01 Impala LIM Replaced

[cchase]

Originally Posted By: wtd
I have a 2004 MC SS with the L67 3800. Does this engine have the same intake gasket problems as the non supercharged ones? These cars obviously use different upper manifolds so does the Supercharged ones have a manifold problem also? I just bought this car and the original owner had the coolant changed last year with the green stuff. Its getting a little wet on top of the intake near where the edge of the valve covers are so I'm not sure if what I'm seeing is oil or coolant. Its drying up from the heat so its difficult to tell.

wayne


If it's wet, stick your finger in it and see if it's coolant or oil. It sounds like intake manifold gasket though. Going back to green stuff from Dexcool can be bad mojo, too.

 

[mechanicx]

You might not have the EGR stove pipe/upper IMG problem the NA motors did, but you could still have the lower IMG problem. They didn't get fixed till like '05.

Dexcool is probably not the only OAT coolant that is incompatible with some plastic gaskets. I think the Green is more compatible with the plastic and silicon gaskets used on the older models, even more than G-05 is. If you get most all the Dexcool out you can switch to green. The only real fix is to replace the gasket with a Felpro problem solver and then it should be compatible with Dexcool.

 

[wizzells]

Originally Posted By: cchase
Dexcool doesn't even sludge, it's the stop leak they put in there that sludges up.

Oh, and people mixing green and pink.


I had bigtime problems with the Dexcool sludging on my 97 Grand Prix (3800). This was both before and after the intake gaskets were leaking/replaced. And yes, it was flushed regularly and before the recommended interval.

 

[mechanicx]

Yeah I don't trust Dexcool not to sludge with a cap on the radiator system. Plus Dexcool is more a standard than an exact formula and seems like some brands of dexcool sludge more.

But if you have a pressurized reservoir and compatible gaskets, Dexcool works very well.

 

[saberz]

I didn't think much of this before, but I remember doing his oil change one time and noticed oily/dirt around parts of the engine. Figured it ws due to an idiot doing the oil change before I got to it. But it was right around the gasket area, so it may have been gone for a while.

 

[mechanicx]

Yeah that's how the IMG does. It slowly leaks overtime. And the coolant leak looks like oil not like coolant. It's easy to mistake it for an oil leak or valve cover leak.

 

[defektes]

when I found the leak on my 4.3 I thought it was oil, it was dripping off the trans bell housing. I got down there and stuck my finger on it, low and behold it was Pink.

 

[454chevy]

Those gaskets have real thin spots on them that fail. They will fail with any anti-freeze because my brother switched out his red anti freeze for the green prestone when his truck was 1 year old. About 4 years later they started leaking anyway. But I think we put new felpro gaskets in it. Problem solved and it was easy to do. They never leaked again and that was over 5 years ago.

 

[wapacz]

Originally Posted By: Trav
The GenI used plastic gasket frames also with green OEM coolant and had nowhere near the LIM issues like the GenII.
Believe and use whatever you see fit its your engine.
As long as things like this are out there i for one don't buy the "it safe" story at all.

http://www.consumeraffairs.com/news04/2006/08/gm_dexcool.html

http://www.aftermarketnews.com/Item/3014...er_dexcool.aspx

http://autotechrepair.suite101.com/article.cfm/050106

http://www.dexcoolsettlement.com/



"Series II

Introduced in 1995, the Series II is quite a different engine. Although the stroke for the 3.8 L engine remained at 3.4 in (86 mm), and the bore remained at 3.8 in (97 mm), the engine architecture was vastly changed. The deck height is shorter than the Series I, reducing weight and total engine package size. This required that the piston connecting rods be shortened 1 in (25 mm), and the crankshaft was also redesigned. A new intake manifold improved breathing while a redesigned cylinder head featured larger valves and a higher compression ratio. The result was 205 hp (153 kW) and 230 lb·ft (312 N·m), better fuel economy, and 26 lb (12 kg) lighter overall weight (to 392 lb (178 kg)). The 3800 weighs only 22 lb (10.0 kg) more than the High Feature V6, despite being an all cast iron design.

The new intake manifold greatly improved airflow. To meet emissions standards, an EGR tube was placed in the intake manifold to reduce combustion temperatures. This increases fuel mileage by a substantial margin."

http://en.wikipedia.org/wiki/Buick_V6_engine#Series_I

Lets see newly designed intake manifold and heads. Inclusion of erg stove pipe in the intake manifold. Nope those changes couldn't have possibly led to having problems in intake manifold gaskets that weren't found in the gen1. So it most of been the dexcool.


The whole gasket problem is pretty much the perfect storm. I will give that dex may have made the gasket more supple and weaker but that alone wasn't the total problem. There where fundamental design issues to start with.

 

[mechanicx]

What your saying is kind of true except the lower intake manifold gasket deterioration has nothing to do with the Series II changes and the plastic upper intake manifold and EGR stove pipe ran through it. The lower gasket was nylon and silicon and fairs worse with Dexcool. To a degree both the gasket and the Dexcool are to blame. The lower IMG should've been sturdier and compatible with Dexcool, but it'd be nice if Dexcool was compatible with more plastics. Green is much more compatible with that lower IMG.


GM had good reasons for using Dexcool and the plastic upper intake manifold with the EGR pipe going through it, but long-term durability was not very well validated. Worst, it took GM almost 10 years to truely fix their V6 IMG problems.

 

[wtd]

It looks like oil but it could be coolant. I'm not leaking any coolant on the ground and the oil looks clean but that doesn't mean it still isn't leaking. I did have to replace the radiator cap recently because it was caked with the brown sludge from the old dexcool. I'll probably have the lower intake gasket replaced in the near future just to be on the safe side.

Wayne

 

[wapacz]

Originally Posted By: mechanicx

GM had good reasons for using Dexcool and the plastic upper intake manifold with the EGR pipe going through it, but long-term durability was not very well validated. Worst, it took GM almost 10 years to truely fix their V6 IMG problems.


Yeah it took them way way to long to fix the problem.

 

[Trav]

The big difference was the EGR pipe that went through an unprotected plastic UIM that had a habit of burning through the UIM wall.
Other than that the differences in specs it has no effect on this issue.
If this were the old 3.8 with a single piece manifold vs the 3800 two piece then you have a point.
The original 3800 series still used a very similar LIM and LIM gaskets.