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