mercruiser apha1-2 vibration

erioud

Recruit
Joined
Oct 14, 2007
Messages
3
since some weeks I noticed that my mercruiser 5.7l with alphaone-2 drive
is vibrating and makes more noise then it should do.

This is running in gear and in free. the engine is starting fine but there is a sort of rumble and the whole boat vibrates. (bayliner 2850 from 1992).

I changed the spark plugs and all looked white except for cylinder 7 that
was black. There were 2 different brands of plugs in there.

Also the oil is smelling for gasoline, but i do not know if a bit is normal or not.

Could you give me some hints where to start first to solve this. Can it be that the engine was used too long on rpm's around 1000? I hardly use it at rpm's higher then 2500. (gasoline is too expensive here in europe, currently around EUR 1.40 for one litre -> around EUR 5.30 per gallon -> $ 7.06 per gallon)

Last winter all bellows and the bearing and the shift cable were replaced.
 

thrasher

Chief Petty Officer
Joined
May 23, 2007
Messages
443
Re: mercruiser apha1-2 vibration

I would start by removing the oudrive and checking the engine alignement. something might have moved, the drive shaft is spinning all the time the engine is turning (doesn't matter if you are in gear or neutral). If the engine is aligned correctly then we can look for other causes, but if the engine alignement has moved it will vibrate and you will damage the coupler and other parts.. It's really easy to remove the outdrive, but you will need to buy an alignement tool (typically $50 on ebay)..

Gary
 

Haut Medoc

Supreme Mariner
Joined
Jun 29, 2004
Messages
10,645
Re: mercruiser apha1-2 vibration

By all means check the alignment, & the ujoints.....
Was water in your bellows the reason that the bellows were replaced?....
If so, then I would recomend replacing the u joints......;)
Your oil should have no gas smell whatsoever.....
Check the tube that goes from the fuel pump to the carb & see if their is fuel present.....
If their is, you have a ruptured diaphragm in the pump & it must be replaced.....
Change your oil, gas is not a lubricant & will hurt your engine by thinning the oil.....
Lastly, when was the last time a full tune up was done?......:confused:
Welcome to iboats, btw.....:)
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: mercruiser apha1-2 vibration

Lastly, when was the last time a full tune up was done?......

Ayuh,........

The White sparkplugs suggests a Lean condition,.......
Have the Fuel Filters been changed lately,..??..
The #7 being Black,..... Might be the Rings or something,.....
How about a Compression Test to see if it's up to snuff,..??......

If it's Vibrating in Neutral as well as In Gear,......
I'd give it a Test Run while you have the Outdrive off doing the other things mentioned above.........
That'll tell you if it's the Motor, or the Drive......
 

erioud

Recruit
Joined
Oct 14, 2007
Messages
3
Re: mercruiser apha1-2 vibration

last year the alignment and the u-joints were checked and OK. There was a little bit brown sludge in the bellow for the gimbal bearing when i replaced it.

I will first check the tube between carb and pump for fuel as suggested by haut medoc. Also i will do a compression test to see if one or more cylindrs are behind.

the oil- and fuel filter were also replaced last year.

A good tune up is probably not done for at least 5 years. I own the boat now for 2 years and i never did it (or let it do). also the guy i bought it from never
did it for sure. So maybe you guy's have a good point there.

what should be doen during a good tune up?

within 2 weeks I will pull the boat out of the water for winterstorage. I will then pull the drive again and check for vibration again if above does not give the solution.

Thanks for the hints and i will keep the forum updated about progress probably after next weekend. (boat now 600KM away.....)
 

Haut Medoc

Supreme Mariner
Joined
Jun 29, 2004
Messages
10,645
Re: mercruiser apha1-2 vibration

last year the alignment and the u-joints were checked and OK. There was a little bit brown sludge in the bellow for the gimbal bearing when i replaced it.

I will first check the tube between carb and pump for fuel as suggested by haut medoc. Also i will do a compression test to see if one or more cylindrs are behind.

the oil- and fuel filter were also replaced last year.

A good tune up is probably not done for at least 5 years. I own the boat now for 2 years and i never did it (or let it do). also the guy i bought it from never
did it for sure. So maybe you guy's have a good point there.

what should be doen during a good tune up?
Change fuel filters, spark plugs, ignition wires, distributer cap & rotor, check timing......
within 2 weeks I will pull the boat out of the water for winterstorage. I will then pull the drive again and check for vibration again if above does not give the solution.

Thanks for the hints and i will keep the forum updated about progress probably after next weekend. (boat now 600KM away.....)
Do a compression test like Bondo suggests, & check the timing so you have a reference point to start from.....
What part of the world are you located?........:)
 

erioud

Recruit
Joined
Oct 14, 2007
Messages
3
Re: mercruiser apha1-2 vibration

I live in the Netherlands, Europe. but actually working now in Toulouse, France.

a distributor cap I found on the boat as spare. For all these tasks I have to ask a mechanic to do it, because i do not have the tools for this. Not the experience yet...... that's why I want to attend all checks/repairs that are done.
 
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