Mercruiser Gaskets...Help Please

[paultallett]

Morning,

I changed the port Manifold / Riser / Elbow on my Mercruiser MAG350 a few months ago...all with no problems. I went down to the boat yesterday to do the starboard side, as I was taking the old parts off, I found that an open gasket was installed between the Manifold and the riser, with again an open gasket between the Riser and Elbow.

My Manual states to fit a Restrictor Gasket between the Manifold and Riser, then an open Gasket between the Riser and Elbow (which is how it was on the port side!!).

I re fitted eveything as per the manual, and once I fired her up the Starboard side is running a bit hotter than the port side now.

So can any one tell me should I leave it this way or should I re install an open gasket between the manifold and riser to balance the temperature?? I wondered if Mercruiser had up dated the gasket insallation advice after my manual was printed??....hence why I found a different gasket arrangement on the starboard side??

Regards,

Paul.

 

[Elessar]

www.dougrussell.com has up to date parts diagrams for mercs - take a look.

 

[paultallett]

Thanks Ellsar,

I've had a good look at there diagrams, but I can't find the ones for my 2003 350 mag... I must be having one of those days!!

Regards Paul.

 

[AquapartPhil]

Hi Paul.
For some reason, Mercruiser changed their stance on this a year or two back, Since the early days common wisdom (including the mercruiser manuals plus the aftermarket manifold companies insallation specs) that you should always put a restrictor gasket between the manifold and the riser, or if riser blocks were fitted then an open gasket at the bottom and a restrictor at the top (to keep the riser block full and avoid hotspots), however in recent Mercruiser manuals they seem to show full flow gaskets all the time. It may be that many of these engines are attached to Bravo legs which have a very powerful engine mounted pump and that the gaskets were choking the flow, (just a guess), but we still recommend fitting gaskets in the time and tested way when supplying new manifold sets.
I don't think I would worry too much which way you do it but keep it the same both sides.
Regards,
Phil.