96 Buick LeSabre Intake manifold leak-how much $ or how to repair?

The subject line just about says it all. This car has about 40,000 miles on it. I'm an old VW D.O.Y. of moderate ability, with little to no experience
with water cooled cars -- aside from once replacing a water pump in an early '80s Chevy.
But when I got the estimate of $600 at a dubious local shop, I figure it's time to learn. I'm in northeastern North Carolina, about 60 miles north or Raleigh, should anyone have a more reliable and less expensive mechanic to recommend.
The guy who looked at it charged my wife $50 and told her he couldn't determine for sure whether the manifold was the problem, and to bring it back in for further investigation -- yeah, sure.
S'long for now, Leonard
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Todd Leonard wrote:

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A lot really depends upon the problem. I assume this is the plastic plenum problem.
GM will sometimes, ballsily, want US$700-1000.
If you are not covered under warranty, and IF this is the case, a price of US$350 or so is probably reasonable.
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Just did one in my shop same car, very common as is the lower gaskets parts were 300.00 including coolant and an oil change, and 5.0 hours labor. The price you got is about right.

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Thanks for the quick responses. This is my first time to the group -- and with a new usenet client, to boot. So I really didn't even know whether my post would get through.
That out of the way, filtering the group with "intake manifold" gave me 272 articles -- amazing! Ι all the way back to 2003.
The engine is a 3.8 litre, which from what I gather, is prone to upper manifold and gasket malformation and consequent leaking. I haven't yet checked the oil for coolent, or the plugs for crud, or anything else in particular. There appears, however, to be some seepage aroud the bottom of the upper part of the intake manifold.
Most of the LOWER intake problems, from the postings here, seem to be with the 3.1 and 3.4 engines. Should the upper part of the manifold need replacement, the way to go seems to be with NON-GM parts, including the upper unit, fasteners, and the gasket itself.
keep it comin', loenard
an asideΙ I really detest these big-three cars. Now, the Hudson, Studebaker, Tucker, and Kaiser -- well, that's a different story - BIG3 drove'm all outa business. My pop worked for Kaiser -- you shoulda heard the stories he had to tell! __________________

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news:2008041722475075249-

I havent checked the price of the plenum replacement recently (since ours went out), but at that time, NAPA supplied it for about US$250. The local shops here would do the work for about $100. (Even the Buick dealership agreed to this price, although they would have preferred to have charged $700-$800.
As Shep indicated, if you have to go deeper, it gets more time consuming, ergo more expensive.
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As always a lot of variables here, so I can understand why the mechanic would want to verify everything.
If the upper manifold plenum is leaking, you would probably smell burning antifreeze. A coolent system pressure test would show up the leak.
Check for coolant in the oil... look for sludge. Maybe pull a plug or two and look at the condition. If there is coolant in the oil or buildup on the plugs, the problem is more complex... perhaps the lower intake is going also.
Replacing the Upper Plenum is pretty easy.... a quick check at www.advanceautoparts.com 1996 Buick LeSabre Upper Manifold shows the part to be about 150.00. ALLDATA shows the book labor to be 1.6 hours for an experienced mechanic. Don't forget gaskets, injector "o" rings.
Other posters have recommended replacing the lower intake manifold gasket at the same time.... add another 2.6 hours labor.
So, did the shop quote you for both upper and lower intake manifold gaskets ??? If they quoted you for both.... $600.00 is a pretty darned good price.
Did they quote you just for just the upper one ?? If so... figure about 350.00
Again... doable for a DIY'r with medium experience... piece of cake if you've done it once or twice before.... if this is your first time... figure on spending a day or so....to get everything right.
(disclaimer..... I work on these things for fun... not for a living... however the last 3800 upper plenum is still chugging along really well).
Here's a informative posting from aarcuda69062 back around march 2005 give aarcuda the credit for this one....
_____________pasted information from aarcuda69062....March 2005 _____________
Here is a picture of the bottom of the upper plenum, throttle body end:
http://ken-co.com/zoom2.asp?Link=manifold/images/3800-6a.jpg
The larger round hole is where the EGR pipe extends up into the upper plenum, the two smaller holes are coolant passages. Here is a picture of the throttle body end of the upper plenum:
http://ken-co.com/zoom2.asp?Link=manifold/images/3800-2a.jpg
There are three oblong shaped holes visible between the two lower studs, the two outside oval holes are adjacent to the EGR hole in the first picture. The two outer oblong holes connect to the two smaller round (coolant) holes in the first picture. Probe from either to the other ( EGR to coolant passage) with a small screwdriver or awl, you'll find soft spots and/or outright holes. Gone on long enough, the whole lower part of the throttle body end around where the o-ring fits around the coolant passages will be soft and crumbly.

I always do the lower intake gaskets when I find a leaking upper, I have yet to pull one apart where the lower gaskets aren't disintegrating also. Your picture shows fluid pooled in the lower intake, I can't tell if it is oil or coolant. If you DIDN'T find raw coolant laying in the lower manifold when you removed the upper, then I'd suspect that the lower gaskets are leaking and that this is where you coolant loss is. If it is oil pooled, the lower manifold bolt threads weren't/aren't sealed. Use thread sealer/locker on the lower bolts and pay close attention to the torque specs for the UPPER plenum bolts. You HAVE to use an inch pound torque wrench because the values are quite low, otherwise you'll crush the new upper plenum. Pay close attention to the O-rings in the PCV cavity, if you forget the O-ring around the base of the PCV valve, you'll set MAP sensor codes. Watch the connections to the purge solenoid, if you reverse them, you'll set EVAP codes. Connect them exactly as shown on the underhood vacuum diagram. If you decide to do the lower intake gaskets, you'll also want to replace the plastic elbow that connects between the right side of the lower to the alternator bracket, hell, I'd do the lower just to replace this elbow since they too are a weak point and prone to failure.
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"Peter" wrote in message

When the plenum went out on my wife's personal car, there was no smell of burning antifreeze nor was there antifreeze in the oil. The car went from no problem to serious involvement in one or two miles.
I had been expecting this to fail for a while, so knew what was going on. Scan indicated multiple ignition failure. Then the engine hydrolocked with coolant in the cylinders.
I would assume some might fail in a slower mode than this one.
I had ours repaired at a Buick dealership, leaving a paper trail in case Buick/GM ever decided to do the right thing and take responsibility for this bastard.
It is not that this is such an expensive problem that irks me. It could have been very serious if it had happened to her out on the superhighway somewhere. And that GM avoided making the required changes to make this engine reliable for YEARS, and dodged the responsbility issue is why I am driving another brand today.
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