Overheating!!
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 48
Likes: 0
From: Detroit Michigan
Overheating!!
I installed an isky cam .450 lift 264 duration, headers and a ZZ4 bow tie aluminium intake recently. I also upgraded to a 4 core aluminium radiator with two 15" cooling fans. {pulling air thru the radiator}. 160 degree thermostat. Coolant seems to circulate correctly. The motor will over heat in 15 minutes whether it is sitting at idle or driving. The timing is set at 8 degrees advance. The car runs great with no hesitation. I have tried reversing the direction of the cooling fans, removing the thermostat and changing the timing. No smoke from the exhaust. No coolant in oil. No leaks.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
Fix your timing and see if it still overheats - you're way too retarded, which will make the engine run very hot. Timing should be 36 total, which should get you about 16-18 degrees initial. Make sure you are running the correct vacuum advance control unit for the engine parameters, and make sure it's hooked up to manifold vacuum.
For detailed info, drop me an e-mail request for my "How to Set Timing" and "Vacuum Advance Specs and Facts" papers.
Lars
V8FastCars@msn.com
For detailed info, drop me an e-mail request for my "How to Set Timing" and "Vacuum Advance Specs and Facts" papers.
Lars
V8FastCars@msn.com
Advanced
Joined: Apr 2008
Posts: 92
Likes: 1
From: Carol Stream Illinois
If you removed coolant from your system and refilled it, I would suspect an air pocket somewhere in the cooling circuit. I recently had the same issue and once I got the air out of the system it operates within range.
Instructor
Joined: Dec 2011
Posts: 142
Likes: 0
From: Tucson Az
What temp switch do you have and why do you have a 160* t-stat ? Do you have full voltage to your fans when they are on? Dual fans draw a lot of amps they need to be wired with 40 amp relays ( individually) or with a 70 amp realy (together) with the proper gauge wiring. Most fans CFM ratings are at 13 volts. This is probably not your primary problem but something to think about and check.
Burning Brakes
Joined: Nov 2006
Posts: 893
Likes: 7
From: Orange Park Florida
Many overheating problems are caused by inefficient radiator airflow. Be sure the fans are pulling the maximum amount of air through the radiator and not from around it. If you think you have an air pocket, use a fail-proof thermostat - the ones that have a small hole in the valve that allows fluid and air to flow continually.
Last edited by JimT; Mar 28, 2012 at 07:28 AM.
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Instructor
Joined: Dec 2011
Posts: 142
Likes: 0
From: Tucson Az
A 160* t-stat will not make the engine run cooler, it will not allow the coolant to stay in the radiator long enough because it opens sooner.I would put a 180* or a 195* in there and change your temp sender to match or adjust the temp switch (if you have an adjustable one) How many volts to fans when they are running? Do you have a new ( good) radiator cap? What lb is it rated for? Do you have a recovery tank? When you say it "overheats" does it actually spit out coolant or does the gauge just read hot?
Last edited by nonracer; Mar 28, 2012 at 09:27 AM.
Instructor
Joined: Jan 2012
Posts: 103
Likes: 0
From: Sonoma Ca.
I recomend at least a 180 degree TS I believe 195's are recomended for c.a.c. cars, a 160 won't let the engine warm up properly during cold weather causing engine ware, pulling the TS will actually makes the motor run hotter, without it water runs through the radiator to fast and doesn't allow the water to cool through the heat exchange proscess.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
Have you "shot" the engine temp with an IR temp gun to verify how hot it's really getting? (How hot do you believe it's getting..?) Often, you can find the problem by "shooting" the IR temp along the cooling system flow path. But first, verify with a different gauge (like an IR gun) how hot it's really getting: My temp gauge says I'm running hot, too, but my IR gun says I'm running right at the 'stat temp.
...and about thermostats:
Keep this in mind: A thermostat only determines the engine's minimum temperature. It has no control whatsoever over max temp. Max temp is determined by cooling sysyem capacity and the engine's heat output. Use of a "too cold" 'stat (like a 160) in the engine won't make it run any hotter or colder than a 190 'stat if the engine's heat output is exceeding the cooling system's capacity: A 160 'stat wide open is producing the same cooling system flow capacity as a 190 wide open 'stat, and either one is making no difference if your coolant temp is 240...
Lars
...and about thermostats:
Keep this in mind: A thermostat only determines the engine's minimum temperature. It has no control whatsoever over max temp. Max temp is determined by cooling sysyem capacity and the engine's heat output. Use of a "too cold" 'stat (like a 160) in the engine won't make it run any hotter or colder than a 190 'stat if the engine's heat output is exceeding the cooling system's capacity: A 160 'stat wide open is producing the same cooling system flow capacity as a 190 wide open 'stat, and either one is making no difference if your coolant temp is 240...
Lars
Racer
Joined: Nov 2011
Posts: 261
Likes: 1
From: Montgomery TX
Lean mixture setting on the carb will also cause the motor to run hot. I suspect you have a few things contributing to the problem. I would agree with the other posters that you have air in the cooling system. Does the coolant tank on the radiator need to be topped off after every run? Are you running a stock water pump? Some rebuilt pumps may have too much clearance in them and poor circulation capacity. Also, make sure your lower radiator hose is not kinked or colapsing when running.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
Racer
Joined: Jun 2009
Posts: 393
Likes: 3
After you do all that stuff if its still overheating that fast,I would think you might have a head gasket leaking a bit pushing heat into the cooling system. You wont always see white smoke from the exhaust when this happens. It s just pushing compression into the cooling system,not sucking it in. Probably very small leak. Maybe, maybe not. just a thought
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 48
Likes: 0
From: Detroit Michigan
I used an IR gun. I have tried different thermostats and taking the thermostat out completely. Is it possible have blocked a cooling passage partially? Is the ZZ4 intake compatible with my stock '74 motor and intake gaskets? I think I have troubleshooted everything as far as I can without pulling the intake, heads, water pump etc. It is running great but I think I am taking it apart tonight and check. I appreciate all the help you guys have been giving me.
Instructor
Joined: Jul 2010
Posts: 120
Likes: 0
I had cooling issues until I sealed around the shroud completely using a 1inch thick very dense foam rubber them added a fan spacer to get the fan as close to the rad as possible then what i think did the trick was I added a stewart stage 2 water pump. it runs WAY cooler now!
Drifting
Joined: Feb 2005
Posts: 1,879
Likes: 38
From: Los Gatos CA
Perhaps it will help to diagnose if you better describe the overheating conditions. Overheating at idle and around town suggests insufficient air flow across the radiator. At freeway speeds you have sufficient air flow so suspect radiator efficiency. You mentioned a new 4 row radiator, so this sounds unlikely. I would try the $5 fix - replace the thermostat. If it is partially stuck you would experience your symtoms...