Dieseling after shut off and loud noise when trim is higher in shallow water

[Romero157]

Hi, I just got my first boat earlier this year in June.

My boat was amazing and lots of fun this season.

A few things I didn't like though were that my engine would "diesel" after shutting off and shake the boat for a second or 2.

Also my engine would suddenly run very loud and rattle even when I trim up high in shallow waters. Anyone else ever had these 2 issues?

My boat is a 2002 Glastron SX 195 with a 3.0L 4 cylinder Volvo Penta Sterndrive engine.

Any experience would help!

Thanks

 

[alldodge]

Welcome
Dieseling can be caused by a few things
Idle to high
Running rich
Incorrect timing

The last thing a dieseling motor may do before stopping is run backwards. This can be really bad for a motor in the water. The water can be sucked up the exhaust and into the heads. Check the list about to make sure your withing spec

The drive should have a trim limit which will keep it from coming up to high. If the drive limit is not working, misadjusted or if you use the trailer function to get drive higher above the limit this can damage your drive. Never even run the motor on muffs with the drive above the limit, best it's close to full down

 

[Romero157]

Thanks for answering.

I've never run the motor dry out of water without muffs.

The issue is only when im using the boat.

When I pull up slowly to my dock in about 4ft of water, I will trim up so my prop doesn't get scratched or dinged.

When I do this, sometimes but not everytime... my motor will begin a loud vibrating/rattling noise that goes away if I lower the trim back down a bit.

Keep in mind the prop is never out of water and running dry.

Thats why I am concerned.

 

[Scott06]

Thanks for answering.

I've never run the motor dry out of water without muffs.

The issue is only when im using the boat.

When I pull up slowly to my dock in about 4ft of water, I will trim up so my prop doesn't get scratched or dinged.

When I do this, sometimes but not everytime... my motor will begin a loud vibrating/rattling noise that goes away if I lower the trim back down a bit.

Keep in mind the prop is never out of water and running dry.

Thats why I am concerned.

Our dock is in shallow water (27") so every time I go in or out we are at max up on the trailer button. Important to keep rpms at a min doing this

Would pull your drive check gimbal bearing, U joints, and engine alignment. Check bellows for cracking or splits. Also a good time to do the water pump impeller if you dont know when it was last done.

Take note of what AD mentioned on dieseling and water sucking into engine. If you cant get it solved turn it off in gear. Can also help to let it idle a bit if just coming off plane/towing a skiier.

 

[alldodge]

I wasn't thinking you ran the drive out of the water, just maybe it's coming up higher then it should. The trim limit switch on the drive should be adjusted so it only has maybe 30 sum degrees total movement. Meaning from tucked in to trim up. It should then stop moving and only way to get it higher is using the trailer switch

Assuming you don't have any noise or vibration when trimming up and on plane. This only happens when docking and only when trimmed higher.

 

[Romero157]

Good idea,

I wasn’t planning on servicing lower unit and final bearing since previous owner says he did last years

But I may just do that this winter to be safe.

Thanks for feedback.

Will be replacing pump impeller aswell.

 

[Bondo]

Thanks for answering.

I've never run the motor dry out of water without muffs.

The issue is only when im using the boat.

When I pull up slowly to my dock in about 4ft of water, I will trim up so my prop doesn't get scratched or dinged.


Keep in mind the prop is never out of water and running dry.

Thats why I am concerned.

Ayuh,..... Welcome Aboard,...... That noise yer hearing is the u-joints protesting the extreme angle they're running at,.....
Don't trim it so high is the cure,.....
In 4' of water, there's really no danger of hittin' bottom,.....

 

[Scott06]

Ayuh,..... Welcome Aboard,...... That noise yer hearing is the u-joints protesting the extreme angle they're running at,.....
Don't trim it so high is the cure,.....
In 4' of water, there's really no danger of hittin' bottom,.....

Agreed trim it back down a hair and the rattling should stop

 

[QBhoy]

Uj is rattling when trimmed up and the other issue is caused by the engine timing conditions. Before you go trying to adjust the timing though…I’d maybe just mention that it’s very likely that what’s happening is that you have water in your fuel or poor fuel…which is causing the affect.