Overheating problem... would love some input...

[MadSammyboy]

This forum's been a great help to me in the past, so I figured I'd come here. I want to give all the background on the problem I'm having, so please bear with me...

Got my 2003 a year ago, and it started overheating. Eventually figured out it was the fan (I was running the AC when it overheated), and then an air bubble in the cooling system, so I had it bled and refilled at a dealership (because schmucks at regular garages don't seem to understand how to bleed air out of the top at the bleeder valve, which I didn't understand either until I started having the problem myself). Anyhow, I never got around to dealing with the wiring issue that made the fan work inconsistently (sometimes it works, sometimes it doesn't), because I'm not really much of a gearhead or wiring guy, and I had just moved to Dallas, and all my Mustang scholars were back in San Antonio. But after I got the air out of the system, I never had a problem with it at all. I just didn't run the AC, and since I drive it mostly on the highway, everything stayed cool enough. I've made two dozen trips to San Antonio and Houston since (each 4+ hour drives) with no problems whatsoever.

Yesterday, though, it overheated- first time there's been any sign of trouble in over a year. I was on the highway, had only been driving a few minutes, and it's cold in Dallas - not a lot of time for it to get hot, so I figured it was maybe a sticky thermostat. I pulled off as soon as it got hot, let it cool, refilled it with 50/50, and took it to get a new thermostat - it didn't overheat after I cooled and refilled it, which furthered my suspicion that it was the thermostat.

New thermostat, new hoses, and I made sure they knew to bleed the system and get the air out (I don't really have the resources to do it myself, or I'd have replaced my own thermostat). Flushed the radiator, pressure tested good, thought I'd solved it. Took it out last night, ran it for a long time to test it, no problems. Today, it overheats again. Back to square one.

Sorry for the lengthy post. What do you guys think it could be? Could it be the water pump? There were no signs of leakage, but maybe it's a slow leak that gradually let coolant out, and yesterday was the breaking point? Could it STILL be air in the system, from when it first overheated yesterday? Like I said, I'm not a major gearhead, but I'm trying to retrace the events to deduce the problem. Called my gearhead buddies and they said the water pump's the next thing they'd think of. Should I have a dealer get the air out and refill it, like I did before? I hate to take it to a dealer since they charge so much and I'm a poor graduate student, but I want to get to the bottom of this.

Anyhow, sorry again for the long post, but any input you guys can give me will be much appreciated, and if anyone knows a reliable, trustworthy shop in Dallas that knows Mustangs and knows Mach 1s, that'd be a great help, too. Thanks in advance!

[specialmach1]

Since you said you have a new thermostat I can't believe it would fail. and you flushed so there should be no debris in the motor to block water passages. Does the water pump make any strange noises. It might be the water pump. Not sure what else you can do, since you flushed it and new hoses and thermostat, Maybe the new thermostat failed, when I had my 97GT I replaced the thermostat when it overheated the first time and then it overheated a socond time and it was the thermostat and the fan was also not working and it had the wrong intake manifold due to the guy who owned it before me jerry rigged everything to make it work. i would for now check the water pump then I guess check the thermostat, If you decide to get a new thermostat I think autozone sells fail safe thermostats that will stay open if they fail. Hope you find the issue with your mach.

[birdman941]

It likely still has air in the system.
Bleed it again.
Make sure the fan comes on.
Check the resistor mounted on the fan by removing it
and inspecting it.
If it has corrosion, replace it.
They are available sparately. (Get it from Itlrun)

[MadSammyboy]

I think you guys are BOTH right - I just got home from driving it to see what it's doing, and the engine's making a new noise - a halting, rhythmic squeaking, like something's trying to turn, but having trouble. I'm letting it cool down before I turn it on again to confirm, but I'm thinking it's the water pump.

However, I need to make sure my system is air-free after I replace the water pump, and now's a good time to go ahead and take care of the fan.

If y'all, or anyone else, thinks of something else, please post, but the noise combined with the sudden heat problem sounds like the water pump to me, don't you think?

[vpMach1]

It's your fan...you said it yourself.

[MadSammyboy]

Roger that... the only reason I was thinking it was something else is because it overheated when I was doing 70 on the highway... doesn't the fan shut off at that speed? Wouldn't the air flowing through at that speed keep everything sufficiently cool? I just didn't think the fan was a sufficient factor in that situation... but I came here to get input from those wiser than me, so the fan I shall fix...

[specialmach1]

The Fan shuts off and turns on time to time to keep the temp down, It should turn on onece and a while going at that speed.

[vpMach1]

If the fan doesn't come on, you will overheat. Period. Unless you live in the arctic.

[MadSammyboy]

Thanks again for the input, everyone. I have a follow-up question: does anyone know what the cubic foot displacement of the fan is? I'm shopping replacements, and don't know anything about the stock fan.

[vpMach1]

Get the same fan. The stock fan is really good.

[eatonmach1]

I was driving my mach about three weeks ago and when I stoped at a light it started running like crap. I looked at the temp gauge and she was climbing fast. As long as I was moving it was ok. Come to find out the plastic ring that goes around the fan was broken and the fan jammed and was not running at all. It also made the noise you described right before it crapped out. When you start your car cold turn on the a/c it should kick the fan on high. If it don't you something if goin on with your fan resistor or your control module id say. How many miles are on your mach? That water pump is easy to take out and look at it just has like 4 or 5 bolts and has an o ring for a seal. Check to see if the shaft is loose from impeller. Could be a bad fan relay or a bad Coolant Temp Sensor. Does you gauge show the temp when it over heats? If so the temp sensor is good. Just a process of elimination. Best thing to do is start it in the drive way and observe it.

[MadSammyboy]

Allright, first, thanks for helping you guys - especially vpmach1. Eaton, your input's really helpful, too - here's why:

Took everyone's advice here (and some mechanic friends who are unfortunately out-of-town and diagnosed over-the-phone), and decided it was the fan. But I wasn't convinced that when I put the new thermostat in, that I got all the air out. Today, I tried to burp it, but it wasn't happening. I filled it from the bleeder valve and raised the front end to try to get as much coolant into it as I could. It still won't burp, so I think I still have air in there. It's driving me crazy.

The fan's actually turning fine whenever I throw the AC on, but I know the wiring's bad, and I'm sure it's not coming on every time.

But the noise I mentioned that Eaton also talked about might be the key. When I start the car, it's fine, but after five or ten minutes idling, it starts this squeaking/shrieking noise. I can't pinpoint it, and I don't have mechanic's ears, but it's coming from the engine - sounds like toward the top, under the scoop maybe. Is that the water pump? My mechanic friends seem to think that if the water pump were giving out, it would already have gone, but the noise is definitely worse today than it was a week ago, when the overheating started. Also, the noise is influenced by acceleration - when I blip the throttle or accelerate, it gets louder and stronger, when it's idling, it's either really quiet or not there at all.

I hope y'all will forgive my ignorance - I'm a novice, and used to getting help, but I'm in a new town where I don't have any mechanic family members to help me. Sorry, too, for all the long posts. Could I be looking at a new water pump in addition to fixing the fan? I changed a water pump in my old 5.0 years ago, but I don't really remember much about it, and I'm not even sure where the water pump is on this engine. Dumb, I know.

Please help if you can - I just want to isolate the problem so I'm not going nuts trying to fix things that aren't wrong to begin with. Thanks so much.

[MadSammyboy]

80,000 miles on the Mach, by the way.

[vpMach1]

The noise your describing sounds like a pully is bad. The water pump is right in the center of the engine. Maybe the WP pully is bad/loose belt???

With the engine cool, open the crossover tube, start your engine, and look in the hole. You should see coolant moving. If it's not moving your water pump is bad. If there is no coolant, there is your air pocket. Fill it until no more goes in. Begin the process again.

I have an electric water pump and is much easier to burp. If you use a funnel at the hole and keep it full with coolant while the engine is running it will help a lot with the burping process. You will see the air bubbles come up and the fluid drain down from the funnel. The thing is without an electric WP you will have to stop and take breaks after your engine gets to normal operating temp and allowed to cool. With an electric pump you can run it without the engine running.

BTW, your fan should be coming on at idle and when it reached normal temp.

[eatonmach1]

Originally Posted by vpMach1

The noise your describing sounds like a pully is bad. The water pump is right in the center of the engine. Maybe the WP pully is bad/loose belt???

With the engine cool, open the crossover tube, start your engine, and look in the hole. You should see coolant moving. If it's not moving your water pump is bad. If there is no coolant, there is your air pocket. Fill it until no more goes in. Begin the process again.

I have an electric water pump and is much easier to burp. If you use a funnel at the hole and keep it full with coolant while the engine is running it will help a lot with the burping process. You will see the air bubbles come up and the fluid drain down from the funnel. The thing is without an electric WP you will have to stop and take breaks after your engine gets to normal operating temp and allowed to cool. With an electric pump you can run it without the engine running.

BTW, your fan should be coming on at idle and when it reached normal temp.

Thats what I was gonna tell him too I burped my buddies mach last night for his Vortech install. I filled the cooling system like vp said this a funnel. Luckly the funnel I have kinda screws into the fill hole Any way when I got it full I blew air into the coolant tank to push the air out of the engine. When water started comming out of the bleeder I capped it! This worked perfect the first time, didn't have to mess with it again. After the car cooled it pulled a little coolant back in too.

Hope this helps on the burping process.

How that you are saying it making a noise it makes my wonder if the impeller has come loose from the drive shaft of the water pump.

Is your altenator charging ok? Could be a bad tensioner not letting the accessories work.

[Screaming04]

80,000 miles, overheating, and squealing noise... I'd be changing the water pump.

[MadSammyboy]

you guys are tops; thanks for everyone's input.

Okay, based on the input of those here and my out-of-towners, it seems like there is an issue with the water pump. Eatonmach mentioned the impeller... I know this is a total novice question, but how can I check to see if that's the case, or if it's something similar? If it's something like this, is it fixable, or am I just looking at replacing the pump?

Thanks also for the input on burping/ filling the system. I think part of the problem in not being able to burp it the other day was that I didn't have it raised enough? I had it on a slight incline, but I'm thinking I need to raise the front end a bit more? I got a good bit of fluid into the system via the bleeder valve, but I know I didn't fill it. Nevertheless, it ran for a good while without overheating today, so what I was able to get in helped. Tomorrow when it's cool, I'll do what vpmach suggested and see if fluid is moving by opening the bleeder when it's cool; I also bought a funnel with a hose, so I can fill it faster, and hopefully get it all the way filled up. I guess if I don't see fluid moving when I check it, that'll confirm the water pump.

So, all in all, it looks like I'm looking at a fan (I'm going to but one of those wiring kits that has a supplemental thermostat, per my uncle's suggestion), a water pump, and making sure the system is free of air. Any other thoughts or theories would be much appreciated, but it seems like I'm at least getting to the bottom of the problem.

I'll update as I make progress. Thanks again to all you guys for teaching me how to do this stuff. I'm learning as I go, which may be the biggest gain in doing all of this. One day, maybe I'll be helping guys like me, just like y'all do.

[vpMach1]

No prob, keep us updated!

[socalmach]

The water pump is a piece of cake.
Remove belt.
4 bolts for the pump and pull out old pump.
Reinstall new pump.
Belt back on.
Refill.

Nice trouble shooting guys.

[JVRMach]

Ok, he comes the the questions. How do you remove the air from your coolent system?

Also replace your thermostat with a fail safe and they lock open instead of closed. I put them on all of my cars as a added safety feature from overheating.

[JVRMach]

Thank you.

[MadSammyboy]

Hey, guys... just thought I'd throw an update out... I pulled out the water pump, and the bearings were indeed loose, which explains the squeaking... threw a new water pump in, and it seems to be doing fine.

I picked up a replacement wiring assembly for the fan from Ford today, and I'm going to try to do it myself. I hate anything involving wiring like nobody's business, but it looks pretty easy.

If anyone else is having this problem, be checking that water pump. I'll put one more update up after I finally conquer my fear of wires.

Thanks to all the pros here for helping me (and others) out with this!

[KissmyAZZure]

I had the same issues with my fan! It would work intermittently(sp) and sometimes it was working, but not at it's normal speed. Finally I went to a junkyard and grabbed a fan out of a lincoln mark 8 or something. It's only 3 wires you can't really mess up.... Good luck hope all goes well

[MadSammyboy]

Okay, here's the rub - I THINK I've figured out why, apart from the faulty fan wiring, my Mach kept overheating.

When I replaced the water pump, I drove it for a day or so, and it was fine, but I went ahead and opened the bleeder valve, just to make sure it hadn't lost any fluid. It hadn't, so I figured everything was cool. When I went to close the bleeder valve, I tightened the bleeder screw down as much as I could. Within a few days, it was getting hot again.

Frustrated, I refilled the cooling system, just to get some fluid back into the engine until I could figure out what was going on (by this time, I'd rewired the fan, so it was working properly).

I think that what I did was over-tighten the bleeder screw, thus severing the screw's o-ring and essentially ruining the watertight integrity of the bleeder valve. Every time I'd drive it, I'd notice the faint smell of coolant, and after a few days, it overheated AGAIN. When I went to refill the system through the bleeder valve, I found the o-ring was broken, so I put the bleeder screw back without an o-ring, until I could get one. Well, I ran the engine, just to see what would happen, and I noticed there was steam coming out of the bleeder valve, even though I had it tightened all the way down (but with no o-ring). I got to thinking: I've been over-tightening the bleeder screw, I ruined the seal, so even when there was an o-ring in there, there was no seal. To make matters worse, it probably warped the reservoir cap, so that seal wasn't airtight or liquid-tight either, and I was losing small amounts of fluid from both, which explained the smell - and because it was losing small amounts of fluid at the bleeder valve, eventually, an air bubble was forming, which is what was causing the overheating.

So I went today and got a new o-ring (plus several spares, just in case), put the new o-ring on, and tightened it way, way down, to see what would happen. Sure enough - I pulled the screw right off, and the new o-ring was broken. It was THEN that I remembered - when my uncle put the new water pump in, he didn't tighten the screw all the way down - he left a little tiny gap in between the screw lip and the lip of the valve. I wondered why he did that, but in experimenting with it myself (thank goodness I got several o-rings), I discovered that the screw 'sets' its seal way before the screw tightens all the way. It's a 'feeling' thing - you just have to tighten it until you can tell that there's a seal, but not anymore than that. If it's too tight, it severs the o-ring and ruins the seal. Then, you're basically cooking a little coolant out as long as the engine's running, and then you get an air pocket, and there you go.

Okay, I KNOW this post is really long, and I'm sorry. I also know I sound incredibly car-dumb, but whatever. I think this has been a problem all along. I refilled the system, tightened the screw just to where it seals, put a brand new reservoir cap on, and took it out for a nice, long drive. Not only did the engine not overheat, but there was no coolant smell, and when I popped the hood (with the car both running and just turned off), everything was all dry. No steam, no spilling coolant, nothing.

I really appreciate all y'all's help, and apologize again for this long post, but does this sound right to you guys? I really feel like this has been a part of the problem, and the fact that it runs fine with no smell and no leaking makes me think I'm right. Am I? If so, y'all should make sure to tell people who are having airlock problems to make sure they don't overtighten the bleeder screw, and to make sure the o-ring is in good repair, and in the right place on the bleeder screw.

I'll update again if I overheat, but I'm hopeful that I've finally put this thing behind me. Please share your thoughts if you're still awake after reading this.

[Lonestar7]

Its usually something simple that can cause a big problem! Great post!


LS