Water pump working...still no water...68 Merc 500

tpalshadow · Apr 28, 2011

OK, serial number 2343858.

I have been finding a lot of great information on this page, I was wondering if there is anyone who can help me with this problem.

Just did a rebuild of the water pump, everything goes back together smooth and motor fires right up, however there is no water coming out the tell-tale. When I drop the lower back out it is evident there has been water falling down around and over the driveshaft.

The water line going up from the pump has a good connection on both the top and bottom so I believe it is pumping water up to the engine inlet, but it isn't making it through the motor and is falling back down.

Additionally, if we unhook the line from the tell-tale and pump water through it, the water comes out through the middle portion to the lower, but it is not coming out through the inlet where the water should be pumped in. It seems to be running through somewhere else.

My thoughts are that either the water path through the motor is being blocked somewhere, or there is a fitting or hose which is cracked/broken/missing. With the top off the motor we don't see any signs of water leaking. Is there any easy way to remove the shields from the bottom of the engine or surrounding the portion between the motor and lower?

Thanks!

tpalshadow · Apr 29, 2011

Re: Water pump working...still no water...68 Merc 500

Hi all, thanks for taking the time to look. Is there any additional information or photos I can provide that would maybe better allow you to help me with some ideas with how to proceed?

douglas1978 · Apr 29, 2011

Re: Water pump working...still no water...68 Merc 500

have you taken the hose off the tattle tale fitting while the motor was running and when you installed the new impeller did you remeber to put the key back in, and what did the old on look like was it missing and fins?

Mi duckdown · Apr 29, 2011

Re: Water pump working...still no water...68 Merc 500

What douglas1978 said. Plus, did you install the impellar while turning the crankshaft clockwise?
What does the crankshaft look like, at the top of the impellar housing? is it pitted and rusting looking?
They were carbon steel then, and prone to rust and seal wear grooves.
PICS

tpalshadow · Apr 29, 2011

Re: Water pump working...still no water...68 Merc 500

Thank you for the replies! I'll try to reply with the information as well as additional things I tried today.

Have you taken the hose off the tattle tale fitting while the motor was running and when you installed the new impeller did you remeber to put the key back in, and what did the old on look like was it missing and fins?

Yes, I took the tattle tale fitting off and when I pump water backwards through it it runs down by the driveshaft, but it doesn't come out the hole where the copper pipe would pump water IN to the motor.

The key was put back in and I could feel it spinning when moving by hand. A photo of the old impeller is below, it actually looked pretty good.

Plus, did you install the impellar while turning the crankshaft clockwise?

Do you mean clockwise when looking DOWN at the pump?

What does the crankshaft look like, at the top of the impellar housing? is it pitted and rusting looking?

It looks good, no signs of wear that would affect the operation.

I do think the pump is working and moving water up, I think it is just getting somewhere into the motor or a connection that is loose and running out before it can make it through the motor.

Today I took the lower off, installed the copper water pipe into the bottom of the motor where it enters and hooked up my garden hose. When I turned the water on the following happened:

- Water did come out the un-hooked telltale hose
- Water fell back down from the bottom of the motor (couldn't tell where it was coming from).
- Water dribbled out from around the number 1 cylinder (edit: by this I meant around the number 1 spark plug).

Thanks!

merc850 · Apr 29, 2011

Re: Water pump working...still no water...68 Merc 500

Here's the parts diagram http://www.crowleymarine.com/mercury-outboard/parts/437_16.cfm
maybe the gaskets are missing or damaged and the copper water tube has two rubber grommets one in the waterpump outlet and one in the powerhead inlet; the water drains into the driveshaft housing and exits on top of the cavitation plate and thru the prop.
If water is coming out at the bottom of the sparkplug hole the water jacket is leaking.

cajunman83 · Apr 30, 2011

Re: Water pump working...still no water...68 Merc 500

tpal

I'm having the similar issues. Have you had any success? Please update. Thanks

Maxz695 · Apr 30, 2011

Re: Water pump working...still no water...68 Merc 500

My bad impeller looks as worn as this does I was going crazy trying to figure it out. This is what i found Take your pinky and stick it into the center of the impeller do not squeese the ruber but just hold it then turn the center ring if it turn and the rubber goes no where replace the impeller

tpalshadow · Apr 30, 2011

Re: Water pump working...still no water...68 Merc 500

merc850 said:
Here's the parts diagram http://www.crowleymarine.com/mercury-outboard/parts/437_16.cfm
maybe the gaskets are missing or damaged and the copper water tube has two rubber grommets one in the waterpump outlet and one in the powerhead inlet; the water drains into the driveshaft housing and exits on top of the cavitation plate and thru the prop.
If water is coming out at the bottom of the sparkplug hole the water jacket is leaking.

merc850, thanks, this might put me in the right direction. When I pull the copper tube out, the rubber grommet on the top (motor end) comes out with it and I don't think it ever gets seated when re-installed. This is the piece or rubber that looks like a portion of hose, about 1-1.5 inches long, correct?

Does the motor need to be pulled to replace the grommets on the top side (motor side) as well as to replace the water jacket? What parts diagram would the water jacket be on? Thanks for all your help!

I did not know water was supposed to drain back into the driveshaft housing as well as out the telltale...thank you for the help!

tpalshadow · Apr 30, 2011

Re: Water pump working...still no water...68 Merc 500

cajunman83: I think I'm on the right track, see the above post...I think I'm going to have to pull the motor to make all the fixes though...I'll update the thread as I'm able to make progress.

maxz695: yeah, I'm sure it was probably bad, I did replace the impeller and all gaskets with a pump rebuild kit as a first step...(I was really hoping that would fix the problem!)

tpalshadow · May 1, 2011

Re: Water pump working...still no water...68 Merc 500

Just re-asking because I need to work on my patience!

Does the motor need to be pulled to replace the grommets on the top side (motor side) as well as to replace the water jacket? What parts diagram would the water jacket be on? Thanks for all your help!

Maxz695 · May 1, 2011

Re: Water pump working...still no water...68 Merc 500

I just got through redoing the whole powerhead gaskets. I found particals of impeller at the base water jacket and in the exhaust cover jacket as well as a hole in the inner exhaust baffle plate. I repaired it with PB Weld only broke 1 bolt on the upper waterjacket cove and got it out easily. If your gonna pull the powerhead get the whole gasket set while your in there. It,s a releif to know the engine is finnaly not leaking into the midsection and all the parts are sealled properly

tpalshadow · May 3, 2011

Re: Water pump working...still no water...68 Merc 500

Does anyone know where I can buy and download a PDF version of the original service manual for this motor? I have the Seloc and it just doesn't give me the information I need.

Thanks!

cowchipz · May 5, 2011

Re: Water pump working...still no water...68 Merc 500

I am having basically the same problem with a 1966 Mercury 60, 6hp.

When you blow air in the copper tube, you can hear it leaking in the housing. I put some water in the tube and hit it with the air hose, and it looked like either the tube had a hole in it, or the rubber grommet was leaking.

The tube wiggles back and forth, but I cannot seem to pull it out. I do not want to tear it up. Should it pull out??

Thanks.

cowchipz · May 5, 2011

Re: Water pump working...still no water...68 Merc 500

Here is a place where you might find some factory info on the motor. I cut this from another thread I was researching.

Here is a link that may help you.Hope this helps.
http://web.ebscohost.com/serrc/pdf?s...&vid=4&hid=107

OR-

http://search.ebscohost.com/
Log in with:
Name: marshall
Password : public
Then select the small engine reference center icon.

tpalshadow · May 6, 2011

Re: Water pump working...still no water...68 Merc 500

Thanks, cowchipz. Does anyone have a diagram of how the water should flow through the motor?

Thanks!

Maxz695 · May 6, 2011

Re: Water pump working...still no water...68 Merc 500

you can wriggle it out and check the top of the tube for holes. it will go back up in usually without damage to a rubber gromet.

cowchipz · May 7, 2011

Re: Water pump working...still no water...68 Merc 500

Maxz695 said:
you can wriggle it out and check the top of the tube for holes. it will go back up in usually without damage to a rubber gromet.

I wiggled and pulled and nothing moved. I even went so far as to screw a bolt in the end, and put a slide hammer on it, and the tube will NOT move.

Any suggestions??

Moxie · May 7, 2011

Re: Water pump working...still no water...68 Merc 500

I had a similar issue with my 68 500. My assumption was that the line was clogged. The motor never did overheat, ran fine. However, lower unit ended up with some water in it and froze over the winter, causing a crack. Motor is currently being looked at, but somewhere in there some seals have gone bad. Don't know enough about the seals to say whether or not it's the cause. Just saying that I've had the same issue for a while now and what the status of the motor is at this point. Related? Not sure....

merc850 · May 9, 2011

Re: Water pump working...still no water...68 Merc 500

Here's an xray of a Mercury
close to your year

I would call a local dealer and see if the exhaust plate-powerhead gaskets are available, then pull the powerhead off and find out what's going on.

Water pump working...still no water...68 Merc 500

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