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Leakproofing Engine Sheet Metal

Here are some quick fixes for frustrating engine oil leaks.

In the vernacular of engines, the timing cover, oil pan, and valve covers are identified as sheet metal. In agriculture, the definition is expanded to include any light-grade metal enclosure that contains a liquid or lubricant.   

sheet metal leaks

Oftentimes, sheet metal parts are hard to seal. Most applications use a gasket between the cover and the main component. If no gasket is used, then a sealant, such as RTV, takes its place.  

A major frustration is a persistent leak even after the gasket has been changed. By using the following measures, such a challenge can be fixed the first time. 

If the leak site is very hard to access, first try to seal it by using Permatex Spray Sealant Leak Repair (#82099). 

If you do end up changing the gasket, make sure you thoroughly clean the sealing surface of both the cover and the part. Be sure to perform a visual inspection for imperfections including high and low spots. Any difference that is greater than the gasket thickness will leak.

The major cause of warped sheet metal is overtightening. The bolts just need to be snug to marry the cover with the gasket and only slightly depress it.

If RTV is used, it needs to be at room temperature to vulcanize. The sealer will not form a gasket in a cold or hot environment. Do not add any liquid to the sheet metal enclosure until the sealer is cured.

Also, just because the gasket fits does not mean it is made from the proper material for the task or the liquid that needs to be contained. It is wise to use name brand or original equipment gaskets. There is a reason why they cost more.

sheet metal interfaces

By far, the most common cause of leaks is deformation of the area around the bolt holes from overtightening. The material is thin, and it will bow out toward the sealing surface. You can check this by turning the part over and looking at the gasket surface sideways. 

Place a small ball peen hammer on the bowed bolt hole while resting the part on the edge of a workbench. Then hit the small hammer with a larger one. 

The goal is to gently bow the sheet metal the other way. When it is tightened, it will then bend flush against the gasket or sealant. This is identified as peening the bolt holes back over. 

Install the cover and all the fasteners so they just touch the sheet metal. Then incrementally and in a crisscross fashion make them all snug. Let the gasket rest for a few minutes and then go around the perimeter of the cover snugging all the bolts evenly. If possible, repeat after a few thermal cycles.