'94 Mercury 175 XRI EFI - no water after impeller replacement

[xhobbesx]

Looked through forums and didn't find anything - maybe I missed it but I just replaced impeller, upper housing, lower plate and gaskets - I'm not getting any water out the tell-tale. That's the short version.

The details:

For testing, I'm using the earmuffs in a large tupperware container. Unfortunately I don't have a container deep enough for full submersion.

Housing nuts/screw - 50 in lbs - checked and double checked - in fact this seems tight to me and the shaft is difficult to turn with this torque.

Fins are pointed the right direction in the housing - assuming clockwise rotation.

Seal is installed on the shaft and fully pressed against the top of the water pump housing.

Key is properly installed in the impeller - I felt it slide over the key during installation.

Also installed new thermostats but to test presence of water, I removed them temporarily just to see if water would pass through but to no avail.

Water tube is lined up with the water pump output port as it should be.

I tried pouring water in through the thermostat opening to see if it would run out the bottom and it does so it seems to have clear passage - yes, some comes out the tell-tale too.

To complicate matters, on this model, there is no tell-tale until the thermostats open once it get's warmed up and I'm afraid to let it run much longer that I have already - as there should have been a tell-tale already.

Any help would be much appreciated - I'm sure it's some dumb thing I missed.

 

[Dukedog]

water hose connected to tha muffs with full house pressure?..

you have a hose on top of tha block behind tha flywheel.. disconnect it from that bib.. start tha motor.. should have water discharge there.. if none then pump isn't gettin' water to tha block..

 

[xhobbesx]

Yes, full pressure to the muffs. I ended up getting bold and just let it run longer and did eventually get the tell-tale. My water pressure gauge danced around which it didn't used to do but maybe there's something with these new thermostats (they are Quicksilver). I thought about putting the old ones back in for comparison since I was only replacing them as a maintenance item - they weren't bad.

 

[Dukedog]

"dancing"?.. explain?.. when in tha water (lake) if its "dancing" you may have a problem.. usually dancing, jumping around or pegs is a sign of air in tha system....

 

[xhobbesx]

Haven't put it in the water since my tuneup I've only had it on muffs. Normally, the pressure doesn't register on the gauge until about the time the tell tale starts - I assume it coincides with the thermos opening up? Before I replaced the thermos and impeller the gauge needle would bounce or pulse a couple times, the tell tale would start, then would be a consistent reading. Now, the needle bounces around a lot more but I haven't let it run a long time to see if it settles down.

I was thinking about putting the old thermos back in for comparison.

 

[Dukedog]

stats have nothing ta do with pressure or pressure numbers...……..

 

[xhobbesx]

Well the pressure doesn't register on my gauge until the tell tale starts, which on this motor is after the stats open. I'll check to see where the pressure gauge is measured from.

 

[Dukedog]

don't care when it starts they have no bearing on pressure.. only thing that will vary pressure is when poppet opens and rpm.. gauge should "T" into hose from top/center of motor that goes down to tha poppet cover,, at tha top …

anywhere beside that spot will not read proper pump pressure...…. on "production motors"..

 

[xhobbesx]

Unfamiliar with the poppet but I just traced it out and it's as you indicated. Taps off a T and heads down to the poppet at the bottom of the head and the gauge taps off that as well. So I see what you're saying now. However, now I'm more concerned about the erratic pressure reading. I've pulled of the lower end three times now checking my installation and everything looks right.

Thanks for your input BTW.

 

[Dukedog]

needs ta be in tha water ta really see whats what.. sometimes "tha muffs/hose" can be misleading....

tha poppet relieves/evens out high pressure.. usually starts ta open around 2000/2500 rpm, give or take a few... depends on actual pressure.

 

[xhobbesx]

So for my education, it seems to me the lower end and block have no water in them until you first start the motor on a given day, is that right ? If that's correct, then I can see why it would take a little time to register any water pressure. It does seem odd to me that the water pressure gauge begins to show building pressure at the same time the tell tale starts. Does it just take that long for water to get up into the block at idle?

 

[Dukedog]

shouldn't take but a few seconds for pressure ta register.. its a straight shot from pump to block at that point.. from there it goes to other parts of tha block, heads etc.

do you have tha oem manual?

 

[xhobbesx]

I have the service manual, yes.

When cold it definitely takes more than just a few seconds to register...but it doesn't overheat either.

 

[Dukedog]

must be something with tha gauge mechanics?.. water/pressure, no mater warm, hot or cold, warm or cold motor, gets to that point when tha pump turns.. never paid much attention to tha time it took ta register, only if it made pressure or not by tha time I looked at tha gauge!.. as long as ya don't get tha dreaded alarm all should be good.... sounds like ya got it under control.. good luck with it!

jus goes ta show no mater what, ya can hear of new things...

 

[xhobbesx]

Manual makes no mention of the cooling system (at least not that I can find)...The only mention of the poppet is in a diagram showing where it is. But no mention of a test procedure or anything - like it does for everything else. Odd.

Thanks again for all your input. I'll keep a close eye on the water pressure.

 

[Dukedog]

dia.

https://i0.wp.com/www.biggerhammer....ewer_2.4_2.5_blizzard.jpg?resize\u003d665,587

 

[xhobbesx]

So I pulled the hose off the bib at the top of the motor - just behind the flywheel. Water does come out there - I'll have to try it again to see if it was a steady stream - it was hitting the wall in my garage and making a mess so I shut it down fairly quickly.

I took a video of the erratic gauge behavior. https://youtu.be/Gv630Z5bt2Q

The gauge didn't do this before replacing the impeller and stats - before it did bounce a couple times and then leveled off but this is really odd. See link.

 

[Dukedog]

looks like tha gauge itself has gone south....

 

[xhobbesx]

Maybe - awfully coincidental though - immediately following replacement of impeller and stats. Like you said, maybe the muffs make it act funny.

If there is air in the system, what are the ways it would get in there?

 

[Dukedog]

you can pull tha tube at tha gauge and point it inta a jar or bucket and check for a small solid stream at off idle.. boat needs ta be in tha water, not on muffs..
gauge's I've seen move like that turned out ta be tha mechanics of tha gauge.. air usually causes it to jump around but more smoothly and not as "jittery" as that.. will also peg tha gauge on and off.. air can get in usually through a bad gasket somewhere throughout tha motor..ie: head, divider, adapter plates.. motor to high and on some types of muffs.... but mostly pump or pump gaskets or intakes..

that's not air...