Problems on the alpha 1 gen 1

[viper1]

Never had so many problems as this one. It was over heated. So I changed water hose in gimble, all bellows, and new impeller twice and thermostat.. Flushed water from thermostat back through intake and exhaust manifold. Started it up and heat gage shows overheating. Pull intake hose at the thermostat housing and no water pumping. What am I missing!

 

[Eric 3.7LX Alpha 1]

Are you doing the full impeller kit with new upper and lower housings or just the impeller itself? Did you try running the engine off a garden house stuck inside the water inlet in the bellhousing when you had the drive off? This will tell you if it's drive related or not.

 

[viper1]

I replaced upper and impeller and plate. I placed out drive in a filled drum and started it. No water coming from outdrive to thermostat. That should prove drives not working. When I had drive seperated and off I ran water through it making sure it wasn't plugged.

 

[viper1]

Never replaced the lower half of pump housing. Is it plastic and could it melt? If so would that prevent water flow?

 

[viper1]

Dont see anything but a plate on diagram.

 

[Bondo]

I placed out drive in a filled drum and started it.

Ayuh,.... Unless you've figured out how to submerge the Entire drive, I'm guessin' ya just smoked another impeller,....

Get yerself a set of muffs,.... a bucket Won't work,....

'n when ya get the drive off, or the lower unit off, back-flush from the t-stat housin', in case a piece of old impeller is lodged in that line,.....

 

[Bt Doctur]

ear muffs are the best method but if you use a drum the waiter level MUST be above the red line

 

[viper1]

Well back flushed the whole thing from thermostat to out drive several times. It flows great. And yes i filled a half of 55 gallon plastic drum so it was buried below the intake. I see the piece your mentioning now. Since the water cover was melted, and the impeller i removed, I'm thinking your right. See its made from plastic also. Just called my parts man and he has it. So off with it again and i'll take out the lower and check. I'm sure you're right. Bet it's sucking air instead of water....Thanks every one. I have never had this problem as i take care and change mine often. But this is the first overheated one i done. In fact i got another upper half because the gear oil leaked when pressure checked. Now testing good. Help pressure for two hours no problem. Well work to do! Thanks again!

 

[Bt Doctur]

I never mentioned the intakes, you dont understand.the water level must be above the red line or the pump sucks air and melts.

 

[bvetter]

You probably already took this into account, but when installing the impeller, the blades need to curl in the proper direction when installing the top cover, if not I'm guessing it won't pump properly? For a right hand drive, the blades need to curl counter-clockwise when looking down the vertical drive shaft I believe.

 

[achris]

You probably already took this into account, but when installing the impeller, the blades need to curl in the proper direction when installing the top cover, if not I'm guessing it won't pump properly? For a right hand drive, the blades need to curl counter-clockwise when looking down the vertical drive shaft I believe.

Doesn't really matter if the impeller is installed the wrong way. After the first half dozen revolutions, they'll be facing the right way. But yes, it helps getting them the right way to start with.

 

[NHGuy]

When you have the drive apart inspect below the impeller housing too. That lower pump section can get heat damage too. It happens from exhaust if the drive isn't in water when the engine is run.

 

[nateo]

Engine coupler?...cough..cough..before you do anything else. If outdrive is still on put in forward gear and try spinning propeller counter clockwise. It should lock. If it doesnt bad coupler.

 

[viper1]

Ok will try to answer all the questions. But first of all the lower unit is on my bench and full impeller parts are removed. You were right! I had the intake covered but not to red line. Why does muff work just on the intakes? Either way your right also that I fried it all. So have the whole kit Sierra 18-3320 Water Pump Kit coming in the mail. Remove lower housing but really see nothing wrong. But will replace it all any way. when it was assembled it was in forward and locked counter clockwise. I had replaced water cover in upper unit. But will recheck. Anything else i need to look at? Got 3-5 days to inspect before getting parts.

 

[thumpar]

Ok will try to answer all the questions. But first of all the lower unit is on my bench and full impeller parts are removed. You were right! I had the intake covered but not to red line. Why does muff work just on the intakes? Either way your right also that I fried it all. So have the whole kit Sierra 18-3320 Water Pump Kit coming in the mail. Remove lower housing but really see nothing wrong. But will replace it all any way. when it was assembled it was in forward and locked counter clockwise. I had replaced water cover in upper unit. But will recheck. Anything else i need to look at? Got 3-5 days to inspect before getting parts.

Because muffs have water pressure pushing the water up to the pump.

 

[viper1]

Ok is there a seal in the top impeller housing? Below the rubber slinger? The lower housing looked ok. But i will replace any way. Maybe this time it was simply my fault not using muffs. But thought the drum might be better. ;( Upper seems ok, water cover dont show heat damage. And seal looks good where spline shaft enters. But after removing the impeller parts and housing the spline shaft had a lot of play back and forth. Can I consider it normal as the housing no longer supports it nor the spline in top unit?

 

[Bt Doctur]

there are no seals in the top housing, the rubber slinger just rests on top of the top housing.
depending on the exact type of drive, the preload pin pushes the driveshaft downward, and the MR pushes the driveshaft upwards.

 

[viper1]

Well got all the crap out of it. Turned out to be hard. The impeller was partly melted. and the busing the rubber is melted on shrunk. So took a pry bar to even move it. added grease to try and help but didnt work. Finally resorted to a cut off wheel. Big mistake. Now i have a nice gash in the shaft. About 3/8 tpp 1/2 ; long maybe .030 deep. Waiting on parts to see where it falls. Hope its high enough to clear bushings. I would think if its above the housing it should be fine. But if its in the top of the top impeller housing it would be scrap right?
So next question how tough is that shaft to change?

 

[viper1]

Thumpar the lake dont! If impeller is working it shold suck up i wold have figured. I had the intakes covered, why does the water need to be to the red line to work. Im missing something.

 

[Rick Stephens]

Vipe,

That pump has a bleed hole to prime itself when submerged. Those pumps truly aren't what you'd be able to call 'self priming'. If the water level is below the pump, then the pump would have to pull water to prime, they just won't do it and the impeller melts quicker'n you can say 'ouch'.

They had a choice when they designed the water pump system in boats - self prime and put it above the water level, or submersion prime and put it below the water level. Pretty much every drive manufacturer chose the submerged method as it instantly starts pumping, and lubricating the impeller, when the motor is started.

Self primed is a LOT harder to do since the pump needs the ability to survive running dry until it primes, which means it needs to be built out of something more durable than rubber. And something harder than rubber causes other problems if it fractures and send pieces of itself into the rest of the cooling system.

Submerged primed means that the pump CAN'T pull water and self prime because the bleed hole prevents the pump from pulling a vacuum in air.

Rick