Overheating issues - again!
Thread Starter
Burning Brakes
Joined: Mar 2011
Posts: 862
Likes: 9
From: Communist party of MD
Overheating issues - again!
'69 coupe here - Driving slow or sitting at traffic lights - temperature going up to about 210 degrees in about 60 seconds. Get the car rolling past 40 mpg and temp will hover around 170 degrees. Last season the car would not get over 160 degrees. Not sure whats going on.
-355 Blueprint engine (1,500 miles on it)
-timing and idle adjusted by performance shop last year
-160 degree thermostat
-new water pump
-new Dewitts radiator
-new engine fan & fan clutch (fan is facing correct direction)
-coolant level good & burped of any air pockets
-fan shroud & seals in place
-temperature was tested using infrared camera last year.
Can anyone help me out before I break down and take it to my mechanic?
-355 Blueprint engine (1,500 miles on it)
-timing and idle adjusted by performance shop last year
-160 degree thermostat
-new water pump
-new Dewitts radiator
-new engine fan & fan clutch (fan is facing correct direction)
-coolant level good & burped of any air pockets
-fan shroud & seals in place
-temperature was tested using infrared camera last year.
Can anyone help me out before I break down and take it to my mechanic?
Last edited by KevinG; Jun 25, 2013 at 03:39 PM.
Race Director
Joined: May 2006
Posts: 18,606
Likes: 2,542
With the engine cold and off, grab the fan and spin it, if it doesnt stop within say a half turn the clutch is shot. You are describing a problem related to the fan who's purpose is to keep air moving when you are at an idle or moving slowly.
Thread Starter
Burning Brakes
Joined: Mar 2011
Posts: 862
Likes: 9
From: Communist party of MD
bad thermostat perhaps? (that was changed 1,500 miles ago)
Last edited by KevinG; Jun 25, 2013 at 04:45 PM.
Instructor
Joined: Nov 2011
Posts: 234
Likes: 24
From: Warsaw Ohio
Or better yet get an Electric Fan . The best way to check for a defective fan Clutch is : get it good and warm 210 is great open the Hood then have Someone shut off the Engine while You observe the fan. It should stop turning almost immediatly after the Motor stops. At this temperature it should be locked up tight, if it keeps spinning replace the Fan Clutch.
Thread Starter
Burning Brakes
Joined: Mar 2011
Posts: 862
Likes: 9
From: Communist party of MD
The best way to check for a defective fan Clutch is : get it good and warm 210 is great open the Hood then have Someone shut off the Engine while You observe the fan. It should stop turning almost immediatly after the Motor stops. At this temperature it should be locked up tight, if it keeps spinning replace the Fan Clutch.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Just about has to be fan clutch or shroud to radiator seals. Runs cool at highway speeds means its not radiator, rad seals, lower hose or air dam.
Low speed the fan needs to pull as much air as possible through the rad. If the shroud to rad seals are leaking it can bypass air. If the fan clutch is weak it will not pull enough air.
Low speed the fan needs to pull as much air as possible through the rad. If the shroud to rad seals are leaking it can bypass air. If the fan clutch is weak it will not pull enough air.
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Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
Looks like you have all the right things in place, and assuming that what you say about your set up is current and correct, I’ll make what may sound like a stupid (but cheap) suggestion.
Test it again with your infrared. It may not be actually heating up. If it’s not, you could just have a bad connection at the sender. I had it happen on my ’58 (pickup) – spent a lot of time testing etc., and it was a simple thing that kicked my ****.
Test it again with your infrared. It may not be actually heating up. If it’s not, you could just have a bad connection at the sender. I had it happen on my ’58 (pickup) – spent a lot of time testing etc., and it was a simple thing that kicked my ****.
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
Pro
Joined: Nov 2008
Posts: 542
Likes: 3
From: Bloomfield Hills MI
Tom beat me to it. I chased a similar issue. Simple to pop off the line, ensure manifold vac at carb or port and test canister with a vacuum pump. The symptom reported of sudden change would be representative of this situation.
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
You said the engine was new, but what about the manifold? Could there be junk built up in the water jackets of the intake manifold? I had this happen once, drove me nuts until I figured it out. The symptoms were similar: temp stay reasonable above 40 mph or so, then would climb above 210 at a stop, or driving slow. I went to an electric fan, new radiator, etc etc until I finally found the problem in the intake water jackets.
Last edited by htown81vette; Jun 26, 2013 at 01:50 PM.