Engine - Rear Main Seal Installation Precaution
NUMBER: 51-0008SUBJECT:
FORENZA OIL LEAK AT THE CRANKSHAFT REAR MAIN SEAL, "CAUSES AND PRECAUTIONS" WHEN INSTALLING THE OIL PAN
The following information was gathered as the result of an investigation into the root cause of oil leaks reported from the rear main seal area of Forenza engines following engine block replacement. A sampling was taken from engine blocks that came in through the warranty part return program, and it was found that the two oil galleys at the rear of the block were more than 50% restricted on average with excess sealant applied during installation. The limited flow capacity caused the oil pressure to rise upstream in the oil drain galleys including the area surrounding the rear crank seal, forcing the seal outward, resulting in the oil leak condition. Further investigation indicates there have been other repairs linking oil pan installation and subsequent reports of oil leaks at the rear main seal.
Oil leak diagnosis:
1. When an oil leak is suspected to be coming from the crankshaft rear oil seal, especially following a repair involving removal and installation of the engine oil pan, check if the outer edge of the visible portion of the rear seal appears to be "raised" or "backed out" from the engine block, as illustrated below. If it is determined that this is the condition found, it may have been caused by the oil drain-back passage(s) being restricted or blocked.
2. When replacing the leaking seal, be sure to remove the oil pan to inspect and clear the oil galley(s) to prevent the concern from duplicating. Please follow steps for "Oil pan installation" listed below when reinstalling the oil pan to the engine block assembly.
Oil pan installation:
3. When installing an oil pan on a Forenza motor, inspect these passages pictured below to ensure that they are clean and clear of any debris before the pan goes into place.
4. Avoid applying an "excessive" amount of sealant to the surface where the oil pan seals to the engine block. Make an effort to apply an even "bead" of sealant sufficient enough to spread thinly across the sealing area. The photos illustrate the results of what can happen when too much sealant material is applied, and the exploded view on the left shows a circumstance where the 2 drain passages were nearly 80% blocked and barely visible, the photo on the right shows the surface of a new block prior to installation of the oil pan.
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