What is this
 

This is in the exhaust tube. What is it for and is it needed.
Thanks for the help.

David

Looks like some kind of check valve?

Mercruiser calls it an exhaust resonator. Supposed to help break up intake pulses that might revert water in to the manifolds. I think they were announced in a service bulletin some time back. I have run with/without them and have still had reversion trouble. They claim they do not reduce power, and have a printed procedure that comes with the kit that tells you how to intall them at different distances from the riser and then check for reversion (to find the best location).

http://www.mercruiserparts.com/Show_...CK%2DOFF+PLATE

So there not necessary. I putting the motors back in with emi thunders- With the new risers/ tube i only have like 5" or so from the transom, I dont think i can get them in there so i was wondering if i needed them or not.

Thanks
David

The Spanish name for them is "Basura":D

Alright I'll get rid of them. Only cause you said so Kirk.:evilb:

Exhaust resonator is what it looks like.