3.8 intake manifold--Al alloy or plastic?

A

abe

Member
Anybody know when they changed the intake manifold on the 3.8L engine from Aluminum alloy to plastic? Reason for asking is because a buddy of mine has had about 6 3.8L engines in various cars, all Pontiacs, and I've had 2. My first was a '91 park avenue ultra, and now I have an '09 Lacrosse. I did a valve job on my old park avenue, and the intake as I recall was Aluminum alloy. I know it wasn't plastic. When my buddy told me that all of his were plastic, I started wondering. He even said my Lacrosse is plastic. I haven't checked yet, because I haven't taken the cover off yet to check. If what he says is true, then when did Buick change from one to the other?
abe
 
If my memory serves correctly the naturally aspirated 3.8s were plastic from around 97 on up. It really depends on the engine in question. :shield:
 
I've owned 2 cars with 3800 engine, both Pontiac. First was series I engine, and it was FANTASTIC. Second one was series II, and it was a piece of junk. When plastic plenum popped FIRT time, it required engine replacement. (Major damage due to hydraulic engine lok=ck-up at operating speed. Next time it blew, it was at rest, so about $500.00 dollars for repairs. My mother's Buick LeSabre with 3800 series II locked up when plenum started leaking, but was not actually running when cylinders filled completely with coolant. Total repairs around $650.

If you have all alloy intake, you have a winner. If it is plastic, GET RID OF IT!!! From what I have seen firsthand, as well as from what others have told me, failure rate is 100%. Can cause major problems beyond the need for new plenum. (The mechanic who fixed Mom's car told me that he'd done over 450 of these things in his shop!)

Again, if it is plastic, get rid of that car! Major expenses heading right at ya!
 
Series I and earlier were aluminum :D, Series II was carbon fiber :angry: , and the Series III went back to aluminum :hurray:.
Those carbon manifolds are a nightmare, especially if they have had Dex-Cool in them.

All supercharged engines obviously had aluminum superchargers.


:shield:
 
blu3800gs said:
Series I and earlier were aluminum :D, Series II was carbon fiber :angry: , and the Series III went back to aluminum :hurray:.
Those carbon manifolds are a nightmare, especially if they have had Dex-Cool in them.
:shield:
Click to expand...
Yep, and from what I have heard, Dex-Cool becomes increasingly corrosive as it nears the so-called 5 year / 100,000 mile typical life. Dex-Cool is not all it's cracked up to be... Dex-Cool or no, change this stuff every other year at least....
 
Yeah my 95 lesabre has the gifted plastic intake. I was warned by a friend of mine about it failing that was seven years ago. Its just under 200,00 miles. No problems with that but I'm on my 5th waterpump. I don't use Dex either I use prestone in both my 3800,3100.
I'm going to start a new thread for that.
Sorry its at 245.000 mi.
 
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yeah, 3800s and 3300s are funny about water pumps. A very common failure is impeller shaft bearing seizure, which usually results in the pulley bolts shearing.
 
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