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Outboard shudder following gear oil change

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Category: General Forums
Forum Name: The Outboard Clinic
Forum Description: Anything related to outboard maintenance here....
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=58281
Printed Date: 10 Jun 2026 at 10:18am


Topic: Outboard shudder following gear oil change
Posted By: Haydan
Subject: Outboard shudder following gear oil change
Date Posted: 06 Oct 2010 at 3:24pm
Just changed the gear oil in the outboard yesterday and this morning when I stuck it in gear and idled off there was a slight shuddering going on for about 30 seconds or so before the engine settled down.
 
Is this normal following an gear oil change?
Is there anything I should check?
 
I had a shop pump in the gear oil so I'm assuming they did it correctly but I'd rather get some encouraging feedback.
 
I did not hear anything alarming when it was doing it (like grinding etc.) just felt as though the engine was runing out of gas for a little bit. However it can't have been that as I'd been ideling for a minute or so at the jetty prior to undocking.
 
Thanks for the advice,


Replies:
Posted By: Outboard Performance
Date Posted: 06 Oct 2010 at 5:41pm

No thats not normal Haydan.

 
Sounds more like an engine issue than the gearbox. What motor is it first off?
 
The outboard could of had an air lock in the fuel line, it will idle for a minute or so in neutral with no load on it. It will take about that long to use up the fuel in the carburettor bowls.
 
I'll wait to hear what motor it is before trting to say anymore.
 
And did it go ok for the rest of the day? Is all the shop do change the oil?

Posted By: Haydan
Date Posted: 06 Oct 2010 at 6:22pm
Its a 2007 Yamaha 4 Stroke (F50FET). The engine went perfectly for the rest of the day, was just at the start. Engine has 78 hours on it now and had a full service at 50 hours.
 
I think you may be onto it with the air lock in the line. The boat was in the drive in the sun the day before I went out. I set off at 4am this morning so the tote probably had a bit of a vacuum on it prior to me disconnecting and filling it up. I didn't prime the line prior to setting out. There is also a large water trap on the fuel line that may also have helped push fuel out of the line.
 
All the shop did was add the oil, I drained the old stuff prior to going, looked clear and clean (not see through, but not milky). I drained it for a good hour prior to heading down to a local yamaha dealer who pumped it fill from they're bulk tank (pumped it till it came out the top fill hole, then did two more pumps into it).

Posted By: Outboard Performance
Date Posted: 06 Oct 2010 at 8:38pm
Sounds like that was your issue....

Happens all the time when servicing. If you have fuel in the carbs, then replace the water seperating fuel filter,  and fit a new one without filling the filter with clean fuel, when you pump the primer bulb it goes rock hard. It hasn't actually drawn fuel into the fuel filter. All it has had time to do is compress the air/fuel in the fuel hose between the full carburettors and the primer bulb.  When the motor is running it uses the fuel already in the carbs and if the motor hasnt produced enough vacuum, and you dont pump the primer bulb again it usually runs out of fuel.

If the feul filter has been drained, or replaced, the best way is either to fill it before fitting, or to remove the fuel hose from the engine, and pump it into a container untill the fuel comes through.

It can be quite dangerous if you head off for the bar and the shop hasn't primed the new fuel filter and it runs out as you climb up a big greeny! (touch wood I haven't done this yest ) ;-)

Posted By: Haydan
Date Posted: 07 Oct 2010 at 6:43am

Awesome thanks for the help


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