And I wouldn't mention it because I've never had this happen before, nor can I explain it.

I recently wrote this in the C3 section and I'll try to duplicate it here. When someone has something like this happen it is makes since to draw a conclusion and nothing I say or anyone else, will convince you otherwise. So for Dennis, the problem was the electric fan and I'm glad it's working for you.

To everyone else, I think it is safe to say nobody in the hobby has dealt with more Corvette cooling isssues than me. I'm not bragging, it's just my occupation and not a hobby. Each year I have 3-4 situations ( out of hundreds) that work exactly the opposite of what I would expect to see. While I can't explain the weird results these people had, I disguard them as the exception and not the rule. With this in mind, I can honestly say I have never had anyone remove an electric fan and it accually work better. (until now)

Let me say that I don't think any car should need an electric fan. If everything is set up correctly and all the gm parts are functioning correctly, the stock aluminum radiator should keep it cool. When someone comes to me with a cooling problem it usually involves a slightly modified engine. This could be a ton of mods or as simple as adding HEI ignition or a high flow water pump. When nothing seems to help, I suggest going to the electric fan and I have never had anyone say that didn't help out, a lot.

To those who say electric fans suck, you don't need them, GM designed it right, etc...I will go on record as saying the electric system works better than the stock engine/clutch system. I know that will raise some hair out there but it is my hundreds of applications that bring me to this conclusion, not one or two. The engine driven system provides very little air when you need it most. (Idle or cruising) To prove this point, look at what they do with the late model Corvettes. The C5 and C6 cars produce way more HP than do the early cars. The aluminum radiator is only one inch thick! Why do they work so well? Because they have electric fans blowing tons of air thru them.

Just last week I had a customer (1962) that insisted his new DeWitt radiator was bad. He had tried everything and it was running 220. I told him it wasn't the radiator but to prove it I would send him another one. But the new one would have the fan brackets weld on it and a fan shipped separately. He installed the new radiator and it ran exactly the same. Then he installed the fan, and it droped it 25 degrees.

In Dennis' case, I would have to guess something was wrong with the fan. Since he says it wasn't going backwards or the blade was wrong I won't go there. Maybe it was a bad bearing and the fan never got up to full speed and when the car on the highway the fan was restricting the flow? A couple years ago Spal (the manufacturer) packaged pushers in puller boxes, but that's a different story altogether.

 

Weaver,
I'll get back to you on the part # as I had it installed at the truck shop that works on and builds those Baha trucks. It looks like it all I know it ran close to $80.00 not $25.00

Micheal,
The radiator came with the fan attached with a shroud completely covering the remainder of the radiator. I hope I explained this right.
I left the original shroud on the car. The fan was wired to a control box That turned it on I'm sure when it reach the right temp?, but I'm absolutely sure it did not shut it off at highway speed. I'm not the engine that designed it but the actual fan system looks minimal and fact I couldn't give it away for use on another application, I was told it was sub standard for what it was intended for.

 

Tom, thanks for getting back to me. You still do not discuss the "phenomenon" of the elect fan causing turbulence or some other cause that does not let air pass through at highway speed.

The temp. started to rise above 180 fairly quickly, due to the thermostat. However, when I took it on the highway, after trying everything suggested it continued to rise at a faster rate and would reach 240+ in a mile or less. I would come off the highway and it would start to cool down, maybe 5 degrees. I would park the car and watch the green stuff come out.

As I stated I spent a lot of time and money not to mention the cost of product with the fan that did not work as advertised. In addition going over all the other situations you and others mentioned. Not once did you bring up the elect fan issue or I would have jumped on it. The fan has one speed and and does not shut off at highway speed. Have you tested your product with this application. I would like to return it and have have check it out. I know it did come on as I observed it many times. I know it was wired right as I could place my hand in front of it and feltl air blowing, and paper stuck to the front of the radiator. Does it or better yet should it shut off at speed letting more air pass through. Does that metal shroud you use to install the fan eliminate more air as it completely cuts off any additional air.

To every one out there, the reason I went for the elect fan was that I wanted or at least I thought this was the best way to go. I new that most new cars used a sepintine belt system with an elect. fan so I felt this was the way. I know now that these cars are enginered that way.
Thanks in advance for your concern.
Dennis

 

Right, I know exactly what you are describing. I've seen those in the catalogs. I suspect that was part of the problem--having to try and force all the air through a shroud that covered the inside of the radiator. The stock fan shroud doesn't block any of the radiator area, just bridges the gap to the fan blades. Also, if you take a look in any of your newer cars you can see that the fans don't use any shrouding.

Its possible that kind of fan/shroud setup would work fine with a larger radiator, or less heat load. I'm just guessing here, but I can imagine if your radiator is not oversized for your application that any decrease of the heat exchanger efficiency would cause overheating.

 

You never know...

Baja 1000 map

http://score-international.com/baja1000/index.ihtml

 

Ed, have friends in San Felipe, have you been there.

The guys at this shop were talking about not being able to take fuel into Mexico, they make you buy it there.

They had some trucks that were worth over a quarter of million. They had bodies and suspension systems that I've never seen before.
Dennis

 

The reason that Tom did not address this "phenomenon" is it does not exist. Anybody who says that a non running fan will cause less restriction than a running fan at highway speed, is just wrong! A fixed fan is the worst conditon as far as restriction. A fan running at half speed is still better than one that is not running, and one that is running at full speed is even better. Furthermore, the Spal Fans that Dewitt sells have flaps that allow air to bypass the fan at highway speeds. They are rubber flaps that simply swing open when the pressure goes up between the fan and the radiator.

Also, anybody that says that modern cars turn off the fan at a set speed is also misinformed. Modern cars turn off the fans when the temperature drops, pure and simple! The fans turn off at highway speeds because large volumes of air are being rammed through the radiator, and the temperature drops. Almost any car out there will not run the fan at highway speeds because it is not needed to keep it cool, but running the fan at highway speeds does not cause overheating, and you can take that to the bank.

The truth of the matter is that the fan will actually spin almost as fast as it would if it was powered simply due to the air going across the fan! You could actually spin the fan faster than it's normally powered speed, if you were going fast enough. If the electric fan was causing a restriction in the airstream with the relief flaps, how could the mechanical fan not be causing even more restriction without the relief flaps? The answer is that it does! To assume that the radiator knows whether the fan is being powered by the engine or a electric motor is a very clouded thought process.

Your trouble-shooting logic is in error, and the electric fan, per se, is not your problem. I absoultely agree with Tom that an electric fan will ALWAYS outperform an engine driven fan, but in most cases is not needed. A mechanical fan will work well in almost every instance, but the true advantage of electric fans in at low engine speeds when engine driven fans do not work well (as Tom stated). This especially important on cars that Air Conditioning as the A/C does not work well with low air flow and it tends to make the radiator overheat as well.

As several have stated, the only reason that I am aware of for a radiator to experience reduced cooling at higher speeds, is if the fan was pushing against the incoming air. This is not a problem at low speeds as the fan can push sufficient air through the radiator becuase it is not working against the incoming ram-air pressure generated by higher speeds.

In closing, I am glad your problems are resolved, but to blame Tom Dewitt for what clearly appears to be a disjointed, and illogical trouble-shooting process on your part is unfair. His radiators work well as do Spal fans, and they will always outperform an engine driven fan when properly installed and and wired.


Regards, John McGraw

 

You must have missed my comment on this above, so here it is again:
I wouldn't mention it because I've never had this happen before

The package you purchased was the SP020. We developed this package in 2004 for a customer that installed a big block crate engine into a small block car. He didn't want to change the core support so we added this fan as a test. He reported back to me that the new engine would not go over 190 and any time. Since then we have sucessfully sold about 100 of them.

I think this question explains the problem. First, it tells me that you do not have a clear understanding of the function of the electric fans. That's not a shot at you but it made me think about how the system is sapposed to cycle on and off when bam, it hit me! How long ago did you buy this and what type of control did you have? I looked up your order and you purchased this (Jan 2006) about 1 1/2 years ago. At that time we were selling Spals new PWM fan controller. This controller turned out to be unreliable and we quit selling it at the end of 2006. You can do a search on the problems and what we did to support customers. My guess is that the controller was making the fan run, but nowhere near it's maximum speed. To answer your question, the fans would shut off when the temps drop to the low setting. In your case, you never got there so the fans kept in trying. We went back to the simple relay harness that always works and the problem went away.



The shroud is not a problem. In fact, I have customers asking us to add more material and make it 100% coverage


Dennis, if you want to return the fan, I would be happy to issue a credit. I would rather send you a new relay/harness and switch (no charge) and prove the system does work.

 

Thanks for backing me up John but you are thinking of the dual fan set up with the flaps. That system is 100% corverage and it does need something to relieve the back pressure of the fans. Not the SP020

 

I have to disagree with this too...All C4, C5, and C6 use shrouding with electric fans. This is the 84-89. The 90-96 is a dual fan with 100% shrouding. The C5 is a dual, and the C6 is a single, again 100% coverage.

 

I had this same Spal 16" puller on my 32 Ford 350/420hp motor and it kept it under 200* in 110* weather with the A/C running in traffic. Now, on my 65 Corvette, I have a mechanical fan, DeWitts aluminum radiator, and had issues with running 220* in 100* temps. Bought a new fan clutch, still ran hot around 200*-210*. Then read an article by John Z and adjusted the spring on the fan clutch, also switched the 195* thermostat for a 160*. Now stays under 200* with the a/c on and 175* in 80* weather. But I have to think guys like John Z who knows the engineering of these cars can tell you what to do and why. And Mr DeWitt who sells his product and has tons of knowledge with cooling should be able to work with anyone who purchases his product. I personally like the looks of my motor with the factory mechanical fan. But, if I was going to swap out the motor for a super high performance motor, I would go with the electrical fan. Again, my 1 cent worth! But ya gotta stop pointing fingers and work together to get er done

 

John I appreciate your thoughts.

All I can say that the elect fan did not work. I replaced it with a mech. fan no clutch, and it works perfect.

What flaps, I have the defective fan and I am not aware of any flaps, and I don't see any rubber flaps, where are they located. There are two pieces of aluminum that the fan is mounted to and they in turn covered the entire face of the radiator, again no flaps and no where for the ram air to go but into the fan that blocked the air.

I don't understand your statement,[ a fixed fan is the worst condition as far as restriction], please explain.

Your claim that a fan at highway speed will not cause over heating, but if it is not letting enough air through,or limiting the air flow how can it not cause overheating.

The fan that he supplies is mounted to a motor, how can it go any faster then the motor, it does not free wheel.

I'm not sure if you jumped in at the end or the beginning but I've stated several times that the fan appeared to be operating correctly. It sucked air through the radiator, you could fell it, I even put a sheet of paper across the front of the radiator and it stuck to it. For this reason I believe it was wired right.

In your next to last paragraph you state and seem to a agree that at a lower speed, the fan can push sufficient air because it is not working against the incoming ram air pressure generated by higher speeds, your words not mine or others. Isn't that what we are trying to say was causing the problem. The ram air pressure as you call it will not move that small fan any faster then the motor was designed to and from what I have learned it was inhibiting the air movement.

I also think Tom makes a good product the radiator works great, but the fan is far from acceptable. Installed the radiator with the factory installed fan, wired it up as directed just as you suggest, had it checked and it worked as previously noted. I feel good judgment was used to come to a logical conclusion to replace the fan as all the other solutions had no effect. Did not let paradines inhibit the thinking process to solve the problem. I stated that I went out of the box. I went to a shop that builds Baja trucks, they took one look at the fan and with his 30 years of experience building race engines and solving heating problems that these vehicles have racing, stated he would bet me double or nothing he could fix the overheating problem. He removed the fan and installed a flex-a-lite fan directly to the engine with spacer to get the proper distance.
And like you said problem solved, it runs in traffic, and the highway in 100 degree dry weather at 180, in fact close to 175 [IR gun]
Dennis

 

Yes. Many nights in the Miramar too.

One of my racing buddy's parents had a house near Rubens Camp just north of town on the beach where Hannie Caulder was filmed. We have been racing or helping other since the mid-80's.

Fuel has to be brokered through SCORE or purchased down there (it's good to know the owner of Kenworth Mexico races and helps others with quality supplies).

Reading this thread it appears Tom may be taking this too personal. You may have received a one-off fan motor with a stator that was wound wrong, or the fan could have suffered a multitude of things that could have degraded it's performance (blade swap, etc.).

The good thing is the car cools properly.

(ALL)

Now if you want something hot, and don't remember the movie Hannie Caulter...

 

Tom, I just got your comments on the probable cause. I would like to send it back to you and have you look at the elect system and fan which as you state never got up to speed, possibly due to the electronics. To save you the expense of returning it tell me what to look for and I will confirm the part.no or what ever. If you need the switch back to go against the supplier it can't be to expensive to ship but the fan and the mounting pieces don't make sense, unless you need it, other wise I was going to through it away. Send me a UPS prepaid return and I'll return what you require.

I would ask you to refund me the difference between the radiator and the fan system as I have removed the fan assembly, all the elect hdwe. I paid to have it removed and the mech. fan installed.

I spent a good deal of time trying to defend your product with several knowledgeable professionals, and they all said at highway speed the fan had to be the problem.

I had a long conversation with you and no mention was made of the problems you have just suggested. We discussed the month purchased because it was you birthday and your co. was offeing a special. I know you make a good product but why did I fall through the crack. Did You post it on the forum?, if you did I missed it. You know the trouble I went through to try to resolve this not including the expense I just incurred having it fixed because, I had run out of ideas.

John must think I grew up next to a nuclear plant.

So I guess with this information we are all correct.

Thank you again for your concern and advice.
Dennis

 

I'll pay you for packaging and shipping for the fan, controls, and shroud if you are going to discard them. Please PM me. Thanks.

 

Dennis
kudos for sticking it out! most guys just sell the car.
.
u can test it if u have a DVM, ammeter. just hook it up and read the amps!
Then check the volts at the motor.
Compare with Dewitts figures. weak motor will have lower amps. thin wiring or shorted winding will show lower volts.
In 94 i bought an elec. fan; it drew 6 amps i returned it, never installed. New but faulty motor.

 

Vogie, you got it, don't forget the controller is a ?.

Matt, I'm more patient, then I used to be.

I purchased this car as a kit car. The person I bought it from started taking it apart 10 years before. I brought it home from Co as a kit car, paid $15000.00 for it. Got maybe $6000. new parts with it. I've spent maybe 25 more, don't really know or want to. Nothing was Id'ed Just in boxes. I had everything rebuilt and replaced just about everything, ask me and I did that, just go ahead and ask. I remmember the guy who wanted a excel spread sheet to keep track, what a way to spoil a good time. Took 3 yrs.

I get tired of product that dosen't work as it's supposed to. Case in point our friend who just purchased a new trans. and is taking it apart so he can repair it. Please don't tell me that's the car hobby.

A brand new coil, that failed, that I insisted was fuel delivery because it would die, when I came to a stop.

Most people around here thank I'm nuts, I just double the dose of heart med's, just kidding. Thats why I vent my frustration here, keeps me upright.
Thanks for all the advice and help

Dennis
New trim pieces that did operate as advertised.

What gives is their no quality control at all.

 

Dennis.

I thought you had the dual fan model and it has relief flaps because it is fully shrouded. The single fan model you bought is not full shrouded and does not need the flaps.

As to my statement about a not running fan being the worst restriction, it is as simple as I stated. You were making the contention that the radiator could be overheating because the fan did not shut down on the highway. Once again, a non turning fan is the worst case restriction to air flow. A fan running at part speed will move more more air than a non-running fan, and a fan running at full speed will pass more air than one running a part speed. This is true no matter how fast you are going.

The electric fans will free wheel in the airstream at speed whether you believe it or not, and at high speeds, they can actually exceed their normal running speed.

You completely misread my second to the last paragraph! Those comments were about a fan running backwards. If a fan is running backwards, it will be able to cool at low speed because it can push air forward through the radiator because there is no Velocity Pressure (Vp) working against the fan trying to push forward. As the speed increases, it will eventually get to the point where the Velocity Pressure of motion will equal the Static Pressure (Sp) capability of the fan, and at that point, the flow will be zero. If the fan is running the correct direction, the Velocity Pressure (Vp), will be additive to the Static Pressure (Sp) of the fan, and it will agument the flow of the fan beyond the original design CFM of the fan. This effect of Velocity pressure is the reason that most cars do not need a fan running at highway speeds.
Because of this additive function, a fan running at part speed will always flow more air than a non-running one, and a fan running at full speed will move more air than one running at part speed. Your concept of a fan having more restriction because it was running instead of turned off, is not possible.

I have had an electric fan on one of Tom's radiators completely fail, and you could not even tell the fan was out if the car was kept above 30 mph. The car would overheat pretty quickly in stop and go traffic, but once air started going across the radiator, the temp came right down. It is hard for me to envision a Dewitt radiator that could not cool a smallblock sufficiently without the aid of a fan at highway speeds, so I just end up back at my thoughts tha the fan could have been running backwards. I know you say it wasn't, and I am glad you got it working, but your reasons that you stated why you think it was not working were incorrect from a scientific standpoint., so one has to wonder about the entire trouble-shooting process.


Regards, John McGraw

 

Keep in mind, I don't make the controller and about 80% of them are still working fine. Spal never acknowledged that there was a problem with these and I got stuck eatting everyone I replaced. Many customers were disappointed when I stopped selling them because they worked well for some. I think a lot of the problem with these was a lack of understanding of the electronic and function. I just need 100% satisfaction, so we quit selling them. Spal still makes them today. I never mentioned a "controller" problem because you never mentioned you had one. In fact, I'm only assuming you do because that's what we were selling at the time.

Dennis, I will put in a call tag tomorrow for the fan and whatever electronics you have. I hope that end this

 

OCS1667, all I can say is you are in an "elite" group - your very first post up above was written to place the blame for your cooling woes on Tom Dewitt, his products and his advice (even though, based on your description, you are not following his basic #1 rule: work with the oem setup, and perhaps add to that, but don't replace parts of it).

As near as I can tell, you now are a member of the "dissatisfied with Tom Dewitt club". Since you are the only member, you can be president, secretary and treasurer. To further ensure your elite status as a member of that foolish group, you have now chosen to debate Tom on a topic he is absolutely expert in, and you have one experience with - cooling midyear Corvettes. Seriously, I don't know what your day job is, or if you are a recognized expert in your field, but in my case that would be like you debating me on insurance regulatory law (that is MY area of professional expertise), based on the fact that you have an insurance policy.

But, and I do mean this, I had a hard to solve cooling problem with my 65 when I first bought it, and that was ruining my experience with the car, so I am happy to hear that a fellow C2 owner has put cooling problems in the done pile and is able to enjoy his car again, without having the fear getting caught in traffic, or a hot day, or putting the AC on . . . .