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Exhaust Riser
C-30 w/ M-25 Engine
85 <-> 87

Part #: Z3074
Exhaust riser assembly for a Catalina equipped with an M-25 Universal diesel engine. Includes high temperature anti seize thread compound for assembly
This particular exhaust riser was used on some 1986 Catalina 30's. It is likely some late 1985 and some early 1987 Catalina 30's also used this riser. We believe it was a transitional part used on the M-25 before it was phased out in favor of the M-25XP. Our #Z3055 (shown below under "May we also suggest") was used on the M-25XP beginning sometime in 1986.

Please see the additional image below for dimensions. If none of the various risers we offer match your dimensions, you will need to send us your old riser to replicate. Unlike the original equipment part, we have the type 316 stainless steel riser electropolished after welding. All additional stainless fittings (elbows etc.) are also electropolished. Electropolishing (often described as the reverse of electroplating) passivates the metal by removing the ferrous metal from both the inside and outside surfaces of the tube. This is especially important at the welds where the welding process disturbs the metal structure and makes it more susceptible to rust and corrosion. Unfortunately, since this part was used only in a few boats, it must be made one-off to order.

The only way to remove the exhaust riser from the boat is to remove the exhaust flange from the engine. This dictates that, at a minimum, you will need to replace the gasket. Most customers report the exhaust flange is impossible to remove from the old riser. The male thread on the end of the riser is typically seized to the female thread of the exhaust flange. If this is true for your parts, you will need a new exhaust flange too. Both are available below under "May we also suggest" below.

Always install a hump hose between the exhaust riser and the aqua lift muffler. The hump hose is more flexible than standard exhaust hose. It will help prevent damage to the muffler caused by the harsh vibrations of the diesel engine. See "May we also suggest" below.
1) CAUTION! This exhaust riser must be used with a properly installed thermal jacket. Due to the extreme fire hazard, we include the appropriate Thermal Jacket with each riser. Installing a riser without a thermal jacket is an extreme fire hazard that could cause death or serious injury and the complete loss of your boat.

2) We cannot overstate or take responsibility for the extreme danger inherent in an inboard engine's exhaust installation.
We strongly recommend you have an experienced boat yard perform exhaust system repair or replacement.

3) Never run your engine without a properly installed Thermal Jacket. In every Catalina installation there are combustible materials close enough to the riser to start a fire.

4) This item does not conform to the shipping table in the Shopping Cart. Additional shipping must be calculated. When you place your order we always call with a shipping quote before billing your card. For a quote in advance, just call 800/959-7245.

5) This riser is equipped with 1-1/4" NPT size threads and is not compatible with "B" series engines, which use 1-1/2"NPT size threads.

This riser may not fit every 1986 Catalina 30 with an M-25XP engine. Since the boats are hand-built, we can never be positive. Only by matching the dimensions of the part in your boat to the dimensions in the photo shown below under "More Images" will you know if this is the correct part.