Subaru Engine >> CYLINDER HEAD CRACKS

Subaru Engine >> CYLINDER HEAD CRACKS

Cylinder Head Cracks On
1985-92 Subaru 1.8L OHC & OHV Engines

AERA members have reported cracked cylinder heads on 1985-92 Subaru
1.8L OHC and OHV engines. These cracks occur in the combustion chamber of
the head between the valve seat inserts (see illustration). The cause of these cracks is usually related to an overheated engine.

It has been determined by Subaru that this crack does not leak coolant into the chamber and the cylinder heads should not be replaced. Extensive testing indicates that under pressure testing, the heads do not leak unless the cracks are termed extensive Pressure testing is still advised to assure your customer of the heads integrity. Checking both valve seats for looseness is also necessary as insufficient press fit may allow the seat to move during engine operation.

A modification to that area of the casting was made during 1991 production to chamfer and increase the distance between the valve seats. That change has reduced the number of heads that crack.

Some AERA machine shops remove the valve seats, weld the cracked area and reinstall valve seats to give the head a more acceptable cosmetic appearance.

The AERA Technical Committee


January 1996 - TB 1300


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