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Lower Intake Manifold Replacement Questions


sarotara
08-18-2008, 12:38 PM
1991 Buick Park Avenue Ultra (non-SC) with 146k miles. I'm planning on replacing the lower intake manifold gasket since the car is leaking coolant. What other parts should I be purchasing outside of the actual gasket, coolant, oil, and oil filter? I have all the manuals for the car, but is there anything that I need to know or be careful with before starting this? Thanks!

HotZ28
08-18-2008, 05:58 PM
Where is the leak, at the end of the drivers side intake? Have you had a coolant flush within the last 4-6 months?

sarotara
08-19-2008, 08:22 AM
Where is the leak, at the end of the drivers side intake? Have you had a coolant flush within the last 4-6 months?

Yep, leaking out of the driver's side part of the LIM. The valve cover gaskets need to be replaced too by the way, since those are also leaking a bit of oil.

HotZ28
08-19-2008, 05:18 PM
Have you had a coolant flush within the last 4-6 months? If so, try about 1/2 tube of the gold or silver dust stop leak. (Do not use the liquid pellets- rabbit turds) I had a leak in the same place about 3-years ago on my 94 LeSabre after flushing the cooling system. The silver dust stopped the leak and I have not seen a drop since! Believe it or not; they use stop leak at the factory to seal minor leaks. If you flush the system, leaks will appear. As far as valve cover gaskets leaking, you have no option except to replace them. :disappoin

Jrs3800
08-19-2008, 05:25 PM
I am usually in agreement, but not on this one..

The Lower gaskets are made of Nylon 66... But over time will degrade, with the car being as old as it is, do not use the stop leak or silver to seal this... The gasket replacement is a must... I have seen these in cases look like complete garbage, and some were leaking coolant internally for a long period of time unknown by the owner... These nylon gaskets are not a life long gasket.. Replace the gaskets and let the car live on for a very long time to come..

In some more extreme cases the lower intake may be pitted around the coolant ports...

Jrs3800
08-19-2008, 05:28 PM
I am usually in agreement, but not on this one..

The Lower gaskets are made of Nylon 66... But over time will degrade, with the car being as old as it is, do not use the stop leak or silver to seal this... The gasket replacement is a must... I have seen these in cases look like complete garbage, and some were leaking coolant internally for a long period of time unknown by the owner... These nylon gaskets are not a life long gasket.. Replace the gaskets and let the car live on for a very long time to come..

In some more extreme cases the lower intake may be pitted around the coolant ports...

Here is a gasket in really bad shape... This was on a 91 3800 V6
http://img.photobucket.com/albums/v294/Jr3800/Engine%203800C%20LN3/Mirrorwiring014Gasket.jpg

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