Running Hot.....Help

mimicons · 10-24-2002, 02:51 PM

Second attempt here, so if you can, please respond and help me out. My car is running pretty hot after I drive it for a while. The only changes I have made are a flex-fan and underdrive pulleys. There are no leaks, etc in the cooling system. Would a different thermostat help? If so, what should I look to get.

Again, any help will be greatly appreciated.

Mike C.

Falcons Talon · 10-24-2002, 03:00 PM

Maybe I can help a little here. First of all Most would agree that you need at least a 180* thermostat, and a handful swear by 192*. What are you running? Secondly, when I got my car back after having an oil pump installed, as I drove home, everything was fine, but after about 20 minutes, the heat started to slowly and steadily creep up. After a changing all the hoses and the water pump, the onlt thing left was cleaning out the radiator. When they took off one side of the tank, they saw that it was half plugged up. This is on a three row radiator. The cleaned out the rows and now my car runs great. I guess what I'm trying to say is take the radiator to a radiator shop and have it pulled apart and cleaned.

84LX89GT · 10-24-2002, 11:07 PM

Does your car get hotter when it's standing still, while it's moving or both?
The fact that you underdrove your water pump and also that a flex-fan reduces in efficiecy as you move (also when they get older i've heard they tend to "flatten out" earlier in the rpm range) could be the problem in itself.

about how many degrees temp do you think you're running? Does it keep getting hotter once it starts or does it top off at a certain temp?

Probably one of the most common fail items is a thermostat and they usually cost under $13. I bought a 180* for my GT and it works great. This is probably where i'd start. You may also want to pressure test your cooling system because if the system doesn't stay pressurized the boiling point of your cooling system goes down and it's ability to cool is diminished greatly because the coolant may start to boil causing air pockets.

Good luck, keep us posted, and get more detailed on what's happening.

Coupe50h · 10-24-2002, 11:09 PM

cap? and yea a 180 stat is always good.

Hozer 88GTConv · 10-24-2002, 11:15 PM

If you are still running your fan clutch and it's a little old, that could be it too.

Strim91GT · 10-24-2002, 11:59 PM

I used to have mine running really hot after i put on heads and intake a long time ago. i changed thermostat to a 160, i know 180 is really what they recommend. and it still ran just as hot as before. then i drained my anti freeze and looked inside the radiator and i could tell that most of the radiator was plugged with the white puddy looking stuff. And so i got a granatelli aluminum radiator from jegs. And it worked great, it never ran over 140 after that so i had to put a hotter thermostat back in it.... and then later on i discovered i also had a bad fan clutch because i could heat it up as much as i could and it would still free wheel. So i would agree with falcons talon and make sure your radiator is good and clean. the granatelli radiator was $300 from jegs but it is a nice peice and i polished it real easy. Also make sure your temperature gauge isn't lying, the stock in dash gauge is hardly at all accurate. my gauge was half way up to 270 in the dash before my mechanical autometer gauge started to move off 140.

HiFlow5 0 · 10-25-2002, 08:16 AM

I know exactly where your coming from!! I was fighting the same problem as you for a while and heres what I did to resolve it. I originaly had a 180 degree stant stat in there and underdrives. Damn car would heat up all the time. I bought a flex fan and thought it would help. Nope, made the car run hotter, upwards of 215-220 degrees! So I got a 195 degree Robert Shaw stat to let the antifreeze stay in the radiator longer to cool more before cycling again. Got rid of the crappy flex fan and got a new fan clutch for the stock fan. Car now ran at 200 degrees. I then tryed putting the stock pulleys on and the car ran at 195 degrees. So I guess I'm saying is stay away from stant stat's. Underdrives will make the car run hotter.

moc · 10-26-2002, 01:54 AM

watch that flex fan , they can be killers , there are mixed fellings in the 5.0 world about there cooling ability . don't no wether you put it on or you bought it that way with the fan but it must be LOUD . ( if you can in the near future ,get rid of it , and use gloves when you are ever around it ,they are VERY dangerouse) get a electric or standard fan for that stang . next ,you may have to much coolant in it . contrary to everyones thinking . antifreez is not a good coolant at all ! and after owning 7 mustangs myself .And being around the hobby for close to 30 years now ,i am not a big supporter of underdrive pulleys . i have never seen in all that time any substance in what the manufactures claim ,and have even asked miss cleo about them . so now you no where i stand ! 192 or 180 is the ticket . check your heater core . do you have good flow . good luck .. Michael

jrgoffin · 10-27-2002, 10:24 AM

I'm with Moc on this - toss the underdrive pulleys. The water pump will turn slower, thus the lack of coolant flow and the higher temps. Get the OEM fan (the 1993 fan is the newest and best) a new Motorcraft clutch, a good 195 thermostat, and put the stock pulleys back on!

Agent_4573 · 10-27-2002, 06:36 PM

Ok... First off... what kinda mods do you have on this car besides a fan and some pulleys? I ran a taurus electric fan w/ undrive pulleys, and a 180* stant thermotstat and the car never ran hot. First, take a thermometer, open the radiator, start the car and let it warm up, then see what temp your stat is actually opening at. You may have a bad stat... it happens, there like 8 bucks try another one. If you don't have a thermometer, let the car warm up and feel the upper radiator hose, if its soft your stat isn't open and no water is flowing.

After this, I would flush the radiator just to make sure theres nothing clogging it. If that doesn't work, your water pump might have gone bad. You say this is your second time going through this problem... what did you trty the first time to fix it?

Falcons Talon · 10-28-2002, 11:27 AM

Agent, IRT the second time through comment, I think he meant that this was the 2nd time he posted the question.
Figure out the problem yet Mimi (shudders at thought of Drew Carey show Mimi )

TMASTER · 10-28-2002, 11:47 AM

I had the same problem, my radiator was 10 years old... I ended up replacing the water pump, all the hozes, the radiator, and a thermostat. The problem was my radiator though, it was clogged up from years and years of running. I tryed to flush it with cleaner but it wouldnt work.

THe best thing to do if it is the radiator is to go buy a new one. 2 core stock radiator is around $120 dollars.. Also I use a 160 thermostat... it runs COOL now!!!

10-24-2002, 02:51 PM	#1
mimicons Registered Member Join Date: Aug 2001 Location: Atlanta Area, USA Posts: 42	Running Hot.....Help Second attempt here, so if you can, please respond and help me out. My car is running pretty hot after I drive it for a while. The only changes I have made are a flex-fan and underdrive pulleys. There are no leaks, etc in the cooling system. Would a different thermostat help? If so, what should I look to get. Again, any help will be greatly appreciated. Mike C.

10-24-2002, 11:07 PM	#3
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	Does your car get hotter when it's standing still, while it's moving or both? The fact that you underdrove your water pump and also that a flex-fan reduces in efficiecy as you move (also when they get older i've heard they tend to "flatten out" earlier in the rpm range) could be the problem in itself. about how many degrees temp do you think you're running? Does it keep getting hotter once it starts or does it top off at a certain temp? Probably one of the most common fail items is a thermostat and they usually cost under $13. I bought a 180* for my GT and it works great. This is probably where i'd start. You may also want to pressure test your cooling system because if the system doesn't stay pressurized the boiling point of your cooling system goes down and it's ability to cool is diminished greatly because the coolant may start to boil causing air pockets. Good luck, keep us posted, and get more detailed on what's happening. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

10-24-2002, 11:09 PM	#4
Coupe50h Registered Member Join Date: Aug 2002 Location: SanAntonio, Tx Posts: 957	cap? and yea a 180 stat is always good. __________________ X-Texas highway patrol ssp 1990 coupe - exploder Gt-40 iron heads, Explorer intake, 19 lber's. E-cam. crane 1.7 rollers. 190fp. 75mm maf. 65mm tb, tubular subframe connectors, mac cai, Asp crank pulley, T-5, king cobra clutch, flowtech 1-5/8 unequals, mac X-pipe Frpp driveshaft, lakewood Lca's. race weight 3,160 12.69 @ 107.35, 1.71 60' 26x8.5 drag's 3.90 gear 13.20 @ 106.91 - 235/60/15 firestones 2.3 60' 3.27 gear

10-24-2002, 11:15 PM	#5
Hozer 88GTConv Registered Member Join Date: Feb 2002 Location: Jacksonville, FL Posts: 706	fan clutch... If you are still running your fan clutch and it's a little old, that could be it too. __________________ 1988 GT Convertible 331 10:1 TW heads, GT-40 intake, MSD, TRW flattops, B Cam w/ 1.7's, MAC exhaust, 24's, 70 TB, 76 MAF, 3.73's, Pro 5.0, Koni's, Anderson PMS, Wideband 02, yatta, yatta... One week with new motor, two speeding tickets...joy

10-24-2002, 11:59 PM	#6
Strim91GT Registered Member Join Date: Jan 2001 Location: Kansas Posts: 59	I used to have mine running really hot after i put on heads and intake a long time ago. i changed thermostat to a 160, i know 180 is really what they recommend. and it still ran just as hot as before. then i drained my anti freeze and looked inside the radiator and i could tell that most of the radiator was plugged with the white puddy looking stuff. And so i got a granatelli aluminum radiator from jegs. And it worked great, it never ran over 140 after that so i had to put a hotter thermostat back in it.... and then later on i discovered i also had a bad fan clutch because i could heat it up as much as i could and it would still free wheel. So i would agree with falcons talon and make sure your radiator is good and clean. the granatelli radiator was $300 from jegs but it is a nice peice and i polished it real easy. Also make sure your temperature gauge isn't lying, the stock in dash gauge is hardly at all accurate. my gauge was half way up to 270 in the dash before my mechanical autometer gauge started to move off 140. __________________ vortech s trim,edelbrock 6032's, b303, cobra intake, 70mm tb, pro m 75mm bullet, granatelli alum. rad., accel 330+ digital ign., msd boost tim. ret., 30# inj., 190 lph fuel pump, t-rex pump, bbk, press. reg., tremec tko, ram billet flywheel, dual friction clutch, pro 5.0 shifter, 4.10 gears, aluminum quadrant, motorsport alum. driveshaft, hooker headers, off road h pipe, flowmaster cat back, subframes, megabyte jr lowers, heavy duty uppers, eibach springs drag springs, koni sport shocks, polished cobra r's, 85-86 taillights, msd pro billet distributor

10-24-2002, 03:00 PM	#2
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Maybe I can help a little here. First of all Most would agree that you need at least a 180* thermostat, and a handful swear by 192*. What are you running? Secondly, when I got my car back after having an oil pump installed, as I drove home, everything was fine, but after about 20 minutes, the heat started to slowly and steadily creep up. After a changing all the hoses and the water pump, the onlt thing left was cleaning out the radiator. When they took off one side of the tank, they saw that it was half plugged up. This is on a three row radiator. The cleaned out the rows and now my car runs great. I guess what I'm trying to say is take the radiator to a radiator shop and have it pulled apart and cleaned.

10-25-2002, 08:16 AM	#7
HiFlow5 0 Registered Member Join Date: Mar 2000 Location: Springfield, Ma, usa Posts: 706	I know exactly where your coming from!! I was fighting the same problem as you for a while and heres what I did to resolve it. I originaly had a 180 degree stant stat in there and underdrives. Damn car would heat up all the time. I bought a flex fan and thought it would help. Nope, made the car run hotter, upwards of 215-220 degrees! So I got a 195 degree Robert Shaw stat to let the antifreeze stay in the radiator longer to cool more before cycling again. Got rid of the crappy flex fan and got a new fan clutch for the stock fan. Car now ran at 200 degrees. I then tryed putting the stock pulleys on and the car ran at 195 degrees. So I guess I'm saying is stay away from stant stat's. Underdrives will make the car run hotter. __________________ NewEngland Auto www.baystategearheads.com -91 Mustang Coupe, ex 4cyl (sold) -99 F150, 3" lift, 35" Procomps, Magnaflow exhaust

10-26-2002, 01:54 AM	#8
moc Registered Member Join Date: Mar 1999 Location: Ocean City , Maryland Posts: 344	First off watch that flex fan , they can be killers , there are mixed fellings in the 5.0 world about there cooling ability . don't no wether you put it on or you bought it that way with the fan but it must be LOUD . ( if you can in the near future ,get rid of it , and use gloves when you are ever around it ,they are VERY dangerouse) get a electric or standard fan for that stang . next ,you may have to much coolant in it . contrary to everyones thinking . antifreez is not a good coolant at all ! and after owning 7 mustangs myself .And being around the hobby for close to 30 years now ,i am not a big supporter of underdrive pulleys . i have never seen in all that time any substance in what the manufactures claim ,and have even asked miss cleo about them . so now you no where i stand ! 192 or 180 is the ticket . check your heater core . do you have good flow . good luck .. Michael __________________ 1991 5.0 NotchBack,Black as of 05/04/09 34,300mi. 2001 LIGHTNING Black 29,872 mi. 05/04/09 (Hangar Queen) SMOKEM UP

10-27-2002, 10:24 AM	#9
jrgoffin Registered Member Join Date: May 2002 Location: The Midwest Posts: 79	I'm with Moc on this - toss the underdrive pulleys. The water pump will turn slower, thus the lack of coolant flow and the higher temps. Get the OEM fan (the 1993 fan is the newest and best) a new Motorcraft clutch, a good 195 thermostat, and put the stock pulleys back on! __________________ '90 LX Too many mods... Rear-Disc tech

10-27-2002, 06:36 PM	#10
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	Ok... First off... what kinda mods do you have on this car besides a fan and some pulleys? I ran a taurus electric fan w/ undrive pulleys, and a 180* stant thermotstat and the car never ran hot. First, take a thermometer, open the radiator, start the car and let it warm up, then see what temp your stat is actually opening at. You may have a bad stat... it happens, there like 8 bucks try another one. If you don't have a thermometer, let the car warm up and feel the upper radiator hose, if its soft your stat isn't open and no water is flowing. After this, I would flush the radiator just to make sure theres nothing clogging it. If that doesn't work, your water pump might have gone bad. You say this is your second time going through this problem... what did you trty the first time to fix it? __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

10-28-2002, 11:27 AM	#11
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Agent, IRT the second time through comment, I think he meant that this was the 2nd time he posted the question. Figure out the problem yet Mimi (shudders at thought of Drew Carey show Mimi )

10-28-2002, 11:47 AM	#12
TMASTER Registered Member Join Date: Sep 2002 Location: TEXAS Posts: 161	therm/radiator I had the same problem, my radiator was 10 years old... I ended up replacing the water pump, all the hozes, the radiator, and a thermostat. The problem was my radiator though, it was clogged up from years and years of running. I tryed to flush it with cleaner but it wouldnt work. THe best thing to do if it is the radiator is to go buy a new one. 2 core stock radiator is around $120 dollars.. Also I use a 160 thermostat... it runs COOL now!!!

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