1970s Merc 500 water leak top of leg

[Baxterdmutt]

Hi guys!
I was given this motor and was told that it hadn’t been used in over a decade but did run back then. I’ve done a lot to it and it seems to run pretty well other than it’s a smoky pig. After replacing the water pump impeller I’m still not getting water from the peepee hole. It’s not plugged. You guys probably know this but there is a hole with a plug in it at the top left (looking from the back) rear of the block that you can check for water. I put a connector in the hole, attached a tube, and started the engine. Water will come out but only if it’s lower than the motor. There is no pressure. So I took the bottom gear box back off and ran water through that tube that I put in that test hole at the top of the motor, to see if water comes out of the water tube in the leg. It does but it also runs out somewhere at the base of the motor. I can’t clearly see from where. If you are standing behind the motor and look up the leg, the water comes out from the left and it sure doesn’t look like it’s coming from anywhere near the copper water supply tube.
Before I go through all sorts of trouble taking the motor off the leg, is there something in that area that is suspect, or is it likely a cracked block.

 

[racerone]

You rarely see a cracked block on these.-----And water that is pumped up MUST be returned to the lake.----So it is injected into the exhaust for silencing / cooling.----Did you use factory parts ?----If testing in a bucket is the water 6" above the impeller ?

 

[Baxterdmutt]

You rarely see a cracked block on these.-----And water that is pumped up MUST be returned to the lake.----So it is injected into the exhaust for silencing / cooling.----Did you use factory parts ?----If testing in a bucket is the water 6" above the impeller ?

Really. 6”? I had the water level above the bolts so thought all the intakes and water pump were well covered. Maybe not. So it’s ok to see water in that area. Ok, well maybe I just have a bad seal at the water pump or I’m just not in deep enough water. How much pressure does the water pump generate? I can push water up the water tube to make it come out the top of the motor, but that’s lots of pressure. It definitely does come out the top of the motor if I open the hose right up.

 

[racerone]

Put boat in the water and test.---- Everybody needs to learn the simple things about outboards.----Look , listen and learn.

 

[Baxterdmutt]

Put boat in the water and test.---- Everybody needs to learn the simple things about outboards.----Look , listen and learn

I don’t want to take it all the way to the lake (it’s not exactly close) unless I’m at least a little sure that it’s been fixed.

 

[Baxterdmutt]

I don’t want to take it all the way to the lake (it’s not exactly close) unless I’m at least a little sure that it’s been fixed.

I want to say thanks for your help. It’s been quite helpful. I had no idea that water in that area would be expected. If it came across in any way that I wasn’t listening and learning, I apologize, because I definitely was.

 

[Baxterdmutt]

You rarely see a cracked block on these.-----And water that is pumped up MUST be returned to the lake.----So it is injected into the exhaust for silencing / cooling.----Did you use factory parts ?----If testing in a bucket is the water 6" above the impeller ?

Yaa-hoo. Success. I have water coming out of the Peepee hole. There was an old impeller blade lodged in someplace. I sent lots of air and water through the system before I put it together the first time. It had to be stuck pretty good wherever. So I gave it an extra specially hard flush this time. I’m now wondering if there is enough water pressure. The water barely makes it to the top of the block test hole. Is that anything to worry about. I’m sending along the video of the peepee hole on idle.
Looks like I can’t send the video. I’m too new.

 

[Baxterdmutt]

I just want to thank @racerone once more. I took the pump apart one more time and found the pipe going into the pump didn’t want to seal properly. I got that fixed and now the water shoots out of that test hole on the top of the motor as well as a nice flow from the peepee hole. I’m having a throttle adjustment problem now. I’ll start a new thread. Thanks again.