Overheating has ME overheated!! 2nd Electric fan(s), I think it's not the fan or radiator

[biomedtechguy]

I would like feedback from anyone using electric fans, whether a single or dual fan setup.
HOW HAVE ELECTRIC FAN(S) WORKED FOR YOU? ANY PROBLEMS?
I find it very hard to believe that the company, Cold Case/Max Performance, that makes a fine quality aluminum radiator would sell a dual 12" fans and aluminum shroud assembly that doesn't work. After making sure everything was working properly and there were no air pockets in the cooling system, I was still seeing temps over 220° in my wife's GTO.
I got with the vendor that sold us all kinds of stuff for both of our cars, and he recommended a 16" two speed fan and shroud assembly, rated 4.9 out of 5 stars, over 70 reviews. I also have the 17" version for my Roadrunner, and soon I will see how it works to keep my 440 6bbl cool. I got Cold Case radiators for both cars.
I tried the factory mechanical clutch fan without the shroud on the GTO and it seemed to run cooler than the dual 12" fans, and that's when I decided to get the 16" fan. The problem is that I didn't take the car on the highway w/the mechanical fan, because that's where it is overheating. Everyone says at 40 MPH or higher the fan is no longer in the equation anyway.
Bottom line is I can't believe that the fan I have in the GTO now, so highly rated by over 70 people, the only brand that this very busy, very knowledgeable vendor sells because he never has any problems with them from customers, is the "second fan and shroud assembly that is so crappy" IT is the reason why the car overheats! No way!
I am convinced that the gap between the water pump impeller vanes and the divider plate (crazy Pontiac design) is too big, and that is causing the pump not to work properly, especially at hjgher RPMs.

 

[Fran Blacker]

If you take water off check impeller isn't turning on shaft. It's a long shot, friend was pulling his hair out and happen to check that bingo.

 

[440Coronet500]

Sounds like you have the cooling properly addressed. What pump are you running? Flow is the second part of the equation, I'd be looking at a high flow pump. 440'

 

[biomedtechguy]

Thanks Fran.
There's a 70 page thread on this on the Pontiac forum, and it mostly deals with the odd way that the water pump is configured. Basically the chamber that makes up the pump has a plate in it, and if the edge of the hole in the plate that surrounds the impeller vanes isn't within about 1/10th of an inch from it, the pump doesn't work efficiently. I suspected that from the start, even though I made the mechanic aware of this being a critical issue to be aware of, I didn't know what the gap should be.
I'm sure it's not the radiator, as it is a 2 row, 1" diameter tubes aluminum, very well constructed unit.
Cruisin the Coast starts next Sunday, and my Roadrunner is still in the shop as well as me having to deal with the GTO. As usual, last minute work on the cars no matter how early I try to get ahead of it.

 

[biomedtechguy]

Sounds like you have the cooling properly addressed. What pump are you running? Flow is the second part of the equation, I'd be looking at a high flow pump. 440'

Apologies for bringing a Pontiac issue to the Mopar forum, but I posted here mainly for feedback on members experience with electric fan(s).
The CVF Wraptor serpentine belt and accessories system uses a high flow aluminum water pump with the cast impeller vanes, all of the best designs and materials that are desired in the Pontiac water pump universe. At 70 miles an hour, what kind of fan and how it's driven is certainly NOT a factor in having an overheating problem.
Running hot has been a huge problem since we got the GTO back from having a lot of work done to it, and I'm pissed off that the mechanic didn't check to be sure it was ready before he collected FIVE GRAND for the work he did and said it was ready to be picked up.

 

[biomedtechguy]

Since my Roadrunner is still in the shop, and I've had a CVF Wraptor serpentine belt and accessories system, Cold Case radiator, and the 17" version of the same fan installed on my Roadrunner, as well as Vintage Air AC system, all just like the GTO, I'm certainly hoping the fan isn't the problem or I'm going to have trouble too. BUT that's what I'm saying, bouncing off you all...I find it impossible to believe that 2 reputable companies, one that specializes in high quality aluminum radiators and the other that makes extremely highly rated and recommended electric fans can BOTH have fan and shroud assemblies that are the cause of the GTO running hot. No way!
It's me venting too, venting about a guy who we were referred to to do work on my impatient wife's car that got paid big for the work he did and released the car to us NOT READY.

 

[Dan64]

Bio, probably a stupid question but have they tried a different thermostat or made sure that a hose isn't sucking closed?. Also did they check the temp. gauge to make sure it's correct. Brake drag?.

 

[black64]

Might want to check lower rad hose for spring internal to hose to keep hose from sucking in restricting flow at higher RPM.

 

[Johnpat]

I'm sure you've tried different timing ,advance & total?

 

[wagonman]

Well here is my take on electric fans. Had a Camaro we set up for 3/8 dirt track, typical 350/350. Ran a large electric fan at Fernley near Reno with temps over 100 at nite. After hot laps engine was close to 240. Put a solid fan on it and temp never got over 200. I hear you on the Poncho pump issue. Had a 67 and 69 Goat both 400/400 when I was in Vegas. Both ran hot 220+ until I put Flow Cooler pumps on them. Pontiac pumps are block,cover and year specific also. 2 or 3 choices iirc. Can you still get the plates for the pumps?

 

[biomedtechguy]

Thanks guys.
Neither the upper nor lower hose have a spring inside. Keep in mind this is a Pontiac 421, not a Mopar, if that matters. I know the upper hose was very stiff when it was at operating temperature, I assume from having pressure in it. I am tempted to throw the clutch fan back on and take it on the highway at 70 MPH just to be sure, but then again, how can a fan affect cooling at that speed unless it's blocking air flow, which is NOT the case. Not only have numerous people, websites, etc said that "over XX MPH" (usually 40 or 45 MPH) the fan no longer is in play, but the Dakota Digital fan control module and other fan control systems have a "speed shut off" value, to shut the power off to the fan over a certain MPH. I haven't set that because I haven't got to a point where it runs at an acceptable temperature.

 

[biomedtechguy]

Pontiac pumps are block,cover and year specific also. 2 or 3 choices iirc. Can you still get the plates for the pumps?

Crazy Pontiac design...
I needed a dimpled timing chain cover because of the water neck and Tripower! Even that was different on mine. I changed from the factory 8 bolt water pump and timing chain cover to an 11 bolt. The water pump came with the Wraptor serpentine belt and accessories system, so I'm thinking I have to use that one, but it's very well made and uses the cast impeller, that is the best design and material. I plan on "tweaking" the plate, massaging it with a hammer or whatever I need to use to mould the dome closer to the impeller vanes.

 

[Fury Fan]

My thoughts, from 25 years of working/learnign on cars, 25 years as an engineer, and a few years working as an engineer at a cooling-fan manufacturer:

The root cause is always 1 of 3 areas:

1. an engine creating excessive heat into the coolant,
2. inadequate coolant flow,
3. or inadequate heat exchange at teh radiator.

Elec fans are a crutch for a cooling system that, for whatever reason, benefits from more airflow across the radiator, to 'fix' the true cause. That's not necessarily a bad thing, though, if actually allows the system to work.

But - those elec fan blades are a restriction to airflow through a radiator, esp when not in use (freewheeling is still a restriction, albiet a reduced one). From discussions at the fan manufacturer I was at, those aftermarket fans have terribly-designed blades (for generating flow) and the finger-guards on them are quite dense and therefore are a restriction also. They may provide a CFM rating on the fans, but usually not at the corresponding pressure drop, so the airflow rating is meaningless when attached to a radiator whose pressure drop across the fins is unknown. This restriction will also get worse if the fans have box shrouds built into them, if they are covering a 22-26" square of heat exchanger with a flat-box shroud with some 12-16" circles for the fans.

I can fully see that a cooling system with some underlying problem, could have a highway overheating problem due to reduced radiator airflow.

With all that said, I would remove the shroud if possible and take a close-to-home highway drive and see the change.
Maybe then take 1 fan off and see if the car can stay cool at low speed (you have no mechanical fan, correct?) and how the highway heat changes.

 

[Dan64]

Bio, i'd look real hard at the lower hose and a new radiator cap also.

 

[Fury Fan]

Not only have numerous people, websites, etc said that "over XX MPH" (usually 40 or 45 MPH) the fan no longer is in play,

What this statement usually means is that at higher speed, the ram-air effect of the vehicle moving through the air is sufficient and a fan is not require to pull sufficient air through the radiator to cool the engine.

 

[biomedtechguy]

The only thing I haven't tried is the mechanical clutch fan on the highway, and now I feel stupid for not having done that, only because it's a box not checked off.

 

[biomedtechguy]

What this statement usually means is that at higher speed, the ram-air effect of the vehicle moving through the air is sufficient and a fan is not require to pull sufficient air through the radiator to cool the engine.

Correct. That's why I don't think it's the fan.

 

[Fury Fan]

Bio, i'd look real hard at the lower hose and a new radiator cap also.

Agreed on the spring, especially if you decrease the clearance on the water pump impeller, as that will create more coolant flow, and increase suction on that lower hose, and that could become a new culprit if it isn't already.

But if you are not actually boiling coolant out, I would disregard the radiator cap as a cause. The cap maintains a pressure rating, which raises the boiling point, but doesn't change hte coolant temperature. Increasing the cap rating also increases pressure on your heater core. I always want the lowest pressure cap required to prevent boiling.

 

[62MAX]

Never had need for electric fan,you know they never overheated when new with all O.E.M. equipment,even with a 30"x 8" grille opening,this has never been over 200* under any condition,idle,on the road or whatever !

 

[Fury Fan]

Correct. That's why I don't think it's the fan.

Does your setup look comparable to this one?