When to replace manifolds and risers?

[marks737]

I bought a '95 Sea Ray 270 Sundancer last season. 7.4L Mercruiser 350hrs. on engine. Don't have records to indicate when the manifolds & risers were last replaced. I'm paranoid about them failing and trashing my engine due to water ingestion.

Marine Max seems hesitant to remove and inspect due to possible problems. The risers look good on the outside, no rust at the gasket joints. However the manifolds look a little rusty underneath (I'm asssuming from bilge moisture)

Should I just go ahead and put new ones on next season, for peace of mind or are there indications that would tell me that they are on the way out?

 

[Shaun78]

Re: When to replace manifolds and risers?

I have a 98 sundancer w/ 7.4L MPI. Mine showed no signs neither but are original so I just ordered new ones today. $900 for everything incl shipping. If you boat in salt water order the ceramic coated stuff. Better safe than sorry... heres a link

Direct links to iboats competition are not allowed.

 

[jcbarry]

Re: When to replace manifolds and risers?

Did they say why they are hesitant to remove the risers and inspect? That is the only way to know what condition they are in. However if you don't mind spending the money, new manifolds and risers never hurt.

 

[Senior B]

Re: When to replace manifolds and risers?

At 12 years old you're due to replace them but there are some things you can do to get an idea in my opinion...The thing I do is see how hot they get when running on the water. I can run my boat a full throttle for a good amount of time and hold my hands on both my manifolds. They are a bit warm, but not cooking hot. They also drain very well when I pull the drain plug. If yours are cooking hot and won't drain well and are full of rust then they gotta go in my opinion. At that age though they should be replaced and not just boiled out and re-installed. The general consensus though seems to be replacement at 4 yrs for salt water and a bit longer for fresh. I've seen plenty of fresh water manifolds go well over 10 yrs with no issues.

 

[marks737]

Re: When to replace manifolds and risers?

Thanks Guys,

I'll probably put new ones on to be sure next season. The ceramic coated ones look good. Is this a job I can do myself? I am mechanical but haven't done much engine work. Any tips or gotcha's when replacing these?

 

[Senior B]

Re: When to replace manifolds and risers?

When you replace them, be sure to clean the threads in the block with a tap of the right size for the bolts. This is to ensure that the mounting bolts go back in easy and that you get an acurate torque reading when you use the torque wrench. This will make for even snuggness on the gaskets and greatly increase your chance for success when it comes to leaks on both the exhaust manifolds and the risers. Since the manifolds will be new, you shouldn't have to tap them but it won't hurt if you do. Also I would use new bolts.. This job can be done by the home mechanic. It's very straight forward.

 

[Mkos1980]

Re: When to replace manifolds and risers?

I just replaced mine. They were origionals from 1990. Looked perfect when I took them off inside and out. Replaced them with Hi-Po Aluminum ones. BTW motor is freshwater only

 

[flabum]

Re: When to replace manifolds and risers?

Since the manifolds will be new, you shouldn't have to tap them but it won't hurt if you do. Also I would use new bolts.. This job can be done by the home mechanic. It's very straight forward.

Lately, the manifolds have been comming through with the threads not so clean. During manufacturing , they paint the parts after the threads have been cut and paint, ceramic coating and such wind up in the holes. . For the past couple years, I have had to chase out the manifold threads.

 

[njlarry]

Re: When to replace manifolds and risers?

Spot check the temps with an IR sensor and sound with a ballpean hammer for starters. But you really need to remove them to take a look. I remove mine every 2-3 years. IMHO if you're going to replace one thing just on the basis of time you should replace to whole boat as the rest of the boat is not new either.

 

[180shabah]

Re: When to replace manifolds and risers?

IMHO if you're going to replace one thing just on the basis of time you should replace to whole boat as the rest of the boat is not new either.

The one question that hasn't been asked is if the boat was used in salt or fresh water???????

If this boat has never seen salt, then the mani's will probably outlast the rest if the boat.

Mine are originals, from 1996, and still look great inside. I still check them every couple of years because this boat started it's life in the salt, and a few gaskets is cheap piece of mind.

 

[Bondo]

Re: When to replace manifolds and risers?

If this boat has never seen salt, then the mani's will probably outlast the rest if the boat.

Ayuh,..........

40 Years is the expected lifetime of Manifolds up here on the Sweetwater Seas,.........
As long as they're not allowed to Freeze when wet...............

 

[marks737]

Re: When to replace manifolds and risers?

Sorry, yes this boat has been in salt water only.