Me, I’d ask my shop to do the appropriate tests to eliminate head and intake manifold leaks as a problem; and if no leaks were found, I’d just t flush out as much gunk as possible from the cooling system, replace the water pump and thermostat, refill , and knock on wood. It might well work.
It sounds like however that you want to take this engine apart. Or at least see if you can. And learn from the experience. If so, go for it. It’s just a hunk of iron, aluminum, and various nuts and bolts after all. If you run into any difficulties, there’s a local auto shop & machine shop that can pretty much solve any problem you run into.
Note to OP: db4690 is a professional mechanic who offers consistently good advice here, and knows much more about this topic than I – a driveway diyer who owns no GM 3.4 L engines at all – knows.
I’m not doubting OP’s abilities as to replacing the head gaskets. AFAIK, this is a pushrod engine, so theoretically, it should be easier, versus a overhead cam engine with multiple chains, or maybe even a timing belt
But I wouldn’t cross that bridge unless/until it was necessary
another thing to consider, which hasn’t been mentioned yet. If you remove those heads, you’ll need to separate the exhaust pipes from the manifolds. Might have to soak the hardware in penetrant. Might even have to bust out the torch. might have to replace some broken hardware. That hardware probably hasn’t been touched since the car was built.
That dark transmission fluid is not a good sign either. That means the fluid is oxidized and darkened from heat and the breakdown of the additives in the fluid along with friction material. You really need to change the transmission fluid and hope trans problems don’t surface later.
You might consider pulling the spark plugs and checking the tips. Quite often engine coolant going into the combustion chamber will have a tendency to bleach the plug tips to a white or offwhite color. Sometimes they may appear slightly wet; one or more of them and all depending.
Get rid of the Dex Cool for sure. When my oldest boy bought a Camaro back in the late 90s it had a tendency to sludge up horribly with Dex Cool. Three water pump failures each time it sludged up. Thoroughly flushed it out, converted to green coolant, and it has been fine since.
That was about 15 years ago and the car is still fine today.
It’s a mystery to me why some people defend that black goo DexCool. It’s much like pit bull owners who swear up and down that they make good pets. They might for the owners but they can be dangerous for the neighbors and visiting friends and relatives. I have 12 gauge shell reserved for a certain white pit as soon as it shows up on my property again. I feel the same way about DexCool and no amount of support for it will sway my common sense.
I didn’t have any cooling system problems with my 2006 Chevrolet Uplander with the Dexcool, but when it was time to replace the coolant, I had the green coolant installed. My son now has the Uplander. It has 180,000 miles on the odometer. I know he has changed the ,coolant as per the manual using the green coolant. The Uplander may have done as well with the Dexcool, but I decided not to take a chance. I don’t know of any advantage to using Dexcool.
db4690, I think you’re probably right that the problem is the intake manifold gaskets. The possibility that the car might have overheated since it failed makes me worried though.
Docnick, My understanding is that it’s the same toxic ethylene glycol, but the corrosion inhibitors are different and last longer. There is propylene glycol for less toxicity though.
All this discussion about Dexcool and the other thread about synthetic oil makes me want to go back to the good old days,when we used non-detergent 30 weight in the summer, non detergent #10 in the winter, put water in the radiator in the summer and non-permanent methanol in the radiator in the winter. DuPont sold methanol under the Zerone label and ethylene glycol permanent antifreeze under the Zerex trademark. We should have left well-enough alone. All this Dexcool and Synthetic oil talk has me confused.
Before going after parts, I agree with db, flush the system out with hose water, refill with the proper mix (I recommend NOT using dexcool), and monitor the new fluid. If that turns to brown crud too, and it might, start looking for the cause.
@hypophthalmus, you are correct that dexcool is just as dangerous as most other antifreezes on the market. It is fundamentally ethylene glycol, only the corrosion inhibitors and detergents are different. @Docnick, you are thinking of propylene glycol originally sold under the trade name “Safer”.
You should inspect the plugs as recommended by ok4450. I don’t know if you are old enough to have ever seen a sandblaster that was made specifically for spark plugs. You would stick a plug in the top and push a button for 10 seconds or so. Anyway, it has been my experience that if the head gasket is leaking, the spark plugs look like they just came out of the sand blaster. But you would have to have seen one of these to understand what the plugs look like.
If there is no evidence of an actual head gasket leak, I would strongly urge you to not disturb the engine. This engine uses torque to yield head bolts so in addition to a torque wrench, you need a torgue angle meter. Fortunately they are not expensive. You should also chase out all the threads so they are clean. Each bolt has to have an equal compression of the head gasket below it and it must also stretch a specific amount. If there is any variation between the head bolts caused by a difference of friction or any other cause, the new head gaskets will leak and the head will warp.
I also don’t like to flush, even with plain water unless there is a blockage. I would just drain and refill with 50/50 or as I do, mix full strength with distilled water. I mix at 2:1 so there are more corrosion inhibitors available. A little remaining old coolant won’t do any harm. When the coolant shows signs of getting cloudy, then it is time to change it again. BTW, all coolants will turn brown and sludgy if left too long in the system, not just dexcool.
I have used dexcool on vehicles other than GM with no trouble. But I am most loyal to my hip pocket (wallet) so I go for a HOAT type antifreeze (mixes with all coolants, all colors). Its a universal long life coolant and I use the brand “on sale”. I do stick with major brands and do not use dime store brands or off brands. Dexcool in usually not “on sale”.
Isn’t an owner of a new Dex-Cool spec’d car – to keep their warranty valid – required to use Dex Cool? Or does the manufacturer offer several brand options?
In order to keep the standard warranty in effect, Dex-Cool was required in the cooling system.
But every person I know who bought a GM vehicle with Dex-Cool, had the Dex-Cool flushed out and replaced with the standard green coolant as soon as the warranty ran out.
The only reason GM was the only company that used Dex-Cool was a marketing gimmick.
I still remember the commercials.
“GM vehicles come with Dex-Cool. This means that the vehicle COULD go for 5 years or 150,000 miles before the cooling system ever requires service.”
Good to know about the angle meters. I was thinking that eyeballing it was an acceptable method (saw it in a video), but it sounds like it’s better to be more accurate than that.
More concerning than the sludge to me (which sounds avoidable enough) is that fact that it eats through the gaskets. Which according to the lawsuit Tester linked to is the reason for so many intake manifold gasket failures in this engine.
Maybe 2-EH is the only chemical to be concerned about with regards to that… but maybe the other OAT/HOAT coolants without it will have the same effect?
I have never had a Dex Cool issue in my 2000 S-10 but probably change the coolant more often than needed so don’t have the issues mentioned here. I know people really either love or hate this stuff. If I have issues I might go with a universal type coolant. People with import cars seem to swear by the Toyota pink coolant. I guess that is good stuff. Why all the different colors/types of coolant? The coolant in my new Mitsubishi Mirage is blue. I almost topped it off with windshield washer fluid but caught it at the last second, otherwise I would have been changing coolant early.
I understand the pit bull analogy perfectly! Some of my neighbors decided to HOARD all the unwanted pit bulls being given away on Craigslist and similar and there are LOTS of them being given away around here. They just let them run in packs, terrorizing everything within a mile radius or so. I lost some goats, a cat, and nearly came under attack myself because of this situation. My property shares the longest boundary with these people so I had the most issues but the other neighbors did too. Between all of us, we probably shot 50-60 of their dogs before they decided to give up this habit. I tried calling every governmental agency possible and no one was willing to do anything about it. Their response was “Do you own a firearm? Use it.” I was hoping the conservation dept (fish and game) would do something as they were killing deer and other wildlife. It is illegal to hunt with dogs but if dogs are hunting on their own, that isn’t illegal. The owners knew full well what they were doing. They tried letting them run at night and that is what night vision is for.
I wish all those who loath and despise Dex-cool would stop saying that anybody who continues to use it is an idiot
Just because YOU have had a bad experience or know somebody who did, does not at all mean it will happen to somebody else, or even the majority of people
Consider a technical service bulletin, for example . . . in spite of its existence, there’s a fair chance you will never have that problem. One of its purposes is to alert the mechanic of a POTENTIAL problem.
Consider cr . . . many of the regulars drive cars which are considered very unreliable by that magazine. But they’ve been good cars to the guys on this website. Part of the reason may be that we’re largely gearheads of some sort or other, and take far better care of our vehicles than the average cr subscriber. As such, many potential problems are headed off and/or avoided
It’s all relative
it’s not all black and white
it’s not “Dexcool is bad. If you use it you’re an idiot.”
Go ahead and change it out for something else, if it makes you more comfortable
But stop implying the worst of anybody that chooses to use it
BTW . . . This is not addressed to anybody in particular
If I end up replacing the head gaskets, is it better to torque it in stages?
It seems that most people torque it is sequence to 44 ft/lb and then go back and torque it to the angle. But it couldn’t hurt to go through the sequence a few times working up to 44 ft foot/lb… right?
@Tester
"The only thing I put forward are the facts about Dex-Cool"
by Tester
Tester: “The only reason GM was the only company that used Dex-Cool was a marketing gimmick.”
There’s one example. Show me or prove to me that is fact (that it is strictly a marketing gimmick).
From everything I have read, regardless of what “horror stories” people perceive/imagine, Dex-Cool is the superior coolant for actually doing what coolant does… cooling.
Not changing coolant or letting it get low and then continuing to operate with low coolant, and/or mixing/adding some other type coolant with Dex-Cool, is what creates ugly looking sludge, regardless of the coolant type used.
I don’t abuse my cars and never have problems with this wonderful product. When I change it after several years use, it looks as good as it did when it came from the jug.
I’m standing by, ready to read about the marketing ploy that you claim is Dex-Cool.
Then I will agree that you only publish facts, Mr. Tester, sir. CSA
