Anyone tried to install an electric aux cooling fan that fits against the radiator. I still don't like the idea of my '79 running 215 to 220 at highway speeds. Just doesn't seem natural that the car runs cooler at idle than at highway speeds. Radiator seals are in place along the top and sides not sure what to look for along the bottom. Radiator had small amount of calcium build up but did not look very bad. (6 years old). What model and type fan will fit?

Mod's I have done already.

Edelbrock high flow water pump
High flow thermostat 160
New fan clutch
Radiator flush
Reduced static timing to 8 degress

 

Check accuracy of gauge
Test accuracy of thermostat
Remove 2 coolant plugs on block to look for crud.

You have classic symtoms of reduced radiator efficiency. Try a better flush if all else passes.
Aux fan won't hurt.

 

Shot it with my IR temp gun and gauge is about 5 degrees hot. The temps I quoted were from the gun. What type of flush?

Thanks,

Capt. Ron

 

Ron,
I was just about to post a thread about the results of adding an aux fan to my 79 so I dont mean to hijack this thread but it seem we have the same problem. I have had the same problem for the last 2 yrs. Hi temps, 230+ on the hiway at 70 mph w/ a/c on. My list of fixes is triple yours inlcuding what you have done. The last thing I just did was add a 10 inch electric puller from flex a lite in front of the mechanical clutch fan. yesterday I took it for a test ride with the 90 plus days. I just installed new digital guages also. Water temp reached 232 deg, oil temp reached 300 deg! That was brand new 5w 30. Probably shot now. I have the aux fan hooked up to a relay that makes it come on with the a/c. I actually bought two fans thinking I would install both but I'm beginning to think the second isnt going to solve my problem. Temps were just as bad without the first fan.
I would change that t-stat to a 180 deg to let the water stay in the radiator a little longer. ALso your timing may need to be bumped up a little, retarded timing can cause a car to run hot. I've tried evrything from 8 to the current 14 deg btdc with no luck. Heres my list of fixes:
new 4 row rad
timing changes w rebuilt dist by lars
rebuilt q jet by lars
new 7 bladed fan
new fan clutch
new water pump
new motor (old one ran just as hot)
calibrated old guages
installed new digital gauges
new chin spoiler
new chin spoiler extension
25% antifreeze solution
water wetter
radiator seals fro doc rebuild
new alum intake, thought the old one might be leaking vac
10 inch elec aux fan
new lower hose w spring


You name it I've done it. Next I might try a tranny fluid cooler so I keep the hot tranny fluid out of the radiator. Maybe the tranny is heating up at higher hi way speed? Just cant figure out where to put it. I dont want to put it in front of the a/c condensor and block even more air flow.
ESU

 

I use some super duper flush from Advance Auto.
Whe draining, try not to drain a hot engine or refill it hot. My take more than one flush.

Later c3's had a aux puller fan.

 

For both above problems:

Can you hook up a temp gauge to the lower rad hose at the radiator to see the outlet temp. Best way to check the efficiency of the radiator. Duct tape sensor if need be.

To ESU
You've done about everything.

Tranny cooler and engine oil cooler will help a little.
Even if not mounted in front of condenser.
Use synthetic engine oil.

What rpm at 70mph
How new is the new engine, new freeze plugs etc?

 

ESU. thanks. At least I don't feel like the Lone Ranger. Where is your temp sending unit? Mine is on the top of the thermostat housing in a brass well, it does not actually touch the coolant. I know that there is one on the drivers side in the head but when I moved my wire to that one I got no reading that sending unit may be bad. Have you considered one of the alumnium radators they "guaranty" a 20 degree drop but about 600 bucks.

What say other '79's??

I know that this subject, heat has been done alot on this site, I am sure I have read every post on overheating on here. It's 90 plus everyday here in South Ga. and I'm just trying to cool it down.

 

I shot the both upper and lower hoses with the IR gun. I don't recall the exact temp difference but the lower was cooler. Don't know what to do now, I was just on Summits web site and had a electric fan in my shopping cart. Will wait on that.

 

Capt. Ron,
I pulled the radiator on my '79 and had it flushed, Installed a 160 degree t-stat and new hoses. While I had the rad. out, I went to a local hotrod shop and bought 2, 12 inch electric fans and mounted them directly to the rad using pads that won't let the fans rub the rad. I had to test fit them to the rad several times to get them to fit with the shrould installed. I did have to cut a small section of the shroud on the lower left for the fan to fit. I also got an adjustable temp sensor with a thermo couple to tell the fans when to come on. I had the radiator shop install a threaded bung below the top left rad hose inlet and installed the thermo couple into the bung to sense the temp. I wired the fans to come on when the temp reached 185 or when the A/C is turned on. I kept the stock fan installed too. When the car had the 350 auto I installed a seperate cooler core for the tranny. I have since installed a manual 5 speed tranny. My car never goes over 190 anymore with the temps running in the high 90's right now. One thing that has helped is the overdrive tranny. With the 350 auto I was turning 3,400 RPM at 70 MPH. I'm now turning 2,100 at 70; this has a tremendous affect on the temp. These things helped to make my '79 a comfortable and fun car to drive in any weather. I hope you get yours the same way!
Bernie.

 

Ron,
we are definitely not alone out there. My temp sending unit is in the block, under the exh manifold, drivers side. My oil temp sender is rear of the block on the top right behind the manifold. I omitted using a IR gun from my post but been there done that also. I had a bout a 20 deg difference on rad temps from inlet to outlet.
I have considered an alum rad like from Dewiit but the cost seemed a little prohibitive right now although there are some less expenive ones out there. I installed a brand new 4 row copper rad last year so I'm hesitant to just throw it away. Besides what if you buy it and it still doesnt work??? You just wasted 500 or so. I know Tom Dewitt says its the cure all especially after doing all of this other stuff but I wonder if he guarantees to take the rad back if it doesnt work? If I was you I'd try giving the rad a good flush or having it boiled out at a shop. I'm actually in the process of trying to save up the 1500 or so for an overdrive auto tranny like the 2004r although it wont be till next year.
Keep on trying and keep us posted, I know I will, ESU

 

Noonie,
I generally use mobil one but my shop did me a "favor" the other day when I was getting my lower control arm bushings changed and gave me an oil change but used 5w-30. I'll go back to mobil one prolly this week. I know that 300 deg oil temp although it wasnt for long must have really damaged the oil. The engine is 2 yrs old, gm 290hp crate, only 3000 miles or less. RPM's at 70 are @ 3200, so I'm figuring 3.55 or 3.73 rear. Definitley going to look at a tranny cooler, they're a quick and in-expensive fix, just trying to figure out where to put it. I have heard of remote mounted coolers but not sure about mounting locations? Any one using one please feel free to chime in.
ESU

 

Heres a photo of my aux fan install.
ESU

 

In my research i did look at a lot of fans for the price and came up with a Flex-a-Lite trimline Model #118. It is both a pusher and a puller but works best as a puller primary fan. But i did try it out when i had my regular belt driven fan on there and set it up as a pusher for stop and go traffic and it worked great. Price is about $140.

later today I'll go take some pics of the install and post it.

http://www.flex-a-lite.com/auto/html...-trimline.html

16" High-performance engine cooling in a LOW PROFILE package
2,500 cfm air flow

More Powerful Motor, Only 3-3/16" Deep!

replaces clutch fan ***'y
increases gas mileage
quicker A/C responce
quicker warmup
quicker cool down
18.5 amp draw
Size: 16-1/2" x 16" x 3-3/16"

 

That is exactly what I was thinking of doing with the fan. Gee, it looks so nice I'm double sorry it didn't work, for you and me. (These red cars look the best) I can understand not wanting to "trash" a new radiator. If the Dewitt had a money back????? I had looked at that fan at (the one from the other post) Summit had chosen that one and was going to buy the wiring kit with it so I could have it on a thermostat. This maybe an airflow design problem???? I just know it will be in the 90's here everyday until October. A long time to run "warm" It is funny however that 220 degrees is in the direct center of the stock gauge. Right were you would want the needle to be. Maybe we should have gauges like my truck, just hash marks no temps.

 

I actually paid more money to get red fans, they had to be drop shipped from flex a lite for summit. They are model 108 i think, either 8 in 0r 10 in Im not sure. I went small to ensure the 2 would fit. I'm not sure if it pays to install the other or try a tranny cooler first?
You're right about red cars they certainly stand out. Unfortunately mines not original, it started life as a lt blue with oyster interior and wound up red on black.
Good Luck, ESU

 

Well, I actually think mine was a "Maroon" when it started but it's red now! I just ran mine down the road (92 degrees today) A/C wide open got back and shot temps. Upper hose read 200's, thermo housing 215, bottom radiator hose 170's. I know if I would have kept on driving it would have gotten a little higher. I don't know what the spread is supposed to be between upper and lower hoses? Re-set timing to 14 degrees. Called the previous owner and he said that it's "always been like that". Not sure what my next step is going to be?? Guess I'll go to a radiator shop and maybe get a boil out. Not so sure what to do.

Thanks for all the posts so far.

Capt. Ron

 

Boiling it out certainly cant hurt.
ESU

 

Too many variables to guess at. Realizing it won't be as accuarate as an internal, it is advantageous to put a temp sending unit on the lower rad outlet so you can monitor and record the rad outlet temp while driving at various rpm speed conditions. It will give you an accurate display af how the rad is really cooling/or not. Especially when combined with the sending unit in the thermostat housing neck. It eliminates a poor thermostat. 100% conclusive. It is also a good method to test the age old argument concerning the 160 vs 195 thermostat, high flow water pump vs stock etc, flexfan vs stock, aux tranny cooler vs none etc. It doesn't have to be pretty, duct tape everything and lay the extra gauge on the pass seat.

BTW, in these old blocks water cools roughly only 40%, oil roughly 60% and engine compartment air is in the equation too.
Cooler oil will help, but don't use it to fix a coolant problem. Synthetic oil has shown a 30 degree drop in oil termp also.

If the engine is only 2 years old and antifreeze/distilled water was used this should not apply, but if the engine is much older, then take the trouble to remove the block coolant drain plugs. I've had engines with new 4 row rads and water pumps etc. and with crud between the sleeves, that ran too hot. It's a real pain to do but check it.

 

I too am fighting this unbelievably annoying problem with my '79 L82. I just bought and installed an new Northern aluminum rad with dual SPAL 11" fans to replace the original mechanical fan and clutch as well as the original electric fan. I am also seeing the same temp reading you are. I just had mine out on I85 today and it was creeping up over 220 so I turned those fans on and it kept it from climbing any higher. This car too has always had this problem. In fact as long as I owned this car, (since 1984) everyone I ever talked with about running their C3 on a hot day with air has bed met with negative response. Remember when buying elec fans that duals that amount to 22" of rad coverage is better that a single 18" that is advertised at X000 CFM. Since my dual SPALs pull 24 amps combined, I also installed a new 120 amp Powermaster alternator to ensure they got enought juice. This also seemed to fix the flickering dash lites at night. I wasn't running my air today because it needs a charge but I think if I was I'd be risking it overheating. I am member of te National Corvette owner Assoc and they have a news letter that Pat Goss answers letters from owners and this comes up a lot. He always says make sure the rad seals are still there and check the gauge for accuracy blah...blah...blah...I am at the point that I think the only real fix for this is a 4 speed tranny !

 

Well if you have an alum rad w/ dual spals and still have the problem then maybe you're right. A overdrive 4 speed tranny might be the only recourse. Certainly would make the car more driveable.
ESU