Cooling System....Again.

[mrcaddy]

This car is a '94 Se with 2.4 and auto. This weekend the temp gauge twice went past 220 and once it went to just the safe edge of the RED mark. Each time it was on the highway. The time it went the highest it did go back down. I talked to my mechanic some about it Monday. He said that he figures that since the Thermostat is where it is in these engines it will open later especially when it's cooler out. I had checked the hoses and the one at the bottom on the passenger side going into the radiator was ice cold. So, with that theory it should open sooner in the summer. It did seem to run cooler in late August of last year. My mechanic did put a new thermostat in it, but it was from O'Riellys. My friend says that any of them are junk.
One more, the owner's manual says 'that if the needle goes into the RED to stop'. So, does that mean that any other temp is fine?
Please help.....I like this car, but am quite frustrated right now. Thanks,Scott

[rixGAphx]

Yes, *basically* 'below the red zone' is OK for driving, but there are a lot of things to consider.
At the very least, a needle above about 230 indicates there is a major problem, and it's only going to get worse, not better.
But if you're in a bad part of town, keep on driving even if the needle is just below the red without worrying about damaging the engine.

Any temp indicated on the gage, below the RED zone, is safe for the engine, IF:
* There is coolant in the engine (basically a full system); AND,
* The system isn't spewing/oozing liquid or vapor out the pressure cap relief (or any other place, like a pinhole in a hose); AND,
* The gage is accurate.

Red Zone = about 250*F.
Plain water will boil at 212 (sea level); with 50-50 antifreeze, the boiling point will be about 220.
50-50 coolant with 14 psi pressure will not boil 'til 260.
When the gage is at the red zone, about 250, there will be parts of the cooling system (right around the combustion chambers and exhaust valves) where the coolant will be over 260, and it actually turns into little steam pockets at those spots).
But the engine keeps on running, and no damage is actually occurring.
The engine is gonna be 'pinging' when you press on the gas, and it doesn't produce as much power.
(I don't have my tables handy, the above temps are close approximations from my failing memememory.)

The big problem is that you'll never know if you have ANY liquid in the system!!!
If a hose blows while you're on the highway, all the liquid may dump out the bottom of the engine bay; you may never catch a single whiff of antifreeze nor see a wisp of steam vapor. But then you have an air-cooled engine, and that little waterpump ain't doing a thing for cooling the engine.
Do not rely on the GA's 'Low Coolant' idiot light, since it will undoubtably fail just when most needed.
By the time the temperature sensor reads the AIR temp of 250*F, the aluminum head is close to melting in some places (900+*F !!!)

BS on your mechanic's theory.
The t-stat should open at it's set-point, 180*F IIRC for your engine.
The gage sensor is RIGHT NEXT TO IT!!!
Even if it takes a looonnnnggg time for the liquid to warm enough to open the t'stat, your gage is reading that temp real-time.
(Assuming your gage is accurate, which is a very dangerous assumption on any 14-yr old car.)

IMO, you still have a major cooling system problem, and you need to keep hunting for it.

Refresh our memories: What has been replaced, cleaned, flushed, checked?

Finally, this might have nothing to do with the engine.
Your auto tranny is also old, and it might be slipping like a mofo, especially it WILL slip if the TCC has been disabled.
All that slipping is actually friction, and friction is heat.
The heat is transferred to the coolant at the tranny cooler in the passengerside radiator tank, then goes straight into engine.

O'Reilly's (and AutoZone and others) sell the cheaper brands of stuff, but they don't MAKE anything themselves.
They may have their name put on a cheap t'stat manufactured by some shady third-worl company, so the chances of a faulty NIB product are higher than a reputable product from NAPA.
Even the finest brands occasionally deliver a faulty product to the consumer.
It's easy to check a t'stat: Toss it into a saucepan on the stove and bring the water to a boil; measure the temp at which the t'stat opens with a candy thermometer. How long it continues to function properly is generally the quality issue that separates reputable and expensive products from their cheaper counterparts.

If you have doubts, replace it with a Stant from anybody or a GM from a dealer (prolly made by stant) or a NAPA house-brand (also prolly made by stant).

Hope this helps,
-Rick

[mrcaddy]

Like I said this is a '94 SE with 2.4 and auto. While this my first GA I can't say that the tranny is slipping. It seems to shift very well. I do know what a slipping tranny feels like and I don't feel that. However, I'm sure it could use a filter change as I have no idea what the last people did. They gave up on the car when the heater core went out. Did they drive it hot? How would I know? We put a new heater core in it in late August/early September. Drove it with mostly water in the system until late October. The grass was still green and it never got cold enough out to freeze anything.
So, at that point I drained the radiator and put in antifreeze. Up till that point any time the car warmed up and was driven anywhere it never got above 160 (the second mark after the first). Then, with antifreeze it would go to 220 and sometimes beyond. We had to put in a new water outlet (and then two more NO MORE O'RIELLY parts for me). It never got hot enough then either. Now with the new water outlet it is creeping past 220. It will go past 220 and sometimes go back down. It has always passed every pressure test we have put it through. It always puts out good heat. It only gets this hot on the highway. Not a problem with in town driving. I carefully washed out the outside of the radiator from the back. We have put a new thermostat in (from O'Reillys).
That's really about it. It never smells like it is running hot and the coolant never boils over. This is really frustrating and I'm about ready to give up on this car and go back to my Suburban! I don't want to, but........How would I know if the head is warped? Is that possible?

[rixGAphx]

A 'slipping' torque converter doesn't 'feel' like anything.
Certainly not like slipping bands or clutches.
All a TC is supposed to do is 'slip', and multiply the torque a little as the fluid from the turbine is slung back against the stator vanes.

When those vanes wear (from friction of granular stuff in the fluid), then more fluid is slung and less work is performed.
But it doesn't 'feel' any different; the engine just revs a little higher before getting any motion from a standstill, and it revs higher by about 100 rpm in each gear.
The heat can be enormous. Much more than a good tranny produces, and more than slipping clutches or bands.

The energy that is 'lost' is somewhat recouped as additional torque when you're accelerating, but it's just plain lost when you're cruising down the highway against wind resistance.
Acceleeration requires torque, which the TC is great a providing.
Overcoming wind resistance requires horsepower, which is lost thru a TC as over-revving.

So much more heat is generated while travelling on the highway than in stop-n-go city traffic.

That's why a TC lock-up is so effective: NO slippage (when it's engaged).
Mebbe yours just flat doesn't work?

The other thing that hasn't been done, best as I can tell, is a flush or inspection of the radiator water passages.
They can become SO plugged that even a chemical flush won't dissolve and clear them.

Your story indicates the problem began after putting in antifreeze.
Prior to that the temp was fine with plain water.
Your '94 came from the factory with a 50-50 mix of water and plain-old green 'conventional' antifreeze.
some previous owner might have switched to DexCool after it arrived on the market in '96.
What anti-freeze did you add (orange DexCool, or green conventional, or ????), and at what percentage (50-50, 60% AF, 75% AF)?
Supposedly, 10% of one AF is OK to mix with 90% of the other.
But there's a new-wives tale floating around, with some strong anecdotal evidence, that half-n-half orange-green creates a tofu-like sludge that just clogs eveything in the universe.
Your radiator might have such a sludge pile.

Contact a local radiator shop and see if they can service your plastic-tanked rad.
I *think* they can bend-back the edge tabs and remove the tanks, then rod-out the tubes the way we did old soldered-tank rads.
With a new rubber o-ring, the tank can be reset and the tabs bent back into position.
I don't know how the cost would compare to a new rad over the internet.

If this is happening (clogged rad), then the t-stat could be wide-open at 180 yet very little liquid would flow thru the rad.
The result would be very little cooled water leaving the rad and entering the engine.

The impellars on the waterpumps wear-out over time. So they flow less liquid, regardless of the condition of the t-stat or rad.
Changing the WP on the 4-cyl is a major undertaking, and I don't know what to say other than that could be the problem.
And wouldn't explain why the hot-running came on all of a sudden.
* * *

When the head warps (usually from an extreme overheat condition and actually running with no liquid for a few miles), it no longer firmly 'sandwiches' the head gasket.
So the head gasket leaks ('blows' is a misnomer): cylinder pressure can blow hot exhaust gas into the water passages, or 14 psi coolant pressure can force coolant into cylinders (on the intake stroke), or 14 psi coolant pressure forces liquid out the side of the block.
Rarely is oil involved.
In the first 2 examples, the pressure in the cylinders during a compression test will indicate the breach.
In the 3rd example, a pressurized test of the cooling system will indicate leakdown, and the leaking water should be visible.

Only when hot exhaust gas actually bubbles into the coolant (example 1) does the coolant temp rise. This exhaust is 'dissolved' into the coolant, and is visible in the reservoir as oily-looking bubbles, kinda like frothy beef soup.

If the coolant level drops (because of examples 2 and 3), then the temp will rise due to poor liquid flow.

Is there anything else I can do to make this more confusing?
:roll:

-Rick

[mrcaddy]

Rick,
Very helpful! I will take this home and digest it. I never thought about the mismatched antifreeze. I doubt that, but one can never tell. The inside of the head looks clean as a whistle.
Now, I may have asked this before, but I need to ask it again. When the temp went to the 'friendly' side of the RED mark I got out and checked things over. I noticed that the radiator (I had been on the highway a couple miles) was ice cold. It was in the 20's out. Wouldn't the radiator be warmer? I noticed it was warm up around the 'upper hose ( driver's side). The 'lower hose' (passanger side) was ice cold and so was 95% of the radiator. I am thinking that might be my problem.
Which direction does the coolant flow? Thanks so much, Scott

[sudden_impulse]

The coolant flows from the upper hose to the lower hose. If your radiator is cold on the lower side (ice cold) then I'm guessing your radiator is clogged. Try either running some chemical cleaner through it (cheap fix), or get a junkyard radiator that isn't clogged and replace it.

[mrcaddy]

I think I'm started to see the light at the end of this frustrating tunnel.........:) I think I might just go buy a new radiator. I'd better be careful where I buy it at. Any hints?

[Andrew21]

I think I'm started to see the light at the end of this frustrating tunnel.........:) I think I might just go buy a new radiator. I'd better be careful where I buy it at. Any hints?

If you can, get a modine.

Also, try this. Disconnect both hoses and shove the garden hose in the top hose. Have someone turn on the hose at high power and see what comes out on the other end. I'm curious to know whats in there.

A-

[mrcaddy]

..........having second thoughts. I just got to work and checked it again. I have a 14 mile mostly highway drive in to work. Some city driving the last 4 miles. I checked things out again and the WHOLE radiator was ice cold AND so was the 'upper' AND 'lower' hose. I still have great heat. My tootsies are staying warm. Could it be the water pump instead? I think my choices are........Thermostat, water pump, radiator, collapsed hoses. I'm going to call a radiator shop today and get their opinion. Any thoughts? Anyone else have this?