Explain how water pump in Drive works

[ChrisCraftJohnny]

Here is my question:

How does the pump in the outdrive get it's power?

Does the throttle have to be moved up a little and put into gear for the pump in the outdrive to run?

In other words, with muffs on, water flowing to the muffs, and you are in neutral with the engine running,
is the pump, pumping? or does the drive have to be turning some?

Thanks,

Johnny

 

[bruceb58]

Re: Explain how water pump in Drive works

The pump is always turning when the motor is on. In the alpha, all shafts are turning except the final propellor shaft when you are in netral. That is because the gears that select F/R/N are on the propellor shaft itself.

 

[ChrisCraftJohnny]

Re: Explain how water pump in Drive works

Perfect explaination Bruce.

Thanks

 

[haulnazz15]

Re: Explain how water pump in Drive works

Agreed, everything but the prop shaft in the lower unit is turning in the outdrive when it is in neutral. Most people don't understand that the shifting is not done in the boat, but rather at the "bullet" on the bottom of the outdrive.

 

[QC]

Re: Explain how water pump in Drive works

Perfect explanations. An additional thing to consider is that if the pump was not pumping, then the engine would overheat whenever you were actually in neutral . . . Another point of clarification is the specific descriptions above are Alpha, most Cobras and Stringers only as Volvos and Bravos have the sea water pump mounted in front of the engine.

 

[longstand]

Re: Explain how water pump in Drive works

from my understanding.. the out-drive pump only pump water when the out-drive is in reverse or forward. not Neutral

weird. maybe iam wrong because.. ok iam thinking.

what happen if the engine is on while your in neutral. how the water gets into the engine..??

maybe your right.

if your rigth. my god. you have save my water pump..
because i have just replace my out-drive water pump and i am working on the engine and when finish i was going to run the engine until it gets hot enough to do the timing. i was going to connect the water hose into the Flush kit. i was not going to connect the MUFF on the out-drive, which mean no water will be going throwout the impeller to the the engine..
if i would have just connect it to the flush kit. i would have damage my impeller pump.. correct??

 

[QC]

Re: Explain how water pump in Drive works

from my understanding.. the out-drive pump only pump water when the out-drive is in reverse or forward. not Neutral

Wrong

maybe your right.

We are . . .

if your rigth. my god. you have save my water pump..
because i have just replace my out-drive water pump and i am working on the engine and when finish i was going to run the engine until it gets hot enough to do the timing. i was going to connect the water hose into the Flush kit. i was not going to connect the MUFF on the out-drive, which mean no water will be going throwout the impeller to the the engine..
if i would have just connect it to the flush kit. i would have damage my impeller pump.. correct??

You should start a new thread to get this one right. This thread referred to an Alpha . . . Your old stringer is probably OK with muffs or the Flush kit, but I am not going to swear to it . . .

 

[haulnazz15]

Re: Explain how water pump in Drive works

Wrong

We are . . .


You should start a new thread to get this one right. This thread referred to an Alpha . . . Your old stringer is probably OK with muffs or the Flush kit, but I am not going to swear to it . . .

If you run the engine with no water going through the muffs on the outdrive, you will need to order a new impeller because you're other one will be TOAST. Sometimes it's difficult to get an engine up to operating temp on muffs because you are forcing cold water. Sometimes it's easier to get a big metal tub and let the outdrive sit in it while running.

 

[bruceb58]

Re: Explain how water pump in Drive works

If you run the engine with no water going through the muffs on the outdrive, you will need to order a new impeller because you're other one will be TOAST.

He was referring to OMC stringer drives. OMC stringer drives do not require muffs...only water going to the flush fitting at the trunion mount.

 

[bruceb58]

Re: Explain how water pump in Drive works

weird. maybe iam wrong because.. ok iam thinking.

Yes you are wrong.

 

[bruceb58]

Re: Explain how water pump in Drive works

if your rigth. my god. you have save my water pump..
because i have just replace my out-drive water pump and i am working on the engine and when finish i was going to run the engine until it gets hot enough to do the timing. i was going to connect the water hose into the Flush kit. i was not going to connect the MUFF on the out-drive, which mean no water will be going throwout the impeller to the the engine..
if i would have just connect it to the flush kit. i would have damage my impeller pump.. correct??

On your stringer, you can either use muffs or the flush fitting at the trunion housing. By putting water in there, even though it is inbetween the impeller and the engine, the water reaches the impeller at its output and keeps the impeller wet with the water.

 

[longstand]

Re: Explain how water pump in Drive works

ahhhh. my god..

i just install a new impeller..

i turn the engine a few times. but just to turn it. engine never start . because i did not have the intake manifold install yet. i just turn it so the piston could lubricate the cylinder with some oil i added..

i turn it for about 6 second or more..

the books said more than 5 second or less could damage your impeller..

i mean its new impeller pump. never been on water at all

.. is it finish. do i need a new one.... hope not..

i mean there is no oil or lubrication around the imperller. it was dry..

Crap iam so worry. LOL.

. remember. i just turn the Engine with the Starter. engine never really fully start. just . TURN TURN TURN STOP. then TURN TURN TURN. stop. over and over for about times. about 5 times. total of maybe 30 Second . but engine never fully started

 

[bruceb58]

Re: Explain how water pump in Drive works

You may be ok. Even cranking is hard on the impeller if it is dry. You should always have water going to the impeller even if you are only cranking the engine.

 

[QC]

Re: Explain how water pump in Drive works

You're probably OK longstand as the speed is so low. BTW, they should be installed with some liquid dish soap BTW . . .

Edit: Sorry Bruce, posting simultaneously . . .

 

[bruceb58]

Re: Explain how water pump in Drive works

BTW, they should be installed with some liquid dish soap BTW . . .

I prefer KY jelly myself...good with rubber products.

 

[Howard Sterndrive]

Re: Explain how water pump in Drive works

I prefer KY jelly myself...good with rubber products.

+1
I use a drugstore brand personal lubricant ... I bought 3 big tubes of it at the drugstore this summer... might have started some rumors

The stuff is very handy for w/p impellers , exhaust hoses and getting the u joint through the bellows on Cobra drives. .

 

[myoldboat2]

Re: Explain how water pump in Drive works

ouch, talk about a hijacked thread...

yes, bruceb58's explanation was perfect.

ChrisCraftJohnny, i didn't see really good cutaway views in the alpha manual, but service manual # 2 has some nice pics of an earlier drive that show exactly what's going on.

The sterndrive consists of the drive housing ("upper unit") and gear housing ("lower unit"). Here is the sterndrive cutaway, from the section 6 cover page. You can see that the engine-driven u joint shaft turns the vertical drive shaft, which goes all the way down to the propeller shaft.

Here is the cutaway of the gear housing ("lower unit"), from page 6A-2. The impeller (6) is inside the pump housings (9 & 11), and are well above the pinion gear (24) that enages forward (25) or reverse (33). You can also see that the shift shaft (22), which is in front of the drive shaft (2), extends down, with the shifting taking place along the prop shaft (42).

As explained by the other posters, when the engine is running, the drive shaft is turning all the way down to the pinion gear. If forward or reverse are engaged, the prop shaft turns. The raw water pump is well above the prop shaft, at the top of the gear housing, and turns whenever the drive shaft turns. If the impeller is dry and not a "run dry" impeller, the vanes get hot from friction and shred, throwing off pieces which then migrate throughout your cooling system and may cause your engine to overheat. As long as you have adequate water flow to the muffs, if the engine is running the cooling system should be getting cooling water.

 

[Dshow]

Re: Explain how water pump in Drive works

Excellent graphics!