Exhaust Riser/Elbow Gasket Question

[tahoejag]

What is the location for the restricting hole on the elbow gasket? Is it bow or aft? According to the mercruiser parts look up, it appears to be aft and the freeflow toward the bow, and exhaust bends or lips on the metal part of gasket are facing up. However...(a big however) I noticed that on my engine the gasket is installed with the restricting hole facing to the bow??? Theres got to be a reason why one side is free flow and the other restricted. I hope they weren't backwards from factory. For a few years back I pulled one side (port) elbow to check the shutters and installed it the same as the strbd side which was factory. So the restricting holes are both to the bow. Feedback please!

Eng ser # OW 380000

P.S. I read the svc bul link for risers/gaskets....however it didn't mention what way the restricter hole faces....

 

[Bt Doctur]

Re: Exhaust Riser/Elbow Gasket Question

holes go fore and aft

 

[achris]

Re: Exhaust Riser/Elbow Gasket Question

From the Merc service manual... Restriction hole at the front (adjacent to the water inlet on the elbow), free-flow hole to the aft... Turbulator lips face up.

Chris...

 

[tahoejag]

Re: Exhaust Riser/Elbow Gasket Question

From the Merc service manual... Restriction hole at the front (adjacent to the water inlet on the elbow), free-flow hole to the aft... Turbulator lips face up.

Chris...this is what I have seen and it shows restrict hole to aft. ???
View attachment DIAGRAM EXHAUST ELBOW.pdf

 

[Fun Times]

Re: Exhaust Riser/Elbow Gasket Question

Eng ser # OW380000

This serial number does not match up with the info in your signature pofile. You say you have raw water cooled but this serial number is for a 4.3L ALPHA CARB FWC with 1.7 RSR (Risers) (Fresh Water Cooled). before i notice this i spent some time looking up & writing out what appeared to be the problem.

Chris...this is what I have seen and it shows restrict hole to aft. ???
View attachment 173017

You shouldn't go by what the parts catalog shows for installation purposes. It's just a guide to help find the right parts not a direction of how to install the items. That is what the service manuals are for.

Chris has you going in the right direction,
Seawater Cooled Models,
IMPORTANT: On seawater cooled models, always position the restrictor gasket with the restricted port on the same side of the exhaust manifold as the exhaust elbow or riser hose fitting.
IMPORTANT: The restrictor end of the gasket must be positioned to the seawater inlet side of the exhaust elbow.

Warm Risers With Dry Joint, Tighten the fasteners evenly using X pattern from corner to corner.
Exhaust elbow to exhaust manifold bolt or nut,
First pass 7 lb‑ft.
Final pass 45 lb‑ft.

Also use perfect seal on the edge of the water ports on the exhaust manifold, riser if equipped, exhaust elbow, exhaust elbow bolt threads.

 

[tahoejag]

Re: Exhaust Riser/Elbow Gasket Question

This serial number does not match up with the info in your signature pofile. You say you have raw water cooled but this serial number is for a 4.3L ALPHA CARB FWC with 1.7 RSR (Risers) (Fresh Water Cooled).

Not sure what you meant by which part did'nt match up; but the pic indicates the exact manifold/riser I have. It is fresh water/sea water cooled and not closed system. Thanks for pointing the "raw water" out to me.

IMPORTANT: The restrictor end of the gasket must be positioned to the seawater inlet side of the exhaust elbow.

I'll have to look again (you can c a small portion of the metal gasket itself by the shape of the riser) and c how the gaskets r positioned...I could swear the strbd side (factory) was backwards and thats what I went off of. :facepalm: Hope not!

Thanks again for the feedback!
John

 

[Fun Times]

Re: Exhaust Riser/Elbow Gasket Question

I meant the serial number you posted does not not match your boat information at all. And the engine information is not exactly the same. The serial number you posted uses 1.7 inch risers and is closed cooled. So it appeared by the serial number you would have needed the gaskets in item number 1,
http://www.mercruiserparts.com/Show....png&inbr=11812&bnbr=175&bdesc=Exhaust+Risers

Not # 9, http://www.mercruiserparts.com/Show...812&bnbr=160&bdesc=Exhaust+Manifold+and+Elbow

Not sure what you meant by which part did'nt match up; but the pic indicates the exact manifold/riser I have. It is fresh water/sea water cooled and not closed system. Thanks for pointing the "raw water" out to me.



I'll have to look again (you can c a small portion of the metal gasket itself by the shape of the riser) and c how the gaskets r positioned...I could swear the strbd side (factory) was backwards and thats what I went off of. :facepalm: Hope not!

Thanks again for the feedback!
John

You are correct, you can identify the gasket by viewing the gasket externally on the engine package.
The outer edge of each turbulator gasket identifies the gasket and the gasket position.
? The full flow gasket is contoured at the edge to show full flow at each water port.
? The block off gasket is straight at the edge to show no flow at each port.
? The restrictor gasket is contoured at one edge of gasket to show full flow. The other
edge of gasket is straight to show restricted flow.

 

[achris]

Re: Exhaust Riser/Elbow Gasket Question

Chris...this is what I have seen and it shows restrict hole to aft. ???

And? I was just quoting directly from the MERCURY MARINE genuine service manual. I have also replaced these same gaskets/plates on my own engine and that of a few I service. I have no idea where that diagram came from (you don't say). If you want to install it like that, go right ahead. You came here for advise and when I gave you the answer FROM THE BOOK, you turn around and tell me I'm wrong.... Not impressed!

...........

 

[tahoejag]

Re: Exhaust Riser/Elbow Gasket Question

I meant the serial number you posted does not not match your boat information at all. And the engine information is not exactly the same. The serial number you posted uses 1.7 inch risers and is closed cooled. So it appeared by the serial number you would have needed the gaskets in item number 1,
http://www.mercruiserparts.com/Show....png&inbr=11812&bnbr=175&bdesc=Exhaust+Risers

Not # 9, http://www.mercruiserparts.com/Show...812&bnbr=160&bdesc=Exhaust+Manifold+and+Elbow

Thats odd about the sr #. For that is what is on the flame arrestor cover as OW380*** d.o.m. Oct 2005 and is the set up as #9 and not the 1.7 rsr's.

• The restrictor gasket is contoured at one edge of gasket to show full flow. The other
edge of gasket is straight to show restricted flow.

After further review...lol. Gaskets are o.k. and restricter ports are to the bow/inlet hose. Thanks!

 

[tahoejag]

Re: Exhaust Riser/Elbow Gasket Question

I have no idea where that diagram came from (you don't say). If you want to install it like that, go right ahead. You came here for advise and when I gave you the answer FROM THE BOOK, you turn around and tell me I'm wrong.... Not impressed!

Diagram came from Mercruiser.com. One would think from such site that it would be correct and that is the whole reason why the question is brought up and diagram posted. From what I understand, feedback/comments are an option on this forum if one desires to post one; and not be used to critize others or look to be impressed! JMO.

 

[barnesville]

Re: Exhaust Riser/Elbow Gasket Question

FYI...I know this is a bit old now, but I just replaced my manifold on a 2005 Mercruiser 4.3 (carb version) and from the factory my restrictor hole was also facing aft. After seeing this and talking to my local dealer service department I replaced it with the restrictor hole facing towards the water inlet (towards the bow). It seems that the parts catalog and the service manual are inconsistent. I was told to rely on the service manual.