overheating problem
Thread Starter
Instructor
Joined: Nov 2007
Posts: 185
Likes: 0
overheating problem
I have a 79 with a rebuilt 350. less than 100 miles on the rebuild, new dewitts radiator, electric fan set to come on at 200 and 180 deg thermostat but the temp in the car just keeps climbing. it shot up before I installed the fan shroud but the fan shroud will keep the rnning temp around 220 or a little more when going between 60-70 on the freeway but if I go 75-80 it starts creeping toward red again. I can't figure out why it keeps going higher. does anyone have suggestions on what I can check? no leaks in coolant or anything like that. I have the break in oil still in it, if that could have something to do with it.
Thread Starter
Instructor
Joined: Nov 2007
Posts: 185
Likes: 0
I bought 50/50 mix cooling and I think the air is out of the syste, is there a way to check? pressure cap is brand new as well but I will double check. I will see if I can find the timing thread, thank you everyone.
Burning Brakes
Joined: Aug 2008
Posts: 845
Likes: 12
From: LAKE BARRINGTON IL
Second the clutch fan...and air dam
I would do a 160 tstat, which should run the engine at 180-185 (read somewhere this was optimal running temp)...
are you sure the clutch fan is coming on properly and not disengaging?
I had this problem and the fan was disengaging...found out by keeping on...with no issue and tweaked from there...
I would do a 160 tstat, which should run the engine at 180-185 (read somewhere this was optimal running temp)...
are you sure the clutch fan is coming on properly and not disengaging?
I had this problem and the fan was disengaging...found out by keeping on...with no issue and tweaked from there...
Race Director
Joined: May 2003
Posts: 11,814
Likes: 9
From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
Second the clutch fan...and air dam
I would do a 160 tstat, which should run the engine at 180-185 (read somewhere this was optimal running temp)...
are you sure the clutch fan is coming on properly and not disengaging?
I had this problem and the fan was disengaging...found out by keeping on...with no issue and tweaked from there...
I would do a 160 tstat, which should run the engine at 180-185 (read somewhere this was optimal running temp)...
are you sure the clutch fan is coming on properly and not disengaging?
I had this problem and the fan was disengaging...found out by keeping on...with no issue and tweaked from there...
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Race Director
Joined: May 2003
Posts: 11,814
Likes: 9
From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
I need to know exactly what you have before I make any suggestions...
You said you have electric fans but then you said you installed the shroud which would be impossible with dual Spals. So, what kind of fan are you using? Pusher or puller? Single or dual? Do you still have a clutch and engine driven fan? Most important, have you checked the gauge reading with an IR gun? If your sending unit has been replaced during the rebuild there is a good chance it's telling you a 20-30 degree lie.
You said you have electric fans but then you said you installed the shroud which would be impossible with dual Spals. So, what kind of fan are you using? Pusher or puller? Single or dual? Do you still have a clutch and engine driven fan? Most important, have you checked the gauge reading with an IR gun? If your sending unit has been replaced during the rebuild there is a good chance it's telling you a 20-30 degree lie.
Thread Starter
Instructor
Joined: Nov 2007
Posts: 185
Likes: 0
I do have electric fans. Not the dual fans dewitts sells with their radiators unfortunately. I have a single puller 16" high flowing fan from summit. It is running right. I checked. I'm not sure how to burp the radiator but I didn't install the engine either. It does have a new sending unit. Where do I check the temp with an ir gun? The temp will not stop at 220-230. It just keeps creeping toward the red. If it stopped I wouldn't be as worried. I couldn't find the thread that discussed timing, can anyone post a link for.me?
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
You can shoot the IR gun at several areas to get a average. The thermostat housing and the upper inlet connection to the radiator. New motors will run a little bit hot until they break in and I wouldn't cruise high speeds until at least 500 miles. Just to eliminate it as a possible problem, I would put the thermostat out to see if that is working correctly. Do check that lower hose for possible collapse.
Burning Brakes
Joined: Aug 2008
Posts: 845
Likes: 12
From: LAKE BARRINGTON IL
my overlook..."clutch fan"...I read it earlier and was spouting ideas off my head.
either way it led to more info...
Second the IR gun...I had a new sending unit not send correctly...found out it with the IR gun...so switched out the new one with another new one and it worked...parts guys said this sometimes happens....>FYI...
either way it led to more info...
Second the IR gun...I had a new sending unit not send correctly...found out it with the IR gun...so switched out the new one with another new one and it worked...parts guys said this sometimes happens....>FYI...
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
If you check the temperature with an IR gun you can verify the sending unit and gauge reading all at once. If the gauge is saying 220 and the IR gun says 190, then you know something is wrong.
Thread Starter
Instructor
Joined: Nov 2007
Posts: 185
Likes: 0
The fans come on at 200 like I set them so I the no its right but I will try the ir gun this weekend to be sure. It also keeps running sometimes when I try to shut it down. Sometimes just for a second tonight it lasted for 2 or 3. Is that a timing issue that could be contributing or something completely unrelated?