Restrictor Gaskets

[comsnark]

OK. . . .so I have;

Twin 1997 5.7L Mercruisers, with risers. The exhaust system was replaced last year.

These engines have dual exhausts, so there are two manifolds, risers, and elbows on each engine.

Someone has recently told me that the the exhaust system was reassembled using restrictor gaskets and I should have had full flow gaskets.

How do I learn, for sure, what gaskets SHOULD be in there? The manual is confusing, as it shows two alternate configurations (the difference being the gaskets: one shows open gasket below riser, restrictor above. The other shows seperator gasket below and open gasket above) The manual says that it is important to note your arrangement as you go through disassembly.

Now. . I think someone has screwed up. How do I straighten this out? Or do I just figure that if the manifolds don't run the same temperature I got it wrong?

PS: I know somebody is going to ask me for the engine serial number. Darn it. . .I forgot to bring that information with me today. I will post it tonight.

 

[H2ONUT]

Do you have raw water cooling? This will make a difference in gaskets also.

Also, on top of the manifold, do you have a block bolted between the manifold and elbow? a 3" spacer or a 6" spacer (riser)

This will help figue it out...

Use this for reference...
http://www.dougrussell.com/partscat...1,30,0,22,31,20,25,26,15,23,24,13,14,2,1,32,4

 

[comsnark]

OK. . .I was billed for "riser". . .so I will go with Riser.

I also have raw water cooling.

From this drawing, it implies that Starboard and Port gasketing should be identical. So, if I have "full flow" as opposed to "restrictor". . . .that shouldn't really make any difference -> all that happens is the pump has a less backpressure and will put out a more flow. (it looks like the restrictor gasket on the bottom closes off two of the four flow channels?)

I will confirm when I am home later tonight.

Update:::::::::
Enigne serials: OK033470 and OK033474

 

[comsnark]

Ok. . my serial is OK033474

Does this imply per the sketch that I should have a restrictor gasket between the manifold and riser?

What if some bonehead (who shall remain nameless) put in a full flow gasket here?

 

[H2ONUT]

Do you have raw water cooling or closed cooling?

Also, do you have the block (riser) between the manifold and elbow?

 

[comsnark]

Riser: Yes.

Cooling: Raw water.

 

[H2ONUT]

Do you have both the riser and elbow plugged or is there a hose from the stat housing to the riser or elbow?

Sorry, forgot to ask earlier. :smt021

 

[comsnark]

Do you have both the riser and elbow plugged or is there a hose from the stat housing to the riser or elbow?

Sorry, forgot to ask earlier. :smt021

No problem. I actually can't answer that question without looking at the boat. . .which is about 120 miles from where I am.

I want to say that I have the riser and elbow water connections plugged. I want to say that water only goes to the manifold. But I could easily be wrong on this. Especially since I seem to think there are "6 connections" to the thermostat housing. But the catalogue reference on the top of this thread would lead me to think "4 connections" on thermostat housing.

So clearly I have little clue :smt009

But if I had to bet: No connections to risers or exhaust elbow. :smt101

(at the moment. . I am more concerned about a possible head gasket leak -> see my other post in this thread!!)

 

[H2ONUT]

Then I would say that the gasket with the 4 slots would go on the manifold and then the gasket with the 2 slots and 2 holes (restrictor gasket) would go on top of the riser and then the elbow.

The 2 holes in the restrictor gasket go front to back.

 

[comsnark]

Back to this thread; I was at the boat today: I have a four hose configuration on the thermostat housing. There are no connections to the risers or elbows.

So: Assuming my coolant flow issue is resolved, I hopefully will see what the real impact is of having restrictor gaskets in one engine and full flow gaskets in the other. My suspicion (based upon running at 2800RPM without overheating) is that one manifold will run 20F hotter than the other, but within tolerance (Hmmm. . .what is tolerance?)

 

[comsnark]

Final update;

Boat: 280SS
Year: 1997
Engines: 5.7LX, with Alpha drives.

Manifolds, risers and Elbows replaced last year.

This year, the starboard engine had an overheat issue. During the course of "hunting" for the elusive cause, the restrictor gaskets in the risers/elbows were replaced with full flow gaskets.

Over the weekend, I shot the engines with a temperature gun while running at 3000 RPM. The boat was not stable enough to do this at higher RPM.

Starboard Elbows (with full flow gaskets): 135F and 125 F. Port Elbows (with proper restrictor gaskets): 145F and 125F. Thermostats working just fine, raw water pump and metal around all temperature sensors reading about 170F.

OK. . based on this, I am leaving the manifolds alone for the rest of the year.