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What is Dry Joint Exhaust?

Dry Joint Exhaust was designed to reduce the risk of water leaking from the gasket between the exhaust manifold and riser. Water Ingestion (Which is caused most commonly due to using the wrong height risers.) has always been a big problem for boaters trying to extend the life of their engines. In 2001 MerCruiser introduced the 8.1L 496 Marine Engine and realized its significant impact on reducing water ingestion.

Along with the new Dry Joint Exhaust on the V6 and small V8 engine models the height and down angle of the exhaust riser changed as well. MerCruiser decided that the overall height of the exhaust riser should be raised to meet the overall maximum height of the engine. Therefore MerCruiser introduced a dry joint exhaust riser which was 1.5 inches taller and also included a 14 degree down angle versus the standard 7 degree.

MerCruiser was forced to introduce the 1.7 inch tall dry joint exhaust spacer and the 4.5 inch tall dry joint exhaust spacer to account for the installations where the standard 3 inch and 6 inch exhaust spacers were already at a package height limit.

Below are examples to help you better visualize the difference.

Dry Joint Exhaust uses only two ports to transfer water from the manifold to the riser.

Non Dry Joint Exhaust uses (4) four water ports to transfer water to the riser.

You won't be able to see the ports with the riser installed so here's a look at the risers themselves:

Dry Joint Exhaust Risers have cast elbows on the front and rear.

Using the pictures above should help you to determine what you have. Another way to help determine what you have is if your engine is before 2002 you do not have factory installed dry joint exhaust.

How to determine if you have the Short or Tall Dry Joint Exhaust Risers

    Short Dry Joint Exhaust Elbow
  • Part # 525-864309T02 Fits:
    Small V8 s/n range 0M300000 and 0W309999(pre 2005 models) – Measures 5.2" from elbow gasket flange to mounting bolt boss pad

  • Tall Dry Joint Exhaust Elbow
  • Part # 525-864591T02 Fits:
    Small V8 s/n 0W310000 and above (post 2005 models) – Measures 6.7 from elbow gasket flange to mounting bolt boss pad.

Converting from Wet Joint to Dry Joint Exhaust

If you want to replace or convert an older Non Dry Joint exhaust with the improved Dry Joint Exhaust system it is possible to do. You will most likely need to use the “Short” Dry-Joint elbow/riser as this will be the closest fit to the old Non-Dry Joint Elbow/Riser being replaced.

The part # needed for the restrictor style Dry Joint Gasket is 27-864850A02.