Perkins 4108 Raw Water Pump Alignment - Help Please....

[makingplansfor]

I have just replaced the Jabsco raw water pump on my 1986 (ish) Perkins 4108. When fitting the new unit it sat about 2mm proud, probably the height of the bush that holds the bearing in place and locates into the engine. When the engine crank was rotated a little, the pump slotted into place nicely. All was good until I started thinking it through many hours later, there are many warnings on tinternet about the importance of aligning the adaptor plate.

My question therefore is whether I should be concerned despite not moving the adaptor plate and there are no apparent symptoms of misalignment during the 3 years I have owned the boat (assuming I would recognise them)?

The alignment process seems pretty simple even for me, so it may be worth doing anyway – therefore supplemental question – does anyone in the Plymouth area have an alignment tool they would be willing to lend me?

 

[sailorman]

I have just replaced the Jabsco raw water pump on my 1986 (ish) Perkins 4108. When fitting the new unit it sat about 2mm proud, probably the height of the bush that holds the bearing in place and locates into the engine. When the engine crank was rotated a little, the pump slotted into place nicely. All was good until I started thinking it through many hours later, there are many warnings on tinternet about the importance of aligning the adaptor plate.

My question therefore is whether I should be concerned despite not moving the adaptor plate and there are no apparent symptoms of misalignment during the 3 years I have owned the boat (assuming I would recognise them)?

The alignment process seems pretty simple even for me, so it may be worth doing anyway – therefore supplemental question – does anyone in the Plymouth area have an alignment tool they would be willing to lend me?

Instructions from my spare pump

 

[contessaman]

I took my pump off and overhauled it as the shaft seals were dripping. I refitted it and did the bolts up finger tight then churned the engine a bit to let it bed in, then snugged the bolts up. Like you I then subsequently discovered horror stories about misalaignment. From what I gather this pertains to removing the adaptor plate. I didnt even notice said plate - I think its rusted solid to the engine anyway. Anyhow, that was a few seasons back and I've no ill effects to date...

 

[makingplansfor]

Instructions from my spare pump

I think this is just a get you home until you can use the alignment tool properly - I am a little nervous about loosening the adaptor plate!!

 

[Slipstream 34]

I had to jiggle the pump assembly to get it to locate on my 4108. As Contessaman says the horror stories are about the adapter plate. I had a similar crisis of confidence when I read about the alignment issue. Our Pump is working well.

If you are still concerned why not remove the impeller plate, rotate the engine by hand and see if the shaft turns.

I am sure all is well

 

[sailorman]

I had to jiggle the pump assembly to get it to locate. As Contessaman says the horror stories are about the adapter plate. I had a similar crisis of confidence when I read about the alignment issue. Our Pump is working well.

If you are still concerned why not remove the impeller plate, rotate the engine by hand and see if the shaft turns.

I am sure all is well

the issue is the pump spindle being "off ctr"

 

[Slipstream 34]

the issue is the pump spindle being "off ctr"

No issue if the adapter plate has not been disturbed.

 

[contessaman]

No issue if the adapter plate has not been disturbed.

Thats how I read it too. Thanks for the tool diagram though sailorman thats accurate enough for me to get the guys in work to machine me one if I ever need it. Out of interest, why would one ever need to remove the adaptor plate in normal use? the only reason I could see for taking it off is to remove the timing cover and on my engine where the pump had been dripping the timing cover/adapter plate seems to have become one entity through the medium of time and rust...

 

[sailorman]

Thats how I read it too. Thanks for the tool diagram though sailorman thats accurate enough for me to get the guys in work to machine me one if I ever need it. Out of interest, why would one ever need to remove the adaptor plate in normal use? the only reason I could see for taking it off is to remove the timing cover and on my engine where the pump had been dripping the timing cover/adapter plate seems to have become one entity through the medium of time and rust...

No idea, i removed the 4108 10 yrs ago but the new engine uses the same pump apart from the spindle differs.
i bought the pump as a spare as the price was right & the info was with it.

 

[nimbusgb]

I replaced my tired old Jabsco with a new Johnson pump on my 4-108. As per contessaman's post I fitted the pump to the timing chain cover that had been undisturbed with lightly finger tight nuts. Then turned the engine over while watching the pump. No movement. Nipped the nuts up a little tighter and cranked the engine some more. Tightened the nuts fully.

That was over 600 hours ago. No leaks, noises or problems with the pump.

 

[makingplansfor]

Thanks guys, I think I'll go with it as I havent moved the adaptor plate. I dont see how that alignment tool works though - there seems to be something that positions the adaptor plate missing!!

 

[PCUK]

The most important thing to ascertain is that the slotted fitting on the end of the pump spindle that locates on the spigot in the engine is not too far up the spindle. If the two shoulders on the fitting are not fully over the the spigot with only a few millimetres on each side the fitting will break very quickly. Therefore it is vital to ensure that the fitting is far enough off the end of the spindle to fully locate onto the spigot. Not sure if that makes any sense so here's a diagram.View attachment 30164