Fox Body GT getting hot...what gives???

GT5OH wrote in news:1184887011.843213.203590 @x40g2000prg.googlegroups.com:

Air pockets in the system, perhaps?

definitely look for air in the system if that is not it do you have a temperature regulated high speed fan? Is it kicking on? do you have the correct anti freeze mix? It needs to have a boiling point at about 235 degrees. I live in AZ too and I had this issue with a 98 Vette. I had the anti freeze mix incorrect and had a slow leak in a hose. fixed both and it worked fine although in stop and go traffic in Phoenix it would heat up to

225 before the high speed fan would kick in. It definitely scared me to see the temp that high but it was working as designed.

I forgot one thing clean the fins in the radiator too with water to get bugs and dirt out. Bugs and dirt will plug up the cooling fins in the radiator.

Time for a new rad?

Here are the a few things that can cause overheating that come to mind:

1) Air in the cooling system. This is more probably after draining the system and refilling. Usually driving will work out the bubble. 2) A bad water pump. Typically there will be a leak present but not always. With a bad water pump the car will usually overheat under all driving conditions. 3) A bad clutch on the fan. This will usually cause overheating in stop and go driving but not during highway driving. At high speeds the there will be sufficient air moving through the radiator to cool the coolant. 4) A clogged radiator. This will usually cause overheating under all driving conditions, especially stop and go driving. Sometimes you can feel the return side of the radiator and find it abnormally cool. Also, an infrared laser thermometer can show hot and cool spots through the radiator that indicates inconsistent cooling and thus a clog. 5) One last thing that comes to mind isn't a good one, a blown head gasket. If this is the case most times you will find oil in the coolant or coolant in the oil. Not always though. The leak can be small and only occurring under combustion at high pressure. In this case the combustion gases get into the coolant, heating it and causing air pockets. There are paper strips some shops use to detect the presence of hydrocarbons in the coolant. They are very sensitive and can tell you a head gasket leak is present when there are no other symptoms.

There is a trick you can use to help diagnose if it is a clogged radiator or clutch fan. When it overheats turn the interior heat on high and the blower fan on high. If this drops the temperature some then I put my money on the clutch or the radiator. Then if it doesn't overheat at highway speeds I say its the radiator.

I have used the heater blasting at full speed in the summer more than once to limp home without boiling over. It is amazing how much this will help cool the engine.

Also, make sure the reservoir is filled to the full mark. Check it, and top it off if necessary, until it stabilizes.

Hope this helps.

Nobody has mentioned the radiator cap! Won't it cause overheating if it doesn't hold pressure?

The cooling system won't be as efficient. Also, the reservoir might not function properly. You're right though it should be checked too.

And timing. I couldn't hear the pinging (old age I guess) but the guy running the dyno did. Turns out the 16 deg advance (spec is 10) caused enough detonation to raise the temperature alarmingly fast under load. The temperature would fall back to normal almost as quickly when the load was removed. In hindsight this problem appears to have originated when I had the stator replaced about 1 1/2 years ago. I'm guessing but that was the last time the timing was adjusted. I replaced the sending unit and radiator cap made sure the rad wasn't obstructed. Nothing changed. Temperature was always normal at cruising speed and around town but if I was climbing a steep grade for a mile or so and wanted to maintain speed the temperature gauge went to the max.

Now, I'm wondering what damage might have occurred that isn't showing up yet. Especially since I'm installing a KB supercharger next Tuesday.

Which leads me to the next question. Is there a aftermarket knock sensor for a '94 5.0. As best as I can determine there is no OEM knock sensor for the

94-95's.

Richard

I doubt much damage at all. You can always do compression and leak down tests to see if there is a problem in the works.

I use one a J&S Safeguard on my '89 LX that has a Blowilla/Flowzilla setup. It is a good unit but pricey. Beats dealing with blown head gaskets though. Here's a link:

I replaced the thermostat when I replaced the hoses, new gasket and everything.

Thanks for all the replys guys, I have a lot of testing/checking to do this weekend :-)

I am gett> All those causes of overheat> > GT5OH wrote:

Check Autozone, Advanced Auto etc. for their radiators. One of them has a high performance one that is designated "extra cooling" or something like that. I got one of these for my car at around $125 and it works great. I have run up to 16 psi of boost and never had a cooling issue.

Just a couple thoughts. I'm also just a mid-level hobbyist, so someone else might have better input... First, I'd wonder about the thermostat. They do wear out and eventually fail, and that would cause your problem. If you have a Chilton / Haynes book, you CAN replace a thermostat yourself. On this motor, they're a pain in the !#@%^# to get to, with some hoses in the way, but if you could replace your radiator hoses, you can do this. Next, anytime the coolant system is 'compromised' ie loses coolant, takes in air; you have to 'burp' it, or purge the air. Basically, if / when coolant leaked, air took it's place. When you refilled the radiator, an air bubble was 'stuck' somewhere and the net effect is that you're low on coolant, even after topping it off. Also, when you tested it, realize that driving on the road, presumably with the A/C on puts more load on the engine and also generates more heat. To 'burp' it, make sure it's parked completely level, or even with the nose slightly high, so the radiator cap is the highest point on the system - air will work its way to a high point. Turn it on, put the heat on high, and let it run. Check every 3 - 5 minutes, and top off the coolant when the level drops. I usually do this over about a half hour. Other thoughts would be the fan clutch (I've had them go bad on two Fox-body 5.0's), or transmission trouble, if it's an automatic (although that's a long shot).

Yeah I replaced the thermostat when i did the hoses, it wasn't too bad but I figured might as well right? :-) Anyway, I also have a brand new "bullet proof" upgraded transmission from Ford, with a nice lifetime warranty on parts and labor from the transmission shop, so that shouldn't be the problem, although now that you mention it, I think I will take it in and have them check it out. As for the rest, I did try to purge the air bubbles but maybe I just didn't get them all out....I am considering getting a loan from the bank to just do a real overhaul on all the old stock parts, I really love this car and it only has 83,000 and change original miles. Thanks for the input guys!

Sean

Thanks for the link. I emailed J&S this evening and received this reply from John Pizzuto.

"Our Universal unit is designed for cars with a distributor and one coil. It's temporarily discontinued, while we design in a new micro processor. The old processor is no longer available. Please check back in two or three months."

Richard

I have dealt with John personally. He is a good guy. Very knowledgeable.

I've had two LX 5.0 fox bodies - terrific vehicles. On one of them that was running hot even after the radiator was replaced the cure was a new heavy duty fan clutch - about $40 at Autozone. Dropped the temp about 10 degrees overall and kept it from creeping up at every stoplight. When I bought my S-10 pickup, used with 130K miles on it, it would sound like it was boiling inside the engine every time I turned it off in the summer. The cure for that was a new radiator cap

- the old one simply was not keeping the pressure high enough and the hot spots in the engine would start to boil when it was shut off and the water stopped moving.

I'm in Phoenix too. My '89 has 175,000 on it. Mostly all orginal. It would sometimes run hot in the summer (80~100 miles/day to work). I put in a Pep Boys 3 core radiator for $120. Decided to replace the cap, temp sender and thermostat with stock Ford parts. Temp Guage was now reading 3/4 all the time instead of 1/2. Firend gave me a portable digital infrared temp gun. The themrostat housing was reading 190 (perfect) and radiator was about 180. So its just the sender. Mostly goes up to 3/4 (now the norm) and stays there no matter where I drive (including up to Williams).

Let me know if I can help (101 and Cave Creek Rd). With that low mileage you shouldn't need to replace much. The best add on I did was a Ford engine oil cooler.

hank