Overheating Question.. Solution?

runasoft

Registered User
hey Guys,
I'm brand new to these forums as well as being the owner of a 1991 SC 5-Speed.

I know this post is really long but I wanted to five you guys full background of the past few days so you all could better assess the situation...

First, a little background. I purchased the car a few days ago for 900 bucks.. The car is in great condition but didn't have the supercharger installed. The guy included a rebuilt one in the price but I had to put it on. Well after 100 bucks in misc parts, (the guy tore this thing off the motor) LOL. We checked the radiator fluid level and it was full.. OF WATER.. so we just said the heck with it and figured we would flush and fill it properly later.. We got the car started and running beautifully..

We took the car out on some back neighborhood roads first and it drove perfect. No pinging, no surging.. No hissing.. Boost gauge was working but the temp gauge was NOT..

We didn't notice anything funny except that the brakes were really hard.. No biggie just used some extra leg power and figured we'd tackle that issue later. So, we head out onto the main road and open her up in 2nd gear and left off when we hit 3rd.. Car pulls like a beast and boost reads about 7-9 pounds.. We keep driving her around for another 5 minutes and decide to take her a little further.. No smoking, no smell.. ok, so we are driving on the highway feeder going about 45mph in third gear and open her up.. nothing happens.. the car just kinda sits there.. Hmm, wierd, we thought maybe we're in 5th.. recheck the gear and no we're in third... so, threw her in 2nd and although the rpm's went up, the car still just sat there with the pedal floored.. Mind you we only floored it for about 2 seconds... Ok, so we pull over, turn around and go home slowly.. never over 30.. it's only like a mile drive.. we live in a small town..

We get home, and open the hood.. the coolant overflow tank is boiling over.. We figure it's got to be the fan, radiator, or the thermostat... So, we remove the thermostat and check it, (put it in a boiling pot of hot water), it opened right up and closed when we stuck in under running cold water.. So, even that said, we just went ahead and left it off... redid the gasket with some gasket paper and gasket sealer and slapped it back on without the thermostat...

Now, we check the radiator.. We removed the bottom hose and ran water through the top of the radiator, essentially flushing it out and just as we thought before, pure water in the radiator.. The water ran straight through the radiator from both openings and really just gushing out as if no resistance which was a good sign. So we figured the radiator is good... Right?

Next, we check the fan.. Well, surprise, the fan is not coming on even with the A/C on.. So we rigged it up with a switch to the inside of the car and just have it running full blast all the time... No harm in that...

Ok, so now here we are.. Radiator seems to be ok, thermostat removed and fan is on.. Car is running great and we decide to take a little cruise again remembering to stay close to home... We drive around for about 5 min and don't notice anything funny.. We open her up again in 2nd.. and all seemed fine.. we opened her up again in 1st and all seemed fine.. it wasn't until we were headed home when we tried a pull in 2nd gear it was like all the power died again.. so we were like 100 feet from home so we drive it right home and again the water was boiling over!!!

This time, we noticed that the water pump hose was cracked and hissing and leaking.. we also noticed that some clamps needed to be replaced on the large upper rad hose and the lower... I was out of cash so it will have to wait till next week. This is just my weekend driver so she can wait..

Ok, so all that said, what do you all think it could be? Could the water pump be bad? if so, what can i do to test it? Are there other things I should check?? I don't think we blew a headgasket because there was absolutely no smoke and the oil is not cloudy nor is there oil in the coolant...

I searched all over these forums and didn't find anything like my issue and that's why I posted..

I'd appreciate any help or suggestions you all can give me.

Thanks..
 
A water pump is a visual test, if its leaking etc. But it sounds to me like that's what it's got to be.. except that, if its boiling over, then water is moving. I would flush the entire system, refill it with coolant (running water in it is a huge rust danger anyway) Is the water brownish? (rusty?) Just run some coolant in it, completely flush it, then run it and watch it. Your fan is probably fine just, without a temperature gauge to tell it when to turn on.. it cant! Do you have access to an external water temp gauge? If so, flush it, run it at idle, and let it warm up. Let it warm up regardless, and watch your water pump, see if it leaks or makes any strange noises or anything. Water pumps usually aren't too expensive so.. you might just pop one on there for the hell of it and see if that fixes it (I'd say 99.5% sure it is.. but the boiling over is strange, I've killed 2 water pumps and the water in the radiator was always cold, because it wasn't being pumped through the engine.. but mine blew with exception, one locked up completely and caused the pulley to be sheared off.. and the other one sheared itself internally and didn't pump an ounce of water)
 
I searched all over these forums and didn't find anything like my issue and that's why I posted..

Thank you for your post but unforunately, the problem is not exactly like mine and I had seen that post. I also asked about other things such as the water pump etc... I looked for an hour on these forums and used the search feature along with many other search terms and couldn't really find anything like my problem. I apologize you feel that I did not search but I did.

- Rudy
 
A water pump is a visual test, if its leaking etc. But it sounds to me like that's what it's got to be.. except that, if its boiling over, then water is moving. I would flush the entire system, refill it with coolant (running water in it is a huge rust danger anyway) Is the water brownish? (rusty?) Just run some coolant in it, completely flush it, then run it and watch it. Your fan is probably fine just, without a temperature gauge to tell it when to turn on.. it cant! Do you have access to an external water temp gauge? If so, flush it, run it at idle, and let it warm up. Let it warm up regardless, and watch your water pump, see if it leaks or makes any strange noises or anything. Water pumps usually aren't too expensive so.. you might just pop one on there for the hell of it and see if that fixes it (I'd say 99.5% sure it is.. but the boiling over is strange, I've killed 2 water pumps and the water in the radiator was always cold, because it wasn't being pumped through the engine.. but mine blew with exception, one locked up completely and caused the pulley to be sheared off.. and the other one sheared itself internally and didn't pump an ounce of water)

Thanks for your reply.. The water was not brownish at all... I will see what I can do about the water pump. I can get a new one for around 40 bucks so I'll slap that on along with all new hoses and some fresh coolant.. I know some people tend to say 50/50 is a good mixture.. But I live in South Texas and we don't get very cold here so I was thinking 75/25.. I don't know much about coolant tho so what do you think? It was actually very clean.. Even when we flushed it, there was no brownish color. I don't know if maybe the guy just happened to fill the system to the brim with water before I bought it or what. I don't see why he would if the car wasn't in running condition.. Maybe he was aware of a problem.. I'll have to call him

- Rudy
 
id bet you headgaskets are going, these motors are notorious for it, id bet the previous owner failed to mention this to you.
One of my last tbirds i had i knew the gaskest was leaking but as long as i drove it normal it would stay at normal operating temp, but as soon as i would put my foot in it, it would send the temp skyrocking boiling hot.
 
also make sure you put that thermostat back in.....your radiator will not have time to do its job cooling down the water temp if its continsouly flowing.
throw in a 180 one too if theres not one there already.
 
dammit i'm really hoping it's not the headgaskets... this weekend i'm going to put in all new hoses, coolant and a 180 therm..

I have an infrared temp gun.. Where would I point it to see the temp of my engine (other than the obvious) and what is normal operating temp?

let's say that I do all of this and everything seems to be ok even when mashing the pedal.. could my gaskets still be going out?

Also, do you have a link for the coolant refill procedure or how much coolant it needs etc??? I know my grand am has a "special" way to do things and only uses dexcool etc.. etc.. LOL

- Rudy
 
Your grand-am got paid to say it had to have a certain coolant I bet ;) Coolant is coolant. Also, regardless of heat or not I still recommend 50/50. As far as a temp gun, you don't actually measure the heat of the engine but the heat of the water in the engine, which with a stock thermostat should be about 196 degrees. I'm not sure how you could use an IR gun to read water temp..

Coolant procedure:

After you put on the new water pump and lines;

There is a round piece in front of the SC that says "Remove before coolant refill, install before engine start" it has something to do with air in the coolant system or w/e... take that cap off (it can be a little tight).

On the lower right end of the radiator there is a drain plug, remove it and let it pour out into a bucket.

Reinstall the drain plug and pour in the 50/50 mix.. I'd have to look up how much coolant you need.. I'll get back to you (I wanna say 2 gallons but that doesnt sound right.. I dunno im kinda tired right now)

Put your radiator cap back on, its recommended by some mechanics to be replaced with a coolant change like this.. if you're out.. pick one up for 5 bucks, it couldn't hurt.

Replace that air pressure cap thingy.. the "install before engine start" tight, and fire her up.

Let it warm up to operating temp, don't let it boil over, if it does... you need some new HG's.. :(

So yeah, nothing special about the "coolant replacement" procedure for these cars, straightforward.

-John
 
For your info, the temp gauge and its sensor has nothing to do with turning the fan on/off. There is an ECT sensor that does this, but its more likely the IRCM module that isn't working causing that issue.

Since your going to control the cooling fan manually, then the 180 tstat isn't such a big deal IF you know what temperature your car is really running at. IF you are going to have the EEC control the fan on/off then do NOT run a 180 tstat unless your going to get a tuner chip to lower those temps for the fan. Our rads are too small to have coolant constantly flowing through without cool down time inside the rad and/or some method of moving the air through them.

Also make sure you have an air dam installed under the bumper or you will start heating up on the highway.
 
Here's my formula for success in the South Texas summers. I've done this to all three of my SC's, and never had ANY problems whatsoever. Even in my 89 driver, running the A/C and sitting in afternoon rush-hour traffic.

Assumptions:
A) The cooling system is in PRISTINE condition; no scale, sludge, debris, etc. (the radiator in my driver had a small "weep" on the bottom tank, so I replaced it with an aftermarket unit from Radiator Express).
B) The engine is in original configuration, with no (heat adding) modifications.

Procedure:
1) Flush cooling system with hoses disconnected.
2) Install a quality brand of 180 deg. thermostat.
3) Install a mixture of 25% E/G 75% distilled water + 1 bottle WaterWetter. I have had NO problems running this mixture in my cars (lower E/C percentage = better cooling). The WaterWetter is important, as is using distilled water.
4) Assure that the air intake area, A/C condenser and radiator are completely clean and free of any debris; bugs, dirt, stones, grass, etc. Then when you're satisfied, clean it again.
5) Confirm that your radiator fan is functioning properly.
6) MAKE SURE you have the factory air dam underneath the front facia. The one on my driver was missing, so I ordered the GM part number, and modified it to fit. It's taller than the original, so it may be marginally more efficient. It's important to have an air dam.

That's it. As long as the car is not modified, these changes should work well. When new, the cars didn't have gross cooling problems, so it's mostly related to restoring/keeping the cooling system in good shape.

As has been stated elswhere, straight water has 2.4 times better heat transfer capability than 50/50 E/C mix. When I next change the coolant in my white car, I'm going to find out just how little E/G I can get away with, from a protection standpoint. I'm hoping to go with about 10% - 15% + WaterWetter, and add some water pump conditioner, corrosion protectant, etc.

JD
 
Here's my formula for success in the South Texas summers. I've done this to all three of my SC's, and never had ANY problems whatsoever. Even in my 89 driver, running the A/C and sitting in afternoon rush-hour traffic.

Assumptions:
A) The cooling system is in PRISTINE condition; no scale, sludge, debris, etc. (the radiator in my driver had a small "weep" on the bottom tank, so I replaced it with an aftermarket unit from Radiator Express).
B) The engine is in original configuration, with no (heat adding) modifications.

Procedure:
1) Flush cooling system with hoses disconnected.
2) Install a quality brand of 180 deg. thermostat.
3) Install a mixture of 25% E/G 75% distilled water + 1 bottle WaterWetter. I have had NO problems running this mixture in my cars (lower E/C percentage = better cooling). The WaterWetter is important, as is using distilled water.
4) Assure that the air intake area, A/C condenser and radiator are completely clean and free of any debris; bugs, dirt, stones, grass, etc. Then when you're satisfied, clean it again.
5) Confirm that your radiator fan is functioning properly.
6) MAKE SURE you have the factory air dam underneath the front facia. The one on my driver was missing, so I ordered the GM part number, and modified it to fit. It's taller than the original, so it may be marginally more efficient. It's important to have an air dam.

That's it. As long as the car is not modified, these changes should work well. When new, the cars didn't have gross cooling problems, so it's mostly related to restoring/keeping the cooling system in good shape.

As has been stated elswhere, straight water has 2.4 times better heat transfer capability than 50/50 E/C mix. When I next change the coolant in my white car, I'm going to find out just how little E/G I can get away with, from a protection standpoint. I'm hoping to go with about 10% - 15% + WaterWetter, and add some water pump conditioner, corrosion protectant, etc.

JD

When you state 25% and 75% water.. How much fluid are we talking about here? is it 25% of 1 gallon, 2 gallons or 3 gallons etc... In other words, how many gallons of fluid do our cooling systems take?

- Rudy
 
i put in maybe half of the jug of coolant plus a bottle or water wetter and then the rest is distilled water.......im guessing that im running 65 water 35 coolant.....im not sure of the total capacity.
 
Here's my formula for success in the South Texas summers. I've done this to all three of my SC's, and never had ANY problems whatsoever. Even in my 89 driver, running the A/C and sitting in afternoon rush-hour traffic.

Assumptions:
A) The cooling system is in PRISTINE condition; no scale, sludge, debris, etc. (the radiator in my driver had a small "weep" on the bottom tank, so I replaced it with an aftermarket unit from Radiator Express).
B) The engine is in original configuration, with no (heat adding) modifications.

Procedure:
1) Flush cooling system with hoses disconnected.
2) Install a quality brand of 180 deg. thermostat.
3) Install a mixture of 25% E/G 75% distilled water + 1 bottle WaterWetter. I have had NO problems running this mixture in my cars (lower E/C percentage = better cooling). The WaterWetter is important, as is using distilled water.
4) Assure that the air intake area, A/C condenser and radiator are completely clean and free of any debris; bugs, dirt, stones, grass, etc. Then when you're satisfied, clean it again.
5) Confirm that your radiator fan is functioning properly.
6) MAKE SURE you have the factory air dam underneath the front facia. The one on my driver was missing, so I ordered the GM part number, and modified it to fit. It's taller than the original, so it may be marginally more efficient. It's important to have an air dam.

That's it. As long as the car is not modified, these changes should work well. When new, the cars didn't have gross cooling problems, so it's mostly related to restoring/keeping the cooling system in good shape.

As has been stated elswhere, straight water has 2.4 times better heat transfer capability than 50/50 E/C mix. When I next change the coolant in my white car, I'm going to find out just how little E/G I can get away with, from a protection standpoint. I'm hoping to go with about 10% - 15% + WaterWetter, and add some water pump conditioner, corrosion protectant, etc.

JD

All good points except the 180 tstat. If you don't have a chip to lower the fan on temps, then your car will run hotter, as has been said by many folks that leave the stock fan on temps with a 180. Its all over these forums about this issue. Our rads are simply not big enough to cool off the coolant enough for a continuous flow without an artificial means of pulling alot of air through the rad such as a fan at the appropriate temperature. Once you get heat soaked with a 180, it will be open all the time and the coolant will just keep getting hotter and hotter until the fan comes on at 220. At least with the stock 197 the stat will close for a bit of time so the coolant in the rad can have time to transfer the heat out before its sucked back into the motor.

The coolant mix, thats another story. It just amazes me that if water was SO much better on its own without antifreeze then you would think that someone would just have an additive to prevent corrosion etc for those folks down in the very hot south and not use antifreeze considering how harsh it is for the environment. Its also interesting to note how one person that swore with just using water, all of a sudden developed over heating issues when he went that route :rolleyes: .

I've seen guys in the summer up here run straight distilled water, and ended up with over heating issues right off the bat. That tells me that "antifreeze" also helps to keep temps down. You keep saying how fast water can absorb heat, but you have never mentioned about how fast water releases heat, which is just as important.

Anyways.
 
All good points except the 180 tstat. If you don't have a chip to lower the fan on temps, then your car will run hotter, as has been said by many folks that leave the stock fan on temps with a 180. Its all over these forums about this issue. Our rads are simply not big enough to cool off the coolant enough for a continuous flow without an artificial means of pulling alot of air through the rad such as a fan at the appropriate temperature. Once you get heat soaked with a 180, it will be open all the time and the coolant will just keep getting hotter and hotter until the fan comes on at 220. At least with the stock 197 the stat will close for a bit of time so the coolant in the rad can have time to transfer the heat out before its sucked back into the motor.

The coolant mix, thats another story. It just amazes me that if water was SO much better on its own without antifreeze then you would think that someone would just have an additive to prevent corrosion etc for those folks down in the very hot south and not use antifreeze considering how harsh it is for the environment. Its also interesting to note how one person that swore with just using water, all of a sudden developed over heating issues when he went that route :rolleyes: .

I've seen guys in the summer up here run straight distilled water, and ended up with over heating issues right off the bat. That tells me that "antifreeze" also helps to keep temps down. You keep saying how fast water can absorb heat, but you have never mentioned about how fast water releases heat, which is just as important.

Anyways.

1) I have successfully ran 180 degree thermostats in my 3 SC's with no adverse effects. Since the engine generates temps greater than 197, a 197 thermostat will also be open continuously at operating temperatures. At highway speeds, the airflow through the radiator will take care of the cooling; not the fan. You're saying that there's not 17 degrees of extra capacity engineered into our radiators? Ford cut it right down to the last degree? Really? Again, the 180's have worked well in MY CARS. But, they're in pristine condition. Your mileage may vary...

2) I'm not making this up; water transfers heat better than a blend. Do an internet search. I don't know why this is so difficult a concept to grasp.

3) There are lots of variables at play. I cannot vouch for, or control, other people's cooling system integrity. If someone can't run a lighter blend in their engine, it's due to other contributing factors, not the physics of the coolant itself. LOTS of people here in the south run ligher blends in myriad vehicles. Everyone (especially northerners) just have the 50/50 mentality ingrained into them. I held that belief too, from growing up in Illinois.

The fact is that cars are mobile (obviously), and the general motoring public are idiots (obviously). Therefore, manufacturers specify the safest blend of coolant for the worst case weather conditions. Suppose Aunt Mildred from Miami decides to drive to her sister's house in Detroit for Christmas. She'd have to remember to change her coolant blend before the trip. Car companies don't want to have to require people to do this. For enthusiests, however, we're smart enough to know what we're doing, right?

4) A given fluid will both absorb and reject heat at a given rate (heat transfer) it works the same both ways; thermodynamics.

This is my personal, practical, hands-on, @$$-in-the-seat experience with 3 supercharged MN12's. Not theory. It continues to work well for me. If you wish to run a 50/50 mix, then by all means, do so (since you're in Canada, then you should be). There is a lot of speculation and conjecture flying around this forum (and elsewhere) regarding this subject, which is why I reject 99% of it, and do the math for myself.

The gentleman originally asking the question lives in South Texas, as do I. Therefore, I feel I have something valueable to contribute. I also don't think you can just throw a 25/75 blend at any car, and solve overheating problems. As my original post states, I assume the car's cooling system is healthy, and the car has not been modified.

JD
 
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When you state 25% and 75% water.. How much fluid are we talking about here? is it 25% of 1 gallon, 2 gallons or 3 gallons etc... In other words, how many gallons of fluid do our cooling systems take?

- Rudy

I can't remember the exact capacity right off the top of my head; it's in the owner's manual. I'll pull it out tomorrow, and get you the numbers. I'll also cross-check the capacity in my specification manual to confirm.

JD
 
When you state 25% and 75% water.. How much fluid are we talking about here? is it 25% of 1 gallon, 2 gallons or 3 gallons etc... In other words, how many gallons of fluid do our cooling systems take?

- Rudy

Easiest way to do this is to determine how much capacity the system has. And figure that this ratio is 3 to 1. 3 gallons water to 1 gallon coolant. I know this is a lot more than needed but you can substitute any measure for gallons needed.

I personally do not measure worth a darn on this stuff, I am sure I've made mistakes, but I do not have overheating issues. I did get a little hot on the dyno a few weeks back but I attribute that to warm weather and back to back full runs on a stock motor with no cool down. Overflow did just that.
 
According to specification manual, cooling system capacity for 3.8 S/C engine is 12 quarts US. Therefore, the blend ratio is:

9 quarts distilled water + 3 quarts ethylene glycol + 1 bottle WaterWetter

I mix everything up in a 5 gallon bucket first, then pour it from there into the engine. After blending, I put the mix back into one of the gallon jugs to make it easier to fill the radiator.

JD
 
See I'm not too far off. 1 gallon AF then fill it up with water.

I will have to look into doing it better though.
 
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