Fan Shroud and Overheating

moemills · 10-07-2008, 09:45:18 PM

What impact does the fan shroud have in cooling the motor? The reason I ask is I broke a motor mount and the flex fan hit the shroud (it's toast -- new one on order). The car was not overheating prior to this happening. I can see the temp go to 190 the thermastat open, temp goes down to about 160 (its got a 180 thermastat). Then, as I'm driving it, it slowly starts to creep up to about 210 over about 10 minutes. I think it would go higher if I continued to drive it. Any ideas? What are the steps to pinpoint if the problem is something else (e.g. thermostat sticking)?

Thanks in advance.

green 1977 · 10-07-2008, 09:47:34 PM

You got it right, the shroud is a big part of cooling these things down

Cougar125 · 10-07-2008, 10:13:11 PM

What the shroud does: It makes the fan pull cold air through the radiator rather than pulling cold air from around the radiator. More cold air = cooler running temps.

moemills · 10-07-2008, 10:40:07 PM

Thanks guys!

tom3 · 10-07-2008, 10:44:33 PM

Also having the fan enclosed in the outer ring makes some improvement in how the fan moves air. There's a term for that but I can't remember it.

moemills · 10-08-2008, 09:43:46 PM

Okay guys ... I put the new fan shroud on and last night all seemed well. Then today, I took it out for a drive and it was running about 185-190 and all of a sudden it shot up to 210 and 215 and at 220 I shut the car off and coasted to the side of the road. I waited a minute, started it up, and it went to 160 and then leveled off at about 185. I checked it later when cool and it is full of a 50-50% mix prestone and water. I'm guessing I also have a thermostat issue??? Any ideas?

rscamaro73 · 10-08-2008, 11:12:51 PM

Stats go bad.

Get a new one, put 2-3 small holes around the edge. Put it in a pot of boiling water (suspended off the bottom) with a cooking thermometer in it suspended as well. Then watch to see when it opens.

You could prolly hold off on a 160 stat and run a 180 since that way it won't get TOO hot and then get a drastic cooling flow and then see-saw back up and down.

moemills · 10-08-2008, 11:19:08 PM

Thanks ... I will pick up another one ... that's an easy change.

Cougar125 · 10-08-2008, 11:39:22 PM

Good idea Wayner. I thought about putting a higher one in the truck for winter purposes. Say...200 maybe.

moemills · 10-09-2008, 06:31:11 PM

THANKS! After I fixed the motor mount, installed the new shroud and new thermastat, she sits right at 180 ... appreciate everyone's help!

Randy

NorCal_71 · 10-09-2008, 07:31:39 PM

Most likely the fast change in temp was due to the thermostat sticking.

I had this happen in a chevy pickup I had and scared me watching the temp all the sudden jump way up for no reason. When I took out the thermostat I could see where it was rubbing metal on metal.

White81Z28 · 10-14-2008, 04:03:15 PM

You may also want to take a look at your fan clutch to be sure its working properly. I had similar overheating issues, and it turned out to be the fan clutch. This of course after I changed out the Antifreeze, flushed the rad, changed out the thermo. Sould have look there first I guess. Anyway, good luck.

Well I guess I should have read all the posts, I see now you have fixed your problem.

79supergasdriver · 02-18-2009, 12:14:48 AM

Does the shroud still matter as much if you're using an electric fan mounted directly against the radiator?

z28cp · 02-18-2009, 06:47:28 AM

Quote:

Originally Posted by 79supergasdriver

Does the shroud still matter as much if you're using an electric fan mounted directly against the radiator?

My personal experience says no. I have 2 fans, a 14" and a 12", both 'pullers', mounted to my radiator, no shroud. 180* thermostat. Fans are set to come on at 190*. Never runs hot.
My car is currently only used for autocross, but had same setup when still using on the street. At autocrosses, I can make back to back runs, or let it sit and idle forever. Never gets too hot.

79supergasdriver · 02-19-2009, 07:19:49 AM

My car overheated last night. 50* and dark, temp just kept steadily climbing, regardless of moving or idle. The pump and fan were running and it was full of 50/50 mix. Last year it sat at 200* in traffic on hot sweaty summer days. So I tested my "fail-safe" thermostat in boiling water; sure enough it was stuck CLOSED! So I finally changed to a water restrictor instead. We'll see if it overheats again this weekend.