Hey guys, I've been searching through previous threads a lot today and I found a pattern of common UIM/LIM failure for this generation of the Bonneville. I got to about page 25 and had referenced a lot of different cars with various amounts of mileage that had the UIM/LIM fail (years 92 to 99.)

I was just wondering if its a random occurrence or if I should replace my UIM/LIM asap?
It'* not leaking or anything, but my 97SE does have 97K miles and I'd hate to be hydrolocked someplace I couldn't do the work to fix it.

Thanks in Advance.

-Dave.

If it'* never been done I would suggest it. The LIM gaskets had a plastic frame that brakes easy. And the UIM degrades around the EGR stove pipe leaking coolant right in to your intake. This is the one you really need to worry about. But when fixing that, it'* not much more work to go one step further and do the LIM gaskets.

when you replace the LIM gasket go Aluminum

Here'* some information on the LIM gaskets. Sorry, I don't have anything on the UIM. https://www.gmforum.com/specifications-general-information-132/lim-gaskets-myth-fact-288248/

Thanks guys, this will really help. Since I'm the second owner I'm going to pull it apart and check my gaskets asap. I'm going to look up more information on the UIM and post it here.

Dave..

Since you are concerned and want to keep your car from having any future issues. The best fixes remove the potential of the issue.

Plug the lower intake manifold coolant ports that feed into the UIM/throttle body with 1/4" NPT plugs. By blocking off the coolant, you remove the possibility of it getting into the intake air delivery area. The ports are there for minimal reason and there is no loss or issue from blocking them.

Change the LIM gaskets to the GM aluminum ones and you are all done. No need to replace your UIM, you blocked the potential issue by blocking the ports.

my car keeps hydrolocking I've changed both gasket uim to metal one plenum gasket put dimes in holes under throttle body. I was wondering what else I can do. It was pressure tested 2 times after work was done. And was fine. I take home drive maybe 2 hours and it happens aging. I have a 2000 buick regal gs. Really want to keep the car but can't keep spending money to have run 1 day. Any help would be appreciated thanks.

Your best bet is to start a new thread in the appropriate section so that we can help track down your specific scenario.