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Old 09-23-2008, 02:56 AM   #1
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Default UIM/LIM, Head Gasket or Balancer

So last week, the heater hose blew on my '99 Bonneville SLE... the person driving claimed they killed it immediately. It got fixed...

This weekend, my mother is driving the car, and hears "something fall off"... then the car no longer was running smoothly.

I figured the rubber shot out of the harmonic balancer. I examined the balancer... and it looks OK... though, I'm not completely sure what I am looking for... I'm used to Chevy 350 style balancers...

So as I'm watching, the engine is definately not running smoothly... then it suddenly smooths out. So, its a misfire, I think... I check out the exhaust, and sure enough... white smoke. Looking in the radiator, its much lower than the other day.

Now, I know I've had a UIM/LIM problem for some time, it was limited to seepage, so I could not get it on my agenda to repair it.

So, I'm trying to figure what'* wrong.

The oil is not milky... I couldn't look for air bubbles or oil in the radiator, but I figured the UIM/LIM might case that as well.

I imagine my UIM/LIM gasket went. However, I do not want to fix that, only to discover the head gasket is shot. Is there a good, definitive way to test the head gaskets?

I was thinking of getting a spark plug adapter for my air compressor. I figured if I brought up each cylinder to TDC on the firing stroke, I could pressurize the combustion chamber... and I would see major air in the radiator. Would that work?

Thanks in advance.

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Old 09-23-2008, 04:58 PM   #2
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I'm not sure how effective pressurizing a cylinder would be, on checking for leaks. Your head gasket may act as a one way check valve. Water seeping through the gasket works through the capillary effect. Just not sure if you can get air to do the same, I don't know. I was replacing the supercharger gasket last week on my 94 ssei. Surprising, to say, it wasn't all that bad of a job. I did notice that the 3/8" bolts on the intake were almost finger tight. I was faced with a decision to just tighten up the bolts and reassemble everything (forgetting about it), or replace the lower intake gasket. I'm glad that I replaced that gasket, because it was really easy. Only issue that I had has removing some bracket that held some watertube to the intake, other than that, if I had to to it again, I can replace both gaskets under 1 hour. So I say, replace the intake gaskets. You have a 50,50 shot on resolving this coolant leak. Investing only a couple hours of your labor
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Old 09-24-2008, 08:31 AM   #3

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This sounds like the UIM. If that'* the case the only way you should find it is pressure testing the cooling system. Then you should hear it in the UIM by the TB.

When you pull off the UIM there should be a crack or hole in the area of the EGR bore.
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