Are MC Stainless Steel Risers Worth it?

[tank1949]

The only salt water going through my exhaust system is through the risers. I have heat exchangers. I have been told that Stainless steel risers tend to crack and leak more so than cast iron ones, due to cold sea water colliding with hot exhaust gasses. SS likes to warp! Anyone experience good results with them?

 

[scoflaw]

Looks more like a design flaw, with the attachment bolts only holding the bottom flange unlike the cast iron version with support from the top.

 

[achris]

The only salt water going through my exhaust system is through the risers. I have heat exchangers. I have been told that Stainless steel risers tend to crack and leak more so than cast iron ones, due to cold sea water colliding with hot exhaust gasses. SS likes to warp! Anyone experience good results with them?

Hey tank1949 Can you please list your engine in the first post of your threads. (model,year, serial number)... It's getting annoying having to constantly guess at what you have.... Thanks.

Stainless steel ELBOWS. Excellent product, but Merc stopped producing them shortly after they started. I suspect because they realised that the SS elbows would cripple the sales of replacement cast iron elbows. My previous engine was a 4.3LX with closed cooling, and I fitted a pair of SS elbows that had come off, I think, a 350Magnum. When I sold that engine 12 years later, they were still on and still looking like brand new.

The only caveat is that you don't run them dry. If you do, unbolt them and drop them in the rubbish bin. They do crack when they get too hot...

Looks more like a design flaw, with the attachment bolts only holding the bottom flange unlike the cast iron version with support from the top.

Not a flaw, deliberate. Due to stainless steel expanding at a higher rate than carbon steel, if the SS elbow had the same attaching design as a cast iron elbow then, as the engine warmed up, the bolt could be stretched or the gasket flattened. Then when the engine cooled the clamping force between the elbow and the manifold would be too low and the gasket would leak.

Chris...

 

[Scott Danforth]

agreed, if you keep up on maintenance of the raw water impeller and never let the exhaust run dry, they will last right up until you do run them dry.

 

[tank1949]

Hey tank1949 Can you please list your engine in the first post of your threads. (model,year, serial number)... It's getting annoying having to constantly guess at what you have.... Thanks.

Stainless steel ELBOWS. Excellent product, but Merc stopped producing them shortly after they started. I suspect because they realised that the SS elbows would cripple the sales of replacement cast iron elbows. My previous engine was a 4.3LX with closed cooling, and I fitted a pair of SS elbows that had come off, I think, a 350Magnum. When I sold that engine 12 years later, they were still on and still looking like brand new.

The only caveat is that you don't run them dry. If you do, unbolt them and drop them in the rubbish bin. They do crack when they get too hot...



Not a flaw, deliberate. Due to stainless steel expanding at a higher rate than carbon steel, if the SS elbow had the same attaching design as a cast iron elbow then, as the engine warmed up, the bolt could be stretched or the gasket flattened. Then when the engine cooled the clamping force between the elbow and the manifold would be too low and the gasket would leak.

Chris...

Thanks for reply. I can't gain (easily) access to motors' serial numbers, because or heat exchanger hardware in the way. 350 Chevy blocks pre 1995 (have the manual fuel pumps and not vortex). Does Barr or Aqua Power make 350 ss risers?

 

[achris]

.... Does Barr or Aqua Power make 350 ss risers?

Merc was the only one producing a cast SS version of the ELBOW... A company called Hi-tek also ventured into SS, but were using welded sheet and tubes :facepalm: to produce a complete manifold and elbow together, and had nothing but trouble. I would very very strongly advise to stay well clear of them....

Chris.....

 

[tank1949]

Merc was the only one producing a cast SS version of the ELBOW... A company called Hi-tek also ventured into SS, but were using welded sheet and tubes :facepalm: to produce a complete manifold and elbow together, and had nothing but trouble. I would very very strongly advise to stay well clear of them....

Chris.....

Thanks for advice! I've performed web search an cannot find Bars or Aqua Power or any other company who makes them.

 

[Scott Danforth]

Merc was the only one producing a cast SS version of the ELBOW... A company called Hi-tek also ventured into SS, but were using welded sheet and tubes :facepalm: to produce a complete manifold and elbow together, and had nothing but trouble. I would very very strongly advise to stay well clear of them....

Chris.....

actually Hi-Tek is more of a short tube header than a manifold and elbow. similar in design to the CMI e-tops, however instead of tube in tube construction, its tube in sheet construction.

 

[achris]

actually Hi-Tek is more of a short tube header than a manifold and elbow. similar in design to the CMI e-tops, however instead of tube in tube construction, its tube in sheet construction.

Agree, but it was still a disaster. Red hot exhaust gasses one side of the tube, nice cool pond water the other... :facepalm:

Chris........

 

[Scott Danforth]

Agree, but it was still a disaster. Red hot exhaust gasses one side of the tube, nice cool pond water the other... :facepalm:

Chris........

agreed, many improper welds along with a few other issues. I believe the first tubes were even 304 vs 316

 

[tank1949]

I learned years ago that welding SS, especially thin stuff, will always result in warping. I was hoping cast SS would be an improvement. Cold sea water rapidly cooling SS while the other side is hotter then hell, always causes issues. THXs to all.

 

[eric102]

The 29 year old stainless elbows on my 91 7.4L are original but I've had to replace the cast iron riser blocks several times due to salt water rot, everything else is fresh water cooled. I wonder if the if the riser blocks might help with the heat dissipation and prevent the elbows from warping?

 

[tank1949]

The 29 year old stainless elbows on my 91 7.4L are original but I've had to replace the cast iron riser blocks several times due to salt water rot, everything else is fresh water cooled. I wonder if the if the riser blocks might help with the heat dissipation and prevent the elbows from warping?

I don't have a clue!

 

[achris]

The 29 year old stainless elbows on my 91 7.4L are original but I've had to replace the cast iron riser blocks several times due to salt water rot, everything else is fresh water cooled. I wonder if the if the riser blocks might help with the heat dissipation and prevent the elbows from warping?

Very unlikely... My SS elbows didn't have risers under them and I never had a problem.

With your setup and having to replace those iron risers, have you looked at re-plumbing the water around them? (to get the risers into the fresh water system) You could switch the gaskets around, block-off at the top (under the elbow) and flow-through under the riser. Then move the sea water hose from the HE from the riser to the elbow, and the fresh water hose at the top of the manifold to the riser (on both sides)...

Chris......

 

[eric102]

Very unlikely... My SS elbows didn't have risers under them and I never had a problem.

With your setup and having to replace those iron risers, have you looked at re-plumbing the water around them? (to get the risers into the fresh water system) You could switch the gaskets around, block-off at the top (under the elbow) and flow-through under the riser. Then move the sea water hose from the HE from the riser to the elbow, and the fresh water hose at the top of the manifold to the riser (on both sides)...

Chris......

No, have never considered that. Do you think the riser blocks would get enough coolant flow through them? Just thinking that Mercruiser might have done it that way if the fresh water system could handle it.

 

[achris]

No, have never considered that. Do you think the riser blocks would get enough coolant flow through them? ....

Yes, if you run the coolant into the bottom of the manifold and out of the riser port, not the port at the top of the manifold. (see attached drawing mods. Apologies for my crap 'paint' skills). You could even use the blind plug you pull out of the riser to plug the previous 'out' port on the manifold...

... Just thinking that Mercruiser might have done it that way if the fresh water system could handle it.

Yep, they did it on later models.

Chris............

 

[eric102]

Yes, if you run the coolant into the bottom of the manifold and out of the riser port, not the port at the top of the manifold. (see attached drawing mods. Apologies for my crap 'paint' skills). You could even use the blind plug you pull out of the riser to plug the previous 'out' port on the manifold...



Yep, they did it on later models.

Chris............

Thanks!