1974 Merc 1150 water pump issue

[Bob37814]

I have a real neat old 1150 Merc inline 6, I have 2 issues to play with...#1, I have dropped the LU and replaced the impeller and found the grommet in the top housing split, So I replaced the impeller and grommet, along with gaskets etc etc......I still have NO pee stream from the pee hole, Lots of water comes from the prop center, and when I rev the motor slightly on the muffs, I get a short burst of water from the exhaust reliefs just under the powerhead. After 5 minutes of running, it begins to get hot. Every once in a while a couple drops come out of the peehole but are hot as heck and usually followed by constant steam. My second issue is that I accidently misaligned the lower unit shift shaft and cannot get it configured right....Can someone help me?

 

[cell]

Re: 1974 Merc 1150 water pump issue

for the lower end see this post.
http://forums.iboats.com/showthread.php?t=306705

make sure you have the water tube lined up or it wont pee...Not sure if this will cause water to come out of the upper exhaust ports or not.

take care of your old tower,and check out this link.

http://http://forums.iboats.com/showthread.php?t=168855

Search the forums for sea foam.It works good.

 

[Chris1956]

Re: 1974 Merc 1150 water pump issue

Bob, If you have water out the prop and exhaust releif, chances are it is pumping fine. If you have water out the gratings above the AV plate, the motor is definitely pumping.

Pull the telltale off the cylinder head water jacket cover and see if the stream out of the elbow is solid. Those telltales clog easily.

 

[Bob37814]

Re: 1974 Merc 1150 water pump issue

Chris, I have water coming out of the grates...I have already pulled off the tell tale off from the back jacket cover, as well as from the tale spout. It only drips a drop or 2 after running for a few minutes followed by constant steam....The few drops of water come out so hot ive burned my hand from them....When I had the LU off for impeller replacement, I hooked a hose to the pipe that runs into the impeller housing...With the motor off, I can fill the water jacket up and it pees just fine like it would if it was running and pumping correctly...On another note, Is there supposed to be a small gap where the top wp housing meets the base? I may be talking myself into changing the whole water pump assembly.....Im putting my money on that is where my problem stems from...Your thoughts?

 

[Chris1956]

Re: 1974 Merc 1150 water pump issue

There should not be a gap between the top and bottom water pump housings. You did install the stainless wear plate and it's two gaskets?

You have a definite problem. I guess there is a small "window" of water pressure where it could cool the bottom 5 cylinders and not the top cylinder, but I have never seen it occur Those inline motors only have 5PSI at idle and 10-15 PSI at WOT.

I guess you need to revisit the water pump. From the waterpump base up, you should install a gasket, the wear plate, another gasket, the impeller and key and then the pump cover. Nothing else. The slinger goes on top of the pump cover.

 

[Bob37814]

Re: 1974 Merc 1150 water pump issue

Yeah, I didnt figure there was supposed to be a gap between the top housing and the base....I do believe I am going to go ahead and top it off with a complete water pump overhaul with a new housing, impeller, wear plate, gaskets, slinger, and pipe grommet....I have been into these inlines before and this ones pump assy. just didnt look right at all. Im going to give it my all on this next work and I believe I can get her going...Thanks Chris, I bet this wont be the last you hear from me...LOL