As a second side note, re: suckered into having the lowers replaced:

The dealers were instructed by GM to do this for any UIM change, but too many techs don't bother looking online before a procedure, because they 'know what they're doing'. The reason GM said to replace both is that the stovepipe is supposed be a pressed fit (i.e., even though they can usually be removed by hand, they shouldn't be able to), not as a way for dealers to screw the drivers.

Also, the sleeved intake really is nice, and it'* about the best solution that'* available, but because of the design of the intake itself, it doesn't much matter what you do, it'* still prone to failure - it'* just a matter of how much time it takes. Of course, we have no idea how long that is with the larger airgap - and for all intensive purposes, it may be such a long time to failure that it won't ever matter. And I can say for sure that if I had to do an intake job tomorrow, it would be done with a dillion sleeved intake.

Thanks for the clarification on the reason why they replaced the lower, mkaake. I only hope they used the '99+ version when they replaced mine. Of course, I consider myself luckier than most, as I got somewhere around 125K+ miles on my original before failure.

Many of us have either removed the plastic engine cover or customized them using expanded metal mesh. We believe that it helps.

I'm not sure that removing the hood insulation will have much positive effect, but others may want to chime in on this.

In the techinfo it lists the felpro LIM gaskets # MS95977-1. I can get the GM'* at gmpartsdirect.com but I'm leaning toward felpro. I've been searching online all over the place and can't seem to locate the part.

EDIT: Found them http://www.partsamerica.com/ProductD...number=MS95977

Is $69 a reasonable price vs the $28 for the GM'*? It seems like a huge difference to me...

I also found a different felrpo part #MS958091for $39. Not sure what the difference is there either.

I've been running without the cover sence the last intake replacemeant.It did'nt make any differance on mine.It'* back on now.

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http://bonnevilleclub.com/forum/viewtopic.php?t=42191

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I'm confused,.... is replacing the coolant periodically a good thing or not ?
If so, is corrosion a concern for the periodic flushing ?

The problem is Dex-cool. It was originally marketed as a long-life coolant that you didn't need to worry about. Just google Dex-cool and you'll get an education. The stuff does not do well when exposed to air and after its "long life" of five years or so, begins to break down into an acidic brew that can attack and degrade gaskets and other engine parts. Dex does not mix with the old green antifreezes. When the two get together, a thick slimy brown sludge forms that can block flow. I have also seen brown crumbly stuff in Dex engines that either were not flushed soon enough or were accidentally mixed with the old green.

The thing is, with the old green stuff, you might have lost the anti-rust protection after a while, but it didn't actively attack engines, when it broke down, or plug up passages with precipitates. Dex does. Bad Dex.

The 3800 Lower Intake Manifold plastic frame and soft bead gaskets have been a source of many engine failures. There are scores of pictures of these here on BC in terrible condition. Some of us suspect that old Dex gone acidic might help to soften and separate the beads from the frame and lead to gasket failure.

If you change your Dex every five years, you won't likely have any trouble with it. As a rule, I prefer to use the newer green "mixes with anything" stuff, and plan to flush it every few years. That way, if someone adds something of the wrong color, my cooling system won't suffer.

To answer your question - changing coolant periodically is a good thing- orange or green. I believe it is more critical to change the orange, but good practice, as you said, to prevent corrosion, to change either color.

get the GM gaskets. They were recently updated to a metal carrier that should eliminate most of the failures that we've seen, by preventing failure of the coolant port plastic...

I used the Felpro MS95809 on my lowers for the 96 SE.

I'm goin crazy with all the different Fel-pro gaskets that seem to fit the LIM. Seriously there'* about 5 different part numbers and varying prices for each.

MS958091 $61.48
MS95977-1 $66.96
MS95977 $45.48
MS95809 $41.48

No idea on the difference between these except the last one is for sure 1st gen