strange overheating problem
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
strange overheating problem
Hey guys I need your help. while driving my Iroc it ran hot so I took the thermostat out and its still running hot. I haven't found any leaks radiator is only a few months old and it seems the pump is working since water is flowing in the radiator and its not mixing with the oil. only way I'm losing water is when it's getting too hot and running out the overflow container.. any help would be highly appreciated
TGO Supporter
Joined: Sep 2000
Posts: 6,775
Likes: 27
From: So.west IN
Car: 87 Formula/ 00 Xtreme
Engine: TPI 305/ v6
Transmission: struggling t-5/ 4l60E
Axle/Gears: 3.08/ 3.23
Re: strange overheating problem
Does the fan(s) come on at any point ?
Assuming the coolant is fairly fresh and mixed correctly, whens the last time it's had a new radiator cap ?
Assuming the coolant is fairly fresh and mixed correctly, whens the last time it's had a new radiator cap ?
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
yeah both fans ar running and have a new radiator and cap about 3 months old and new water pump as of last weekend...and new coolant afterwards
Supreme Member

Joined: Dec 2012
Posts: 1,356
Likes: 15
From: northern VA
Car: 88 Sport Coupe Camaro
Engine: V6 2.8
Transmission: Borg-Warner T-5
Axle/Gears: RPO/GU6: 3.42
Re: strange overheating problem
You've probably got a vapor lock in the top end of the cooling system.
Make sure your thermostat has a hole in it.
See https://www.thirdgen.org/forums/v6/6...low-after.html
Make sure your thermostat has a hole in it.
See https://www.thirdgen.org/forums/v6/6...low-after.html
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
I tried that earlier this morning hoping it would work out I drilled 2 holes in the thermostat and topped off the engine with coolant.... still overheating
Member
Joined: Feb 2013
Posts: 346
Likes: 2
From: Tampa
Car: 1990 IROC-Z/1980 Firebird
Engine: 5.7 TPI
Transmission: 700R4
Axle/Gears: 3.27
Re: strange overheating problem
I remember reading a forum on here about different types of water pumps as far as direction they are supposed to spin. It may be worth checking into if you can't figure it out. Maybe one of the more experienced members has some info about it. Also, are you sure the thermostat is installed correctly, and radiator cap shut all the way (not just in the vent position)? I know these seem like no brainers, but I'm just trying to throw some ideas out. I forgot to close the radiator cap completely and had the same problem you are describing. Let us know what you find out.
Trending Topics
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
I never had a air dam until the other day I went and got one and put it on just to see.. Yeah the caps on all the way...I feel like I'm missing something it never used to do this it used to stay below 160.
Member
Joined: Mar 2012
Posts: 323
Likes: 1
From: Iowa
Car: 14 scion tc/91 camaro rs
Engine: 2.5/ 360 pooch
Transmission: 6spd man/th350
Axle/Gears: na/2.73
Re: strange overheating problem
Radiator hose sucking shut, possible head gasket, mess with your timing any?
Joined: Sep 2005
Posts: 27,893
Likes: 2,436
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: strange overheating problem
Define "overheating".
It's probably not, actually; just, pushing coolant past the cap.
Put a new cap on it.
It's probably not, actually; just, pushing coolant past the cap.
Put a new cap on it.
Supreme Member
iTrader: (15)
Joined: Oct 2003
Posts: 3,449
Likes: 5
From: Charlestown, IN
Car: 1971 Camaro
Engine: 427
Transmission: TKO600
Axle/Gears: 3.73
Re: strange overheating problem
If your car never got past 160 something is wrong.
You must run a thermostat.
Get a new cap too.
Pressure test your system.
You must run a thermostat.
Get a new cap too.
Pressure test your system.
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
never messed with the timing, hose is new and not closing... temp gets about 240.. was running a thermostat when It was running that cool... could be combustion gases leaking?
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
alright..hopefully pressure test will tell me something...hopefully not head gasket.... weird thing is I drove it to work about 8 miles from my house and it ran about 160 again
Joined: Oct 2001
Posts: 12,219
Likes: 1,141
From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: strange overheating problem
Sounds like you may have had air in the cooling system after the pump change. (which shouldn't happen if you have some holes in t-stat.)
Also make sure you have the correct rotation pump.
Also make sure you have the correct rotation pump.
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
Im gonna get another sensor to be safe but I was still boiling out
Senior Member
Joined: Mar 2009
Posts: 870
Likes: 0
From: Brick, NJ
Car: 91 Trans Am
Engine: 355 TPI
Transmission: Built T-5
Re: strange overheating problem
ok so def overheating. whats your coolant mix? have you done a pressure test yet? I would also do a compression check. Also verify your water pump is working and flush out your heater core using a hose
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
i have flushed and honestly coolant wise 60% water or close to it. havent had compression or pressure checks done yet
Senior Member
Joined: Mar 2009
Posts: 870
Likes: 0
From: Brick, NJ
Car: 91 Trans Am
Engine: 355 TPI
Transmission: Built T-5
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
haven't gotten the test done yet but it may have been the air lock cause now she's driving at lower temps. Will post back after tests
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
sorry for the extremely late reply been busy with other things....everything checked out but still when driving for a while it will overheat but when im stopped at a light or behind people itll cool back down.
Joined: Sep 2005
Posts: 27,893
Likes: 2,436
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: strange overheating problem
it will overheat
Define "overheating".
For example, when you shoot the water outlet with your infrared thermometer, what is THE ACTUAL TEMPERATURE? (not the temp gauge reading) If all it's doing is boiling over, have you replaced your radiator cap?
Member
Joined: Mar 2012
Posts: 323
Likes: 1
From: Iowa
Car: 14 scion tc/91 camaro rs
Engine: 2.5/ 360 pooch
Transmission: 6spd man/th350
Axle/Gears: na/2.73
Re: strange overheating problem
That sounds like a stuck t-stat, just curious are you still running stock crank and water pump pulleys?
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Re: strange overheating problem
If you don't like having one-sided conversations with yourself, or listening to a bunch of "maybe it's this maybe it's that" from only people who have no experience and are sending on left turns down irrelevant pathways into the weeds, you might try TELLING US WHAT IT'S REALLY DOING.
Define "overheating".
For example, when you shoot the water outlet with your infrared thermometer, what is THE ACTUAL TEMPERATURE? (not the temp gauge reading) If all it's doing is boiling over, have you replaced your radiator cap?
Define "overheating".
For example, when you shoot the water outlet with your infrared thermometer, what is THE ACTUAL TEMPERATURE? (not the temp gauge reading) If all it's doing is boiling over, have you replaced your radiator cap?
laser reading is 245 after a 15 mile test today. yes it's a new cap.
Last edited by RolandTD; Jun 17, 2013 at 11:18 PM.
Thread Starter
Junior Member
Joined: Feb 2012
Posts: 30
Likes: 0
From: LaGrange Ga
Car: 1987 Iroc Z/ 1983 iroc z
Engine: 305 carb/ LT1 750 dbl pmp carb
Transmission: 700r4 shift kit both
Axle/Gears: 3.73 both
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: strange overheating problem
If you don't like having one-sided conversations with yourself, or listening to a bunch of "maybe it's this maybe it's that" from only people who have no experience and are sending on left turns down irrelevant pathways into the weeds, you might try TELLING US WHAT IT'S REALLY DOING.
Define "overheating".
For example, when you shoot the water outlet with your infrared thermometer, what is THE ACTUAL TEMPERATURE? (not the temp gauge reading) If all it's doing is boiling over, have you replaced your radiator cap?
Define "overheating".
For example, when you shoot the water outlet with your infrared thermometer, what is THE ACTUAL TEMPERATURE? (not the temp gauge reading) If all it's doing is boiling over, have you replaced your radiator cap?

Have you burped the system to purge all air from it? If not, it will run "hot", cold, "Hot", cold, as the air bubble circulates.
How old are your hoses? It's possible that they are "sucking shut" at higher RPM's as the water pressure increases causing a no-flow or low-flow situation.
Supreme Member
iTrader: (2)
Joined: Aug 2002
Posts: 1,018
Likes: 1
From: Western NY State
Car: 87 bird
Engine: enough to break stuff
Transmission: manual th400
Axle/Gears: 4.10
Re: strange overheating problem
also didnt see where you said if you cleaned the rad fins and condenser
Thread
Thread Starter
Forum
Replies
Last Post










