Low water pressure on '87 15hp

[iwombat]

I just got done replacing the impeller. I fired it up on the muffs to test it all out and I'm getting just a dribble out of the tell-tale. I'm getting a small stream of water coming out from somewhere under the powerhead though. Everything all worked fine before the impeller change (go figure).

This is a long shaft, and my theory is that the block of rubber that seals the pump to the water tube is too loose to force pressure up the tube and it's coming out the sides and following the outside of the tube up until it finds a place to come out.

My manual (non model specific) doesn't specify anything about how to seal this part up, or if it should be sealed. When I pulled it apart it was pretty much a mess of crud and pretty solidly set in place. So, cleaned it all up and now it slides around pretty easily.

Anyway, I'm sure someone knows all about this little item, including how to tell if it's worn out and how it should be sealed in properly.

 

[DJ]

Re: Low water pressure on '87 15hp

That grommet should be relatively tight. You caqn buy that grommet. They are included in most OEM H2O pump kits.

 

[iwombat]

Re: Low water pressure on '87 15hp

Kinda what I figured. Looks like it's back to the dealer on monday.

 

[iwombat]

Re: Low water pressure on '87 15hp

Well, I'm a little more concerned now.

I dropped the LU and inspected my handiwork on the impeller. Everything checked out okay. Paying close attention to the grommet, it appears that I replaced it with a new one after all - there must have been one in the kit. I sealed it all back up and I'll put it back on tonight. I'm expecting the same problem to occur though since I really didn't find a suspect.

Now I'm wondering what could be the cause of my problems. I don't think it's the tell-tale itself since I get a dribble out of it and hardly any water out the prop.

This is also my first time running a kicker motor on the muffs. It seems like the hose should generate enough pressure to force water out the tell-tale w/o the motor running.

I wonder if a back-flush is in order.

 

[Silvertip]

Re: Low water pressure on '87 15hp

Are you sure you have the correct impeller? Did you get the drive key installed? If the drive key fell out or is not installed the drive shaft simply spins inside the impeller. Are the vanes pointed in the right direction? If the vanes point the wrong way, some will contend they will straighten themselves out once the engine runs but I've seen many that did not.

 

[iwombat]

Re: Low water pressure on '87 15hp

I double checked both the key and the impeller direction when I pulled it apart thinking that I'd pulled a "D'oh!".

Both checked out okay.

 

[Bruce San]

Re: Low water pressure on '87 15hp

I had a 80 something 15 a few years ago that came with a jon boat trailer package deal. It wouldn't pump water even though the guy said he changed the impeller. I disassembeld and through some troubleshooting ( compressed air ) determined the water tube was blocked. Upon further dissassembly I discovered the grommet at the top of the water tube where it goes into the power head had somehow worked it's way into and blocked the passage. Go figure.

 

[mikesea]

Re: Low water pressure on '87 15hp

Bruce is hitting it on the money.The grommets actually clooapse because the alum.that surrounds it often starts to corrode,like steel swelling,the rubber thus is forced into the water passage.The correct and only way to remedy permanently is pulling powerhead and replacing the grommet,once done be sureits flushed well after use.sometimes,for a quick fix,I have taken a wire clothes hanger,make it a strait piece of wire ,long enough to reach the grommet.Mash one end down until its a flat round cutter type head,helps if you heat it to harded a bit,file it down to sharpen,its basically arotor router when connected to a variable speed drill,and can buy some time if you want to get the season end

 

[iwombat]

Re: Low water pressure on '87 15hp

I suspected that may be the cause. But, to do that between impeller changes?

It seems like a very big coincidence.

 

[iwombat]

Re: Low water pressure on '87 15hp

If I can't get it to pump properly I'll try the coat-hanger trick. If that works I'll break it down and fix it properly. Since I'm getting water coming out just underneath the powerhead I'm guessing that's the problem. The timing of it all still seems weird though.

 

[iwombat]

Re: Low water pressure on '87 15hp

Not having disassembled a 9.9/15hp unit before . . . Is there an easy way to get at that or is it powerhead removal time?

 

[iwombat]

Re: Low water pressure on '87 15hp - Update

Re: Low water pressure on '87 15hp - Update

Fished a coathanger up there with a little hook on the end, hoping that it may grab onto the culprit. It seems clear - back to head scratching.

 

[iwombat]

Re: Low water pressure on '87 15hp

Problem solved!

Turns out it was part diagnostician and part motor. After looking REAL close I could see some water coming out the prop and a tiny bit out the side vents, so I decided to let it run and see if it got hot.

After 20 minutes it was fine. I'm used to seeing a little spitting out the top exhaust port in the tank. Maybe that's not normal on the muffs. Anyway, I figured the problem must be in the tell tale. So, I took the whole assembly off and sure enough there was a loose chunk of gunk behind the fitting on the powerhead blocking it all, just enough to cause restriction.

 

[Bruce San]

Re: Low water pressure on '87 15hp

Nice! Glad you didn't have the same problem I did. It turned out pretty ugly in the end.

 

[iwombat]

Re: Low water pressure on '87 15hp

I was all set to take the powerhead off.

I'm saying "Phew!" now.