No Raw water flow 5.7 merc w/ alpha 1 gen 1-gctid808534

[grey.wilfong]

Started the critter and put her in neutral with the stern drive submerged in a big rubber maid bin full of water. Let the engine idle for a couple of minutes and no water from the exhaust. Impeller system checks out, but there's no water from the intake hose at the thermostat housing. The stern drive intake hose isn't pinched or collapsed. I'm thinking possibly a clogged oil or power steering cooler.

Did let it idle long enough to prime?Think I'm on the right track?Any other ideas?

[Pcpete]

Yup, it's a clog somewhere, do you live in an area with critters like zebra muscles that could be clogging the intake? I've read members posts about that happening. From there, I'd start at the cooler and move forward. Let us know if there's no flow at the power steering cooler. If you don't have anything there, hook some earmuffs to the drive and run it to make sure it goes into gear and not something broken in the drive train causing the impeller to not be operating. Likely just checking the box, but

[grey.wilfong]

The drive train is working smoothly, the shift works perfectly, prop locks appropriately when in gear, and motor spins the prop as it should. but there were a few of the half an M&M shaped barnacle like critters with the brown and white stripes clinging to portions of the outdrive. i'm thinking the clog will either be at the through hull fitting or at one of the coolers, just hoping to nail it down in time for MRS B-day! How long do you usually idle before the impeller primes up?

[Ruffryder]

Steering cooler could be it...

Undo the transom side hose at the cooler, do a flow test.

If not, there are a couple more things to be checked transom side.

[Chief_Alen]

Remove the hose from the transom off the t-stat housing back wash, see what comes out.

[grey.wilfong]

Ok, removed lower sterndrive and poured water back down the hose from the t stat housing. A bit difficult single handed but could hear the water splashing out from the copper pickup tube coming out of the upper sterndrive unit. no blockages. Remounted lower unit, refilled gear lube, primed everything from the inlet hose at the tstat. Left the hose disconnected and fired up at idle...no flow.Removed the transom end from the bell housing fitting, still no flow. Attached hose back to the housing hoping the engine circ pump may help or having air open on that end may be a problem. It took a min or so but I finally got water coming out the exhaust. Temp started at 150 or so then climbed to 170 then just kept climbing. shut her down .

The tstat is brand new 160 degree, The impeller fits into the housing with a nice twist, and the vanes mate to the housing sides nicely. The little molded ribs on the top and the bottom of the impeller are still intact so no wear there. There are no etched rings on the top of the housing and only very light ones on the bottom plate. The plate gaskets look very new and are intact. I verified that the impeller was in the correct direction.

Now what? I did notice tonight that my tstat housing doesn't have the check valve balls. Could that be an issue? Whats the best way to check the circ pump? Perhaps a description of the theory of operation tstat open and closed may help. i will also check the exhaust flappers at next opportunity.

[grey.wilfong]

After some sleep on it, I'm thinking that the impeller is having issues priming. Perhaps I need a bit deeper tub. The current one comes up to the Cavitation plate but the drive usually is deeper than that in the water and at the cavitation plate the impeller may not be completely submerged. SOOOOO...either get it on muffs(difficult at my storage location) or take her out to the ramp and see what she does.(Thinking that would be better as it is closer to actual operation and doesn't have the extra PSI you would get from the hose.)Then if I get good flow to all the places I've already checked, I'll either be cooling good or Dig deeper.

[2850Bounty]

Remove the hose from the transom off the t-stat housing back wash, see what comes out.

[color]blue wrote:
If you want to give this a try, first remove the lower gear unit!

If not, the seawater pump impeller will prevent any debris from exiting via back-flushing.

[/color]

.

[grey.wilfong]

lower unit was removed when I back washed from the tstat housing

[2850Bounty]

"grey.wilfong" post=808689 wrote:
lower unit was removed when I back washed from the tstat housing

[color]blue wrote:
OK.... did you find any debris, such as previous impeller vane pieces or small crustaceans, etc? [/color]

[Pcpete]

It really sounds like a blockage in the lower housing below the raw water pump. I hate to say it, but I think I would pull the lower drive housing again, remove the water pump entirely and do a "rotorooter" on the water intake.

[grey.wilfong]

Bounty, Nope no debris and thanks for the rundown...for what ever reason i was having trouble picturing the inner chambers of the T stat housing.

Pete, I did check the lower housing and I'm seeing daylight/ flashlight from both side intake ports when eyeballing down into the lower unit under the flat lower impeller plate.

[Vic_Stewart]

I have a feeling the vanes on your pump are going the wrong way.....just a guess

[grey.wilfong]

With housing in left hand, I rotated the impeller into the housing counter clockwise. So looking into the housing the vane tips curl clockwise. Looking down onto the housing from above the shaft as installed they are currently pointed counter clockwise.

[grey.wilfong]

Outdrive is an alpha one gen 1