Hey all. I’ve had a problem with my car overheating since I changed the coolant on it yesterday morning. I’m having a terrible time finding what the root cause is and wanted to see if anyone here could help.
It all started when I noticed a low coolant light turn on the instrument cluster. That prompted me to inspect the engine cabin where I found a hole in the hose that runs vertically in front of the drive pulleys (I think it’s called the overflow hose). The hole was created because I have BBK underdrive pulleys on there, which if you’re familiar, use the stock harmonic balancer as a piggyback to the replacement pulley. Basically, it pushes the front of the pulley out by about an inch, which caused it to come in contact with the hose and wear a hole into it.
So since I needed to fill my coolant and replace that hose, I thought it would be a good time to replace the remaining coolant. Here’s the process I followed for that:
-drained radiator
-drained coolant from the block using plug that’s just above the oil pan
-replaced hose
-poured into expansion tank (a.k.a. degas tank) pure coolant
-poured pure water into expansion tank in equal quantity to the coolant I added
-started engine w/ heater on full and let it run until it reached operating temp (I noticed a loud screeching sound from the water pump pulley that I hadn’t heard before, so I sprayed some WD40 on it and it promptly went away, but retuned after a few minutes. The next day I checked to make sure the four pulley bolts were tight, but it still screeches—this is a clue for later)
-turned engine off and let cool
-topped off expansion tank w/ 50/50 water/coolant
-replaced cap until it clicked and checked for leaks at radiator, hoses, and drain plug (no leaks)
-took car for test drive (which was really just a normal drive cus I was pretty sure everything was ok). Atmospheric conditions were ~70 degrees, cloudy, very windy.
When I drove it, it took the normal amount of time to heat up and remained at the normal temp on the highway, I believe. I don’t know for sure because I only noticed a high water temp reading and steam coming from the engine cabin after I pulled over into a side street. I drove very lightly until I reached my destination, which was about another 5 minutes. Total time of approx 20 minutes. At that point I noticed coolant on the top of the expansion tank, but the tank was full. Also steam was coming out of the bypass pipe cap (the thing in front of the alternator).
I didn’t know what to do, so I let it cool as I went to lunch (about an hour) and called around. I found out that the most likely cause was air in the system. Then I drove it to the local parts store where I removed the bypass pipe cap to release any extra air that might be in there. I also topped off with 50/50 premixed coolant.
I drove it home little-by-little—about five minutes of very easy driving, then stopping to let it cool for about 10 minutes. I also removed the cap a couple more times.
After I got it home I idled the engine in the garage with the cap off for about 15 minutes. I was sure by then that the air had been removed, so I took it for a test drive with the engine already warm. Within 1/2 mile it had already overheated, so I returned home.
At this point, I’m pretty sure it’s not air in the system. I’ve also checked the belt, which is tight, the radiator is free of obstructions, and the fan works. The upper radiator hose gets very hot (too hot to grab for more than 1-2 seconds) and the overflow pipe does as well. That means that the thermostat works. The suspicious thing I noticed is when I take the overflow cap off I didn’t see any coolant flowing through there. Shouldn’t there be coolant flow? Also, when the car is idling at operating temp and I pinch the upper radiator hose with my hand and then release it, I don’t feel a surge as if coolant is rushing through. That also means I must be having a pumping or flow problem.
I’ve owned the car for 2 ½ years now and I’ve driven it hard and this is the first time it has ever overheated on me, so I feel like it can’t be a coincidence.
Could you please tell me what you think the problem might be? The thing I’m thinking is that the belt rubbed up against the water pump pulley so that it may have slowed its rotation and damaged the pump? Other than that, I don’t know what the problem would be.
My guess is you'll need to change the thermostat, sometimes it'll get blocked after service. The noise from the pump pulley is concerning, and wd40 is not a good idea on a pulley, it may quiet it down, but it will make the belt slip and can exsacerbate the problems. Make sure there is no fluid coming from the weep hole on the pump and try changing the thermostat. If the problem is still there after a new thermostat, I would say there is either a problem with the pump or the radiator. You can try flushing the system, but you have to do this BEFORE you change the thermostat, flushing often causes the thermostat to get clogged, so flush the system and then change the themostat.
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That hunk of junk? Yeah, well I've made a few special modifications to that yellow 99 Gt, it makes the Kessel run in 12 parsecs and eats turbo japs and poops chevy's
Trapped air downstream of the thermostat is infamous in these cars. Many builders drill a small hole in the thermostat to handle this. If you remove the thermostat and test it and it works normally, this is cheap insurance.
Its also quite possible that the hole in the hose was not the only problem, particularly if the waterpump has a lot of miles on it. Coincidence DOES happen...
But my first thought is that you may have dislodged a lot of crud and it is now giving you grief somewhere in the system. If the thermostat checks out, and no air is being trapped anywhere, AND the waterpump checks out, check to make sure the belt is properly tensioned (another part that often fails with some age) and the pump is getting plenty of rotation. I am no fan of the BBK piggyback UDP's, and you should also examine that noisy pulley - it might be wallowed out.
Finally, and perhaps most likely given the coincidental timing, you might have an obstruction in the cooling network inside the engine. Another power-flush sequence might solve this, in that case.
Best of luck, and get back to us with your results.
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tripleblack
"You can never be free until you let yourself go."
Since the hose gets hot to the touch, i'm thinking the thermostat is good. Also now-a-days thermostats come with a tiny hole in them. If the hose wasn't getting hot at all i would think thermostat. but then again, you never know. With the degas bottle, i've never seen coolant moving around in there hot or cold, running or not running. I'm sure you can squeeze the hose and don't feel a surge but i'm sure it would be more evident at a higher rpm speed.
being your car is 10 years old, could be the water pump or something obstructing in the coolant system.
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1995 Mustang GT-Heavily Modded-Sold 2003 Ford Lightning-Sold 1997 Saleen-5.4 conversion-Sold 2005 Mustang GT-Torch Red-Sold 2003 Mustang Cobra-Oxford White 2003 4Runner V8 Sport Edition 4X4
Did you burp the system? To do it correctly in our cars you fill the system through the crossover tube. You'll see a plug with a fitting for a 1/2 drive socket wrench. That's where you fill it. once full, you plug it and start the car. Take it around the block and come back. Let it cool off and pull the plug off again. Fill it up again, and repeat. Do it until it no longer shows any air. Thats it. No problem! If you need clarification pm me and I'll try to answer any questions.
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C&L 80mm mass air and True Flow pipe, Mac CAI, BBK 65mm tb, Steeda non-piggy back ud pulleys, MGW shifter, RAM HD clutch and aluminum flywheel, 3:73 gears, 2.5" Dynomax o/r x pipe, 3" MAC cat back system w/ 3 1/2" tips, Kenny Brown(front and rear strut tower brace, caster plates, subframe connectors,extreme matrix brace,jacking rails, torque brace, lowering springs), Bilstein shocks, 03-04 Cobra(side scoops, rear bumper cover, top), 6pt roll cage, white FR500's, FMS 2000 Cobra R air dam.
Hey guys, thanks for the replies. I got on here thinking I had been totally ignored :-(, but my e-mail must just be out of date cus I have lots of replies :-D THANKS
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My guess is you'll need to change the thermostat, sometimes it'll get blocked after service. The noise from the pump pulley is concerning, and wd40 is not a good idea on a pulley, it may quiet it down, but it will make the belt slip and can exsacerbate the problems. Make sure there is no fluid coming from the weep hole on the pump and try changing the thermostat. If the problem is still there after a new thermostat, I would say there is either a problem with the pump or the radiator. You can try flushing the system, but you have to do this BEFORE you change the thermostat, flushing often causes the thermostat to get clogged, so flush the system and then change the themostat.
I may change the thermostat, but I think it's working properly since the upper rad. hose gets hot. I may do it anyway. I didn't see any leakage around the pump. I agree the noise is concerning. I don't know why I would've started to hear that just recently if it had nothing to do with the recent problems.
Quote:
Trapped air downstream of the thermostat is infamous in these cars. Many builders drill a small hole in the thermostat to handle this. If you remove the thermostat and test it and it works normally, this is cheap insurance.
Its also quite possible that the hole in the hose was not the only problem, particularly if the waterpump has a lot of miles on it. Coincidence DOES happen...
But my first thought is that you may have dislodged a lot of crud and it is now giving you grief somewhere in the system. If the thermostat checks out, and no air is being trapped anywhere, AND the waterpump checks out, check to make sure the belt is properly tensioned (another part that often fails with some age) and the pump is getting plenty of rotation. I am no fan of the BBK piggyback UDP's, and you should also examine that noisy pulley - it might be wallowed out.
Finally, and perhaps most likely given the coincidental timing, you might have an obstruction in the cooling network inside the engine. Another power-flush sequence might solve this, in that case.
That's true. It could be a coincidence, but it would be a remarkable one.
Belt is properly tensioned. It's nice and taught and the water pump pulley is running perfectly in synch with the belt.
What does "wallowed out" mean?
How would I find out what a power flush entails?
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Since the hose gets hot to the touch, i'm thinking the thermostat is good. Also now-a-days thermostats come with a tiny hole in them. If the hose wasn't getting hot at all i would think thermostat. but then again, you never know. With the degas bottle, i've never seen coolant moving around in there hot or cold, running or not running. I'm sure you can squeeze the hose and don't feel a surge but i'm sure it would be more evident at a higher rpm speed.
being your car is 10 years old, could be the water pump or something obstructing in the coolant system.
I would tend to agree about the hot hose thing.
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Did you burp the system? To do it correctly in our cars you fill the system through the crossover tube. You'll see a plug with a fitting for a 1/2 drive socket wrench. That's where you fill it. once full, you plug it and start the car. Take it around the block and come back. Let it cool off and pull the plug off again. Fill it up again, and repeat. Do it until it no longer shows any air. Thats it. No problem! If you need clarification pm me and I'll try to answer any questions.
I kept reading about people burping the system, but had no idea what it involves. I'll give your described method a try. That plug is the one I've been taking off to release air already, but I haven't poured fluid down there. BTW, it's a 1/4 inch drive (for others who may read).
Well, one would think this would be a simple process, but nothing is easy, I guess!
You initally should have left the radiator cap off and filled the coolant through a funnel at the crossover tube. Putting coolant into the overflow with none in the crossover first is asking for air trouble.Filling at the C Over you'll see the overflow tank start to fill up(as well as the hoses and radiator) once the overflow is full, tighten the radiator cap then start the car, as it's idling and getting up to temp continue to add a light stream of coolant at the crossover, once you see it about an inch down from the top stop then let the car idle til it warms up, it's gonna start popping air and liquid and overflowing a bit, let it do that for about 20 seconds then turn the car off, put the cap bolt back on. that's the procedure! you said you let it run with that cap off for awhile? did you let it overflow? Try pouring coolant in an overflowing it when it's idlling. I don't think it's the T Stat if it didn't have problems before you added coolant!
BTW, it's a 1/4 inch drive (for others who may read).
I stand corrected! A half inch socket would make it huge! I mis spoke, I meant 1/4". Thanks for pointing it out.
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C&L 80mm mass air and True Flow pipe, Mac CAI, BBK 65mm tb, Steeda non-piggy back ud pulleys, MGW shifter, RAM HD clutch and aluminum flywheel, 3:73 gears, 2.5" Dynomax o/r x pipe, 3" MAC cat back system w/ 3 1/2" tips, Kenny Brown(front and rear strut tower brace, caster plates, subframe connectors,extreme matrix brace,jacking rails, torque brace, lowering springs), Bilstein shocks, 03-04 Cobra(side scoops, rear bumper cover, top), 6pt roll cage, white FR500's, FMS 2000 Cobra R air dam.
1999 Cobra Overheating After Coolant Change 
