Cooling problems

Rubedogg · Apr 23, 2009

I have a '94 GT that has been having some cooling problems that have recently gotten worse. I actually changed out the thermostat about a month ago with a Mr. Gasket 180 degree unit and also replaced the hoses with the Goodyear hi-milers. It was running fine after that but now that the weather has been warming up here in GA, it is starting to run HOT! The temperature slowly creeps up as I make the drive back home from work (~40 miles) until the needle on the gage (not very accurate I have heard) is pointing right at the "L" in NORMAL. I also noticed the needle bounces around a bit and sometimes will drop all the way down to the "O" and then right back up to the "L" or close to it. It also seems to be running hotter when driving at a faster speed, like 70, and not so bad when only going 55 or 60.

When I installed the thermostat, I'm not sure if the weep hole was pointing up or not. If the weep hole was not on top, would that cause these symptoms? I think there might be air in the system as well but it would be odd for this to be a problem after a month of no issues. Also, is it possible my sending unit is bad? I intend to jack the car up and "burp" the system this weekend and see if that helps. Should I possibly enlarge the weep hole or just get a new thermostat?

Another possibly unrelated problem is that I have bad grounds as well. As the car warms up and I'm stuck in traffic, I notice my voltage drop significantly until I rev the engine and get going again. I've seen other posts with a great photo of the grounds but I think it's a photo of a 3rd generation 'Stang. Are the grounds on a SN95 on the panel near the radiator, up near the front of the car on the driver's side? I see two screws there and they are getting corroded slightly. I plan on cleaning those as well as the grounds for the starter down near the oil filter (I think). I could use some advice on this problem as well.

This site is great! Lots of great posts and I appreciate all y'alls help ahead of time!

yukisho · Apr 23, 2009

I'm actually going through the same-ish issue right now. Only difference is that the temp gauge goes up to the N and never past. Trouble shoot it. I have solved a lot of issues doing so.

ProKiller · Apr 23, 2009

sounds like air in the system to me. try burping it first. and yeah those gauges aren't that accurate, you'd have to actually get real numbers to be sure its actually overheating.

99FiveOh · Apr 23, 2009

If you're car isn't charging when you're sitting still, your alternator has one or more bad diodes in it. It will surely fail all together soon. Go have it tested by a real alternator shop and they can test the diodes for you.

Stopsign32v · Apr 23, 2009

Rubedogg said:
It also seems to be running hotter when driving at a faster speed, like 70, and not so bad when only going 55 or 60.

Time for a new radiator

desertcox05 · Apr 24, 2009

try running some radiator flush through it before you have to spring for a new rad. is the air dam still mounted to the bottom of the core support?

Rubedogg · Apr 24, 2009

desertcox05 said:
try running some radiator flush through it before you have to spring for a new rad. is the air dam still mounted to the bottom of the core support?

I actually had the radiator flushed about a year ago and the cooling system seemed to be performing well until recently. I think the service interval on flushing the radiator is two years but I'm sure some do it more frequently. Should I do it more often since it's an old (original) radiator? Also, I drained it when I replaced the hoses and I didn't notice an abnormal amount of corrosion products in the coolant. I re-used the same coolant since it looked okay and I also put in a bottle of Water Wetter. Maybe the Water Wetter is the problem...

My air dam was actually torn off (long story) wayyyy back in 2000 or 2001. I'm sure it could be contributing to some of these problems so I will most likely get a replacement and install it.

Do I have to drain the coolant to replace the sending unit on top of the lower intake manifold? Is coolant going to spew up and out and soon as it's removed?

I forgot to mention another issue within this problem in my original post: coolant does not seem to be circulating into and out of my coolant reservior. The level never changes when going from cold to hot and I touched the outside of it yesterday after returning home from work and it was not very hot. I looked at the hose connecting it to the radiator and it is hooked up properly. I think this might have something to do with the problem. Could it be caused by the air bubble possibly?

I'm also planning on cleaning off 16 years of bugs on the front of the radiator. That can't hurt!

Dino Dino Bambino · Apr 24, 2009

Grounding problems can cause the temp. gauge to fluctuate so I suggest you fix that first. If the gauge still fluctuates it's likely you have air in the cooling system. It seems to me that your radiator cap isn't allowing any air trapped in the system to escape, and could also be the reason why the level in the overflow reservoir doesn't change. Replacing the radiator cap would be a cheap and easy fix.

Stopsign32v · Apr 24, 2009

The air dam does not help at all, don't waste your time and money. Anyone that thinks so is retarded. I've had mine off for 2 years now and the car doesn't go past the N on Normal. This is on a high compression stroker and this was also on a turbo setup.

Stopsign32v · Apr 24, 2009

Oh and when you fill the radiator jack the front of the car up high. That will help get the air out of the system.

PS I still say the radiator could be at fault for the getting hot the faster you go. Sounds like it isn't flowing that well.

HISSIN50 · Apr 24, 2009

Stopsign32v said:
The air dam does not help at all, don't waste your time and money. Anyone that thinks so is retarded. I've had mine off for 2 years now and the car doesn't go past the N on Normal. This is on a high compression stroker and this was also on a turbo setup.

I'll stand behind science as opposed to your opinion.

Also, you might want to get a real temp gauge so you know what's actually going on. You based your statement against a gauge engineered with great hystersis.

Also keep the childish attacks to a minimum. I don't like being called retarded.

pirotec354 · Apr 25, 2009

your water pump could be going bad. It would cause it to run hotter because of poor circulation especially at higher speeds. It wouldnt take long to check, just take your belt off and see if you can move the shaft from side to side or up and down. If you have any play in it that would idicate that the bearings inside of it are going bad. Check the weep hole and see if it is driping and see if the wp makes any noise when you spin it(another indication of bad bearings) Just a suggestion. Hope you get it fixed.

- Justin

$t@ngB0ii · Apr 25, 2009

ii g0t tHa sAm3 pr0b mAn
& ju$t g0t a n3w rAdiaTor

99FiveOh · Apr 25, 2009

Justin has the right idea, but it isn't bearings that will cause the water pump to stop working (unless they lock up and then it won't spin at all and your belt will go up in smoke!). If the water pump is bad it is because the impeller has worn down to the nub and isn't moving any water anymore. I've seen some rusted up so bad it was just a disc spinning!

$t@ngB0ii said:
ii g0t tHa sAm3 pr0b mAn
& ju$t g0t a n3w rAdiaTor

And what the heck is this??? Is that supposed to make the post look cool or something ?

pirotec354 · Apr 25, 2009

The_Mustang said:
Justin has the right idea, but it isn't bearings that will cause the water pump to stop working (unless they lock up and then it won't spin at all and your belt will go up in smoke!). If the water pump is bad it is because the impeller has worn down to the nub and isn't moving any water anymore. I've seen some rusted up so bad it was just a disc spinning!

QUOTE=$t@ngB0ii;7886879]ii g0t tHa sAm3 pr0b mAn
& ju$t g0t a n3w rAdiaTor

And what the heck is this??? Is that supposed to make the post look cool or something ? [/QUOTE]

Yea true. Dont some manufacture's make there impellers out of plastic or is that just some gm models that have that. Im pretty sure ford doesnt do it but i was just curious.

99FiveOh · Apr 25, 2009

no, usually some kind of coated steal.

Stopsign32v · Apr 26, 2009

HISSIN50 said:
I'll stand behind science as opposed to your opinion.

Also, you might want to get a real temp gauge so you know what's actually going on. You based your statement against a gauge engineered with great hystersis.

Also keep the childish attacks to a minimum. I don't like being called retarded.

Then go out and do a back to back comparison with real gauges and let us know if the stupid airdam works or not instead of crying about it. I can save you some time and tell you it doesn't though. The stock gauge isn't the greatest but mine is pretty accurate I'd say.

HISSIN50 · Apr 26, 2009

Stopsign32v said:
Then go out and do a back to back comparison with real gauges and let us know if the stupid airdam works or not instead of crying about it. I can save you some time and tell you it doesn't though. The stock gauge isn't the greatest but mine is pretty accurate I'd say.

I have done comparison tests. I found it to have a very tangible effect, especially when ambient temperatures increase (near triple digits) or when people are having issues keeping marginal cooling systems functional. It does work.

Just to inform you, the air dam not only helps direct air across the front of the radiator but it also creates a low pressure area behind the radiator. Both help to pull air through the coil.

And the stock gauge is not accurate, certainly not enough to do diagnostics or comparisons.

fordtech28 · Apr 26, 2009

Stopsign32v said:
Then go out and do a back to back comparison with real gauges and let us know if the stupid airdam works or not instead of crying about it. I can save you some time and tell you it doesn't though. The stock gauge isn't the greatest but mine is pretty accurate I'd say.

I second Hissins answer the stock gauages are NOT accurate no matter what you say everyone has used a aftermarket gauge to determine the correct temperature
and most results would suprise you mine kept saying I was running cool when actually I was running hotter than I thought the air dam does actually work unless you are running a bigger radiator then it wouldnt make a difference.As for the issue most likely you will need a new radiator if its the original no matter how many times its flushed it its probably pretty clogged with corrosion and the only way to clean it is to take it to a radiator shop and have it cleaned professionally and because of the labor charges its probably better to get a new one.

99FiveOh · Apr 26, 2009

I dont' think they can clean radiators with plastic tanks, at least the shop here in my town. They said they only do metal tanks because they have to weld them back together.

Cooling problems

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