Overheated! My caddy doesn't like them mountain roads!

[epricedright]

I just got back from the mountain roads of Tennessee (Pigeon Forge/Gatlinburg/Smokey Mountain Natl. Park) and the caddy overheated twice. She did not like those crazy steep mountain roads at all. I babied her the whole way as she appeared to be laboring climbing those hills, or maybe just seemed to as my exhaust has a leak somewhere causing a throaty sound. I changed the coolant 1.5 yrs ago. I checked the coolant level before leaving home and had to add maybe a half quart. The first 2 days I was there, no mountain roads to speak of, except for the steep road to our log cabin. The first day of mountain roads, drove to Cades Cove and then up to the New Found Gap/Clingman's Dome-very steep drive, no overheating problems. The second day of mountain roads, while on the Roaring Forks Motor Nature Trail (pretty steep grade and car was loaded down with luggage), she began pinging, so I immediately pulled her over (ground was uneven and car was tilting towards driver side), turned her off and I then began hearing it bubbling and boil over, my surge tank filled up and overflowed, leaving some coolant on the ground. I noticed my cooling fans weren't on so I started it up and they then they came on and the boiling subsided. Do the fans not normally run after shutting off the car, even when it's hot? I let her sit about an hour to cool off before proceeding, luckily the rest of the way was downhill. Didn't bother to check coolant level, figured not enough came out to be a problem...mistake! Later that night, on our way out of town heading home, on the road maybe for 15 minutes, my service engine light came on, I immediately back tracked to a gas station I just passed and pulled in, popped the hood, coolant level at normal cool mark (maybe a little low considering engine was warmed up), felt radiator cap, felt cool, opened cap, coolant sprayed out, put cap back on, surge tank was now empty. I then added a little less than a gallon of generic coolant/water I purchased there at the gas station. The rest of the way home, babied her, no more overheating. I checked my codes and only get P091-park reverse, neutral switch. I think I've gotten that code before...not sure what that's about. Do you think my overheating problems were due to low coolant /mountain roads? I've never had any coolant on my garage floor.

I want to drain it and refill with new coolant. Last time I changed coolant, I put coolant tabs in. Are coolant tabs necessary for the 4.9? The reason I ask is I'm not getting any heat out of my driver side floor vent. Adallak suggested maybe my heater core was partially blocked and needed flushing. I was thinking maybe the coolant tabs caused the blockage there. So I was thinking of trying to flush the core while I was at it. Do I drain the coolant through the bottom radiator hose? Going to change my thermostat while I'm at it. Has anyone used that premixed coolant that's good for both red and green coolant cars...Prestone makes it I believe? My '94 requires the green coolant.

In Summary, my questions are:

1. Do the cooling fans not normally run after shutting off the car, even when it's hot?

2. Do you think my overheating problems were due to low coolant/mountain roads?

3. Are coolant tabs suggested/necessary for the 4.9?

4. Do I drain the coolant through the bottom radiator hose or is there a drain cock?

5. Has anyone used that premixed coolant that's good for both red and green coolant cars?

BTW, the Smokey Mountains National Park is Beautiful! I've been to the park a few times before, but never ventured to the places we went to on this trip and saw it's beauty. Being it's a National Park and has it's strict leave it as you found it rules, the untouched forests scenery, mountain views, mountain streams, waterfalls and wildlife are truly breathtaking. Truly God's Country! Be sure to check it out for yourself before you leave!

[Ranger]

1. Not sure

2. Hard to say without knowing if the system was low to start with.

3. Sealant tabs are mandatory on the 4.9

4. There is a drain cock, but the hose will do if you can't find it or reach it.

5. Never used it. I always mix my own.

[adallak]

1. No

2. Hard to say. Too many possibilities. I suspect wrong concentration of antifreez.

3. Supplement is a must for 4.* engines.

4. You can siphon the coolant thru the radiator neck with 1/4'' plastic tube. You'll get some 1.5 gal out.

5. The mix you used should be fine.

BTW, E091 code might be caused by switching to neutral while coasting down a hill. Do you have such a habit?

[epricedright]

I may have put it in neutral accidently while going down a mountain. I did a lot of downshifting and upshifting on them dang roads.

That makes no sense the fans don't run when it's hot after turning it off. My minivan fans will run after shut-off.

So I need one tube of that gold bars leak from walmart right? And add it to the radiator where the cap goes, right?

I've never used that Prestone pre mix before, just saw it is all.

That southern Tennessee twang rubbed off on me it appears.

[adallak]

I may have put it in neutral accidently while going down a mountain. I did a lot of downshifting and upshifting on them dang roads.

So I need one tube of that gold bars leak from walmart right?

I've never used that Prestone pre mix before, just saw it is all.

That southern Tennessee twang rubbed off on me it appears.

You need two tubes from Wal-Mart.

[JimD]

....

So I need one tube of that gold bars leak from walmart right?

Two tubes would not be too much.

[epricedright]

Being I maybe having some cooling issues, do you guys recommend me using that Prestone flush beforehand?

[acklac7]

That makes no sense the fans don't run when it's hot after turning it off. My minivan fans will run after shut-off.

My fans won't stay on either....I assume there was a reason the lack of auxillary fan power...For the life of me I can't figure out why you WOULDN'T want the fans to stay on if the car has been overheated

[BodybyFisher]

I would either remove the lower hose or open the petcock. The petcock is on the lower left side of the radiator and its hard to get at. Thanks to another member, I used a 3 inch broom handle with a groove cut into it as a tool. The reason I say to open the radiator is to drain out any sediment. I wouldn't flush the radiator with tap water where you might add minerals, etc, remember what happened to Matts 4.9. Make sure your fans are running high and not free-wheeling. Make sure your thermostat is in good shape. Hills will cause your cooling system to get hot and have to dissapate more heat as the tranny creates a lot of heat (converter). If you didnt have a 50/50 mix you could boil. What condition is you radiator in? Could you be leaking pressure from stress cracks in the plastic side tanks? How is your cap, is the system holding 15-16 psi? Remember that if your cap releases too early or too low the pressure release will cause spontaneous boiling.. I would pressure test your system to make sure it holds pressure..

Do you know what temp she boiled at?

[JimD]

Being I maybe having some cooling issues, do you guys recommend me using that Prestone flush beforehand?

I would not "flush" if you mean using tap water and Prestone chemicals to clean out whatever evil fluids you feel might reside in your cooling plumbing. At the very least you will lose control of the desired 50/50 water-to-antifreeze ratio (Alaska residents excepted). Introducing possibly sinister flush chemicals would only make me more nervous.

Drain it and refill with the recommended antifreeze and distilled water mixed 50/50. Drive it for one tank of gas and repeat the drain and refill. It would not do any damage to drain and refill a third time.

Avoid tap water where possible. Water that is safe for human consumption could contain minerals and chemical additives that are not friendly to aluminum engines.

[adallak]

Here is a good and inexpensive concentration tester you can buy at Wal-Mart:

http://caddyinfo.ipbhost.com/index.php?sho...7738&hl=preston

[epricedright]

I would either remove the lower hose or open the petcock. The petcock is on the lower left side of the radiator and its hard to get at. Thanks to another member, I used a 3 inch broom handle with a groove cut into it as a tool. The reason I say to open the radiator is to drain out any sediment. I wouldn't flush the radiator with tap water where you might add minerals, etc, remember what happened to Matts 4.9. Make sure your fans are running high and not free-wheeling. Make sure your thermostat is in good shape. Hills will cause your cooling system to get hot and have to dissapate more heat as the tranny creates a lot of heat (converter). If you didnt have a 50/50 mix you could boil. What condition is you radiator in? Could you be leaking pressure from stress cracks in the plastic side tanks? How is your cap, is the system holding 15-16 psi? Remember that if your cap releases too early or too low the pressure release will cause spontaneous boiling.. I would pressure test your system to make sure it holds pressure..

Do you know what temp she boiled at?

I replaced my thermostat and cap when I changed my coolant 1.5 years ago. I will replace those again though. Come to think of it, I had to add coolant last summer when I went to Myrtle Beach, so maybe I do have a leak. I have smelled coolant (very faintly) in the past, but never saw any coolant or residue on the side tanks of the radiator or on the ground or anywhere for that matter. I'm not sure what the temp was when it overheated. I wasn't sure how to get to the temp through diagnostics. I was trying to find it and couldn't find any reading near 200 and I then remembered the reading was is in C, not F, and I didn't have a C to F converter with me nor did I have my FSM with me on this trip...won't leave home w/o it again. I need to print out a C to F converter as well and keep that with my manual as well.

So how do I do a pressure test? Should I take it to a radiator shop? Could you explain how releasing pressure or a leak causes boiling/spontaneous boiling? I've never understood that.

What was the best thing to do when it overheated? When I first popped open the hood, after pulling over and turning it off, the surge tank was empty, I then noticed it began to boil, then surge tank filled up and overflowed. After a couple minutes and realizing my fans were off, I started her up, and the fans came on, but they looked to be turning slowly(maybe at the normal speed, I'm not sure). The boiling then subsided. I was torn though as what to do next as I figured running the car will make it hotter. I considered driving it back down the mountain to let the cool mountain air hit my radiator to help cool it off, but I was worried driving it while hot may damage the engine. So I decided to just let it idle long enough to cool the coolant (the fans actually shut off after a couple minutes), I then shut it off. I then decided to play it safe and let it sit for an hour and cool off. Was that the best thing to do or ??? Pretty scary to have car troubles on top of a mountain with a curvy steep one lane road as your only road, no water and no cell phone reception. We had already checked out of our cabin to boot!

[adallak]

Boiling point (temperature) of liquids depends on the pressure. Say, your coolant temp. is close but below the boiling point at 16 psi. As soon as you open the radiator cap, the pressure drastically drops to atmospheric one, and that little difference may be just enough to make the coolant boil.

[BodybyFisher]

The Pressurized System

Up until the late 1950's, liquid cooled systems did not operate under pressure. This was primarily because these cars had much larger radiators, more open air under the hoods allowing for more natural heat dissipation, and richer fuel mixtures causing lower (and less efficient) combustion temperatures. With the manufacture of smaller vehicles, with smaller radiators, larger engines, and emission controls along with the current use of unleaded fuels, more efficient cooling efficiency became necessary.

The cure for this was to operate the cooling system under pressure, thus isolating it from atmospheric pressure. A system under pressure can handle higher temperatures, and offers a higher static boiling point.

For every pound of pressure exerted on the coolant in the system, the static boiling point of the coolant is raised by approximately 3° F.

Most liquids have a specific "boiling point", which is the temperature at which the liquid begins to change to a gas. If pressure is applied to the liquid, it must become hotter before it can boil. Pure water in a cooling system will boil (at sea level) at 212° F. At higher altitudes, atmospheric pressure is less than at sea level. Example: Water at 5,280 feet will boil at a mere 203° F. A cooling system that is under 15 pounds of pressure however, will now allow the water to reach nearly 250° F before it can boil. Even at this temperature the water is able to circulate through the engine, cooling parts that are at a much higher temperature without the water boiling. As long as the coolant remains in liquid form it can do it's job and transfer heat to the radiator so it can be dissipated. Coolant that is boiling cannot transfer as much heat and engine overheating is likely to occur if the coolant turns to a gaseous state. Steam adjacent to a hot surface, such as a combustion wall, can actually act as an insulator - thus preventing any heat transfer to the coolant.

Pressurization of the system is achieved by a special radiator filler neck and radiator pressure cap. The filler neck has an upper and lower sealing seat with an overflow tube connection between them. The lower seat is engaged by the pressure controlling valve on the cap and the upper seat (in an open system) is engaged by a spring metal diaphragm in the cap. The radiator pressure cap features a spring pressure relief valve which closes off the lower sealing seat in the filler neck. This pressure relief valve allows pressure to build up to a specified level, the permits excess pressure to escape through the overflow tube when it exceeds the range of the pressure valve spring. This valve protects the cooling system from damage from excessive pressure. This pressure relief system also includes a vacuum relief valve that allows air (in an open system) to enter as coolant contracts. This prevents the radiator hoses and tanks from collapsing from the partial vacuum that would be created if air was unable to enter

[BodybyFisher]

Coolant and Coolant Additives

Even though some time ago water alone was used for many years in automotive cooling systems, the fact that it only has a 32 F° freezing point, a 212° F boiling point (no pressure), it evaporates easily, creates rust and corrosion, and leaves mineral deposits has made it less than optimal as the sole coolant. It is much more efficient to utilize a chemical added the the water to improve the efficiency of the coolant. This chemical is commonly called "Anti-Freeze", but the more accurate name is ethylene glycol (EG). In recent years (EG) has been replaced by propylene glycol (PG). This is a much less dangerous chemical.

Since antifreeze as a 50-50 mix with water elevates the boiling point to 227° F, and lowers the freezing point to -27° F, it should also be called anti-boil. Good quality antifreeze contains water pump lubricants to help maintain the efficiency of the pump, rust inhibitors to keep unwanted deposits from forming, and acid neutralizers to help protect the inside of the radiator, heater core, and hoses from corrosion.

[BodybyFisher]

Here is some good info:

http://www.centuryperformance.com/coolingsys.asp

[epricedright]

Thanks for that info! Any thoughts on my other questions?

[epricedright]

Being I maybe having some cooling issues, do you guys recommend me using that Prestone flush beforehand?

I would not "flush" if you mean using tap water and Prestone chemicals to clean out whatever evil fluids you feel might reside in your cooling plumbing. At the very least you will lose control of the desired 50/50 water-to-antifreeze ratio (Alaska residents excepted). Introducing possibly sinister flush chemicals would only make me more nervous.

Drain it and refill with the recommended antifreeze and distilled water mixed 50/50. Drive it for one tank of gas and repeat the drain and refill. It would not do any damage to drain and refill a third time.

Avoid tap water where possible. Water that is safe for human consumption could contain minerals and chemical additives that are not friendly to aluminum engines.

Makes sense! I won't be doing a flush then. After determining if I have a leak or not, I plan to replace my thermostat and cap, drain and refill with 50/50 Prestone and distilled water, drive out a tank of gas and drain and refill again to know for certain my mix is 50/50 and add 2 tubes bars leak.

[BodybyFisher]

This is expensive, but this is the tool you need. You might find that a good radiator shop can pressure test your cooling system as I am sure they have this tool. Do a search, you might find it cheap at a place like sears:

http://www.etoolcart.com/index.asp?PageAct...ROD&ProdID=8572

I have never seen the cooling fans come on after I turn the car off. That used to bother me when I was on a long trip in hot weather because when I made a rest stop my temp would rise to 245 or so. It immediately drops once the water circulates however.

Not that its the same as the 4.9 but the concept is the same, when I run up hills my temp increases. When I was in Phoenix a couple of years ago, there is a 5 mile incline from Phoenix to Sedona. There is a sign that states "turn your AC off for next five miles". I had a new rental car and I was like "forget that".... Well, I passed about 5 cars that had overheated, and I looked down and my temp needle had increased to 1/2 from 1/4.... I immediately opened the windows and turned the AC off. Hills will do you in...

Kim, you being a long-time member, you need to ask if the cooling supplement is necessary? Remind me to smack you in the head when I see you! Are you telling me that you have not used them? They are very important in the 4.9

I think we determined that pre-mix was a waste of money...

I opined on why I think you overheated above in my previous post. Now keep in mind that Ed Fenwick (Hawaii) also had overheating problems with his 92 4.9 and it initially showed itself on hills. Unfortunately it ended up being his head gaskets. Do a search under Ed Fenwick.

[BodybyFisher]

epriced why is your temp reading in centigrade and not farenheit? You can change that if you want, you are in Chicago no? Why do you want centigrade?

There is not much you can do if she is boiling, you definately don't want to open the cap. If you are no more than 240 and not boiling that is ok, even 245 is ok. I have seen 245 in traffic in August and the guru calmed my nerves. IF you have a 50/50 mix that you have checked with an accurate gage, good hoses and good side tanks with the cooling supplement and the fans are operational, you should be fine.

However, I recall that you have AC problems. Realize that when your AC is on, the system commands the FANS on all the time. If you are running with the AC off, (your AC clutch coil was a problem no?) your FANS will NOT come one till 228 degrees, so that might be what you are seeing. You WILL see wider ranges of temp with the AC off as the fans cycle on and off and you will see higher PEAKS in my experience. Mike

[epricedright]

This is expensive, but this is the tool you need. You might find that a good radiator shop can pressure test your cooling system as I am sure they have this tool. Do a search, you might find it cheap at a place like sears:

http://www.etoolcart.com/index.asp?PageAct...ROD&ProdID=8572

I have never seen the cooling fans come on after I turn the car off. That used to bother me when I was on a long trip in hot weather because when I made a rest stop my temp would rise to 245 or so. It immediately drops once the water circulates however.

Not that its the same as the 4.9 but the concept is the same, when I run up hills my temp increases. When I was in Phoenix a couple of years ago, there is a 5 mile incline from Phoenix to Sedona. There is a sign that states "turn your AC off for next five miles". I had a new rental car and I was like "forget that".... Well, I passed about 5 cars that had overheated, and I looked down and my temp needle had increased to 1/2 from 1/4.... I immediately opened the windows and turned the AC off. Hills will do you in...

Kim, you being a long-time member, you need to ask if the cooling supplement is necessary? Remind me to smack you in the head when I see you! Are you telling me that you have not used them? They are very important in the 4.9

I think we determined that pre-mix was a waste of money...

I opined on why I think you overheated above in my previous post. Now keep in mind that Ed Fenwick (Hawaii) also had overheating problems with his 92 4.9 and it initially showed itself on hills. Unfortunately it ended up being his head gaskets. Do a search under Ed Fenwick.

I couldn't remember if the tabs were necessary for the 4.9 as I recalled them being spoken about mostly in the N* threads. Soon after I bought the car, I had the coolant changed and added the supplements. I was just now starting to second guess myself though thinking maybe I read about the supplements being necessary for the N* and mistaked it for the 4.9. I was also second guessing them because I have that odd No Heat issue with the driver floor vent and Adallak suggested maybe my heater core was blocked. But yes Mike, I did put the pellets in at the last coolant change.

I read Ed's as well as other past threads regarding head gasket failures...now I'm getting worried. I'm considering doing the exhaust gas test for my coolant using a combustion leak tester. I'm wondering if I should do that before the coolant change or afterwards. I'm thinking doing that test before a coolant change makes more sense. I would also like to do a cooling system pressurization leak-down test after replacing my rad cap to determine if there's a leak I'm not seeing.

[BodybyFisher]

FYI, I was busting your chops..with the pellets... You might just need to flush your heater core. BUT... your coolant could be low also causing the no heat problem. Don't panic. The 4.9 isnt really prone to head gasket issues..

[epricedright]

epriced why is your temp reading in centigrade and not farenheit? You can change that if you want, you are in Chicago no? Why do you want centigrade?

There is not much you can do if she is boiling, you definately don't want to open the cap. If you are no more than 240 and not boiling that is ok, even 245 is ok. I have seen 245 in traffic in August and the guru calmed my nerves. IF you have a 50/50 mix that you have checked with an accurate gage, good hoses and good side tanks with the cooling supplement and the fans are operational, you should be fine.

However, I recall that you have AC problems. Realize that when your AC is on, the system commands the FANS on all the time. If you are running with the AC off, (your AC clutch coil was a problem no?) your FANS will NOT come one till 228 degrees, so that might be what you are seeing. You WILL see wider ranges of temp with the AC off as the fans cycle on and off and you will see higher PEAKS in my experience. Mike

Mike, No, I'm from Indy. I have no temp gauge...why that is...I have no clue. Probably for the same reason I have no light under my hood. I guess Cadillac figured that year the only ppl that buy Cadillacs are ones that would never pop a hood or need to know their engine temp. I can only get my temp via going into diagnostics mode. I wasn't aware I could change those readings to Farenheit. How do I make that change?

Yes, I have no AC, as my clutch plate is too far from the hub to engage. There was no reason to have the AC on anyways as we were up around 6000 feet in the mountains and the temp was 50 degrees F. I will need to somehow check to make sure my fans are going to hi speed as they seemed to be turning awfully slow considering my engine was boiling. I did notice with the drivers side fan, the fan blade was wobbly, but I figured at the time it was just bent being they are made of plastic.

[epricedright]

I stated this earlier:

"When I first popped open the hood, after pulling over and turning it off, the surge tank was empty, I then noticed it began to boil, then surge tank filled up and overflowed. After a couple minutes and realizing my fans were off, I started her up, and the fans came on, but they looked to be turning slowly(maybe at the normal speed, I'm not sure). The boiling then subsided."

Once I had turned the engine off, I wonder why the overflow tank suddenly filled up and overflowed? Did the radiator cap open up once it began boiling and allow the coolant to go to the overflow?

Being the fans don't work when you shut it off, I wonder what is the correct procedure to follow if the car overheats? Did I do the right thing? What would you have done?

I think I'll rent a car for our next mountain road trip, as this was our 2nd time in a row having problems with this car while on vacation...both times in the mountains...not a good feeling! Those mountain roads within the park are TOUGH and STEEP! No matter how old your car is, new or old, those mountains have to be hard on any car!

[BodybyFisher]

One of my fans was burned out and just free wheeled. If your tank was empty when you stopped, you were low before you started out. That would explain the heater problems. In addition, being low, she probably got hotter because of cavitation and air pockets and its possible that you had less than 50/50 mix if she boiled. 50/50 Coolant under pressure should not boil till over 265. I really dont think you have head gasket problems.

PRESSURIZED BOILING POINTS OF GLYCOL SOLUTIONS

NOTE: The following chart gives the boiling points of Ethylene Glycol solutions under pressure.

Pressure ranges covered are from 0 - 300 kPa (0 - 45 psi). In the automotive cooling system the

pressure exerted by the radiator pressure cap usually falls between 75 - 100 kPa (11 - 15 psi).

Boiling points of all radiator fluids increase with pressure, even water has a much higher boiling

point in a pressurised radiator.

See the PRESSURIZED BOILING POINTS OF GLYCOL SOLUTIONS chart here, its in centigrade:

http://www.are.com.au/techtalk/coolants.ht...COL%20SOLUTIONS

A faulty radiator cap can cause major overheating problems in a vehicle. Always pressure check

the radiator cap for correct pressure release. If the pressure is low the vehicle will boil and 10se

radiator coolant prematurely. If the pressure release is too high the radiator or radiator hoses

can split or burst. Also check the centre vacuum valve in the cap, as the modern vehicles,

coolant recovery system will not function if this valve is faulty.