Mercury 650 not "peeing" after impeller install

[ssand746]

I recently put a new impeller on my 1967 Mercury 650 because it was not "peeing". The impeller was not that bad, but I thought it was no big deal. After replacement, I made sure that the peeing hose was free of obstruction, which I am able to suck air through it (kind of tough though). It still does not pee at all, but there is a bit of water coming out from the bottom of the block area (not out of the hose where it connects to the block). It is pumping water out the bottom like it should. Will this overheat my motor? Any ideas on how to fix it? Oh, and what is the outlet I keep refering to as peeing? Thanks everyone!

 

[jbjennings]

Re: Mercury 650 not "peeing" after impeller install

You did get the impeller key back in right? Are you sure your main water tube that goes from the water pump to the block is secure in its grommets. That's a common problem. I'm unsure where you said the water is coming out of as far as at the bottom of the block. If your telltale hose is unclogged and no water is coming out, it will definitely overheat quick--in just a few seconds.
Have you taken the powerhead off? The reason I ask is that you say water is coming out of the base of the block. Got any pictures? Exactly what all have you done to the motor?
Curious in order to be more helpful,
JBJ

 

[ssand746]

Re: Mercury 650 not "peeing" after impeller install

You did get the impeller key back in right?
Yes, the key is in right.

Are you sure your main water tube that goes from the water pump to the block is secure in its grommets.
I am fairly sure it is secure, there was no problems with getting the lower unit back in place.

The reason I ask is that you say water is coming out of the base of the block. I mis wrote, the water is coming from somewhere at the base of the engine, and is flowing out the upper mounts in the front (very slow, almost not a stream).

Got any pictures?
No pictures, as it is dark here.

Exactly what all have you done to the motor?
I have just removed the lower unit to take out the old impeller, thats it.

Is there any chance that when it was in actual water, it would work right? I was using a hose with suction cups.

Thanks for the quick reply! Steve

 

[Todd Gerber]

Re: Mercury 650 not "peeing" after impeller install

Did you try running the motor briefly at higher rpm's? My old 650 didn't flow much as a slow idle.

 

[jetwhine]

Re: Mercury 650 not "peeing" after impeller install

Try blowing some compressed air back through the telltale. Even try it while engine is running. Has worked for me.

 

[jnorswor]

Re: Mercury 650 not "peeing" after impeller install

when you blew air through the tale tale hole was the lower unit off? I have a 74 and the lower unit is off and there is no restriction to air flow...I can blow or suck air with no restrictions at all....maybe it is more difficult if the lower unit is on but I think you may have some restriction

 

[James R]

Re: Mercury 650 not "peeing" after impeller install

Can't recall exactly but I think the lower has to be submerged to pump correctly. There may be an intake under the cavitation plate in addition to the ones on the sides.

 

[jetwhine]

Re: Mercury 650 not "peeing" after impeller install

When I first did the compressed air it was with the LU off. Then after I started I did not get water out of the telltale. I then blew comp. air back through the telltale while the engine running to force the water back down the other way. That worked for me. I think that I must of had a piece of old impeller up in the engine somewhere and after blowing while engine was running the water started comming out very strong. Hope that helps.

 

[jbjennings]

Re: Mercury 650 not "peeing" after impeller install

If you had the muffs on right, and I'm sure you did, it should pump water great. It should also pump plenty of water on idle. A correctly working mercury water pump puts out a hard stream of water on idle if the hole at the end of the tattle-tail is the right size. Just an idea, but are you sure you got the correct water pump impeller? I've heard of the wrong one not being tall enough and leaving a gap above it inside the impeller housing. Also, my other guess is that your water tube is not inside the grommets somewhere. Did your old impeller have any broken blades? If not, and it was working correctly right before you changed it, then it can only be:
incorrect impeller, impeller key not in correctly, water tube/tubes not in grommets. BTW, that thing must have huge water jackets because it takes several seconds on the muffs for my 65hp to fill up the jackets and start pumping water out the telltale, and after you shut it off, it seems like it drains water out the telltale for 3 or 4 min.--no joke.
HOpe you find it,
JBJ

 

[jbjennings]

Re: Mercury 650 not "peeing" after impeller install

One more thing you might try if all else fails. Take off the lower unit, use some duct tape to tape the end of your water hose to the main water tube and turn on the water. If there aren't any restrictions in the powerhead water jackets or the tubes or the grommets, water should run out the telltale just like normal.
JBJ

 

[ssand746]

Re: Mercury 650 not "peeing" after impeller install

Thanks to all for the responses. It turns out, like many suggested, that the main tube was not in the grommets like they should be. When installed correctly, the telltale works as it should. Amazing! Thanks again!