Starboard exhaust manifold warmer and inspecting

[MarcelSydney]

If installed 2.5 years ago and we see no sign of leaking from that joint I’d say you’re still good. Another check I do is I replace the plugs in the spring after burning off the fogging oil. Look at the electrodes on the old plugs for any sign of corrosion. Even if you wouldn’t normally change plugs still inspect them for any corrosion and if you do see any then yes it’s time to drain the water and check the exhaust.

Thanks Lou. Really helpful.

 

[achris]

Thanks Chris. That's great. Works now.
BTW, as Lou mentioned earlier, is it possible to replace manifolds and elbows from wet joint to dry joint?

Yes. I did a post with all the part numbers. See if I can dig up the document on my computer.. (standby)

Chris..........

 

[achris]

Here you go....

Wet joint
Manifolds
V6 – 864612T01
V8 – 860246A15

7° (4”) parts

Exhaust elbow – 807988A03
Inter elbows (with NO riser)
V6 - 14478T01
V8 - 11086T (port)
V8 - 14343T (stbd)
Y-pipe - 807130A4 (Originally -44266T)

14° (3”) parts

Exhaust elbow – 98504A3
Inter elbows (with NO riser)
V6 – 99758A1
V8 – 94444A1 (port)
V8 – 94443A1 (stbd)
Y-pipe - 99877A10


Dry Joint

Manifolds
V6 – 99746A17
V8 – 865735A02

7° parts

Exhaust elbow – 864309T02
Inter elbow (with NO riser)
V6 - 14478T01
V8 - 11086T (port)
V8 - 14343T (stbd)
Y-pipe - 807130A4

14° parts

Exhaust elbow – 864591T02
Inter elbow (with NO riser)
V6 - 865947A01
V8 - 865951A01
Y-pipe - 807130A4

 

[Lou C]

Thanks Chris, I might look into converting my OMC/Volvo exhaust to Merc dry joint if the angles etc will line up. I do like the superior design of the dry joint although I have not had problems since installing the later style OMC/Volvo 2 piece units (5 years ago) after using the old OMC one piece batwings (which I never had a problem with either, although always changed them after 6 seasons max)...
I'm not sure but I think the OMC/Volvo design uses a 7* down angle too, but whether or not the parts line up depends on a lot of other measurements.

 

[MarcelSydney]

Here you go....

Wet joint
Manifolds
V6 – 864612T01
V8 – 860246A15

7° (4”) parts

Exhaust elbow – 807988A03
Inter elbows (with NO riser)
V6 - 14478T01
V8 - 11086T (port)
V8 - 14343T (stbd)
Y-pipe - 807130A4 (Originally -44266T)

14° (3”) parts

Exhaust elbow – 98504A3
Inter elbows (with NO riser)
V6 – 99758A1
V8 – 94444A1 (port)
V8 – 94443A1 (stbd)
Y-pipe - 99877A10


Dry Joint

Manifolds
V6 – 99746A17
V8 – 865735A02

7° parts

Exhaust elbow – 864309T02
Inter elbow (with NO riser)
V6 - 14478T01
V8 - 11086T (port)
V8 - 14343T (stbd)
Y-pipe - 807130A4

14° parts

Exhaust elbow – 864591T02
Inter elbow (with NO riser)
V6 - 865947A01
V8 - 865951A01
Y-pipe - 807130A4

Thanks. This us great

 

[Superjetjim]

Maxum 1800 SR with 1999 mercruiser 4.3L V6 with Alpha One, gen 2
Engine #OL 323311
Drive#OL140489

Salt water boat on trailer. Flush and wash after every use with salt away.
Manifolds and risers were replaced in 2019 about 100 hra ago, new impellor 6mths ago, new t-stat. In the past few months when running on the muffs when flushing, I've noticed the starboard manifold is hotter than port side and less water coming from that side out the back, and its quite hot to put hand under the water coming out. When the boat is in the water it's even temp.
1. Is this indicative of blockage developing?
2. Can you back/reverse flush the system to see if it clears anything? How do you do it if so?
3. How often should I inspect manifolds risers and what exactly am I looking for?
4. Should I be changing gaskets every so often (read that on another forum to do it every year)?

Thanks

I had the same issue, hotter on side / less water and worried - see flow below, motor wasn’t level.
View attachment IMG_4668.MOV

 

[Superjetjim]

Guys on here suggested levelling out and retesting - sure enough it was spot on then!
View attachment IMG_4707.MOV

 

[MarcelSydney]

So, just circling back after some experimenting. Thanks all for the input.
Seems like you are all on the money.
In the water, it's generally fine.
On the trailer, our road slopes so that the starboard side is higher, as a result the port gets most of the water and the starboard manifold get hotter.
If I put chocks under the tyres to level out, it's pretty even.
If I put an extra chock under the port side wheels so that the port side is higher than the starboard, most of the water comes out of the starboard side and now the port side manifold will hotter than starboard.

Guess I'll just carry a chock in the trailer to level it out each time so I get a proper flush after use.

Cheers