Reoccurung water pump failures...
 

Hi folks.
My 1995 Formula 271 has a 502efi and Bravo 3.
This boat is in good shape and lives on a trailer when not in use.
I posted a while back regarding ongoing sea water pump impeller failures.
This boat has a seawater/fuel pump combo.
The consensus at the time was that the internal hose in the drive may have a restriction or be weak and collapsing from time to time and I was using the wrong muffs
I had been going thru 3-4 impellers per season., the boat being used 8-10 occasions per season.
There is no pattern for failure. Sometimes it failed running on the hose in my prelaunch start up/check over.
Sometimes it fails at initial start up in the water, after being just run ok on the hose.
I use the Mercruiser muffs that have the pin and locking tab to keep them tight on the drive.

http://www.ebay.ca/itm/Genuine-Mercu...733?rmvSB=true

The boat now has a brand new B3 drive and is still eating impellers.
I also ensure that the drive is lowered on the muffs so there is no chance for hose restriction.

Any ideas..........

Yes, change the hose that goes from the bell housing to the transom. I found the same problem when I saw my water PSI go to zero. I bet that solves your problem😄

¸

Do you mean the internal hose in the drive.

The drive is brand, not rebuilt, I can`t imagine that hose being my current issue.

No, the hose from the back of the water pump housing to where it connects at behind the motor. Also, see if the neck it attaches to is cracked and you're sucking air in.

The line you need is 1 1/4" dia wire reinforced hose

That`s easy enough.
Generic hose ok, or Merc hose required.

There is no internal hose in the drive. You can see the hose when the outdrive is down. It's in the bell housing to the water inlet on the outside of the boat. It's molded hose and has no wire in it.

If you did not replace the Transom Assembly then you did not replace the hose in question.


The hose in Transom Assy. is P/N 32-8M0090859

That`s the hose I thought you meant, I just mis-descibed it in my reply.
As I said, the drive is new, as well as the transom.

Can`t imagine that hose being the issue at this point, but I can check it.

Everything is new from the flywheel.
Coupler, steering ram, transom, gimbal, drive, props etc, All new Merc gear.
The hose from the transom to the water pump housing is likely the original, could be part of the problem

Yes, replace the hose from the inner transom assembly to the sea pump, they can collapse internally just like a radiator hose

Edit: make sure you don't have them reversed.

Might as well, that`s the only thing that`s not new.
They are not reversed.

I had 2 days boating last weekend and flushed it on the hose in the driveway when I got home. No issues.
It sat for the week and Saturday morning I start it on the hose and zero water flow.

To be clear, when it screws up, it is from no water flow, it seems like it loses prime and won`t pick up water from the drive to the pump.
When I start it on the hose, I go to the stern on look over to the exhaust pipes to check for water flow, if there is none I shut down right away.
It does not pick up water flow and lose it, it either is some or none.
It doesn`t run long enough to over heat.

Is the belt tight running the pump..........

yipper, double checked that to. Tensioner bearing ok as well.

I was boating yesterday and got home late so I didn`t flush it.
I will after tonight and see what happens, I will double check everything and see if I can observe any hose collapsing.

How do the impellers look when you've replaced them?

Do you know the issue is at the sea water pump or could there be blockage down the line?

An easy thing to check is to pull the lower hose from the oil cooler and check for old impeller pieces or other crap. Grab a pick/hook set from Harbor Freight - http://www.harborfreight.com/Pick-an...-Pc-69592.html (or equivalent) as that makes it a lot easier to loosen the hose - use care and some common sense.

If you are going to replace this hose, go ahead and install a Fresh Water Flush point with a "Tee" in this hose, so you can hook your garden hose directly in front of the SWP. This way you can throw your muffs in the garbage.

This is a rudimentary picture I grabbed off of Google, but you get the idea.
http://www.thehulltruth.com/attachme...1&d=1384872612

Also, have you replaced the plastic housing and impeller in sets? I've heard the housing can get scored/beat up and impact the water flow....

The way I see it, this can only be (3) things causing this:

* No water from the drive to the pump (backflush the inlet hose from the sea water pump thru the drive as a quick check)

* Seawater pump not functioning (not sure this is a good idea but remove the hose at the first cooler, point it somewhere safe, hook up the hose and run it at low rpm or maybe even just feel for water at the first hose)

* Blockage (remove hoses and backflush from the thermostat housing back to the sea water pump - again, pay close attention to the inlet side of the oil cooler)

There is lots of good information if you search for overheating, backflush, sea water pump, etc....

Hope you get to the bottom of it, I would have been fed up a long time ago.

Next time you are at the launch and it won't pump water, try purging the air out of the intake hose before calling it a day.

Loosen the intake hose at the water pump, let the air purge out then re-tighten the hose clamp. The way your hose is routed from the pump to the transom assembly may be allowing it to siphon out on your way home on the trailer, then you have an air pocket.

The impellers are trashed when I pull it apart, most if not all the vanes broken.

I could be wrong but I think if there was a blockage on the outlet hose or cooler, I would have the temps go up and maybe only a little of bit water out of the exhaust tips, but you would not expect to see complete blockage and no water out the tips.

I have pulled both hoses off and checked for debris and checked the inlet on the cooler as well.

And, as soon as I change the impeller, as is well.

That is a good idea and I will likely do that.
But that is not going to help when the boat is in the water and still won`t pick up water flow

That is another good suggestion, but by the time you know there is no water flow, the impeller is toast.

I could undo the hose and burp it before starting it though. That might help.

Read Glens post again #7. Type in part number in Google. I bet you a beer your replace the hose correctly and your problem will go away😎

Ok, but the transom is brand new, no more than 10 hours on it.
Surely it would be supplied with a new hose.

Check to see if the hose is twisted then. The plastic insert used to hold the hose to the bell housing sometime will let the hose turn causing a kink.

True, but relying on the SWP to draw water up from your drive when using the muffs is always a gamble. I think that this will likely decrease the wear on your impellers over time, and also help with your longevity issues. Also, this "Tee" being installed in that hose from the transom to the SWP will virtually guarantee that it cannot ever completely collapse.

Will do

This could also serve to release any air lock in the hose.

After going thru this is even before changing the drive and double checking everything numerous times, and evaluating every ones advice, I think an airlock is the likely core of the problem.
That may explain why I have no water pick up on the hose or in the water.

I think I will get a new inlet hose, and put a tee in it as shown.

Have you replaced the impeller housing? If you smoke an impeller the plastic housing is usually junk as well

Not every time, but most.
I check the housing for wear though.
The one I put on Saturday was a kit with the housing, Merc product.

Just to update, before starting it tonight to flush the weekend water..
I checked the hose from drive to transom, no kinks or twists,
checked the belt tension, ok.
checked the hose from transom to pump housing, no leaks and the hose has wire braid and is solid as a rock.

Started up on the hose with the muffs good and tight and instant water out the exhaust.
Did the same on Saturday, no water out of the exhaust...

The only thing that makes sense is some kind of air lock in the hose from the transom to the pump.
An airlock could occur or not occur depending on how the system drained while sitting on the trailer parked or towing to a launch.

I can't imagine a scenario where any of the hoses are collapsed sometimes and not other times, or there is an obstruction in the system that comes and goes.
It ran flawlessly all weekend.
The fact that it can burn up an impellor in the water gives credit to the air lock theory imho


I don't know why mine would air lock and others don't.
So how fix it,
the tee in the inlet hose should work, if it was open to the atmosphere before flushing or starting in the water, it should vent.
Or, maybe put a vent petcock on the t/stat housing or somewhere high on the coolant system.

Make sense????

My father fought a collapsing line on his crown line this year. The one in your transom assembly. Pumped water fine on hose and at idle but would close enough at 3000 and up to starve the pump and melt the impeller. We pulled our hair out trying to find the cause. If everything else checks out, replace it and see if it helps. His looked fun but apparently wasn't.

when it wont flow water, try bumping the starter, without starting it and see if water comes out, just to move the pump a bit

Would it do that consistently or just some time.
Mine burns the impeller instantly at idle.
The hose/drive is brand new.

What do you lube the new impeller with and what direction do you put the vanes in when you install ?

a dry impeller is toast in 20 seconds or less.i use white lithium grease or dish soap for initial start it sounds like you might have a pinhole or a crack in one of the hoses or a loose clamp somewhere in the system.it is a lot easier to suck air than water.when the drive was installed did you use a new o ring and did you use bellows adhesive to hold it in place?without the o ring it will suck air.

A small bit of dish soap.

I put the impeller in the housing and use a spare pump shaft to turn the impeller and flip the vanes in the correct direction before installing the impellor and housing
on the shaft in the boat. The rotation arrows are on the housing.
I have enough room that I don't need to pull the whole assembly to do the repair.

[QUOTE=mike tkach;4474284]a dry impeller is toast in 20 seconds or less.i use white lithium grease or dish soap for initial start it sounds like you might have a pinhole or a crack in one of the hoses or a loose clamp somewhere in the system.it is a lot easier to suck air than water.when the drive was installed did you use a new o ring and did you use bellows adhesive to hold it in place?without the o ring it will suck air.[/QUOTE

The drive and transom were professionally installed at my dealer.

I had the same impellor issue with the old drive.

When I install a new impeller it always gets it's prime right away and works fine.
It fails after sitting for a while or after being towed to a launch.

This is why I am thinking it's an air lock issue,

Don't do this 'prelaunch start up' routine you have, and just start it when dunked. See if this changes the life of the impellar.

I can't tell you how many people have issues with the Bravo set up on the trailer but totally fine when in the water.

I know what you mean but it has failed twice in the water.
I launch it, get under way, at low speed both times and a few minutes later, the temp alarm is beeping and steam coming out of the exhaust.
I carry a kit with me, and fix it on the spot, takes about 45 minutes and is a pita next to a hot manifold.
Again, works fine with a new impeller and I enjoy the rest of the day.

https://www.gcsmarine.com/content/impellers/impellers

maybe this would at least help you to identify the location of the cause without having to stop and change out another impellor

Consistently and it was right after a brand new transom assemble was installed by a dealer. Triple check it