anti freeze question etc

[gbrtng]

Thanks Hib for blasting another myth. I did not know the 95s had Dexcool from the factory - interesting. Saturns began with Dexcool in 1991 and the industry reason was because of the aluminum head and block design. I figured if it's good enough for my 92 Saturn, it's probably good enough for the 91 turq. So I converted it to Dexcool in 1997 and it's been OK so far.

But you should see the Dexcool rants on Bob is the Oil Guy ...

[scottfab]

I ran dexcool for 5yrs with no problems. I succumbed to the rumors/facts that head gasket problems were an issue and switched back to the green stuff but change it every 2yrs.

It's certainly not clear to me that the reported gasket failures were due only to dexcool and not another cause (tap water or previous use of poorly maintained green stuff and/or poor maintenance etc).

I guess it's like the ZF6 damage reported after using Redline. When in doubt ..... avoid it. I do know that replacing the water pump is a real PIA.

[GOLDCYLON]

Hib is actually both right and wrong in this discussion. His 95 did indeed come from the factory with Dexcool. As long as he continues to service his ride with Dexcool he wont have a problem as he contends. There has been a lot of online debate on Dexcool but it appears if you flush regularly like you should do on any system after about 25K miles you wont have a problem. GM has faced many claims and lawsuits becuase they published a change interval of about 75K or 100K miles on the change ntervals. Results were contaminated systems, sludge build up and destruction of gaskets. Hib obvioulsy maintains his cooling system.

However the problem with Dexcool comes from owners who have added it into the system with the green stuff. In combination it is corrosive and will harm the head gaskets. Proven many times by M Haibeck and others after many Head Gasket exchanges. Remember one product contains silicates the dexcool does not. Dexcool was formulated to be less corrosive on aluminum than the green stuff was as well.

So the sage advice for the earlier ZR-1 owners is to avoid mixing the two because of this problem. So how could this happen? Well if you changed the hoses, or the radiator and proceed to fill the car with Dexcool guess what??? Plenty of green antifree resides in the block and will still cause the problem. Eventually. So maintain your cooling system.

No Myth. So if your car was not equipped with Dexcool. Avoid. GC

[USAFPILOT]

When did the dexcool start? My 94 had dexcool in it when I bought it, but have switched it to regular and had it flushed twice.

[GOLDCYLON]

Originally Posted by USAFPILOT

When did the dexcool start? My 94 had dexcool in it when I bought it, but have switched it to regular and had it flushed twice.

I believe 94 was the first year. If you flushed it out twice you maybe ok the problem is when its just added and forgot about. Thats when the corrosion starts.

[Hib Halverson]

Marc and I exchanged emails about the coolant issue.

His belief is that the problem with DexCool and the LT5 engine is not the oxidation/sludge issue that comes up with S/T trucks and old B-cars, both of which have heater cores above the level of coolant. It's also not caused by people mixing the two types of coolants and the resulting combination becoming corrosive.

Marc feels the problem is the calcium-based corrosion inhibiter package in DexCool causes the non-metallic parts of the head gasket to swell and/or disintegrate.

I have not seen nearly as many high-mileage LT5s as has Marc so, while I'm not going to stop using straight water and Red Line Water Wetter in my LT5, there is evidence from engines Marc has worked on pointing at DexCool.

I wonder if other LT5 rebulders have seen the same trend?

[Hog]

Hib, the fill scenario you describe is one I use on my 1996-1999 pickup/SUV's as well. As with your Vortec V6 4.3 in your Blazer, the 1996-2002 Vortec 350/L31, 305/L30 can be affected as well. These vehicles use aluminum lower intake manifolds and iron cylinder heads. The difference in expansion/contraction rates of these dissimilar metals can cause the intake gaskets to "roll" during heating/cooling.
This issue is compounded by the fact that these intake manifolds are held down by bolts that do not apply clamping forces in a perpendicyular fashion to the gasket face. The bolts are pointed straight down to the ground, while the head/intake interface is at an angle. This puts the gasket in a state of shear force. Combined with the difference in expansion/contraction rates of the intake and cylinder head, these engines have known intake gasket issues.

The final torque on these intake bolts is only 11 lb/ft on their final pass, and these bolts are located in pairs only at the corners of the intake manifold. The V6's being shorter arent as bad as the londer V8's. There are only 8 bolts with none in the middle of each intake gasket flange. GM by making these intakes easy to install on the assembly line, have sacrificed ultimate durability. Felpro offers their "Problem Solver" intake gaskets for the Vortec 4.3/305/350 engines. They arnet cheap, but the are much more robust than even the redesigned GM gaskets. Back in 1996 when these Vortec engines were introduced in teh trucks/SUV's the encapsulated silicone intake gaskets were heralded as "REUSEABLE". What crap, they certaonly are NOT.

Stock "encapsulated silicone" Vortec 4.3/5.0/5.7 gasket(many other GM engines use this type as well)


FelPro problem solver intake gasket


Keep the cooling system in good shape and keep the air out, use proper water and Dexcool is fine. Dont maintain those systems, and I have seen Dexcool etch cast iron cylinder heads, not good.

At least the LT5 is mostly aluminum, that helps the gaskets stay in good shape.
Was their any changes in waterpump durability once Dexcool was introduced in the LT5?

peace
Hog

[Hib Halverson]

On the S/T truck stuff, I guess we're sorta hijacking this thread.

That said, the coincidence of you mentioning the L35 is uncanny.

Last summer I did a top end overhaul of my 4.3. The engine had about 125,000 miles on it. Cooling system maintenance was done regularly and the coolant was 50/50 DexCool and water.

I had none of the problems you discuss with intake gaskets. I don't doubt that others do experience those problems, but I did not. Since, I always use Fel-Pro gaskets on jobs like that, I guess I installed those Problem Saver gaskets and didn't give it much thought.

[lbszr]

Originally Posted by Hib Halverson

I'm not going to stop using straight water and Red Line Water Wetter in my LT5, there is evidence from engines Marc has worked on pointing at DexCool.

I wonder if other LT5 rebulders have seen the same trend?

You mentioned in an earlier post that the Red Line Water Wetter has the same inhibiters as the Dex Cool. I too use straight water and Red Line in the summer for track use and switch back to green in the winter, for about 3 years now (head gaskets are only about 6 years old).

I'll still keep using it also, but for curiosity. Does this mean basically, that I'm switching back and forth from DexCool (water wetter) to green? Even though that may not be a problem.

[Paul Workman]

My understanding (from Marc and reading up on it) the issue with our LT5s and Dexcool is one of possible chemical incompatability of the coolant and the specific chemical makeup of the gasgets initially used in the LT5s. If "Dex" was used as factory fill in the 95 ZR-1s, it might stand to reason that issue was resolved before the last production LT5 was assembled, back in '92(?). Not agruing with those using Dex in their LT5 successfully, but I've seen some of Marc's evidence in person. Y'all do what you want, but pulling the heads to change gaskets on an LT5 is a WHOLE nuther thing, compared to a SBC. Just sayin.

Originally Posted by Hib Halverson

*snip*.

Ok.
You're probably wondering what I use for coolant if I don't need freeze protection.

Yeah, Hib: keeps me awake at night!

Originally Posted by Hib Halverson

Distilled water and Red Line Water Wetter. Straight water is a better coolant than 50/50 mixes of antifreeze and water. Of course, you have to use some type of water pump lubricant/corrosion inhibiter and that's where Red Line Water Wetter comes in. It has virtually the same lubricants and inhibiters in it as does DexCool. Additionally, Water Wetter is a surfactant which improves heat transfer from the engine cooling jacket surfaces to the coolant.

NOT SO FAST, pard! (Taking exception to advertising hype here...)

"Water Wetter" (WW) ...Because I'm veering OT, I'll keep it quick...

WW may or may not improve heat transfer, but compared to what???

I've always felt that once again some fundamental laws of physics are being trampled by the hype used to sell (in this case) WW. Pickin' a nit, perhaps, but specifically I've never bought into the surfactant explaination as the key to how heat transfer efficiency is affected by using it. Instead, known stuff like...oh..."heat of vaporization" and "specific heat" and "heat transfer coefficient" etc ALL have direct, scientifically predictable, affect on heat transfer. Sorry...surfactant ain't on the list (but sounds plausable to the uniformed).

To your point about pure water being a better coolant than 50/50 mix of water with glycol-based coolant is because the specific heat (capacity) of gylcol is lower than that of water. However, the offsetting fact is the boiling point of pure water vs. the boiling point of the 50/50 mix with glycol results in the mix being far more effective at cooling than pure water would be, due to the water coming to a boil. This fact too has direct consequences, in terms of ability to transfer heat.)

The beneifit of corrosion inhibitors and lube not withstanding, here's where I'm coming from: 1) Ordinarily, the ratio of pure (distilled) water to WW is not 1:1 (50/50) as typical for glycol anitfreeze, but more like 16 or 18:1 water to WW. So, the improvement of heat transfer is unlikely due to a significant increase in the specific heat characteristic of the mix (if any). I'd sooner be swayed to any improvement over pure water as 2) a function of raising the heat of vaporization (boiling point) and the resulting improvement in heat transfer coefficient (from the metal to a liquid coolant vs. metal to a gasseous (steam) coolant). (Oh, BTW, the flash boiling of coolant in direct contact with the metal, is not the culprit some think - as long as the bubbles (steam) are flushed away by the water circulation...(trust me).) And 3) the fact is the "specific heat (capacity)" of water is quite high, comparitively.

So if WW (or the like) can raise the boiling point without significantly reducing the specific heat capacity (of water), then the result is the best of two worlds: higher boiling point = more efficient heat transfer, higher spcific heat also = better heat transfer...compared to pure water as a coolant.

As for the surfactant claim, I would hope anything added to (water) would NOT foam. But, as I said, I believe the ability of additives (e.g. WW) coolant mix to be more efficient (compared to pure water, for example) are based on raising the boiling point (essentially) and NOT from that advertising BS claim re surfactant.

As for silicates and other stuff to prevent corrosion and lube the seal/shaft contact area of the water pump...sounds good to me.

Just because there is conventional belief (by some) that the universe rotates about the earth or the earth itself is flat, or BS advertising hype trumps true science, does not make it so. I always thought this topic would make a good experiment for a high school physics class...assuming their school even has a lab anymore... (Don't get me started!)

RE experimenting, this link touches on some of what I've been trying to say...

http://www.thetruthaboutcars.com/200...%C2%AE-review/

Not pickin' a nit wid ya Hib. It's just that sales hype is often written by "word smiths" that - wouldn't know a dB from a dollar bill!


P.