Why do I have a cracked Bravo raw water pump impeller housing?

[HT32BSX115]

Howdy all,

Spent a great 10 days at Shasta Lake recently and my 1987 ('97 Mercruiser 454 Bravo III) Four Winns Liberator ran pretty much flawless the entire time!

On the last day, I was motoring at idle over to the ramp to put it back on the trailer and drag it home, when at the dock, I heard water running!

I looked back and noticed a stream of water coming out of the starboard side/rear (bilge-pump discharge) of the boat.

My auto bilge pump had come on. With the engine still idling I raised the engine cover and noticed water literally spewing out of the front/starboard side of the engine.

Closer inspection revealed the raw water pump pumping a LOT of water into the bilge!

At first I thought it was a loose or leaking hose on the discharge side of the pump.

Turned out the pump housing is cracked close the output side of the pump.

Now that I am home, I took a few minutes to remove it and inspect.

It's a pretty normal looking pump with about a 2 year old impeller.

Close inspection revealed the cracks closest to the discharge or outlet tube.

The right hand outlet below is the discharge.

Now, I don't know exactly why it cracked. It's possible that I had a bit of water pooled in there last winter and it could have gotten cold enough in my shop (but I doubt it)........I also had the bolts pretty tight too.

This sort of pump uses the pump housing to provide some of the structural integrity in the fuel/raw water pump mount and it's possible that the belt was a leeetle too tight! (although it's been this way for about 3 years or so!! and I don't intentionally run v-belts all that tight!)

The OTHER possibility, is the CHEEP housing wasn't made by Mercury and simply wasn't strong enough to do the job!
(I bought it from an after-market source!!.........Obviously that worked out WELL!!)


So.......I am thinking maybe a Mercury housing is next or maybe a bronze housing!

Anyone else ever had this happen?






Cheers,


Rick

 

[alldodge]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

Have one just like it in both boats without an issue. I had a bronze ones but like the composites better for ease of install and impeller replacement. Looking at your pics it could be a manufactures defect, the face plate it bolts to is damaged, bent or a thin piece of forgien mater was caught beteen the face and plate. It could also be a little to much torque on the bolts.

 

[HT32BSX115]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

Have one just like it in both boats without an issue. I had a bronze ones but like the composites better for ease of install and impeller replacement. Looking at your pics it could be a manufactures defect, the face plate it bolts to is damaged, bent or a thin piece of forgien mater was caught beteen the face and plate. It could also be a little to much torque on the bolts.

Yeah. I did a little searching around and found sseveral people that had them break for no apparent reason.....

One of them mentioned that Sierra admitted that there was a run of them that were defective and could break.

I did have the bolts pretty tight.

That could be the problem.

 

[Tail_Gunner]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

Down here in portland we did have a 3 or 4 day below freezing. That is a long enough time for something like that to crack and that thing cracked across the whole body.

 

[r.j.dawg]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

That's why I always buy OEM. I can't remember if it was Don or Bondo that said, You get what you pay for.

 

[Bondo]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

Now, I don't know exactly why it cracked. It's possible that I had a bit of water pooled in there last winter and it could have gotten cold enough in my shop (but I doubt it)........I also had the bolts pretty tight too.

This sort of pump uses the pump housing to provide some of the structural integrity in the fuel/raw water pump mount and it's possible that the belt was a leeetle too tight! (although it's been this way for about 3 years or so!! and I don't intentionally run v-belts all that tight!)

Ayuh,.... I've never been a fan of engineered plastics for applications like that,....

 

[HT32BSX115]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

Ayuh,.... I've never been a fan of engineered plastics for applications like that,....

You have a suggested alternative to this plastic thing?

I haven't been able to find a suitable bronze/brass/steel etc equivalent for the raw pump (integral fuel pump model)

 

[Bondo]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

You have a suggested alternative to this plastic thing?

I haven't been able to find a suitable bronze/brass/steel etc equivalent for the raw pump (integral fuel pump model)

Wish I did Rick, but don't,.... never Had too,...

I'm sure a metal pump could be Adapted,...
the fuel pump can go electric,...

 

[bruceb58]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

I did have the bolts pretty tight.

Make sure you use a torque wrench next time.

I am a firm believer in torque wrenches when installing almost everything. If it has a torque spec, it gets tightened with a torque. wrench.

 

[Fun Times]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

You have a suggested alternative to this plastic thing?

I'm going to try my best to help out here when I can, But oh man, it sure seems like (at the moment) all these questions are going to be a bit tougher to answer without the help of Don providing accurate backup assistance to a lot of tough questions day in day out. I went back and counted Don's last day on iboats, he made 42 post that day and 30 something the day before. That is a lot of boats to work on in one day. He must have known something was not right that day and wanted to keep posting/helping. Don will be missed deeply here on iboats, May he be able to rest in peace on the smooth waters ahead of him now.

You're stock Mercruiser part number for a complete new kit would be, 46-807151A9 item number 1,
http://www.mercruiserparts.com/Show...7.png&inbr=4854&bnbr=150&bdesc=Sea+Water+Pump

Hardin Marine has a better solution for you to consider,
Stainless Steel "Lifetime" Sea Pump Overhaul Kit - Hardin Marine

The list,
Hardin Marine - Mercury Sea Pumps


P.S, those do crack from time to time for no apparent reason, especially if it's aftermarket. See my signature line. I don't see anything you did wrong. Good luck.

 

[HT32BSX115]

Re: Why do I have a cracked Bravo raw water pump impeller housing?

Wish I did Rick, but don't,.... never Had too,...

I'm sure a metal pump could be Adapted,...
the fuel pump can go electric,...

Yeah. I had never heard of one cracking until mine did. Then I went looking for other and found several people on other sites talking about it.

I actually like the idea of going electric........I seem to remember you telling someone some time back of a Merc Kit for an electric? That would sure be a good good way to get that mechanical pump off that assembly.

When I put the new fuel pump on, I did notice a gasoline smell in the pump oil reservoir. It was still oily so I don't think it had enough cause poor lubrication in the past. so I just flushed it out and replaced the oil in it.

Make sure you use a torque wrench next time.

I am a firm believer in torque wrenches when installing almost everything. If it has a torque spec, it gets tightened with a torque. wrench.

Yeah.....even though it went about 6 years like this, I am pretty sure I probably had the bolts too tight!

I'm going to try my best to help out here when I can, But oh man, it sure seems like (at the moment) all these questions are going to be a bit tougher to answer without the help of Don providing accurate backup assistance to a lot of tough questions day in day out. I went back and counted Don's last day on iboats, he made 42 post that day and 30 something the day before. That is a lot of boats to work on in one day. He must have known something was not right that day and wanted to keep posting/helping. Don will be missed deeply here on iboats, May he be able to rest in peace on the smooth waters ahead of him now.

You're stock Mercruiser part number for a complete new kit would be, 46-807151A9 item number 1,
http://www.mercruiserparts.com/Show...7.png&inbr=4854&bnbr=150&bdesc=Sea+Water+Pump

Hardin Marine has a better solution for you to consider,
Stainless Steel "Lifetime" Sea Pump Overhaul Kit - Hardin Marine

The list,
Hardin Marine - Mercury Sea Pumps


P.S, those do crack from time to time for no apparent reason, especially if it's aftermarket. See my signature line. I don't see anything you did wrong. Good luck.

What a shock about Don! I was just in Ketchikan at the beginning of the month and was going to send him some more pictures..... I was puzzled by your post until I realized what you were talking about! I feel like I have been living under a rock!


Thanks for that info on the Hardin Marine pump. I think it will be my next pump.