My 383 is running hot! Even at idle the temp will continue to climb with the dual electric fans on.

I have a new double pass radiator with dual 13" fans (3600CFM) that I bought from Prodigy Customs (Fank at GP Superstore) and the temperature varies greatly across the unit. At the inlet, which is on the passenger's side, it get's extremely hot and it is also extremely hot at the bottom outlet, which is also on the passenger's side. Where the filler cap is, on the driver's side, it will be hot but not nearly as hot as the other side. The middle is warm (I can hold my hand on it even when the temp gauge in the car reads 240), and the fins are cool.

The water pump is a new aluminum high flow unit.

What is going on? Could the water pump be bad? Why then would there be such variances in different parts of the radiator?

I drove the car a few times in the spring and never had a problem. Now that the air temps are around 70, the car is running much hotter ... too hot.

Couple ideas...
Thermostat - bad, installed upside down?

Water pump - Doubt it's bad since it's new but any chance you got one with reverse rotation (clockwise) instead of normal rotation (counter clockwise)?

I'd ditch the double pass radiator and get a good single pass crossflow setup. It takes a lot more pressure to get the same flow through a double pass radiator.

If there is no 'shroud' then the fans are not pulling directly thru the radiator and not cooling properly.

Sounds like your radiator might be plugged or the thermostat is not opening.

Pull the radiator cap and check to see if the coolant is flowing

The filler cap is on the drivers side...? Ive never seen that before. Id get a shroud and go single crossflow anyways tho. IMHO

Thanks for the help so far, but (I forget what I actually paid) at near $900, there is not much chance of me ditching that radiator. The thermostat is installed correctly, and the water pump is supposed to be standard rotation. The radiator is brand new so I assume there is little chance of it being plugged. Tomorrow I will idle the car up to operating temps and see if coolant is flowing.

If it is the water pump, what would be a good unit that might be an upgrade from the one I have?

Frank at Prodigy ... if you read this post, do you have any ideas?

Here is a pic of the rad:

http://img.photobucket.com/albums/v92/djbartu/67-69camaroLS1FS.jpg

That looks like a very nice setup. Should be plenty to cool the motor and then some. When the car is running, do the fans eventually come on?

Yes, idle the car, pop the cap off and make sure the fluid is circulating. Also make sure all airpockets have been purged. Look for bubbles (sign of trapped air) as you're watching the water circulate. When your thermostat opens up the upper hose from intake to radiator should get firm as water will be passing though it.

That looks like a very nice setup. Should be plenty to cool the motor and then some. When the car is running, do the fans eventually come on?

Yes, idle the car, pop the cap off and make sure the fluid is circulating. Also make sure all airpockets have been purged. Look for bubbles (sign of trapped air) as you're watching the water circulate. When your thermostat opens up the upper hose from intake to radiator should get firm as water will be passing though it.

The fans are on a manual switch (for now, anyway) as the only hole tapped into the intake is being used by the temp gauge. This brings up another question, where can I hook up the sending unit from the fan relay? There are no other places tapped in the intake manifold or the heads.

As for the hoses getting firm, I have the rigid/bendable type as shown in my engine photo below.

http://img.photobucket.com/albums/v92/djbartu/DSC08232sm.jpg

looking at that pic, it looks to me like they blocked way too much of the core with the shroud- the only place air can get thru is where the fans are. some aftermarket setups like that have hinged flaps on the shroud that let air pass thu the rad core when going down the road.
and the fans overhanging a couple of inches on each side like that just looks poorly thought out. i'd think a couple of slightly smaller fans that were staggered high on one side and low on the other with all of the fan over the core would actually work better.

is it also possible that you've got some air trapped in that fancy dual pass radiator core?


i know people spend a lot of money on these setups because they think they are the best, but they aren't really necessary in probably 99% of all cars on the road. i had a crusty old 2 core radiator out of a 6 cylinder Nova with an electric fan out of a 4 cylinder 86 Celebrity that kept the vortec headed /HOT cammed 355 in my Nova right at the 185 thermostat temp on all but the hottest days. and even then, they never got up past 200.

We sell a lot of these and run them is very high horse extreme applications and never have a problem keeping the most stuborn applications cool. It is pretty much impossible it is pluged unless something huge has crawled into the radiator, LOL! I almost have to assume it is water pump. The fact that is is not reasonably even accross the core tells me the water pump is not pushing the water through. it does not take a special water pump to use a double pass, the additional effort is nothing for any healty wtaer pump, but you are making 2 passes through the core so there is more fluid movment.

So can you see fluid moving through the radiator?

As for where to mount the fan sender, if you have another port in your intake like the one you are using for your temp sender, would be perfect. you can also use a port in the side of the cylinder head.

At the inlet, which is on the passenger's side, it get's extremely hot and it is also extremely hot at the bottom outlet, which is also on the passenger's side. Where the filler cap is, on the driver's side, it will be hot but not nearly as hot as the other side. The middle is warm (I can hold my hand on it even when the temp gauge in the car reads 240), and the fins are cool.

The outlet should be the coolest part of the radiator. It looks to me like the plug/dam that forces the coolant across the radiator is leaking.

Well, I may have solved the problem (at least I hope I did) ... it may be the water pump. I pulled of the new "high flow" aluminum pump and replaced it with the cast iron pump off of my old 307. I let the car idle in the driveway and the temp never got above 200 with the fans running. The air temp was in the upper 70's. I'll give it a real test tomorrow (weather permitting) when I drive the car to work.

If this seems to be the solution, I'll order another aluminum high flow, but this time NO EBAY! I'll spend a few extra bucks for a name brand part from a reputable supplier.

I do believe the radiator and fan set up to be OK. Frank from Prodigy Customs / GPSuperstore even called me after reading this thread to offer some advice and see if he could help out ... now that's customer service! I would recommend anyone who has not checked out his website go to www.ProdigyCustoms.com (http://www.ProdigyCustoms.com), or if you are looking to join a group buy and save a few bucks, check out www.gpsuperstore.com (http://www.gpsuperstore.com). I've purchased a few things through them and have been quite satisfied.

Thanks everyone for the posts! What would I do without Team Camaro?

For anyone who has been following this thread ... here is the final update:

It was the thermostat. Even though I purchased a brand new Mr Gasket high-flow unit, it failed. Last week I finally got back into getting my Camaro on the road again, so I put in the thermostat from my old 307. Well, the temp stays in the 160 - 180 range WITHOUT using the electric fans! (The air temp here last week was in the mid 70's.) Yeah, I know, always start with the simplest, easiest solution first.

I'm now sure that the radiator / fan set-up will keep my 383 cool even on the hottest days. I must once again thank Frank at Prodigy Customs/GP Superstore and John at PRC (Performance Rod & Custom). They both were more than helpful. They were truly interested in fixing my problem and always returned my phone calls promptly. I know this paragraph sounds like a commercial, but I think It's great to find customer service like that in this day and age.

All that needed to be done is to look and see if the coolant was moving through the radiator as posted multiple times here to diagnose a faulty t stat.

looking at that pic, it looks to me like they blocked way too much of the core with the shroud- the only place air can get thru is where the fans are. some aftermarket setups like that have hinged flaps on the shroud that let air pass thu the rad core when going down the road.
and the fans overhanging a couple of inches on each side like that just looks poorly thought out. i'd think a couple of slightly smaller fans that were staggered high on one side and low on the other with all of the fan over the core would actually work better.

is it also possible that you've got some air trapped in that fancy dual pass radiator core?


i know people spend a lot of money on these setups because they think they are the best, but they aren't really necessary in probably 99% of all cars on the road. i had a crusty old 2 core radiator out of a 6 cylinder Nova with an electric fan out of a 4 cylinder 86 Celebrity that kept the vortec headed /HOT cammed 355 in my Nova right at the 185 thermostat temp on all but the hottest days. and even then, they never got up past 200.

Not true. My radiator is fully shrouded with two fans similar to this and it cools down the road extremely well. I will also add that a dual pass radiator is run by most of the racers.

Glad you figured it out. In my heart I was sure it was not the radiator, but we were sure ready to cut it apart if it came to that. We have these things cooling some extreme situations. Some really bad climates and real high horse applications.

We recently had a problem with a car with this radiator set up we built that was running a tick warm over time. Over a 1 hour period it would constantly get a tennie bit warmer and warmer until finally we had to shut it off. After trying everything else we did a leak down test and found a MASSIVE head gasket leak instanly. Not a little leak, a really bad leak. But there was no steam from the exhaust or water in the oil. So without those 2 symptoms. The fact it would run for a hour in 95 degree heat, no one here would even consider a head gasket. A head gasket would be a much worse heating situation with a bad head gasket. But the radiator was so efficent it was actually masking the problem and the radiator set up was ALMOST keeping up. So it really fooled us.

And remember, there is no such thing as OVER KILL with radiators!

Hey motor mouth, can you have one built with a large oil cooler??

All that needed to be done is to look and see if the coolant was moving through the radiator as posted multiple times here to diagnose a faulty t stat.

I did watch the flow with the cap off. When it was cold, a little trickle of water was observed. As the temps got hotter, the water in the radiator would bubble up (not actually air bubbles, but more of a coolant percolating thing). It would expand and move around so much that it would overflow the radiator. So, in my inexperience, I thought water was flowing properly through the radiator. What causes all of the moving / pulsing of the coolant if the thermostat is not opening? I understand the basics of a cooling system, but not what would cause this.

If you still have the old T stat, stick it in a pot of water on your stove with a candy thermometer and watch when it opens and the temperature as it does so. Sounds like it was jammed and stopped opening just past its rating.

Good lesson: check the easy simple stuff first. Initial t-stat test or change would have saved alot of time and aggrevation.!

i've had one of those "balanced " robert shaw's fail also. threw it in boiling water and nothing> new one; wide open the instant it hit the water.

Hey motor mouth, can you have one built with a large oil cooler??

No internal, need a Oil Cooler! Check out this little bad boy we run on the Bull Run Racer! looks so good you want to mount it on the hood!

http://i169.photobucket.com/albums/u212/ProdigyCustoms/Extreme-Oil-Cooler.jpg

That's trick man.....what are the dimensions? Puller of pusher fans?

15 X 7 X 2 1/2. If you can got it in front of the radaitor you wont need the fans. The fans will push or pull whatever we specify

That is the only place it would fit. That puts me back to running a t stat and packaging issues with a condensor. I'm sure I'll eventually put the ac in the car.

We stacked them on the Bull Run Racer. No little fans required. Just had to cut away a little of the vertical hood latch support.


http://i169.photobucket.com/albums/u212/ProdigyCustoms/DSC03842.jpg

http://i169.photobucket.com/albums/u212/ProdigyCustoms/DSC03845.jpg