Thread: 97-03 NA L36 UIM Failure

Oh man. Guess I've seen it first hand. Customers car, but only after I worked on it.
My boss thought I blew the head gaskets since I just did the water pump and manually bled the cooling system. It was running great, in the air as I was checking for leaks. Then it starts chugging, and pouring smoke out the exhaust. That's apparently when the intake was filled up.
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Swapped intakes, pulled all plugs and got all the coolant out. Changed the oil and fired it back up, runs good. Still smoked a lot for a while as the exhaust filled up. That pic of the smoke is a minute after starting it after swapping intakes. Not nearly as much smoke as when it started. It smoked out the whole shop in seconds before.

Ain't that crazy? I once fixed a guy's car in the Advance Auto parking lot. His car started running bad and he pulled into the lot. I happened to stop in and ask if he wanted me to tell him what was actually wrong with it.

An hour later..he was back on the road and happy.

192K miles, coolant was pretty low when it came in the door. Probably driven like that for a while.

Seen it again at work. Is it just Bill and I that experience this issue? Lol




This one was a 1998 Bonneville, 152k miles.

So it came in as a no start. No other odd symptoms mentioned. I was working on it in the parking lot as it was pretty nice out. I could smell fuel when cranking, out the exhaust I assumed. I also got spark out of all 3 coil packs. Odd, next I pulled the plugs. Every one was fouled out and also had what looked to me like oil all over them. At this point I already had the UIM failure in my mind but continued with removing all 6 plugs, cleaning them and re-installing them. Turned the key, and it fired right up. ran on at least 5 cylinders at first, then as I pulled it in the shop it was running on 6. No smoke out the exhaust yet. Hooked it up to the scanner, and started it to see if it saw any cylinder imbalances. Saw a little on #4, but it smoothed out. Turned around, and it was smoking the shop out with white smoke, and smelled like coolant. Knew right then what it was.

We apparently installed LIM gaskets on it a few years ago (before I worked there), but they're plastic. The oil is slightly milky. Not sure whether coolant seeped past the rings or the LIM gasket is going again. I know the fel-pro plastic gaskets don't even last as long as stock plastic gaskets. Money is an issue for the customer or I'd say do the whole LIM job. We'll see

That's where my milkshake went haha.

Plug the coolant ports with the LIM on the car, stuff the upper back on and ship him down the road for an hour or two of labor only.

Plastic lim's won't be an issue.