Manifolds/Risers - OEM or Aftermarket?
Eisboch
>
> I plan on replacing the risers/manifolds on my Volvo (GM) 5.7L engine
> in the next week or so, and had one final question. Should I go with
> the factory original replacements, or are the aftermarket versions
> just as good. Also, someone commented to me that I might consider
> stainless steel risers and manifolds. I would imagine these are
> rather costly, and what about this "dissimilar metal corrosion" I
> continue to hear about. Does this mean the corrosion would transfer
> from the manifolds to the block? Why go stainless if this is the
> case?
>
> Any suggestions?
>
> Thanks and Happy Holidays!!
Replaced mine last season - if you have manifolds that have the
risers towards the rear - there is a replacement that has the
risers in the center of the manifolds. Supposed to be better.
Dick Eriksson
Michael Arbisi
Carl G. Craver
If you go with aftermarket manifolds and risers, I suggest you get Barr
brand. They have
made manifolds for major manufacures in the past including Volvo.
Carl G. Craver
Evinru...@home.com
Michael Arbisi wrote in message <3678603c...@nntp.ix.netcom.com>...
Lee Bell
with it. As for why stainless, because they last longer, much, much longer
on a boat operated in salt water.
Whatever you do, be real specific regarding your motor and configuration. I
have a Marine Power Premium 350 in Volvo configuration (300 hp model) with
fresh water cooling. It took three trys to get the right risers out of
Marine Power. The first set were for a 350 but not a volvo. The second set
were for a Volvo but not for a freshwater cooled Volvo. They were on the
boat before anyone noticed that one of the water ports seemed to be missing.
The third set were right.
gene_t...@my-dejanews.com
manufacturers of marine exhaust. The exhaust will still plug before it rusts,
so stainless is not much of an improvement, in my opinion. I have had
manifolds and risers cleaned at a machine shop in the past, but it only got
me by for 2 more years before I had cooling problems on one side. I replaced
them. Make sure you get painted parts. Some of the cheaper suppliers don't
paint (or only prime), painting is a lot of extra work.
Good luck
Gene Thompson
In article <3678603c...@nntp.ix.netcom.com>,
mar...@ix.netcom.com (Michael Arbisi) wrote:
> I plan on replacing the risers/manifolds on my Volvo (GM) 5.7L engine
> in the next week or so, and had one final question. Should I go with
> the factory original replacements, or are the aftermarket versions
> just as good. Also, someone commented to me that I might consider
> stainless steel risers and manifolds. I would imagine these are
> rather costly, and what about this "dissimilar metal corrosion" I
> continue to hear about. Does this mean the corrosion would transfer
> from the manifolds to the block? Why go stainless if this is the
> case?
>
> Any suggestions?
>
> Thanks and Happy Holidays!!
>
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
John Boatman
manifolds (Aqua Power, Barr, Osco, & Sierra). Barr & Osco are the primary
manufacturers. Sierra buys from Barr and Osco and puts their own label on
them. Aqua Power makes a few of their own (mostly MerCruiser Center
Discharge style for the V6 & V8 and the 4 Cylinders) and then buys the rest
from Osco and private labels them. Almost all of the marine exhaust systems
(both aftermarket and OEM) and cast at the same foundries (Sterling Casting
Co & Decatur Casting, both in Indiana), so the quality of the iron (Grade 30
cast iron) is the same no matter where you buy them.
The difference is the tooling used to get the casting. My current pick is
the Osco. Over the last 10 years they have re-done much of their tooling,
and now have a very reliable, product.
Stainless Steel manifolds are very hardy and will last a long time, but
there are often problems with galvanic corrosion to the cylinder heads. In
the long run it seems best to keep the manifolds the same as the cylinder
heads (cast iron).
- John Boatman
Boatman's I-Net Marine
www.i-netmarine.com
----------------------------------------------------------------------------
---------------------------------
Michael Arbisi wrote in message <3678603c...@nntp.ix.netcom.com>...
Lee Bell
>Stainless Steel manifolds are very hardy and will last a long time, but
>there are often problems with galvanic corrosion to the cylinder heads. In
>the long run it seems best to keep the manifolds the same as the cylinder
>heads (cast iron).
Rust in my manifolds are not a real problem. I have fresh water cooling.
My risers are as vulnerable as anyone's and get changed with the same
frequency. As for differing metals, having the same metal in the manafold
as the heads is not an option. I have aluminum heads (I think). As for
risers which clog before they rust, I wish this was consistently true. It
would have saved me an engine replacement. At least a clogged riser gives
you a sign that there is a problem (overheating). The first sign that a
riser has rusted through is salt water in the engine, a relatively sure
engine killer if not discovered and remedied quickly.
Lee
Grin&BearIt
replaced (before its too late)?
--
Regards
Michael Smith
M/V GRIN 'N BEAR IT
St. Stephen, New Brunswick
Lee Bell wrote in message <75clmk$1...@dfw-ixnews9.ix.netcom.com>...
JJames915
sandblast the loose rust off where they could get at it. They still seemed
pretty thick where I could see so I put them back on. The problem area is the
metal beween the exhaust and the water jacket and you have limited ability to
examine that. Sounds like there are some who simply plan to replace them every
x years. Don't know how you decide what x is though.
John Boatman
>So how does one identify that their risers have rusted and need to be
>replaced (before its too late)?
Unfortunately there is no sure fire way to prevent (or even detect, unless,
of course, your engine is full of water) rust-through in your exhaust
risers/elbows. You can get a good idea of the general quality of the metal
in your riser by removing it from the exhaust manifold, then performing what
I call the "screwdriver test".
The screwdriver test:
Take a flat-head screwdriver and scrape it along the water passages in the
riser (scrape the water passages where the water passes through the manifold
into the riser), don't be afraid to press hard while scraping. If you hit
solid metal right away you are probably in good shape. If you scrape up
pieces of gunk with lots of rusty metal, then you will need to replace them
sooner rather than later. The results you get from the test give you a
sample of the quality of metal in your riser. Use your judgement to
determine your course of action.
As a general rule risers in saltwater need to be replaced much more
frequently than risers in freshwater lakes/rivers etc. And the warmer the
water and longer the boating season you have, the more likely it is that you
will have to replace your risers sooner rather than later. For example, my
customers in Florida, Puerto Rico, Virgin Islands, etc., replace their
exhaust every 2 to 5 years (most of them don't wait more than 4 years).
Customers in Mid-Atlantic States replace their exhaust every 5 to 10 years
(8 years seems to be the medium), and in the Northern Atlantic/New England
States they get 8 to 20 years out of an exhaust (most replace it after about
12 years). Southern CA gets about 8 to 10 years, Northern CA to Washington
State gets10 to 15 years, etc.
As you probably know, the consequences of not changing the exhaust is that
you may fill your engine with water (not much fun). Preventative
maintenance is the only way to solve that.
John Boatman
Boatman's I-Net Marine
www.i-netmarine.com
Specializing in Marine Exhaust & Cooling Systems