still overheating

[JohnnyE]

So I was overheating at red lights with my stock rad and Mr.G belt driven fan and when I would start driving my car would cool off, ran great on the highway at 160*. I decided to put in a three core rad from dual electric fans and a shroud from eBay (Champion cooling systems). Now the car will run ok at the lights 190*-200* steady but overheats while on the highway or when I really give-er up to 220*. The temp is rising so fast when going up hills it just seems not normal. The fans stay on all the time once up to temp because it won't cool down enough for the 160* switch to turn off the fans. I am running 160* thermostat with hyper tech switch for 160* and an Edelbrock water pump and champion rad with fans. I'm not sure what to try next so any help would be appreciated. Thanks

[dhutton]

Probably a dumb@ss question, but are your fans blowing in the wrong direction?

Don

[Randy67]

What is the cfm rating on the fans, are they blowing the right way like Don said? That fan shroud is blocking a good bit of the radiator, so at highway speeds it may be restricting the airflow.

[dontlifttoshift]

yep, I say punch some holes in that shroud.....those fans look small for that shroud

[MuscleRodz]

check fan direction as mentioned. Second, make sure you do not have any air in the system. What rad cap do you have on it?

[JohnnyE]

The fans are 12" and are rated for 3000cfm together, they are both pulling air through the rad with a tranny cooler in front.

[dhutton]

Is your trans cooler generating all that heat? Almost sounds like it could be based on your symptoms, heating quicky going up hill and at highway speed.

[TheJDMan]

Just throwing this suggestion out there. Try removing the electric fans and reinstall your engine driven fan and see what happens. I suspect restricted air flow from that shroud.

[JohnnyE]

I am going to try my old fan to see how it compares with the new rad, I think that would be a good start. The tranny has a temp gauge hooked up to it and with no tranny cooler and stock lines it would stay in synch with the temp of the coolant in the rad, now with the cooler it barely moves which makes me think the gauges work and are accurate.

[speED]

I had same problem with different companies product. Shroud creates about 50% restriciton of airflow. In 50 degree weather engine would run 175 - 180 degrees on the highway. Removed shroud and engine would not run hotter than 145 degrees. Tried putting holes in shroud, only dropped 6 degrees. Company is currently sending me a new radiator with 2 - 1-1/4" core (had 2 - 1" core). I also made my own shroud to accomodate more airflow on the highway as well as at idle. Will not have everything re-installed untill next week but I'm pretty positive I will be running cool with new radiator core and new shroud design.

[JohnnyE]

Today I checked the coolant level and it was down about two or three inches and the overflow was sitting at the cold level line. I filled up the rad to the top and put the cap back on. I have a hyper tech #4026 temp switch that is supposed to turn on @176* and off @166* plumbed in to the back of the drivers head in the intake manifold, and my coolant temp is plumbed into the intake where the upper rad hose is. You can see them both in the pic I just took.

So I'm driving the car from cold and the fans don't start until 225* and then you can see the engine temp cool off quickly to around 200* where it maintains if I drive lightly. I went for a spin on the highway and within 12 city blocks I gained 20* at 3400 rpm so I pulled off the highway and she cooled off a bit until I started up a hill then back up again to 220*. Then I got some beer and came home to look at the system again! I ran the fans with the engine off and they would blow hot air for 45 seconds and then it would cool off so I started the engine and instantly it blew hot again, I did this a few times and the temp dropped to 180* so I believe they are working properly. I will try the belt driven fan this weekend and post up the results and the belt fan also has the stock shroud.
Here is a pic of the clearance between the rad and tranny cooler

[JohnnyE]

One thing that I also noticed was that the over flow was still cold and at the low temp level when I got home and the upper rad hose was hot and full of pressure, may be nothing but thought i would mention it. Thanks for taking the time to help me out.

[grenade inspector]

might want to try watching your trans temp as well so see if that's spiking high.

[JohnnyE]

tanny temp stays 40-50 degrees lower on average with the cooler but without it would be in synch with the rad temp guage and spike with it.

[JohnnyE]

but yes it was reacting with the with the rad at the higher temps.

[grenade inspector]

perhaps try moving the tranny cooler then to see if that helps the radiator enough.

[TT302Z28]

A few more things to look at just be sure....

1. Belts slipping?
2. Voltage at fans when on?
3. Bubbles in the radiator when fully warmed up? (Napa sells a test kit that draws air from the radiator and will tell you if there is any exhaust gases present)
4. Your shroud is really close to the radiator core fins. The people before me are really on to something there. I would try and stand it off the core by at least 3/4" with some aluminum square stock if the first 3 above suggestions are ok.

Oh....I had an engine I chased overheating on for 6 months. Turned out at higher engine speeds the impeller on the water pump would slip on the shaft causing the water to of course not move like it should. Open the cap, let it warm up and rev the engine. Is the water moving as you would expect it to?

[TT302Z28]

If you can return the radiator, call Prodigy and get one of his setups.

Not too expensive and worth every penny!

[sn75]

Interesting. I would do as the last couple posters stated to check your setup to make sure it's all working properly.

On a side note, I have a three core Champs aluminum radiator along with a Lincoln Mark VIII fan (sucker really moves some air!) in my '72 Chevelle. Engine is a 475 hp/tq 383 small block, 180* thermostat and my temps while driving (stop and go in town or on highway) have never gone above 185/186*. I purchased the Mark VIII fan from an eBay seller named gt_recycler (in case you're interested).

[JohnnyE]

I took the family for a cruise to the lake today and the car was still overheating any time I would go up hills or put my foot into it up to 225*. So I put in the ugly old shroud and belt driven fan and it actually worked pretty good. Stayed around 175-180* at 3500-4000 rpm on the highway but would build heat in traffic still never broke 200*. The weather was at 21*C. I still would like to keep the electric fan setup but these fans that came with the rad suck. My vote is the fans are inadequate for my engine so I should buy some better ones and give that a try. Any suggestions on fans? Thanks John