I have purchased from a heating and cooling vendor a cleaner that cleans condensors. I'm going to give that a try. also I notice in my overflow tank a black looking greasey deposit on the dip stick and around the inside of the tank. I have just replaced the tank so it is clean . I have clean it serveral times now. Anyone have thoughts on this? Thanks again for any and all thoughts....Bob yates

 

[SurfnSun]

You can pull that fiberglass shroud that covers the radiator in about 10 minutes. You might do that. When you say black greasy substance in your overflow it made me think of oil. But who knows. You might want to pull your radiator out and have it acid dipped to clean out whatever that black substance is.

 

[c4cruiser]

It may be that the radiator itself is clogged up judging from the descritption of what you're finding in the overflow tank. Oily substances are not a good thing to see in the coolant. Do a pressure check of the cooling systm to see if it's holding pressure. No pressure or low pressure will cause overheating and the cause may be something like a head gasket or even a crack in the block or a head.

If the radiator is the original, it may be ready for replacement. Another possibility is a weak lower hose; it could be collapsing and causing a reduction in the flow of coolant.

 

[Bob Yates]

Thanks everyone...Let me clear up something I am not having a heating problem. My vette does fine and runs great. I was just wanting extra cooling for when I was sitting idling. I thought the auxiliary fan in front of the raditor would fit the bill. Again don't believe everything you read or what a vendor tells you. I was told by the vendor that I would get immediate relief but as I stated when the auxiliary fan kicked on the temp kept rising. I was looking for a better way of cooling. On my 81 C3 it had an auxiliary electric fan and I used a manual switch to control it . I guess that's what I'll do on my main cooling fan now. I pressure ckecked the cooling system and it is OK. I've decided to do a full cleaning of the cooling system inside and out when warmer weather comes. Thanks again to all....Bob Yates

 

[Edmond]

Bob,

I would call the fans first aid with the real solution being when the car moves and you have cooler air entering the compartment. The fans are to keep from overheating more than cooling. Seeing 230 degree's won't damage anything; our cars are meant to run hot because of emissions. Some, like myself, don't like seeing 230 so we do things to lower that temperature.

 

[Bob Yates]

Hey Edmond,Your as right as rain. All the times I see the temp going up I'm thinking my engine is going to cut lose and I'l be stranded and have to call a wrecker. I've never met a wrecker driver who had a gentle side for hooking a car. Besides I need to remember that engines are built to run hotter for emissions and all I need to do is keep it serviced good . See Ya....Bob Yates

 

[Doutdoor]

Another option would be to install a custom programmed PROM that will turn your fans on sooner to lower your temp. My car now never get's above 195 deg. even in the summer. Of course I live in Seattle and not Phoenix but it worked for me. A cooler running car will give you better performance. Plus you can get some other PROM controlled performance improvements done now or in the future with the custom PROM. Jeff from the forum here did mine for $100 + shipping.

 

[Bob Yates]

D.Door.... I might look into that later after I clean out the cooling system. Thanks for the info.....Bob Yates

 

[Alfonso Gomez]

Hi Alfonso,

How do you go about cleaning your radiator? My '88 stays cool until I sit still and then it will sometimes go past 235 (summer driving) until I turn off my A/C or start moving again. Maybe a cleaning is in order.

Thanks,

J Bonnell

As I said before, it is a Royal PITA to clean the area between the radiator and the AC condenser. It is best to remove the radiator and have a radiator shop clean it (acid dip) and check it for leaks. If the radiator is clean inside and needs only cleaning in the outside, you can use degreaser and a garden hose. Lay it on its side in your driveway, spray LOTS of degreaser and let it sit for 10-15 minutes. Then rinse using the garden hose in a spray pattern, not the high-pressure stream. Then, flip it to the other side and check if all the dirt and debris has gone away. Repeat if necessary. CAREFUL not to bend the fins. If some fins are bent, you can try to carefully straighten them out.
After all this is done, reinstall the radiator, check all hoses and replace any that are even slightly suspect. Fill the system with a good quality coolant and a bottle of Water Wetter. Start the engine (remember to put the radiator cap on ) and thoroughly check for leaks.
I know it's a hassle but this is part of the fun owning Corvettes.
Good luck.

OOPS! Almost forgot. When you have the radiator out, is a good time to check if the AC condenser is clogged. DO NOT TRY TO REMOVE IT. You can use degreaser and the garden hose to clean it without removing it from the car. Also check for bent fins.

 

[Bob Yates]

That's a good start on cleaning a cooling system but I go a little further to include the engine block. You will need a flushing adaptor kit that will come with a tee that will go into a 5/8 heater hose or 3/4 and has a graden hose adaptor on it. You will also need a 6 inch piece of 5/8 or 3/4 heater hose and clamps. Most extra hose clamps come with the flushing kit. Which can be bought at any auto parts store.The two most diffcult things to do after the raditor is removed is to take the thernostat out and remove the drian plugs from the side of the engine block. I put my car up on ramps to do this. I go into the return side of the heater core hose and install my tee. Hook the garden hose to the tee and turn the water on. I turn it off and on a couple of times to get a good flush. When the water runs clean after 4 or 5 minutes turn off the water. I have an air compressor and a blow gun and I rig the blow gun to the tee in the heater hose ,turn down the pressure to 5 lbs and blow out any water that remains. I use low pressure as to not damage the heater core. Remove the tee and reinstall the plugs in block and a new thermostat. Nows a good time to replace all water hoses. Reinstall the raditor if you have removed it. Add your 50/50 mix of coolant and water wetter if you use it . Start engine and check for leaks. Check fuild level later after a cool down and you should be set to go........Bob Yates

 

[Bonnell]

Whew! That sounds like exactly what you describe - a ROYAL PITA. But for the sake of cooling... Thanks!

 

[jcdouglass]

I told how to make a screen grille to keep paper and junk out of the air intake area

A big thanks to everyone for their post. To clear up a few points, I replaced my thermostat last summer and use a 50/50 mix. In one of my early post. I told how to make a screen grille to keep paper and junk out of the air intake area for the raditor. So this area on my car is clear of debris. I can't see between my raditor and A/C condensor but when my main cooling fan comes on the temp goes down so I assume it is clear. It's when my auxiliary fan comes on that the temp keeps climbing and has no cooling down effect. If I put a manual switch in and control the fan that way it still won't cool my temp down so I've gained nothing there. I have purchased from a heating and cooling vendor a cleaner that cleans condensors. I'm going to give that a try. also I notice in my overflow tank a black looking greasey deposit on the dip stick and around the inside of the tank. I have just replaced the tank so it is clean . I have clean it serveral times now. Anyone have thoughts on this? Thanks again for any and all thoughts....Bob yates

I need to make a intake screen on a 96 lt-4
I hope I can find your post for some hints. I had my radiator replaced and it was totally blocked and had cracked the plastic on the side.

 

[douglas foster]

father & son

Can you please let me know about water wetter? where can i find it?,and its ben

ifits. thank you

 

[WhalePirot]

Wow. Old post; long life.

I don't understand why someone would spend big buck$ on Water Wetter for a cooling problem. Properly maintained, the system can handle much more than a stock engine.

A $5 Robert Shaw 180* solved my overheating, but I am well past twice the original engine's power, while running a stock fan. I now suspect that my Z51 radiator and stock pump should have cooled this car just fine, but I dropped nearly a G-note to find that out.

One major missing piece of information in the original post is the year of the C4. The controls for the fan(s) changed. In later cars, the ECM controls the fans, as the newer computers had more capacity to take on more functions.

A cooler machine (within reason) typically runs better and lasts longer, so I understand (and have mine run) at cooler temperatures. HOW to do that, depends on your model year, unless you like manually switching fans on/off. I do not.