340 dancer risers and manis

[Partyoffive]

My risers on my 05 340 were definitely changed. I can see they are actually taking a smaller foot print than the originals. They also are definitely not cast, appear to be very shiney to look at as opposed to the more typical matted finish on the cast ones. A very knowledgeable friend says they are either stainless or some kind of copper material and do not degrade like the cast ones do. They therefore don't need the 3-5 year replacement. Does anyone have any thoughts here as to maintenance? Does this sound correct? Also, the manifolds are mercruiser. The motors are the 8.1 horizons. Aren't the manis fresh water cooled which would require far less maintenance ? I recently looked at mani temps under full load conditions. Hot spots were about 138 degrees. Any thoughts greatly appreciated. Thx.

 

[BillK2632]

You might have aluminum manifolds.

 

[Bay B's]

Are the manifolds and extensions cast? Can you post some pics? I agree with BillK2632. Could be aluminum, Could be SS.

My risers on my 05 340 were definitely changed. I can see they are actually taking a smaller foot print than the originals. They also are definitely not cast, appear to be very shiney to look at as opposed to the more typical matted finish on the cast ones. A very knowledgeable friend says they are either stainless or some kind of copper material and do not degrade like the cast ones do. They therefore don't need the 3-5 year replacement. Does anyone have any thoughts here as to maintenance? Does this sound correct? Also, the manifolds are mercruiser. The motors are the 8.1 horizons. Aren't the manis fresh water cooled which would require far less maintenance ? I recently looked at mani temps under full load conditions. Hot spots were about 138 degrees. Any thoughts greatly appreciated. Thx.

 

[carterchapman]

My '05 340 came from the factory with aluminum manifolds. They do not last long in a salt water environment - there was a "secret" recall on them - if you asked your dealer, they would replace them with cast iron.

 

[Partyoffive]

Here is a photo. Thank you

 

[Air O'Nautical]

Your elbows are stainless and should last forever(ish)..

All Merc 8.1's have raw water cooled manifolds and elbows.
There was some misleading info about fresh water cooling when these engines were introduced. The block IS fresh water cooled, the manifolds are not...!
(Crusader brand engines can be different, with block and manifolds cooled with antifreeze).

Your manifolds are either cast aluminum or cast iron, aluminum won't work in saltwater for long and should be changed ASAP.

I not sure the consenses of how long the new dry joint raw water cooled cast iron manifolds should last?

 

[Air O'Nautical]

Here is a photo. Thank you

Just so i follow, the top round part is the shiny elbow which is stainless painted black (FYI these are commonly mis-called risers)
The lower part looks like an original saltwater cooled OEM exhaust manifold and will not last as long as the elbow.

 

[Partyoffive]

Thank you Mark. Very helpful. I believe the manis are cast. They appear to have been changed also. Either way , I checked the temps on the manifolds under load with a thermal gun. Hottest recorded temp was 138 degrees. I'd guess this would be much hotter if they were beginning to break down. Do you guys agree??

 

[onthejob]

The manifolds look exactly like the cast iron ones I just installed on mine over the winter. Try using a magnet. Then you'll know for sure. My aluminum ones the paint was beginning to flake off. Check the center bottom of the manifold where a 3/4" hose goes from the manifold straight down. That's one of the first spots the aluminum one start to break down. Check for paint flaking and bare metal. But again I think those are cast iron.

 

[Air O'Nautical]

I'd check with a magnet and change if not iron.

No, I don't agree, that running cool to be any indication if being ok.

Again, I don't know the newer dry joint manifolds to last any longer then the older style and personally been changing them at 5 years old for my customers boats that I help manage.

I realize @ $400 / manifold + gaskets and labor ... It's not a bill anyone wants every 5 years but, the engine is $16000 + labor to replace.

 

[Bay B's]

Dry Joints Here...and Whoa there! How much? Unfortunately my configuration of twin 5.0's with manifold, 2 sets of extensions and then elbow per side X 2 is more like $4k in parts alone. That's right, $4K plus labor. What world are you living in at $400 with labor? Oh, and thanks Sea Ray!

I'd check with a magnet and change if not iron.

No, I don't agree, that running cool to be any indication if being ok.

Again, I don't know the newer dry joint manifolds to last any longer then the older style and personally been changing them at 5 years old for my customers boats that I help manage.

I realize @ $400 / manifold + gaskets and labor ... It's not a bill anyone wants every 5 years but, the engine is $16000 + labor to replace.

 

[Partyoffive]

Really good discussion gents. Will definitely check with the magnet test. Will also examine the 3/4 inch fitting. Does anyone know what the recommended maintenance on the cast dry joint manis is from searay?

 

[Air O'Nautical]

Dry Joints Here...and Whoa there! How much? Unfortunately my configuration of twin 5.0's with manifold, 2 sets of extensions and then elbow per side X 2 is more like $4k in parts alone. That's right, $4K plus labor. What world are you living in at $400 with labor? Oh, and thanks Sea Ray!

Your correct, around 4K for complete R&R of your system + labor because, you have more parts to replace.

I did underestimated the 8.1 manifolds, closer to $700-800 each these days depending on supplier.
But the the 8.1 elbows should still be serviceable, there different than yours and last longer.
If he also needs to R&R the elbows the parts cost jumps to around $5600.

My numbers didn't include labor..and are aprox. guesses because, I didn't have the engine ser.#

IMHO, Merc. exhaust failure is easily the #1 killer of boat engines.
They don't last nearly long enough and neglecting them will first, cost a top end valve job..if left just a little longer .. new engine.


Don't shoot the messenger.

 

[Partyoffive]

Manis are definitely cast as they passed the magnet test. In a best case scenario they are 4 years old. Is the recommended course of action here to replace these manis at the 5-6 year mark??

again thank you all

 

[Air O'Nautical]

Now that's the question......how long are are the 8.1 dry joint manifolds good for?
I have swapped some at 5-6 years and they did appear good but, ya never know.....also, swapped some small-block dry joints at 12 years and they were leaking.
I honestly don't have a good answer..

 

[Partyoffive]

Thanks mark. Really appreciate the education

 

[onthejob]

I just did the job myself on 8.1s. They were $445 a manifold which includes a gasket plus shipping ($45) X 4 = $1960.
http://www.michiganmotorz.com/mercruiser-exhaust-manifold-p-788.html Price went up since I've done them.

I did not replace the stainless steel elbow and the 8.1s in 340's do not have a riser.

 

[sdleo26]

Check the pricing at nuwave marine; you should be able to do dry joint manifolds and risers for both motors for under 3k in parts. I did mine last year and it was 2400 delivered to the door for OEM 5.7

The 8.1 it a bit more, but not that much. They have the lowest cost anywhere I checked; even Michigan Motors. If they don't, they will match or beat any price.

 

[juggernaut1]

I just had the manifolds on my 8.1's replace by a local Mercruiser agent/mechanical business here in Australia. Mani's were 9 years old all with salt water use. They said the elbows are stainless steel and didn't need replacing. I'll let you know if they fail any time soon.

 

[Partyoffive]

Thanks Jaugger...

do do you know how the manis looked when removed?? Ty!! Hope all is well "Down Under"