Thru-holes for mounting water pump to engine bracket

LaRea

For my raw-water pumps, I have a question about replacing tapped holes with thru-drilled holes and a nut/bolt.  

I'm talking here about a Merc 350, 496 or other engine with the raw-water pump mounted on the front of the engine.  There are two horizontal bolts that hold the pump to the mounting bracket.  These bolts mate to threaded holes in the pump body.  Removing and installing them can be a real pain.  The bolt heads are on the back side of the pump, so they are hard to reach.  On one bolt, there's not enough room for a socket wrench, and barely enough room to even get the bolt into the hole.  Because everything is so hard to reach, it's easy to get these bolts cross-threaded, which causes even bigger headaches.  

I want to thru-drill these two holes, and use bolts with lock-nuts.  I think it would be much easier.  I could use a socket wrench on the front side, where there's easy access, and a box wrench on the back side.  And if a nut ever gets cross-threaded, just replace the nut and bolt.  

Is there any reason not to do this?  

LaRea

In other words, instead of having a threaded hole in the pump body, I would drill out the hole to a larger diameter so a longer bolt could pass through it to a nut on the other side.  

Willhound

Can't think of a good reason why you couldn't.

skennelly

I usually remove the entire assembly...pump and mounting bracket when replacing the impeller.

It would be awesome to have all the bolts accessible from the front so I didn't have to do that.

I don't see the advantage of doing this just to the mounting bracket....maybe I'm not understanding @LaRea reason.

LaRea

@skennelly - You remove the pump and bracket as an assembly?  I'll have to see if that's possible on my boat.  

I remove the pump from the bracket.  It's three bolts.  The vertical bolt is easy to reach.  The two horizontal bolts are a PITA requiring triple-jointed monkey-long arms.

reneechris14

If you remove the idle pulley and bracket the pump should pull out enough to get the 10mm bolt. And then I use a 10mm ratchet wrench to remove the front have of the pump leave the back have and hoses there.

reneechris14

Dream_Inn

@LaRea, you may just want to start removing the idler pulley and take bracket off with the pump.  Then the bolts are pretty easy to take on/off and don't have to worry about cross threading.  Much simpler (IMO) than the route you are taking.  & I actually have a ton of room to do it the way you are speaking of, but it'd still be more difficult.

Oh, and I don't see any reason you couldn't drill thru and use nuts on the back.

skennelly

@LaRea - Yes exactly what the others are saying is what I meant.

pistole

the pump is held to metal bracket (which looks like a question mark) by 5 or 6 longish bolts. There is no need to add nuts to their ends since there isn't much torque applied. that bracket in turn is bolted to the engine block with two rather small bolts. These bolts can seize.

LaRea

OK, I'll have to admit it's much easier to remove the idler pulley and bracket, and then remove the pump + bracket as an assembly.  All these years, I've been doing it the hard way.  But I'm not too old to learn -- or too proud to admit my mistake!