Evinrude 150xp Water Pressure

[mgoodling44]

So, I've replaced the water pump last week due to low water pressure from the **** hole. Reassembled, and now, I have no water circulation, causing the temp alarm to sound while hooked up to the hose. Immediately shut down, and allowed to cool.
Took the lower unit back off, and started my testing. Here's what I can share, and hopefully get next steps.

1. Took lower unit to the hose, hooked up the muffs, and I have water source to the impeller. Put in gear, manually turned the prop, and I can see that water is being forced up the outlet as I turn. Remember I was hand cranking, so I could see the "surge" as the impeller rotated.
2. Next, I took the water hose, and directed water directly into the water inlet pipe. I could get water to gently flow out of the block (where the tube that connects to the **** hole attaches). So far, so good.
3. Connect the **** hole tube to the block, and nothing. There's such little pressure there that I literally have to syphon the water through that tube, and then I can at least get a water flow (barely any pressure at all).

So, now I'm baffled. What could cause little to no water pressure from the tube to the block outlet? I'm open to suggestions for the next wave of testing.

 

[Bosunsmate]

Are you saying the flow at the telltale inlet at #2 is gentle but ok? If thats the case then it would be a blocked telltale tube

 

[mgoodling44]

What I'm saying is that there is now no water circulation out of the block when assembled. Very little pressure when the lower unit is off, and a water hose is directly connected to the water intake tube (only visible when the lower unit is off).

 

[mgoodling44]

The tube from the block, to the **** hole is clear and free. There's no pressure out of the block. A very little amount of water out of the block with a water hose directly connected to the intake tube from the lower unit (clear tube that connects to the impeller housing).

 

[mgoodling44]

Would it be possible that the water inlet tube (that runs to the block from the pump) could be not sealed at the top (block) side? If I force water up the tube from the bottom with a garden hose, should there be water running out of the mid section?
I'm also going to remove the thermostats and see if water is flowing from the inlet pipe up through the casing/water jackets.

 

[jakedaawg]

Was the old impellar missing vanes?

Are you confident the h2o pump base plate was installed correctly?

Are you confident the h2o pump outlet was mating with the water tube?

Was the key installed in the impellar?

With lower off, back flush the block. Use hose and put water in t-stat housing and out water tube. This could flush any old impeller chunks out that may be causing you grief.

 

[mgoodling44]

Ok. Couple of updates. I've checked the base plate....check. All is well. I can hand crank the drive shaft, and see the water surges from the impeller. Check both forward and reverse. All seems to engaged. Yes the key was installed. Check.
Back flushed as recommended. Here are the results of the back flush:
* Water hose directly connected to the inlet pipe. No water getting to the T-Stat openings. Water is draining as the hose is on.
* The nipple out of the bottom on the block does get water flow. I plugged that to see if water would eventually fill the water jackets, but it did not. Seemed to be draining faster than the water supply. Would that be expected using a garden hose?
* During the flushing out the T-Stat holes, the water didn't drain out of the inlet pipe. The water drained around the inlet pipe, but did not flow/drain through the inlet pipe. Would this be expected?

I hope I'm getting closer to the root cause. I doesn't seem like a complex process. Just giving me fits right now. I think the biggest thing I need to confirm from the experts is if the water flow around the pipe is normal during a back flush (or when I have the hose directly shooting up the inlet pipe). If so, I'm reasoning that the hose simply isn't enough water flow to fill the water jackets, and the pump/impeller is actually much more pressure (and water volume) than water hose.

Everyone's help is greatly appreciated as I work through the variables.
Any suggestions, advice or comments on the above info?

 

[jakedaawg]

Sounds like you found your problem, the upper water tube connection.

 

[Bosunsmate]

yep likely the above

 

[mgoodling44]

Thanks guys, that stinks. Just to be sure, I wanted to share this with you also.
I was able to shine a light up to where the water inlet pipe enters the block (or housing), and it appears to be secure and seated properly, at least from what I can see.
I was also able to see a 2nd hole, opposite from inlet tube, but same position. Is this hole a drain for overflow from the water jackets, or should there only be water running directly out of the copper water inlet pipe when putting water directly into the T-Stat openings.

 

[jakedaawg]

I just dont know the answer to that...I dont spend alot of time looking at the bottom of powerhead/top of midsection...

Someone will be along to answer.

You sure you aren't seeing the crankshaft?

The water tube could be split. I suppose the casting could have a bad spot/gasket failure/grommet failure.

 

[jakedaawg]

Is it possible you are seeing water come out the exhaust. That would be a normal path for it

 

[mgoodling44]

Thanks. I'll check it tonight when I get home. I'll try and get a picture. Before pulling the block off, I want to eliminate all other possibilities.

 

[racerone]

A leaking head gasket is a possibility.----Do a " no money spent " compression test.

 

[mgoodling44]

Ok. I'm going to do my best to describe my observations. Can't get any pictures. Just too tight of a space, but I have some additional news to share. I ran water through the T-Stat opening again to pinpoint where the actual water flow was coming from. Below are my observations.

1. The opening opposite of the inlet water tube appears to be a "dummy" opening. No flow.
2. The grommet/seal where the inlet pipe appears to be good. I couldn't see any water flowing around that either.
3. Looking from the bottom, there are basically (3) openings. a. Drive shaft to lower unit. b. exhaust manifold. c. The opening where the inlet water tube runs.
4. The water flow was coming out of (c) mentioned above, but not at the inlet water pipe grommet at the top, where it enters the block. The water flow is definitely flowing from the (c) opening, but I cannot see where. I'm assuming this is may be normal, but I cannot confirm, as I've never tore down this part of the outboard before. If an expert could confirm, that would be great.
5. Just to reiterate, prior to changing impeller, the engine did have water flow out the pisser, just not a very 'commanding' flow, but definitely flowed. Since the flow wasn't great, I thought it was time to change the impeller. The reason for the impeller change was to improve the water pressure/circulation out the pisser.
6. Nothing else was touched. I simply swapped the impeller (a pretty simple and standard upgrade), but man, have I had issues with getting this to work now.
7. Is there any other tests to do before I take to the shop? I'm at a loss, but it's driving my up the wall that I cannot pinpoint what's going on. I really just want to do it, to do it. Just the way my mind works..........thoughts? Comments?

 

[Bosunsmate]

Without knowing that model i cant be sure but if you connect a hose and water is coming out around the inlet pipe and not the exhaust manifold then id suspect a leak in it somewhere-grommet, split pipe etc.
The first few seconds after you turn the hose on should be the easiest to tell