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Performance Product Technologies Question & Answer Forum
Topic: Marine Exhaust
Question: What happened to the older Mercruiser stainless steel exhaust risers?
Response: Mercruiser introduced the stainless exhaust riser p/n816900c in the early 1990's in attempt to combat the ever enduring problem of corrosion within the marine exhaust system (read more). While the stainless riser served this particular purpose quite well they had several other "issues" that forced the death of the product in or around 1997. Here are the main issues faced with the product;
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Stainless steel is inherently hard to machine. Therefore a short fastener design was used. This design did not function well with regards to allowing the fasteners to stretch while maintaining torque. Therefore the risers always leaked.
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The risers were cast using a patented process called "The Hitchner Process". This process is a vacuum assisted casting method however as required with stainless steel the pouring temperature is so high it was difficult to yield parts that did not leak.
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Once it was relaized the manufacturer was investing more into the reworking process versus actually producing good parts that didn't require reworking to correct casting leakage.
Which risers do you have?
Link to ........Stainless Riser Exhaust System
Link to.........Cast Iron Riser Exhaust System
If you have a remote located oil filter - When replacing the stainless riser exhaust system today with the cast iron riser system, it should be noted that you will need to order the remote oil bracket for the cast iron risers as well as the longer riser bolts to mount the bracket.
Remote Oil Bracket for Cast Iron Risers (Qty 1 per engine)
Required Fasteners for Cast Iron Riser Oil Adapter Bracket p/n 10-44387 (Qty 2 per engine)
Mercruiser Service Bulletin Details
