Time for new riser?

[Jmunk]

Well, I got around to pulling the riser and manifold off my 98 3.0L. I'm confident that no one else has ever had either the manifold or riser off the boat, the paint on the bolts looked that way. The riser had a lot of blockage at the ports, but they cleaned up decent, however the flange isn't as flat as I would like it. I wasn't having any problems, jut doing some preventive maintenance.

The manifold looks good, I have yet to scrap all the gasket material off, but looks okay. The gasket on the block looked good as did the ports on the head, no signs of water ingestion. Everyone's thoughts on the riser needing to be replaced ? I think that the riser is done, but want to make sure I don't throw money in the trash can. Everyone's thoughts on Osco brand risers, the place where I buy most of my parts from seems to only stock that aftermarket brand. Thanks

 

[Bondo]

Re: Time for new riser?

Ayuh,.... Clean 'em off with a flat file,... There's still ole gasket on 'em causin' the bumps....

Those don't look to bad,... Are ya in saltwater, or sweetwater,..??

 

[Don S]

Re: Time for new riser?

Clean all the gasket off, and look at the area marked by the arrow, in the picture below. Then post a new picture of that area. From the picture I see, the area is thin and corroded making the riser scrap at this point, would bet the manifold looks similar.

 

[Jmunk]

Re: Time for new riser?

This boat has been used in everything: saltwater, brackish water, freshwater only for past few years. I will clean up the riser some and see where it gets me as well as the manifold. Is it normal for them to get a blockage as posted prior to me cleaning them ? That had to restrict flow a lot.

 

[Jmunk]

Re: Time for new riser?



Here are the pics after I cleaned them up, I have never encountered gaskets so stubborn. The picture on the left is the riser, the right is the manifold. I think that the riser is thin in the area that Don pointed out. I think the manifold is good, or atleast I hope so.

 

[Bondo]

Re: Time for new riser?

Ayuh,... It Appears to me that there's Still gasket material on Both of 'em....

 

[Don S]

Re: Time for new riser?

I think you have problems from here. Here is some areas you need to check. I use an old wood chisel as a gasket scraper, and when I see this black carbon substance shown in the circled areas below, I scrape it hard to see if it scrapes off. If it does, it's that carbon, if it doesn't it's metal. From the looks of them to me, you need a new manifold and riser.

 

[Jmunk]

Re: Time for new riser?

I went through a bunch of razor blades on my scraper, I was about to use a wood chisel, but wanted to go easy on them. I will try the chisel and report back. Seeing how the riser and manifold were original from 1998, I figure that they don't owe me too much.

 

[Bondo]

Re: Time for new riser?

I went through a bunch of razor blades on my scraper, I was about to use a wood chisel, but wanted to go easy on them. I will try the chisel and report back. Seeing how the riser and manifold were original from 1998, I figure that they don't owe me too much.

Ayuh,..... Use a Flat File to clean 'em up...

Just try hard to keep things Flat...

 

[Jmunk]

Re: Time for new riser?



I hit the manifold flange with a chisel lightly. I scraped the black carbon off and it's down to solid material. I will hit it again, but I have to go to work in a few. I pointed to a spot with the tip of a file that is maybe 1/64" or little more lower then the rest of the manifold. I'm not sure if the gasket will seal that up or not. If these are useable how much life is really left in it ? To me if it's only going to last a year then I will save the work from replacing it in a year and bite the bullet and get a new manifold and riser now. How does these compare to freshwater manifold and risers after 14 years ?

 

[Don S]

Re: Time for new riser?

I wouldn't use them if it was my engine.

 

[Jmunk]

Re: Time for new riser?

I've decided to do it right and get new manifold and riser. However, the part # on my original manifold is 806867C. Engine is a 1998, 3.0L Mercruiser, Serial # 0L046463. I have looked at replacements and going to get either OEM or Barr. I get confused looking at all the different part numbers for these manifolds. Is this the new, correct OEM part number 860235A03 ? In my searched 860235A04 pops up and is cheaper, I want to get the right part since shipping a manifold back is expensive.

 

[Don S]

Re: Time for new riser?

Is this the new, correct OEM part number 860235A04?

Nope, that's for an older late 80's model. You want 860235A03 for your serial number.

If you want accurate part numbers, go here and type in your engines serial number. http://www.mercurypartsexpress.com/us/parts-search.html#epc::machine_find