Major cooling system failure

[sudden_impulse]

I have been having problems with my car lately, mostly that if I turn the heat on before the engine is up to operating temp, I need to let it get over operating temp, turn the temp control to cold, and back to warm, which results in heat coming back and the temp gauge to drop below operating temp. Thursday night as I was driving into work, I watched the gauge climb very rapidly, and the temp control didn't do anything this time. I pulled over, sat for a few minutes, and started the car again, which was at operating temp now, with working heat. I opened the hood and checked under the car, but didn't find any coolant spilling out. I ended up leaving the car parked at work overnight, and my parents came in the morning to pick it up. Needless to say, the car overheated twice on the 5 mile drive to my grandparents house, without touching the fan. I'm pretty sure the LIM is leaking again (mechanic "fixed" it while my aunt owned it), and I'm thinking either the thermostat is bad, waterpump is bad, or both. Also, not sure if this has any relevance in this, but the mechanic told my aunt that cylinder 2 (IIRC) has low compression, which was causing some misfiring, but hasn't happened for 2 months now. A family friend, who is a mechanic, thinks my waterpump and head gasket might be bad. What do you guys think?

[BIGGGPOPPA]

Does sound like a thermostat H20 pump issue
or maybe just a simple flush with fresh new coolant
Let us know what u find

BP :???:

[Igor Gavric]

OK, first, check following:

Check -->> OIL <<--, and ensure it is not milky white in color (or visible traces of coolant), if it is, stop driving car IMMEDIATELY! as you probably have intake manifold gasket leak.
It could go two ways, exterior leak, which you may not see right away, or interior engine leak, which may be leaking into the fuel or oil.
Interior engine leaks are dangerous, and could possibly seize your engine.

Another thing, check coolant reservoir for coolant, ensure there is some in there.
Failure to see coolant in reservoir or radiator will ensure you have a leak somewhere in the system.

Also check for oil in cooling system, another sign of leak from intake manifold gasket.

Though if oil can get into coolant, by all means coolant should be able to get into oil, it doesn't always happen this way for some reason.

You could of course just have a thermostat failure (very uncommon with never vehicles as they mostly stick to open now), but none the less... Check those things and get back to me, I might be able to help you further.

[sudden_impulse]

Oil is good, I just changed it and it wasn't milky at all. Reservoir was empty last weekend, when I had a slight overheat. I filled it and bled the system when I changed the oil. No oil in cooling system AFAIK. The car is going into the dealership tomorrow, I think we're gonna end up changing LIM gasket, head gasket, thermostat, and possibly water pump, I'll keep you guys updated when I find stuff out. My grandma works at the dealership, so she can keep an eye on the car, and it'll probably cost about $1000 to do all that work (hopefully).

As a side thing, is there really any effects (good or bad) from changing the thermostat to a 180* instead of a 195*?

[Igor Gavric]

Nothing too positive... Early release through system, which for your car is not needed, specially considering where you live and what time of the year it is.
All you're gonna do is make yourself 15 degrees colder in the car... lol
Your fan will still kick on at the same temperature, unless you have your a/c on, and your car will run a little cooler.
Basically, you will freeze your a$$ off for no reason.

[rixGAphx]

Nothing too positive... Early release through system, ...
Basically, you will freeze your a$$ off for no reason.:D :D :D :D

Best description I've ever read of the 180 vs 195 t'stat debate!!!
* * *

Sudden: NOT SO FAST!!!

Do you just WANT to throw money at the dealer???
Throw it at me instead!

First off, you only have TWO symptoms:
* Mysterious Disappearing GM Coolant Syndrome. Could be many things (including LIM gasket or headgasket), but could also be cracked heater core hose nipples, cracked radiator, leaking hoses, or more likely IMO a faulty reservoir pressure cap.
Something's leaking, but you have NO reason to believe it's something catastrophic/expensive like a LIM gasket or headgasket.
* 'Overheating' (though you don't describe if this was merely a gage needle registering high (say 240) or actual 'boilover' with liquid/steam issuing from the pressure cap).

BS on headgasket based on 'low compression in No 2.'
Not that it isn't possible, just that 'headgasket' isn't a logical conclusion (it's one of several).
And what kind of dealership mechanic lets a fellow employee leave with a faulty headgasket?

I would first analyze the leak, as follows:
Top-off the reservoir.
Install a new pressure cap ($13 at Checker/AutoZone).
Spray-clean the engine at the coin car wash, after placing plastic freezer bags over the major electrical stuff.
Put some Universal UV dye in the coolant system ($5 for a little bottle, also at Checker/AutoZone).
Examine the engine under Black Light in a dark garage, and find the leak locations.

Hope this helps,
-Rick

PS: LIM gasket leaks have several symptoms and scenarios, but coolant canNOT leak into the fuel, nor will oil-in-the coolant result from a LIM leak.
There is just no possible route or method of physics for such to happen.

[Blackhawk]

The dealership is thinking that the coolant disappearing is a faulty res cap, but they said that his car has an oil leak too.

[rixGAphx]

The dealership is thinking that the coolant disappearing is a faulty res cap, but they said that his car has an oil leak too.They should stop 'thinking', and test the damned $13 cap, or just replace the sucker. :sheesh:
I've spent more than that wasting my boss' time just writing about this.

Glad it's not my time :D :D
* * *

Oil leaks on 2.8/3.1/3.4 V6's are NEVER serious.
Just messy, never any seized engines as a result (unless that oil pressure sensor just vibrates loose and oil goes 'sploosh!' all over the engine bay. Even then the engine will stop from lack of oil pressure, or the driver should just pull-over).
Oil can only leak from a few places on this V6:
* Non-pressurized (gravity):
1. Valve cover gaskets.
2. Timing case gasket.
3. Front crankshaft seal.
4. Front (or rear) LIM-to-valley seal.
5. Oil pan gasket.
* Pressurized:
1. Rear main seal (this is the worst to repair, since the early 2.8's had replaceable 2-piece seals, but modern versions require R&R of the tranny for access).
2. Oil pressure sensor (this is most common major leak, and takes 15 minutes to fix).

[sudden_impulse]

Got the car back today, they replaced the reservoir cap, flushed the heater core, and replaced the water pump. I don't have an overheating engine anymore, and I have heat inside now. Not sure on the price, since they're letting me take it for a few days to make sure everything is good. I'm guessing the price is around $200, since I only pay 10% over the dealership's cost on parts.

[Igor Gavric]

since I only pay 10% over the dealership's cost on parts.

Warranty, or are you dating the owner's daughter? Just curious...


--------------------------------------------------------------------

Water pumps on 2.8 to 3.4 V6 GM engines are horrible!
Your rad cap blows, sends air in through the cooling line into the water pump, water pump sloshes, causing the shaft and seal to screw up, and it starts to leak EVERY TIME!!!!
It is almost safe to say that if you have a coolant leak of any sort *blown hoses or rad cap*, it WILL BE followed by a water pump problem.

So, make SURE you check your car for coolant leaks, and keep up on your hoses, and rubber parts.

#1. Tale tale signal - Look at the hood padding, see if it is wet or has antifreeze marks, or around the vehicle (on the ground, etc.)
#2. Check hoses, squeeze if you have to (don't be afraid to rupture a hose by giving it a little squeeze) see if there is cracks in the hoses. If the hose ruptures if you squeezed it (with your hand), it was time to replace it a year ago...
#3. If you checked your rad fluid and it is topped up (when the car was COLD)
THEN
When the car is hot, feel (look) around the rad cap for leaks (DO NOT TAKE RAD CAP OFF WHEN CAR IS HOT), unless you feel like taking a trip to the hospital for burns....

Those are just a few simple steps to making sure you're good to go.

MAKE SURE YOU NEVER MIX GREEN COOLANT WITH DEX-COOL, AS IT IS POISON FOR YOUR CAR DUE TO CHEMICAL REACTION THAT WILL EAT YOUR GASKETS!!!!!!!!!

Of course, you could eliminate the problem by doing it my way...

One of my preferences, is removing dex-cool completely from your system, and replacing it with green coolant... But thats me, and I am different than your average GA driver :) LOL

[sudden_impulse]

I get the discount because my grandma works there, and they give me her price on stuff. I'm sticking some UV dye in the cooling system to see if/where I'm leaking coolant. I think coolant might be leaking out of the valleys between the UIM and LIM, but I'm not sure, since it's such a hard place to see. Prior mechanic switched to green coolant before this all happened, I might switch this spring back to Dex-cool for the longetivity, I'm not sure, but I'd probably replace all hoses and then power flush the system. It's not so much that Dex-cool and the green coolant eat gaskets away, it's more that they clog up your cooling passages.

I've seen somebody open the rad cap when he thought the vehicle was cool enough. There was about 3 seconds in which all was fine, then he got a bit on his face - lucky he was wearing goggles.

[sudden_impulse]

Well, started up again. Overheated this morning while trying to get out of the driveway, just sat without running the wheels and watched the gauge go up. Dealership is thinking head gasket, so I have an appointment for next Wednesday to replace head and intake gaskets. There was coolant where I parked overnight, so I know the problem wasn't fixed. Damn, with my discount the cost is $1375, plus whatever the cost was from yesterday and Monday. Luckily my aunt is willing to help pay for it, since her mechanic didn't fix anything, and I bought the car from her.

[Blackhawk]

Igor, I've always been told that if you don't have more than 10% of one type in coolant into the other that you're fine. Personally I may switch to the yellow Prestone coolant that is supposedly compatible with all types and has the same life as Dex-Cool.

[Igor Gavric]

Igor, I've always been told that if you don't have more than 10% of one type in coolant into the other that you're fine. Personally I may switch to the yellow Prestone coolant that is supposedly compatible with all types and has the same life as Dex-Cool.

That may be true, I speak form experience as proven to me by my friends in the industry. I have had experience with over 8 cars that I've driven that have been GMs (6 ran dex-cool), and statements that mixing both will cause cooling problems form clogging to blowing gaskets, depending on that car.
so, 10% or not, why would you risk trying, and I don't like running coolant that is harder to get at fuel stops (at least where I live).

Everyone has different perspective on coolant types. I will tell you something different than Rick or your mechanic might tell you.
I am a Dex-Cool non-believer, because I believe that it has caused me more problems than it's worth.

I would rather do cooling flushes every 2 years or whatever, than to run Dex-Cool, as since I changed it to Prestone Regular Anti-freeze, I haven't had any problems with my car, while running dex-cool, I was replacing cooling system parts constantly. And this isn't just in one of my cars, its in all of them.

My family runs GM everything due to how cheap parts are and the easy availability of parts to get, and we all switched to regular anti-freeze, and haven't had cooling problems since.

I guess all of the above are my personal preferences, but they worked for me, and I tend to wanna stick with things I know & trust :)

[Peyman]

just curious because im having a similar problem w/ my car, what does the pressure cap do?... how could it effect anything by becoming faulty?

does anyone have a part # for the pressure cap? i called pepboys and the guy says they dont carry it, and autozone only shows a pressure cap for the power steering

[jonnythan]

Faulty pressure cap could let the coolant boil off by not maintaining system pressure.

http://www.autozone.com/addVehicleId,2523702/initialAction,partTypeResultSet/initialN,16300147/shopping/vehicleSelected.htm
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=STB&MfrPartNumber=11248&PartType=116&PTSet=A
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=BK&PartNumber=7031390&Description=Radiator+Cap

[rixGAphx]

Edit: Cliff's Notes: You MUST have a pressure cap!!!

'Modern' cooling systems, say mid-'50's onward are DEPENDENT on having a PRESSURE cap, rated at about 15 psi.
Nascar engines are running 40 psi!!!

The pressure raises the boiling point of the liquid, to keep it from 'flashing' into vapor (steam).
For plain water, this boiling point is 212*F (100*C) at sea level; for 50-50 antifreeze-water mixture, it's about 218*F.
For discussion, let's stick with plain water (212).

Ever use a stovetop Pressure Cooker? With 10 psi 'blow-off' on the lid, it won't boil until about 25 additional degrees F (about 2.5*F per 1 psi additional pressure).
So you can cook your vegetables at (212 + 25) = 237*F. Green beans cook in only half the time.

Now look in the engine:
195* water leaves the t-stat, and enters the radiator.
At 75* outside temp, the 195* water loses ~40* flowing across, so it leaves the rad and enters the waterpump at ~155*F.
It flows in the block and picks-up heat from the cylinder walls, rising 15 degrees to 170.
It flows thru passages into the head, then across the tops of the combstion chambers which are REALLY HOT. Here it picks-up more heat and rises to 195*, then flows thru the intake manifold (to heat the incoming air-fuel mixture and throttle body) and exits thru the t-stat at 195*.
Repeat.

Think of a saucepan on the stove, where you're heating plain water before adding spaghetti to the boiling water.
The water is rising from tap temp (about 65*) toward 212, by heat coming mostly from the metal bottom of the pan; only a little heat comes from the sides.
This is an upside-down version of your engine cylinders, where the water gets a little heat from the cylinder walls but most heat from the tops of the combustion chambers.
Now look in the saucepan, as the water temp gets near boiling, say 195.
The bottom of the pan is REAL HOT, hotter than 212, from the flame/electric coil touching the metal.
Bubbles are forming (they are steam) but dissipating as they release heat to the cooler surrounding water.
When all the water reaches 212, you have a 'rolling boil', with lots of big steam bubbles coming from the bottom and bursting at the surface.
This is fine for cooking beans, but terrible for removing heat from the pan (or you cylinder heads) because the metal is MUCH hotter than 212 and the steam doesn't carry much 'heat' compared to liquid water.

So, if you have a 1949 engine without pressurized water and an old 180* t'stat, something similar is happening in the head: The water isn't boiling (it's leaving the t-stat at 180*, but the water RIGHT AT THE HOT COMBUSTION CHAMBER (and specifically, around the exhaust valves) is boiling into steam in little pockets.
So the metal head can't cool very well, and the INSIDES of the metal (the combustion chamber itself) is so hot (practically glowing red at about 1150*F)that it's affecting the incoming air-fuel mixture and the actual combustion process.
The result is 'pinging' and 'knocking' as the A-F mixture detonates before the spark plug actually fires.

Therefore, ALL modern cooling systems, even though the t-stat is in the 180-195 range, are subject to very hot water (and antifreeze) right at the combustion chamber.
The liquid can easily be 230*F right there, all the time. That's OK, the engineers knew this when they designed and tested the engine.
But to prevent this 230* liquid from 'flashing' into steam, the system MUST be pressurized about 15 psi, which gives us a 237*F boiling point. Only 7*F margin of safety, which is adequate for a road car.
If you're running a half-million dollar race car around Daytona at 220+ mph, you want a greater margin (and you're producing a helluva lot more power and heat), so Nascar engines are pressurized much higher to avoid localized 'flashing' within the engine. Stewart gets real pissed when Junior dumps a bunch of coolant in front of him.

Anyhow, you MUST have a pressure cap that holds pressure, not just prevents the coolant from evaporating.

Have a wonderful weekend,
Class dismissed!
-Rick

PS: Those heads hold a lot of 'latent heat' in the metal when you shut-off the engine.
When the liquid stops circulating, the temperature right at the exhaust valves can easily exceed 237*, and you get a 'surge' of pressure within the pressurized system as that liquid 'flashes' to steam (which takes up a lot more space).
This CAN force some liquid out thru the overflow/pressure relief.
It takes about 3 seconds for this surge to travel from the head to the reservoir, and many of you will have experienced the geyser effect 3 seconds after loosening the cap on a system you *thought* was cold enough to open.
Hopefully, you weren't staring down into the mouth of the volcano when this happened.

[sudden_impulse]

We brought the car into the shop today to change the thermostat (which almost seems like it's sticking from the symptoms), and when we had the hood open, we could hear air being sucked into the reservoir tank by the cap. It's a brand new cap, so could the tank itself be leaking? The cap threads down lower than Cody's does (because somebody cranked down on it, cutting the stop bars), so could this be causing the o-ring on the cap to not make a proper seal with the tank?