Excessive Smoke from Mercruiser 165

[chrisCA]

Hi Guys,

Working on tuning my Bertram 25 with twin 165's.
Portside motor is smoking alot, and it is like soot soming out, it seems to run ok, but seems that it is just fouling up.

Do you think it is the timing? anyone has seen this before?

The water pulling under the boat is covered in black soot.


https://drive.google.com/open?id=10XyDs ... p=drive_fs

[Tony Meola]

I would do a compression test on that engine. If it is causing soot it has to be idelyng rough. Fouled plugs possible, but sounds like more than fouled plugs.

[Chanse]

if you had your plug wires off for any reason I would
check to be sure they didn't get crossed.

[chrisCA]

Thanks for suggestions, I'll start with compression check and report back.

Since it is a twin I swapped the wires from the other motor and no difference, the sparkplugs are all new and new ignition coil.

I had a friend also say that the smoke looks like unburned fuel vapour. Engine runs ok but does have rough idle. I think i might have to do a head rebuild . I did that on the other motor while back and it works great.

We'll see I'll report.

[Carl]

When did this start happening?

-After you started to tune the motors
-Beginning of the season
-After getting fuel...
-After a heavy, driving rain
...just noticed one day there was a funk?

If after a tune up...I'd start checking items you worked on. Starting with the firing order...I assume you know if counter-rotating they have a different firing order. But even still crossing a pair of wires can do that, easy to do...

Fuel...recently get fuel? old? water??? Have you checked your water separators?
If carb...water in bowl or dirty jet?

If you have soot n unburnt fuel, I'd be pulling the plugs n reading them. Looking for a wet, black fouled plug...could be a bad plug or not-so-good wires. Have you opened the hatch to watch the motor running in the dark? Lousy wires n bad plugs can cause arcing between wires giving misfires. A mechanic friend of mine taught me that one.

A compression test is good too...

[Tony Meola]

Carl

I went straight to compression test since he said it was running ok. But I am not sure how he defines ok now that I think about it.

[Carl]

Tony, lots of tidbits with little overall information to go on. I believe he said it was running ok, but a rough idle.

Which means not running correctly.