The boat is a ‘99 4000 Express with 3208’s.
My port and starboard underwater exhausts are uneven at idle with the starboard side being far more “animated” than port. The port side is more a gentle bubble, almost entirely contained under the swim platform while the starboard side does a lot more “sloshing.” It almost appears like the starboard side is in gear at the dock.
Both motors are at a steady 600-650 idle, and all pressures and temps are where they should be throughout the full rpm range. They otherwise run great, but am not even sure which side is the correct side at this point.
I took short 10sec videos of each side, but the site won’t let me upload them. If you think you have an idea, I’d be happy to text or email them to you!
It may simply the way they are 'plumbed' inside the boat. Since both exhaust have to exit the same side of the engine inside the ER, there may be more downward tilt on the exhaust causing more water movement. Maybe, just a thought. If you think otherwise, then maybe your raw water impellers need to changed as one MAY not be pumping as much water.
Is your generator running? On some boats, the genset exhausts and discharges water through 1 of the main exhausts... which could explain 1 side being more "animated" than the other.
max
Yeah, the gen is usually running, but mine exhausts out the port side.
I considered the impellers too, but wouldn’t that also give me a slightly higher operating temp on one? Both are dead even at the gauges (for what that may be worth). The impellers are getting redone this offseason regardless.
I guess the good news for me so far is two of you responded and neither indicated it’s anything catastrophic at this point.
At least in mine (40 express model year 2000)the engine exhaust at idle is relieve thru a couple of dedicated openings under each side of the platform at the water level, however if the boat is listed (inclined) to one side or the other ( for any number of reasons), even if not very noticeable, the openings on the listing side might be completely submerged while the ones on the other side might be completely above the water line and that might explain the difference between the engine perceived behavior / noise.
Good intel - thanks jlobon. I got some schematics from Tiara for the system, and I have the same set-up you mentioned. On the port side I can clearly see the water coming from the thru-hulls with just the occasional bubble from the skeg. There’s so much action on the stbd side, though, it’s hard to tell if exhaust is coming from the skeg, but I can feel it coming from the thru-hulls.
I’m going to try putting some weight on the port side and see if that fixes it. I’d love for nothing to be wrong more than a slight list, pushing that exhaust further under than the other side!!
I had a 40' sport fisher (not a Tiara) that would surge water on the port side. Starboard would run nice and even but the port would push a bunch of water every 5 seconds. After digging around in the engine room I noticed the engine exhaust was exiting on the starboard side of each engine so the stbd engine ran straight from the engine out to the back if the boat. The port engine exhaust came off and made a 90 degree turn across the rear of the engine then made another 90 degree turn towards the rear of the boat. This allowed water to build up in the exhaust tube and once it got to a certain point the exhaust would overtake it and push it all out creating the surge.
I lifted the exhaust to make a cleaner angle and the surge disappeared.
(10-20-2020, 05:04 PM)MC1600 Wrote: [ -> ]The boat is a ‘99 4000 Express with 3208’s.
My port and starboard underwater exhausts are uneven at idle with the starboard side being far more “animated” than port. The port side is more a gentle bubble, almost entirely contained under the swim platform while the starboard side does a lot more “sloshing.” It almost appears like the starboard side is in gear at the dock.
Both motors are at a steady 600-650 idle, and all pressures and temps are where they should be throughout the full rpm range. They otherwise run great, but am not even sure which side is the correct side at this point.
I took short 10sec videos of each side, but the site won’t let me upload them. If you think you have an idea, I’d be happy to text or email them to you!
I have the same boat, same year, same engines but "sloshing" occurs on the starboard site. I believe the issue is related to my boat slightly listing to port side exposing the 2 thru hull exhausts on starboard side and making the water splash while port side is under water entirely. I have been trying to balance it with fuel but could not get it to completely level. Check the waterline to see if you have the same listing issue.
I should have followed up on this. That’s exactly what it was (is). I can even out the exhausts by just walking back and forth on the swim platform. Thought it was a bigger problem than it was. Relieved it’s nothing! Ha!
Have you checked the boat trim? If the boat is listing even 1"-2" it's enough to but the exhaust exit farther underwater. And 1"-2" is not easily discerned on 40' boat with a 14' beam . Is the fresh water or holding tank on the side with the higher noise?
All other things being equal as you've describer might just be a bit more weight on one side.
you can always check if its just this by having a few friends heal the boat opposite and see if there really is more "systemic" issues.
Just a thought