Fan shroud blocking airflow?

[40cpe]

I took a trip of about 55 miles one-way with my rebuilt 276" engine, cleaned/tested stock 4-row radiator. The temps were in the low 80s. When running about 65 (3.78 rear), the engine temp goes to 195 and the electric cooling fan cuts on. I turned the fan off and the temp gradually climbed to 205 before I turned the fan back on. With the fan running the engine temp stays about 185. That tells me I have an air flow problem. I have the sheet metal air deflectors in place in front of the radiator. I'm using the Cooling Component fan and shroud pictured. The shroud covers all but about 3" of the core just under the tank. I'm thinking now I would have been off better to use a 16" Spal fan without a shroud. Am I missing something? In the past I've always been able to turn the electric fan off on the highway.

[FlatheadTed]

Stock fan and shroud works good ,Your Electric fan runs continually to achieve a similar result ,I would say yes your shroud is blocking it .Ted

[zorro4153]

The fan and shroud are doing it's job. If you had an air flow problem, it would run hot with or without the fan on. The real test is sitting in traffic in 80 deg. weather, with a 16' fan and no shroud you are only pulling thru the radiator where the fan is and no where else.
Then you will have an air flow problem

[paul2748]

Zorro is right. The purpose of a shroud, in conjuction with a fan, is to pull air from the full area of the radiator (or the full area of the shroud), not just where the fan is. Theoretically, the shroud should cover the entire radiator for max air flow.

The fact that the temp goes down with everything working seems to mean that it is okay.

[FlatheadTed]

The fan should not run continually to cool which is what he is trying to explain ,with no shroud on when on the freeway it cools quite ok ,Ted

[rich b]

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Put a couple of rubber flap doors in the lower corners of the shroud. They will permit more air to pass when on the road; but still seal at low speeds. Of course; it is a guess how effective they will be on your set-up.

[expavr]

" In the past I've always been able to turn the electric fan off on the highway."
Did that setup have a shroud?

[40cpe]

Originally Posted by expavr

" In the past I've always been able to turn the electric fan off on the highway."
Did that setup have a shroud?

That was on a '40. It only had a Spal 16" fan. The fan on this car was installed when the engine was put in the car so I have no history of it without the fan and shroud.

[Drbrown]

Your 185 running temp sounds fine too me. A lot of folks here prefer 180 deg stats.

My '47 has newish radiator, 160 deg stats, and 16 amp 2400 cfm 16 inch elec fan with curved blades in a square shroud/frame like yours. I may have a larger radiator than you as the shroud covers most of the width of the radiator but only the upper 2/3 of it. I love the quiet fan. It had an adjustable temp control on it - type with sensor that sticks into top fins. It's operating temp was adjustable from abt 150 up to 200 degrees. I kept it at factory setting of 165 deg. The setup worked good but the temperature controller acted-up and under warranty I changed to a fixed 190 deg controller - a little high for my taste, but it works well. On open road in summer (say 80) my system levels off at what I feel is an ideal 180-185 deg .... so fan doesn't operate.

However, in city traffic at slower speeds the engine compartment seems hot and I now sometimes experience vapor. Didn't happen where it had a 6-blade noisy belt driven fan that blasted a lot of air thru there. My choice seems to be just use my Airtex elec pump at vapor lock times, or maybe change over to expensive and distant non-ethanol gas.

[G.M.]

Try setting the fan to come on at 175 to 180. It may be getting
to hot before the fan comes on and can not recover. On a 39
truck or car which I have both the mechanical fan runs all the
time and they run very cool. In fact I have Bob Shewman's 180
stats in both and they run between 178 and 182 in warm
weather. G.M.

[19Fordy]

40cpe:
On the Cooling Components website it says that part of the shroud can be trimmed for maximum cooling. "The top and bottom flanges may be removed to provide maximum cooling".
Seems like you initial suggestion that the shroud is blocking air flow may be correct. Check it out.
http://www.hotrodhardware.com/index....od/prd7151.htm
Other Ideas:I have a Griffin radiator and shroud in my 40 and the shroud opening is slightly larger than the dia. of the fan. I have also read that the fan blade should not extend more than 1/3 its blade width inside the shroud. However, you fan blade design may not require that. Just to be sure, give the company a call.
QUESTIONS and THOUGHTS: If this fan is in your 40 have you blocked off the air flow under the front of the hood so hot air won't keep recirculating under the hood? The last photo shows 2 pieces of thin sheet metal siliconed in place under hood nose. You could also use thin tempered hardboard or even rigid cardboard. Keep it light weight.
Are all the sheet metal side panels and chin panel installed around the front area of the radiator so as to funnel the air into the radiator? Also, some folks remove the engine splash pans to allow hot air to escape easier from engine compartment. If your timing is too retarded engine may overheat.

[V8 Bob]

Originally Posted by 40cpe

I took a trip of about 55 miles one-way with my rebuilt 276" engine, cleaned/tested stock 4-row radiator. The temps were in the low 80s. When running about 65 (3.78 rear), the engine temp goes to 195 and the electric cooling fan cuts on. I turned the fan off and the temp gradually climbed to 205 before I turned the fan back on. With the fan running the engine temp stays about 185. That tells me I have an air flow problem. I have the sheet metal air deflectors in place in front of the radiator. I'm using the Cooling Component fan and shroud pictured. The shroud covers all but about 3" of the core just under the tank. I'm thinking now I would have been off better to use a 16" Spal fan without a shroud. Am I missing something? In the past I've always been able to turn the electric fan off on the highway.

Fully shrouded and shut off electric fans can easily block sufficient air flow at speed to cause overheating, and is why some shrouds have "air doors" that allow more air flow. As a general rule, imo, electric fans do not need a shroud, and agree with just using a 16" Spal without a shroud, my choice both on my running '32 and project '40.

[Sal]

I just installed a cooling componants fan and shroud on my 302 Ford powered model AI was told by the company rep. to butt the shroud all the way up to the top radiator tank, for maximum results.

[expavr]

The function of a shroud is to provide more efficient cooling at lower vehicle and engine speeds, eg stop and go traffic. If that is not a concern eliminate the shroud. What isn't clear to me in this discussion is that it sounds like the shrouded system works just fine if the fan is left on so why turn it off? Its not robbing engine HP as a conventional fan would and at higher driving speeds I can't think that the noise from its operation would be anymore objectionable than a conventional fan. I have a 3500 CFM shrouded electric fan cooling a 400 CI hemi that is set to cycle on at 185* and it doesn't care whether I'm idling at a stoplight, going 20 MPH or 70 MPH which IMO is the big advantage of electric fans in general. When the coolant reaches a temp of 185* its on and I have the peace of mind knowing that to be true.