Engine Gaskets Question

[georgert]

I am replacing the engine in my boat (actually my local mechanic is) with a remanufactured 5.7l long-block V8. The reman company shipped the engine but did not include cylinder head or exhaust manifold gaskets. The boat will only be running on freshwater. Do I need to use "marine" gaskets or will automotive gaskets work? Is there a difference? Thanks from a somewhat mechanically illiterate waterskier.

[Rednucleus]

I'm just a back yard fix it guy, but I thought by definition a "long block" would already be assembled head gaskets in place? Also, is this a marine motor or automotive crate motor??

[georgert]

Yeah, you're right, the head gaskets are there because the cylinder heads are attached, but the carburetor is coming off the old engine and that need's gaskets, and then there's the exhaust manifold.

 

[UWSkier]

The gaskets should be specific for the marine version of whatever piece is going on it. I.e. if it's an Indmar intake manifold going on a base long block, it should have the correct intake manifold gasket for that part and engine combo.

 

Interestingly enough, Indmar doesn't recommend the use of exhaust gaskets on pre-catalyst 5.7 models. Those are built using Permatex Ultra Black instead. Risers need gaskets though if using two piece manifolds.

[Orlando76]

Keep in mind riser gaskets have a direction to them for port and starboard, or at least PCM does and I assume Indmar too. Is your mechanic a marine mechanic?

[georgert]

@Orlando My mechanic is just a really good mechanic. He's not a marine mechanic per se. He's worked on a few boats, but mostly automotive. The local boat shop charges $120/hr for labor and my guy goes for $50/hr, so it's not really a contest.

[Orlando76]

There’s a difference in auto vs marine. For safety sake I hope he’s aware of the differences, surprisingly not many do.

[Jetsetr]

deleted

 

[2Valve]

we just replaced the head gaskets on a buddy's '96 ProStar (350 Chevy) and went with regular old Felpro automotive gaskets. If we were running in salt water, then we would have installed marine specific (stainless steel) gaskets. As such we didn't see the need with a raw water cooled motor. 60 hours on it since the fix and no issues.

[JackQ]

Marine head gasket are much preferable for fresh water also. Raw water is much more corrosive that in at automobile with a 50/50 glycol mix that contains corrosion inhibitors.

[DW]

@georgert - I suggest you review not only the gasket differences for a marine application but also the other engine differences between marine and automotive so your mechanic has the information to properly attend to your boat. If a good mechanic certainly more than qualified to work on your boat, simply may need to know the important differences if he is not familiar with boat work.

 

A key is to know all the fuel spill and spark arrest technology and thus unique components used in the marine application. In addition, many corrosion resistant parts are also used. A short list - carburetor, fuel pump, spark arrestor, distributor cap, starter, alternator all have specific marine components to minimize spark and fuel spills. From a long block aspect, head gaskets, core plugs are marine specific to reduce corrosion.

[Orlando76]

@DW is a nicer guy than me as he really touched the safety items that most non-marine guys are completely unaware of such as specific fuel lines at specific location within the system. Often times a mechanic can be fairly judged by a starboard picture of a carbureted marine engine. But at a rate of $50 an hour you’ll have money left over to fix those things.

[oldjeep]

Also remember that a marine water pump is different if you are planning on replacing that. The auto ones have tin impellers and backplates that rot out in lake water, a marine water pump has a bronze impeller and stainless back plate.