exhaust manifold issue

C

chazaroo

New Member
Dec 4, 2006
415
Florida
Boat Info
1996 Sundancer 250
Engines
single 5.7 w Bravo III
I took our boat in to have the risers checked (been a year and 250 hours since it was done) and the mechanic just called. Risers are fine but one of the exhaust manifolds has a crack in it. New ceramic coated ones from Mercruiser are $250 each. I'm sure I can find something cheaper in aftermarket but the mechanic recommended OEM. So...go with his recommendation or look for something cheaper? Also, replace just one or both? And should I consider replacing risers as well? They look fine and are newer than the manifolds. Advice welcomed.
 
If it was me, I would do both sides, risers and manifolds.

The way I look at it, take care of it now instead of having something fail during the summer and being without it for a few weeks during prime time.
 
At the minimum I would to both manifolds. You might check to see if you have stainless risers. Merc used them for a while and painted them black. If they are stainless, you can keep them without worry. Aftermarket manifolds can be a little cheaper but usually the cost savings are offset by poor fitment, missing hardware and a iffy warranty.
Even the mose expensive exhaust system is still cheaper than a motor.
 
Stay with OEM castings. I've saved some money once on aftermarket ones only to lose the use of the boat for 6 weeks while I forced them to honor their warranty. I bit the bullet and went back to Mercruiser parts from the dealer to get the boat back in service. The hassle was getting the manifold maker to pay me in cash rather than more junk parts.

If the other manifold checks ok, I don't know why you'd change it. A crack isn't wear or corrosion related and besides, manifolds don't usually corrode until the riser above it begins to leak.
 
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I've decided to at the least replace both manifolds. Reasoning is that I'm not sure of the age and the new ones from Mercruiser are ceramic coated whcih sounds like a good idea.
As for the risers, I'm not sureif they're stainless or not. How do I check that?
 
One more question regarding the cracked manifold. What causes it to crack in the first place?
 
perfprotech.com. They were the R&D for merc for 25 years and they offer ceramic & EDP coated with a 3 year warranty and they come compl w/all hardware. I just bought a complete setup for my 7.4L. I am big on OEM also but I figured they are a reputable company and very knowledgeble. I had OEM's that leaked so I don't think OEM's are any better than perfpro's at least. (much cheaper too)

As for a cracked manifold(water that froze could crack them)
 
Oh yeah and if I were you I would replace manifolds & risers. I was in the same boat,I probably could have went 1 more season on them but I figured just replace them now so I have no problems later on.
 
SAshton,
Yeah I've decided to go ahead and replace everything. Manifolds, risers and extenders. No point in trying to save the stuff for one more year. As for the cracked manifold, I'm baffled. Water doesn't freeze here. What else could cause it?
 
Can't tell from your profile where you boat, but if it's salt water then I'd replace both sides. Otherwise, 250 hours is typically a little premature for manifolds.
 
Sorry for the confusion. Boat has 500 hours on it. The 250 refers to the hours since the risers were checked. And we do indeed boat in salt. Actually a combination. We're wet slipped at our house in brackish water but often boat in salt water. We're going to go ahead and replace manifolds, risers and extenders. Better safe than sorry. Regarding brand, the marina recommends OEM, which they say are ceramic coated. Others on this forum seem to be happy with perfprotech.com (also ceramic). I'm leaning towards OEM based on the marina recommendation even though OEM is more money. Not sure if that's smart or not.???
 
Well, you had an OEM manifold on your engine and it cracked. So hummmm Is OEM better?? They all(aftermkt & OEM) use the same casting process and materials and with the perfprotech also being ceramic coated and ALOT cheaper and a better warranty I decided to give it a shot. The same company that coats the OEM's also does the perfpro tech's as both plants are near eachother. I have mine but I havent installed them yet,to cold. Also on these they use a seperate stud for the spacer to manifold and the OEM uses one VERY long bolt which in my opinion isn't as good as the perfpro tech setup.
 
SAshton,
From what I've been able to find out, the casting process is not the same. Perfprotech uses the green sand casting process, while Mercruiser uses the lost foam process. Found this on the Bayliner website: "To improve life in saltwater, MerCruiser manufactures the elbows from cast iron using lost foam casting process to provide better control over the wall thickness, preventing thin spots that can corrode through prematurely. Many models feature a ceramic coating baked on between the epoxy paint and cast iron surface, coated both inside and out for an added layer of corrosion protection."

Having said that, and not being a metallurgist, I have no idea what the difference is between lost foam and green sand casting. This takes me back to my original thought that the mechanic and the marina know what they're talking about and are giving me good advice. We'll see.

Oh and a word or two about warranties. If you read them (any of them) you'll see that they only cover the part, not the damage the failed part does. So if the manifold fails and dumps water into the cylinder, you pull off the manifold, mail it at your expense to the manufacturer. They then decide if there is a defect and their opinion is final. If they decide the part was faulty, they send you a new manifold for your hydrolocked motor. Swell. I figure that pretty much takes the warranty discussion off the table. Now we're left with whether green sand or lost foam is the better process. And I haven't got a clue.
 
Perfprotech website under tech articles for exhaust sytems explains both processes a little. I still went with them but it's your boat and your call. I'm just telling you what I did.
 
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I have owned my 2001 290 Amberjack since new, I have about 525 hrs. on both engines. Last month I had the dealer replace the risers and manifolds for the 3rd time as they were showing signs of corrosion/rust at the joints. I always have boated in salt water (Gulf of Mexico)and flush the engines after each use (boat is kept on a lift). The first changeout was covered under the Merc 3 year corrosion warranty and after that at my expense. Other Sea Ray owners in my area (Tampa Bay) also have done the same, as a preventative measure at the first sign of corrosion. Don't second guess yourself, change everything and avoid a bigger problem down the line as these parts are known for failing due to salt water corrosion. Just my humble opinion....
 
From everything I've seen on line in the aftermarket arena, it seems like Perfprotech is the one that does the most in terms of explanations. Their site is certainly loaded with info Also they're the only ones other than Mercruiser that does the ceramic coating, which seems pretty smart. Right or wrong I'm commited to OEM for this situation. But Perfprotech is certainly right up there and I'll probably give them a shot next time, which hopefully won't be too soon. Thanks for your input. It's important to think these things through and I apprciate your opinion.
 
CsiDave said:
I have owned my 2001 290 Amberjack since new, I have about 525 hrs. on both engines. Last month I had the dealer replace the risers and manifolds for the 3rd time as they were showing signs of corrosion/rust at the joints. I always have boated in salt water (Gulf of Mexico)and flush the engines after each use (boat is kept on a lift). The first changeout was covered under the Merc 3 year corrosion warranty and after that at my expense. Other Sea Ray owners in my area (Tampa Bay) also have done the same, as a preventative measure at the first sign of corrosion. Don't second guess yourself, change everything and avoid a bigger problem down the line as these parts are known for failing due to salt water corrosion. Just my humble opinion....
Click to expand...

CsiDave,
Yeah, everything is going to get changed out. I don't want to gamble on the motor. But, a couple questions. Were the ones you used the ceramic coated manifolds and risers? Was the problem at the joint between the riser and the manifold? I read, I think on the Perfprotech site that the torque process on the installation is critical. You're supposed to start at 10 lbs, then go to 25lbs and finally (I think) 33lbs. Then you're suppposed to let the engine run a bit and retorque. Then do it again at 20 hours. I had my risers checked last year and I know they did not do the 20 hour thing. Didn't even mention it to me. I'm using a different marina now and intend to discuss this with them when I pick the boat up. Seems like the problem is more often than not, the gasket not the riser. Anyway FYI on the torque issue.
 
It is tough as there as alot to chose from and who really knows whats the best. I was thinking about GLM's also. They claim to have better water flow and they use the lost foam method and supposidly a galvanized coating I think but like I said who knows. I hope mine don't leak or fail anytime soon. Anyone use the Perfpro tech's manifolds & risers???

I did a little homework on last foam casting. It is the future of casting only because it's ALOT easier to cast and it looks prettier on the outside. It also makes the inside walls alot easier to create even thinknesses. Perprotech still uses old method but they claim they nearly perfected there casting process as they sell alot of parts and have been doing it this way for years. They will eventually switch to lost foam though.....
 
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What is the price for OEM versus aftermkt. I figured OEM was around $14-1500 for a big block setup. I paid $900 for perfpro tech compl setup.
 
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