Installing new exhaust manifold and riser gaskets....

[tdappleman]

Doing some preventative maintenance on my boat. Noticed a slight oil leak from one of the valve covers so decided to replace them all. I had to take my exhaust manifolds and risers off to get the valve covers off so I inspected and cleaned them as well as all of the hoses, etc. While cleaning off the old gaskets it appears they used anti-seize on the gasket surfaces. I know guys who do that on cars - is that recommended on marine applications as well?

Side note - I hadn't noticed the valve covers were plastic prior to taking them off to replace the gaskets and bolt seals. Nice to have one less item to rust on the boat! Be nice if they could make an oil pan out of a similar composite material - mine are both good but I know boaters who have had to pull motors in order to replace the pans.

 

[tobnpr]

Anti-seize? Sure you're not talking about gasket sealer? Anti-seize would be for the bolts...

 

[tdappleman]

Definitely not gasket sealer (which dries anyway) - it's silver in color, still liquid not like a silicone would be. I guess it could be the liquid sealer - but that's not very common in the aftermarket. I know people use anti-seize on gaskets on cars - keeps the gasket in place while moving things around and keeps the gasket from sticking to the surface in the future.

 

[Quint4]

Install them dry using the good graphite impregnated gaskets. Clean up mating surfaces good and proper...re-torque to spec (35ftlbs I believe). Don't skimp and buy the cheaper ones. I did it this Spring....here is a pic of the bottom gasket I used. The top gasket was of the restrictor variety with small holes in place of two of the slots.

 

[tdappleman]

Thought I'd update everyone - the stuff was anti-seize on the gaskets. I checked with a friend who does marine work and he uses it as well - it allows you to pull the pieces off for inspections and not damage the gasket. Just thought I'd pass that along.

 

[jellyfish]

Here is a nice set of instructions form Merc.

 = Revised January 2001
Exhaust Manifolds, Risers and Exhaust Elbows
Models
All standard V6 and V8 gasoline engines with center outlet exhaust manifolds.
New Gaskets
IMPORTANT: These new gaskets are installed dry. No sealer is required.
P/N 27-863726 Gasket – 4 Slot.
P/N 27-863724 Gasket – Restrictor (with 2 holes and 2 slots). The 2 holes always go fore
and aft.
P/N 27-863725 Gasket – Block-off (without holes or slots). This gasket stops coolant flow.
Fastener Torque Change
33 lb-ft (45 Nm). Use this new torque on all fasteners when installing exhaust elbows or risers
onto exhaust manifolds.
Assembly
1. Clean all gasket surfaces before reassembly.
2. Check all gasket surfaces for damage.
NOTE: The following specifications are used only if the gasket surfaces on used exhaust
components have to be machined to remove minor corrosion. The maximum material that
can be removed is .010 in. (0.25 mm). The machining flatness specification is .003 in. (0.07
mm) maximum overall, with not more than a .001 in. (0.02 mm) difference within 1 in. (25
mm). Make sure that mounting bolts do not bottom out in threaded holes after machining.
EXHAUST MANIFOLDS, RISERS AND EXHAUST ELBOWS
Page 2 of 3 JANUARY 2001 99-10
3. Look at the condition of the metal around the exhaust outlet in the casting. Inspect for
damaged metal caused by salt water or exhaust gas corrosion in the manifold, elbow
and riser (if equipped). Replace all damaged parts.
76341
a
a - Inspect Area Around Exhaust Outlet
NOTE: The type of gasket used in certain locations has changed from what is shown in older
service literature.
4a.
Raw water cooled engines with all the water from the thermostat housing going to the
90-degree fitting on bottom of the exhaust manifold:
Use P/N 27-863726 Gasket – 4 Slot between the exhaust manifold and the exhaust
elbow.
If the engine has 3 in. (76 mm) or 6 in. (152 mm) risers, use P/N 27-863726 Gasket –
4 Slot between the riser and the exhaust manifold and exhaust elbow.
4b.
Raw water cooled engines with the bypass water from the thermostat housing going
to the fitting on the exhaust elbow and the warm water from the thermostat housing going
to the 90-degree fitting on bottom of the exhaust manifold:
Use P/N 27-863724 Gasket – Restrictor between the exhaust manifold and the exhaust
elbow.
If the engine has 3 in. (76 mm) or 6 in. (152 mm) risers, use P/N 27-863724 Gasket –
Restrictor between the riser and the exhaust elbow. Use P/N 27-863726 Gasket – 4 Slot
between the exhaust manifold and riser.
4c.
Closed Cooled engines with the raw water from the heat exchanger going to the
90-degree fitting on bottom of the exhaust manifold:
Use P/N 27-863726 Gasket – 4 Slot between the exhaust manifold and the exhaust
elbow.
If the engine has 3 in. (76 mm) or 6 in. (152 mm) risers, use P/N 27-863726 Gasket –
4 Slot between the riser and the exhaust manifold and exhaust elbow.
EXHAUST MANIFOLDS, RISERS AND EXHAUST ELBOWS
99-10 JANUARY 2001 Page 3 of 3

 

[stevea661]

Just an observation, since installing my engine I've had to break the exhaust manifolds loose 2x to remove the valve covers. The rebuilder used a felpro marine gasket set and the exhaust manifold gaskets are paper faced. I have not had to replace the gaskets yet and have had no problems. They don't stick to the engine or the manifold.

 

[tobnpr]

I wouldn't compare automotive exhaust to a marine engine. Marine manifolds are wet...cars are not. I don't know if coolant could ever displace (wash-out?)the anti-seize compound and cause a problem, but personally I wouldn't take the chance over a gasket that might cost a few bucks to replace after doing an inspection. Just my $.02...

 

[Quint4]

This is not an area to skimp and re-use gaskets. This is one of the biggest killers of marine engines. If the gaskets have even a slight leak they may allow water to seep into your cylinders between runnings, and it's all downhill from there (and quite and expensive mistake).

 

[stevea661]

Not the riser gaskets, If you reuse those you are asking for trouble. The exhaust manifold gaskets. I wouldn't have reused them if they looked bad. I needed to pull the exhaust manifolds about 1/4" off the block to pull the valve covers. I did not remove the risers or even touch the riser bolts. I was able to loosen up the rubber couplings, loosen the exhaust manifold, pull it away from the block, get the valve covers off, adjust the valves, I had a loose one. And tighten and retorque everything. No problems.