After water pump impeller change out, water doesn't seem to come back out... pls help

[Hai Nhi]

Good Thursday everyone.

As I mentioned on my other post, I've been working on my boat for the last couple of weeks, on and off. Here's the status update:

- I got the rotor sensor changed out so it started again (was a crank but not start problem).
- Went ahead and change all bellows, water pump impellers, oil tubes, water tubes on both drives (all new gaskets etc...). I then filled the gear drive oil for both, hooked the hose muff up, and started them both one by one.

Problem: Water doesn't seem to come back out in the back at all. Risers and manifolds are quite hot to touch. I watched the thermostat and both keep rising up. They did not pass 160 yet but I was afraid to wait too long so I shut engines down.

One quick note: before I started the outdrive service, I did try to start the stbd side and saw rusty water rusting out back, then seems to be either white smoke or steam. I then turned it right off after about 90-120 seconds. The temperature did go up pass 170. I checked, and turned out the water hose got bent so water couldn't pass through quick enough or something. Now after the service, no white smoke/steam - nothing.

Some other observations:
- Garden hose water pressure is great. I touch water back there at the drives, all cold, so definitely not from engines.
- I opened the biggest hose up next to the pulley on stbd side, there's hot water in them. No blockage.
- I opened all drainage plugs (3 for each engine) and water came down hot.

Should I take the lower unit out and feed the garden hose through the water tube? I know (hope) water runs inside but not sure why it doesn't seem to circulate through. Anything I should check/do?

I might have sometime early tomorrow morning to test it before going back to the camping.

Thanks in advance.

 

[Bt Doctur]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Did you remember the impeller keyways? Did you correctly have the plastic guide tube aligned to accept the copper line?
"
Should I take the lower unit out and feed the garden hose through the water tube?"
No. you wont have any oil in the drive if you start the motor. Best to remove the drive and insert the hose into the water inlet hole.
If everything is now good, the issue is with the new impellers

 

[Lazy Daze]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Remove the intake hose from the t-stat housing and direct it into the bilge. Turn the water on and start the engine. Observe how well the water flows out of the intake hose. This will narrow down the problem to the drive side or the engine side. Rusty water is typical for an engine that has sat for a while. Since you just did an outdrive service, and the problem is on both drives, at this point the most logical thing is something amiss with the service - impeller put in backwards (and didn't flip), water tube in drive not lined up, etc.

When you removed the old impellers, where they intact?

What do you mean by "I watched the thermostat and both keep rising up"

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Impeller keyways were both installed, for sure. Water lines were aligned correctly. I verified it a couple of times both sides since I noticed how important it was. Also, water did get into the engine sides.

Old impellers were excellent since they both got serviced/changed one season before I bought it (so about 3 years ago). I put them back exactly the way the old ones were. One thing though: I didn't check on stbd side but on the port side, the shaft where the impeller goes into didn't turn neither way by hand. It only moved back and forth about 1/4". I thought it was normal so I went ahead and installed it anyway. Should it be that way? If it's not, what's wrong?

When I started each engine, I monitored the temperature gauges closely since the stbd side went pass 170 like I mentioned just in case. And both gauges showed temperatures keep rising. I turned engines off after just a short while just to make sure though. So anyway, I was just reporting what's going on - that's all .

thanks.

 

[dpmulvey]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

What else have you done to the engines? Any exhaust manifold work by chance?

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Hi David,

Only some tune up works done: cap & rotor, plugs. Haven't reached the oil & filters change out yet.

Previous owners stated he changed exhaust manifolds & risers just 2 seasons before he sold it to me 2 years ago. He's always used it in fresh water.

Pls note that this happens to both engines, so something fundamental might be wrong here. Not sure what yet.

I didn't have a chance to do any further testing this morning yet. Hopefully will today afternoon/tomorrow morning.

 

[dvx216]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

I would be concern that you didn't get the connecting tube between the lower unit raw water pump attached to the upper part of your out drive. The upper tube can get bumped by the drive shaft and then they will not line up so the water is not going up to the motor.The motor on a hose muff will run cool with or with out a good impeller because of the hose pressure does the job of the pump. The one thing that is important is you rotated the shaft the right way when you installed the housing over the impellers.

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

I was lying down looking up when installing the lower unit. And I'm sure the hoses are mating correctly.

However, I think I'm gonna remove one out to verify just to make sure. Before I'm doing that, can someone pls tell me the direction of the impellers so I can double check that too? Should I be able to rotate the shaft freely by hand? At least port side is not.

Thank you

 

[CliffA]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

I'm not sure it really matters how you put the impeller in the housing......a few weeks ago I changed the impellers in both my engines.....I decided to do a simple test with one impeller.....I installed it in the housing with the blades curving the wrong way on purpose.....then I reassembled the housing and manually turned the pulley to spin the impeller the opposite way the blades were curved...I separated the housing and noticed the impeller blades had automatically corrected themselves and were now curving the right direction....

However i would still suggest you install the impeller correctly to start with and not depend on the blades correcting themselves....

cliff

 

[Westie]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

This is what the service manual says regarding the direction.

Position the water pump body over the drive shaft and water pump locating pins. Rotate
the drive shaft in a clockwise direction, while pushing down on the water pump body to
ease the water pump over the impeller blades.

 

[Lazy Daze]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Did you try the hose trick I mentioned above? Yes, driveshaft should rotate, unless you bumped it into gear... but that wouldn't explain not rotating in BOTH directions... unless you just didn't rotate it hard enough in one direction and stopped when you felt the lightest resistance. It will click in one direction if it's in gear.

A couple other things that aren't making sense... you said:

"Some other observations:
- Garden hose water pressure is great. I touch water back there at the drives, all cold, so definitely not from engines.
- I opened the biggest hose up next to the pulley on stbd side, there's hot water in them. No blockage."

What water where you touching? The water spraying out from the muffs? Or water coming out of the transom exhaust and/or prop exhaust?

Having hot water in that big hose does not negate a blockage.

But... if everything was working fine after you changed the rotor sensor as you said above, then (unless there's more to this story) some kind of error happened during your impeller change.

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Cliff, thanks for reassuring.

Dennis,

I'm gonna go try that right after this message.

Your picture of the impeller direction and what Westie suggested is the same as what I installed. But looking at this diagram, it suggests otherwise. http://www.mercruiserparts.com/Show...c=GEAR+HOUSING(DRIVESHAFT)(STANDARD+ROTATION)

I assume they are the same for both drives.

Clarification of my statements:
I touched water falling down at back of the drives just to confirm my observation that nothing is coming back out since water is cold still.

The hose I took off is #11 (t-housing to water pump) http://www.mercruiserparts.com/Show...r=5388&bnbr=120&bdesc=Standard+Cooling+System

 

[Lazy Daze]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

I touched water falling down at back of the drives just to confirm my observation that nothing is coming back out since water is cold still.

The hose I took off is #11 (t-housing to water pump) http://www.mercruiserparts.com/Show...r=5388&bnbr=120&bdesc=Standard+Cooling+System

"back of drives"... do you mean "forward of the drives" - the transom plate (the part directly attached to the hull)? That will be cold for a bit until the engine gets up to temp.

#11 - yes - just having water there won't show a blockage or not.

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Thanks Dennis, as always, for quick reply.

I opened the intake hose as you mentioned, started the engine and water did come out but not strong enough. I immediately double checked my hose. It seemed like I do have enough pressure and water supply. But this hose is on my well pump right now. So just to make sure, I swapt to city water line with much stronger (at least double) pressure. Hooked up, started! ...

after a short while, sure enough water did come out of the two exhaust holes. Yeah!!! Yep, on both drives.

A couple of other things though:
- temperature is at about 150-160 at idle (~600-700 rpm). It did go up pass 170 deg when I rev'ed up to about 3000. Kinda stayed there but not sure since I only rev'ed up a little bit (15-20 sec) a couple of times only. Manual said "thermostat: 160".
- stbd side wouldn't gear on reverse.

 

[thegotoguyr]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

I could be wrong, Im sure someone here knows for sure but I have read that a garden does not feed enough water for engines running much higher than idle, therefore will not cool properly at 3000 rpm.

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

I could be wrong, Im sure someone here knows for sure but I have read that a garden does not feed enough water for engines running much higher than idle, therefore will not cool properly at 3000 rpm.

If that's true then I can take it down to the water and test it. All things correct it should stay at 160, correct?Thank you.

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Hah, page 97 on my mercruiser manual says, "do not use full water tap pressure. Also, do not run engine above 1500 rpm, as suction created could cause water hose to collapse causing water supply to be cut off."

 

[thegotoguyr]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Mine shows 170 on the dash with a new and tested 160 thermostat and fresh water pump, so I used my ir thermometer on some frost plugs while on the lake, it was reading 155-160-ish, my point is , dont get too hung up on exactly 160 on the guages, closed systems run much warmer with the same engine so I dont think 170 will be doing much of anything other than getting better mileage.

 

[Hai Nhi]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

Actually, mine was pass 170 on stbd, and is a raw water, not a closed cooling system.

Where do you read with the IR thermostat again?

 

[Lazy Daze]

Re: After water pump impeller change out, water doesn't seem to come back out... pls

The gauge will usually read higher than the stat. 170-ish is the normal range to see on the gauge. Don't get caught up with that IR gun a few degrees one way or the other. Also, who's to say that the gun is accurate? Use it more for "trending" than an exact reading. Engine cooling is not an exact science and trying to make it one will only cause headaches.

Think automotive cooling is better? Nope. My old 528's temp needle, when dead center in the middle (the "normal" area) has a 50* buffer built in. From 175* to 225*, it will stay dead center. Our boat's temp needle has no buffer so you actually see the swing. The Bimmer has a swing too, but with the buffer built in, customers don't see it and BMW doesn't have to worry about threads like this.:smt001

No reverse... Since you were taking the drives off, I'll assume you know what the shift lever is - check that to see it's connected correctly.

As mentioned... Don't make it a habit to run much higher than idle (for extended times) on a hose.