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In the last 24 hours ive been told by (mostly) auto parts people that the intake in my 1994 bonneville is going to need changed soon?? Why? I noticed that it is not aluminum but what does this matter? Just curious and this seems like the best place to be curious so if anyone knows or has an opinion lets hear it! Thanks fellas

The 3.8 is notorious for upper and lower intake leaks my advice is to change lower gaskets on intake and replace plenum and gaskets before it leaks so bad that it hydro locks the motor like mine did,good luck

I would be much more concerned if yours was a 95, when they changed to the lower intake gaksets and upper intake design that was prone to issues. 94 and before are not overly prone to failures. Its LIM gaskets can age over time and start to leak, but aren't all that likely to fail and kill the engine like the 95+ would. And in all my years on Bonneville forums, only one person has reported finding any issues with the pre-95 upper intake, and that was just recently in the south west. With the age yours has on it, I'd probably go in and change the LIM gaskets, but I wouldn't be sweating it unless you see that it's losing coolant with no visible external leaks.

They are plastic which spells trouble. Expanding and contracting rapidly is bound to cause a gap and leak antifreeze in the cylinders, I would do it regardless. Just found out today that mine is ORIGINAL! cant believe it. it was manufactured september 26,1995. it is a 1996 model with 250k.

There are probably 30 or more major Series II LIM gasket or UIM failures for every 1 seeping Series I LIM gasket.

Well all of this was good to know. Thanks to everyone

Just to seal the deal on this thread, I was the one who reported the bad UIM on mine.

The failure:


You will note that on the composite upper, there is a gasket around the intake runners. The coolant will leak out usually long before it goes in to the runners.

Mine leaked a LONG time, and the leak turned catastrophic before I just did a LIM gasket job, and replaced everything down and back.

Upon changing the plugs, the only plug that smelled of anything was #1, and that was oil, I suspect from the PCV.

But in short, most are referencing the Series 2, which ran 95-2005. If you are concerned about it, just keep tabs on your coolant level. If it starts to drop, track down the problem.