Crank driven pump wobble

[DAMIEMARIAH]

Hi all,
I have fitted a new Johnson F6B-9 crank driven raw water pump to my mercruiser 5.7 tks engine and it has a slight wobble at low rpm but seems to wobble less when the engine is revved up.

I have retrofitted this pump to this engine as i have had to use this motor as a replacement to the Volvo engine previously fitted because it froze, i couldnt find a suitable replacement and this engine was good value as a bobtail drop in, but as it was mercruiser alpha motor it didnt have the raw water pump. i did some research and it seemed that some of the bravo engines had this type of pump, the 3 holes in the crank pulley lined up perfectly, althought 2 were slightly closer to the center hub than 1 of them, i found this out because the 14mm socket fitted over 1 bolt but the other 2 had to have a spanner to thighten them.
i have seen some other posts mentioning wobble, is this normal though?
Sorry for the long thread!

Many Thanks.

 

[Bondo]

Re: Crank driven pump wobble

Ayuh,... I deleted yer other thread in the Mercruiser forum, as you've got a Frankenpackage, 'n postin' the Same question in more than 1 forum is frowned on, as it leads to confusion...

 

[Don S]

Re: Crank driven pump wobble

You don't have the holes lined up with the bosses and holes in the pump. Get them right and it won't wobble.

 

[DAMIEMARIAH]

Re: Crank driven pump wobble

Hi Don,
The inside of the pulley was flat apart from the 3 bolts holding it to the harmonic balancer, the pump has some large holes in random places and 3 smaller holes, i used the 3 smaller holes as these matched perfectly with the holes on the pulley, i looked for some slight adjustment but the holes fit the bolts fairly snug not allowing for any side to side movement. The wobble is slight but i am worried about damaging the pump eventualy. i have seen some other threads with similar problems and the answers were it is fairly normal?

When i was tightening the bolts up i did notice that 2 bolts were closer to the center hub that the other 1 was, it seems that the holes are not perfectly symetrical?

You don't have the holes lined up with the bosses and holes in the pump. Get them right and it won't wobble.

 

[Don S]

Re: Crank driven pump wobble

The three bolt holes can turn to 3 different positions. The other holes will only fit flat in one of those three positions. If the pump wobbles, you are in one of the two places it shouldn't be.

 

[DAMIEMARIAH]

Re: Crank driven pump wobble

Ah i see what you mean, i will take off and rotate the pump and refit, Your help is fantastic as usual Thanks Don.

The three bolt holes can turn to 3 different positions. The other holes will only fit flat in one of those three positions. If the pump wobbles, you are in one of the two places it shouldn't be.