To replace your old muffler, confirm that the dimensions above and the dimensions on the photo below under "More images" will fit in your boat. It is designed to replace the muffler produced by Ultra Marine that is no longer available. That said we have no way to guarantee that that muffler was installed in your boat as Catalina didn't maintain records as to which muffler design was installed in each hull. Each boat was hand built so there may also be variations in your particular boat that might make the installation more challenging.If the dimensions don't match, call our technical support line found under "Contact Us" below.

Engines in Catalina 310s known to have used the Ultra Marine version for which this is a replacement:
• M-25XPB

• Base: 9" X 9"
• Top: 8" diameter
• Inlet and outlet tube outside diameters: 1-5/8" or 2" (you must let us know)
• Height: 10"
• Drain plug: 3/8" MPT
• Resin: Class 1 fire retardant epoxy vinyl ester thermoset
• Glass: Corrosion-resistant E glass
• For additional dimensions, refer to the annotated photo at left.

Important Cautions!
Some customers will attempt to repair their old mufflers. Since Carbon monoxide is odorless, colorless, tasteless and deadly, any repairs should be done by a qualified, experienced fiberglass technician.

Two ways I have seen an old muffler fail are:
A) The seam at the bottom edge can fail. This can sometimes be repaired by removing the muffler. After a thorough cleaning, you may be able to saturate the failed joint with WEST epoxy, clamp and allow to cure.

CAUTION! The muffler must be pressure tested to 5 PSI while immersed in a water bath to check for leaks after any repair is attempted. Given the above cautions about carbon monoxide, If it leaks after a repair, YOU COULD KILL SOMEONE. We highly recommend the installation of a carbon monoxide detector.

B) The bond between the inlet tube and the box itself can fail. This typically occurs because the vibration of the engine is transmitted directly through a rigid hose to the stationary muffler. In this case, it is impossible to achieve a successful repair. Even with the installation of a new hump hose to help isolate the vibration (which we highly recommend), there will be much vibration transmitted to the fiberglass tube. To be strong enough, the repair would have to be made on the inside of the muffler where you have no access. In order to leave the enough fiberglass tube exposed for the hump hose, a repair from the outside would be too small to be secure enough given the serious safety concerns involved.

1) 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.

2) A 50% nonrefundable deposit will be billed when your order for this special order item is accepted. The balance will be billed when the product ships.

3) This is a custom made part. You provide the information we need to build this product for you. Once you order it we are going to build it just for you, just as you asked. We never want to see it again, and no one else wants it either. So be careful and order it correctly the first time because it can't be canceled, returned, or magically changed into something different!