cost of replacing risers - manifolds

charlieft

charlieft

Member
Nov 14, 2006
166
Plymouth, MA
Boat Info
2003 300 Sundancer,
Engines
T-350 Magnum w/Bravo III
Can anyone give me a ballpark cost for replacing risers and manifolds on twin 350 magnum engines?
I'm looking at a 2003 290 amberjack ... everything looks great, but I question the condition of the manifolds and risers.

Thanks,
Charlie
 
You can pull the risers and have a look, gaskets cost about $100 or so and you'll know when you pull them. The prices have been going up for replacements but the last time I got a quote for manifolds and risers for my 4.3's was around $2600 with labor.
 
that 2600 sounds about right, but that's two motors. I had a cracked exhaust manifold and ended up buying a used motor with a good manifold, it was the cheapest way to go. The corrosion on the new one wasn't bad, but my motors have a closed cooling system. Mercruiser wanted 1200 for the one on my 4-cyl, only one manifold. I think West Marine sells them for the small block chevys at a pretty good price.
http://www.westmarine.com/webapp/wc...URL=true&storeNum=6&subdeptNum=68&classNum=69
 
One word of caution - there has been much ado about aftermarket castings on this SR board and the last one. If you are going to do the work yourself, put a small portion of the big bucks you are saving towards genuine mercruiser parts. I'm a big fan of saving money on ignition components and filters that are all probably coming from the same manufacturer, but I would NOT mess around with Osco or Barr stuff. But hey, that's just me.
 
Thanks Ron, Mike, Eric,

I've been told the boat has ceramic coated exhaust components and they last a lot longer than earlier components.

-Charlie
 
Ah yes, the 350 Mag Horizon comes with ceramic coated innards as well as closed cooling. That's a real good setup. I had the same motor in my last boat ('02 Crownline). I still tapped into the hose that draws water up from the drive to the pump and installed a flush system. Installed a flush system on this boat as well. Not sure if it makes these components last "forever," but eliminating all salt water from each engine is my main goal before leaving the boat for the week.
 
I don't buy either the ceramic coating or the flushing. As the manifolds heat up and expand, the ceramic coating is going to expand at a different rate than the cast iron causing cracking. Salt water will collect into those cracks and also the pores of the cast iron. As the iron cools, it contracts capturing the salt in the pores, and microscopic cracks, and fissures in the material. Flushing at idle doesn't heat up the exhaust the way running hard does, so the salt isn't released.

Never saw anyone get more life from manifolds and elbows that are flushed than those that are not. My 2*10^-5 boat dollars worth.

Best regards,
Frank
 
buy only original merc parts,the $100 more is nothing compared to a $5000 engine you can damage.just my thought
 
For my boat with 8,1s engines the parts alone from Mercruiser was right at $2960.00 per engine. This was for elbows, risers, manifolds, new bolts, clamps, all hoses, etc.

Plus around eight hours labor.

For my input and from my surveyor, stay away from Barr's, this is what was being replaced. The previous owner claimed he had just put the Barr's on a year earlier, and they were shot.:huh:
 
holy crap thats expensive!!Did you shop the web?theres a guy near me selling Merc risers and manifolds for small block with everything for spring special $495.I would try shopping.
 
Frank
I agree that because of different coefficients of thermal expansion for cast iron and ceramic, the coating is destined to fail eventually, regardless of what type of water passes through the system. I respectfully disagree about the effectiveness of flushing. The corrosive effects of salt water are much greater than that of fresh water. By merely diluting the salinity, you'll add years to the lifespan. Our boats are only in the water roughly 5 months or 20 weeks (or 140 days) give or take. If I can keep salt water out of the jackets and passageways 5 days a week, or 100 of those days, I'm confident that I'm getting exponentially more time from those vulnerable components.

Note to self: don't buy a boat with 8.1s! WOW, a quick internet search at a site with pretty good prices confirms what Pseudo says. I know nothing about the 8.1L engine and I guess it depends on whether you have risers in addition to elbows, but it appears to be a more complex system than 7.4s and short blocks.

http://www.mercruiserparts.com./Show_Pictures3.asp?dnbr=881785002&ivar=images/COMMON/14496.png&inbr=11507&bnbr=160&bdesc=Exhaust+Manifold%2C+Elbow+and+Riser
 
How many years do you get from elbows?
 
I only have risers and no spacers. Are risers and elbows the same? Anyway, I bought this boat in mid-summer 2004. In the fall of 2004 I installed the flush system (when the boat came out of the water). My flush ritual has been the same since spring of 2005. I flush when I'm done running the boat for the weekend - ie: if I take the boat out on Friday and know I'll use her again on Sunday, I flush upon return to the dock on Sunday. If I use he boat on Saturday and know I won't be using her again that weekend, I flush when I get back to the dock. If I do decide to go out the next day, I'll flush on Sunday when I return. If we are on a trip, I do not flush when arriving at a new place. I flush when we return to our marina. For me,flushing is like tying the boat up.

I don't know when the PO did risers so I pulled them in the winter of 2005/2006 and they were in VG-excellent condition. I haven't pulled them since. Probably due for a looksee next winter or the one after. They continue to run at a "touchable" temp when under way.

My friend (you know Rudy) blew out an impeller. He has Bravo2 drives mated to RWC short blocks. When we pulled the pump and found NO vanes, we took all the hoses off looking for remnants. We also pulled his risers (and spacers) at that time (fall of 2007) to check on them. His were in like new condition and were original (the boat is a 2001). His boat has always been in the brackish waters of the Metedeconk River and he does not flush.

So, I can't say how many years from personal experience. Only what "they" tell me. In real salty water, they say 5-7 years. In fresh and brackish 6-9 years???
 
Risers rise the Elbow up to prevent water from entering the Manifolds.
 
I just replaced the elbows on my engines and did shop around. You have to be careful what you are looking at. Many of the internet places guote "For Merc engines" or something similar to lead you to believe they are Merc parts, but if you dig, you'll find they are not. I too believe in Merc parts for the elbows, but not the gaskets. I've had better luck with Sierra gaskets and hi temp RTV then with the teflon Merc ones. Plus, they're easier to remove. I get 3-4 years on elbows in saltwater year round. I usually pull, inspect, clean out, and reintall every year. Manifolds are part of closed cooling have not been replaced in 7 years.
 
Ok, so the thing in the upper left corner of this pic (#9) is an elbow, and the thing in the lower right corner of the pic is a riser (#12). In that case I have elbows, no risers and only one gasket to deal with.


14011.png
 
doing my yearly pull the elbow and risers, they need to be replaced this year. $1900 in parts alone. WOW!!! they have really gone up in price this year.

Freakin things better arrive in gold plated boxes.
 
Last edited:
Sounds like you are pushing your luck. Used elbows need inspection more frequently than 4 years.
 
I agree, 4 years is too long. Seems like when they reach a certain degrade, they go rapidly.
 
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