Still not pulling water from drive

[vwbugman69]

Re: Still not pulling water from drive

Think about that question for a minute, if it's under water, how could it suck air?

Absolutely! That is what I could not understand and didn't make sense to me why I would have to change it, but I was grasping at anything that might cause an unseen air leak until I really thought about it for a minute. This air leak has me frustrated beyond all belief and I needed something that may have been a possibility.

So, what is the best way to find this "mystery" air leak?

 

[vwbugman69]

Re: Still not pulling water from drive

SUCCESS! Well, sort of. Went to the landing today and initially no joy. Only after revving for 2-3 seconds at 2k did it start to pull water. No bubbles in the pump intake or discharge lines and cooled just fine. Did not take it out on the water - just on the trailer.

I tried revving after reading this thread: http://forums.iboats.com/showthread.php?t=558123

So after this discovery I am left scratching my head. I spent an hour last night pressurizing the cooling intake system looking for "the leak" but could not find it. Since on the trailer the entire transom shield is submerged, the only place for it to be is inside the boat which leaves the following:

- water tube/ connection on transom shield
- intake hose
- connection to impeller housing

My initial thought since I saw no leaks was the connection to the impeller housing so I threw another hose clamp on to ensure it was sealed but it made no difference this morning.

Don, have you ever seen the intake hose fail before? It confuses me because I can see no visible water dripping anywhere. (well, except for the dripping out of the circ. pump weep hole, but that should arrive tomorrow)

 

[iliketurtles]

Re: Still not pulling water from drive

Did you ever figure it out? I have a 99 5.0 gi doing the same thing.

 

[vwbugman69]

Re: Still not pulling water from drive

No, unfortunately I did not find out my issue. Since it would cool fine after I reved it for a bit in order to prime the pump, I used this method to get me through the summer. I plan doing some more testing in the coming weeks to put this issue to rest. I will give an update whenever that is.

 

[vwbugman69]

Re: Still not pulling water from drive

When the boat is on the water (not muffs) disconnect the water pump inlet hose. (Be ready to put it back quick!)

It should have a full flow of water(engine off) just sitting there because the water hose and pump are below the water line. "IF" you don't have good flow the inlet / line is blocked.

I can not speak for any other engine, but the inlet hose on my 3.0L has a bend up after the transom shield that makes the hose above the waterline, therefore, there should be no flow with the hose disconnected. If there will be full flow, how would one change the impeller out on the lake?

 

[Don S]

Re: Still not pulling water from drive

If there will be full flow, how would one change the impeller out on the lake?

Squeeze the hose closed, or remove it from the pump and put a plug in it, or remove it from the pump and lift it above the water line.

Might want to go to this link, http://forums.iboats.com/showthread.php?p=2360521#post2360521 and download item #1 and read it.

 

[dypcdiver]

Re: Still not pulling water from drive

I can't help but think that you have a problem that you identified in an earlier post.

"The only oddity I noticed was the cap was just laying in the housing instead of being on the impeller. Could this be an issue?"

The only way that the cap can become displaced is if the impeller is the wrong one, as it should be touching the housing with no room for the cap to fall out. If there is clearance enough for the cap to fall out then there is no way it will pull water.

 

[vwbugman69]

Re: Still not pulling water from drive

Hmm, I doubt it. Not saying it isn't possible but I have never seen a VP done that way. VP mounts the raw water pump as low as they can for this very reason. It doesn't have to "pull" water up and in to prime the pump.

Here is a pic looking at the starboard side of the engine. The elbow represents the highest point on the intake hose and sits 3" above the point where it goes through the transom. It all looks like it came that way from VP, even with a VP PN stamped onto the hose. To me, that point is above the waterline.

 

[Jeepster04]

Re: Still not pulling water from drive

Something we did was buy a clear hose from lowes. I bought one long enough to reach from the intake on the impeller housing to over the side of the boat into the lake. We ALWAYS fill the hose with water to prime the pump so the impeller never runs dry. The impeller sucked some water doing this but wouldn't suck any if it was hooked to the normal intake from the OD. Ended up being a wrong sized impeller causing the problem.

Also, our volvo 500A has the turned up intake hose. No lake water comes in if the intake hose is unhooked.

 

[iliketurtles]

Re: Still not pulling water from drive

I'm not sure if you read my thread about pressure testing the system but try that (sorry can't link from phone). Perhaps your sea water pump is suspect like mine was. How does the bearing feel? It only takes a few minutes to take off for further inspection.

 

[boatguya1]

Re: Still not pulling water from drive

It sounds like you may have a leaking shaft seal in your pump allowing the pump to pull some air in around the shaft and reducing the amount of suction on the water hose.

 

[dypcdiver]

Re: Still not pulling water from drive

Only things I would suspect would be the intake hose where it passes through the transom shield, make sure the outboard and inboard clips are tight, other than that shaft seal as above could be the problem.
Unless there is an air leak, when you disconnect the inlet hose from the pump you should get a flow of water, because it will syphon the water despite the hose going to the top of the drive to enter the boat, well it does on mine!

 

[vwbugman69]

Re: Still not pulling water from drive

UPDATE:

Thank you for all your suggestions everyone. I think I finally have this figured out now. After being able to hold a vacuum from the raw water pump inlet hose through the drive using my Mightyvac, I knew the issue was was the pump itself.

So, I ordered a new one up from ebay and installed it. I haven't been able to test it out yet, but upon looking at the old pump I am confident I found the problem.

Yes, there were 2 o-rings installed: :facepalm:



When I changed the impeller for the first time, I thought it was strange there was no oring and continued to install a new o-ring and impeller. What I didn't notice or realize at the time that the oring sits in a recess on the pump and doesn't come out as easily as I would have expected, as I thought it would just fall out.

 

[dypcdiver]

Re: Still not pulling water from drive

And that is why the end cap fell out as you mentioned last Year!!

 

[vwbugman69]

Re: Still not pulling water from drive

And that is why the end cap fell out as you mentioned last Year!!

That is a great point. The lesson here is that 2 orings is definitely not better than one.

 

[dypcdiver]

Re: Still not pulling water from drive

The first question you should have asked was, how did it seal in the beginning without an "O" ring? Welcome to the learning curve.