manifold/riser gasket for a full FWC engine?

212rowboat

my new engine is staged and ready for install... I've installed the FWC, but.... there is something about it that bothers me.  

the coolant/raw water is separated at the riser/manifold union by a simple gasket- gasket material is all that keeps the coolant and the raw water from mixing... I ain't buying that.  

I've ordered stainless steel plates to better separate the two, and will install them while the engine is still out... my question is: is that truly how these systems are designed?  a simple gasket keeps the fluids separate?  Is that something y'all trust?

212rowboat

There won't be a sixth. 

Handymans342

Well all gaskets have some metal so good choice

reneechris14

This gasket has metal

212rowboat

thank you @reneechris14 , but that is for a dry joint system, hence the exterior (of the riser/manifold union) part of the gasket... looks like ears or tabs... 

my question is if the supplied gasket (straight up gasket material; the same as other manifold/riser gasket material but with the passages blocked) is enough to safely rely on so that the coolant and raw water won't mix?  my instincts say "why chance it?".... but... if that's the way Merc designed it..... it's a little perplexing... 

reneechris14

I believe the standard gasket a stainless piece in the center.

212rowboat

it's a full kit @Alswagg.. in from foot, through p/s cooler, (strainer optional), to exchange, to risers spit into exhaust stream.  risers/manifolds separated.  

the 'other' side is.... well, you know what the 'other' side is... 

the engine is a 357 4bbl.  the guy called me to tell me the EFI was out of stock and it would be a week or two extra, but that he'd drop $1k (which i negotiated to $1200) off for the 4bbl in stock.. brand new mercruiser with all the paperwork.  it literally came with everything from fuel lines to shifter and throttle clips to elbows/boots/and clamps for the Y. 

I had the FWC kit in a box... just never opened it until i could get around to prepping the engine.  the kit was frustrating as it didn't have enough clamps, and the manner in which i had to plumb the riser (especially port side with oil filter in way) meant i had to order hoses with the 90* bend formed in them... there was zero chance due to clearance that i could run the provided hose without kinking it, and there isn't enough room to insert an elbow... 

i have all of that squared away, now... it's just these gaskets- i can't bring myself to believe that is all that is required to separate the raw from coolant.  I have stainless steel plates inbound- and will feel a lot more comfortable with those in there than 'just' that gasket... i mean, that can't be right, can it? 

mercrusier AND the marina i got the engine from also confirm the pump in the alpha's foot is sufficient for flow on the engine (rated 275hp)... is this your experience too? or, should i consider an electric or belt driven sea water pump? it'll never be a better time to do this... 

212rowboat

^exactly.  the exchange seems to be the same one mercruiser uses... it's amazing how much more efficient water-to-water coolers are in comparison to water-to-air.  doesn't take much room at all... and that exchange is copper inside and out (painted outside) which surprised me.  

212rowboat

it's not mercruiser labeled.  comparing it to a mercruiser kit, it seems to have ****-for-tat same items, though.  the exchange itself is the same, too... are the mercruiser's not copper?  I was pretty surprised that one was... i expected mercrusier's were the same?