Mercruiser Alpha 1 pump problems

Sea beaver · Oct 16, 2008

Hi, I have a problem with one of my legs!! When i connect the muffs to circulate water, the water does not go upto the engine side it leaks out of exhaust. Also if i connect the hose to the engine side to flush out the inlet the water comes out of exhaust through prop. Is this a faulty pump or just blocked?? I cant see why it would come out of the exhaust.?? please help!!!!!!!!!!

JDParts2008 · Oct 16, 2008

Re: Mercruiser Alpha 1 pump problems

When i run my merc. I turn on the hose...no water...start engine...2 secs later water comes out of the exhaust/prop hub...this is normal operation...water only flows when the impeller is turning...

Sea beaver · Oct 16, 2008

Re: Mercruiser Alpha 1 pump problems

i only use the leg pump to cool exhaust and straight out. Even with engine running and the hose off no water goes up to exhaust but it flows out of exhaust prop hib. how can that happen? pump must have problems...

Bt Doctur · Oct 16, 2008

Re: Mercruiser Alpha 1 pump problems

If you use the leg to cool the exaust, whats cooling the engine

Don S · Oct 16, 2008

Re: Mercruiser Alpha 1 pump problems

Somehow I think you have a FULL Mercruiser fresh water cooled system that cools the engine and manifolds, but not the risers. The thermostat housing distributes the water to the risers (and out the prop) and also to the engine for cooling. You may get a little water out of the prop, but is there any water coming out of the exhaust idle reliefs under the transom shield? You say you hook muffs to the drive, are you also running the engine? Is the impeller and raw water pump in good shape?
Depending on the engine, the year, the type thermostat housing, type water pump, or anything else needs to be known for sure to help you out.
The thread below should help you get us the info we need.
http://forums.iboats.com/showthread.php?t=220416

Sea beaver · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Hi, Il give you full details. The boat had 120 hp mercruiser petrols. one died a big end death. So me and a friend have pulled both engines out and fitted 2 ford diesels. As i am a skipper of a standby vessel i can get all the diesel i want for free. So me and my mechanic friend embarked on the swap. The engines are cooled by bigger radiators and bigger fans, and run colder thermostats. I have made a home made wet exhaust with water injection cooling. When the engine runs with muffs the water doesnt get up to the inboard side, but comes out exhaust. Same as when water is pushed down engine side it comes out exhaust instead of inlet. The other leg which had the good engine and was working fine allows water up from inlet into engine side and when forced back it comes out inlet. I am assuming that there is a linkage pipe inside as i dont think the water pump is plumbed in correctly. I know previous owner had the leg reffitted and i think it was done by monkeys???

chiefalen · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

You got a picture of this monkeyed up system?

achris · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Sea beaver said:
.... When the engine runs with muffs the water doesnt get up to the inboard side, but comes out exhaust. Same as when water is pushed down engine side it comes out exhaust instead of inlet. The other leg which had the good engine and was working fine allows water up from inlet into engine side and when forced back it comes out inlet. ...

You are going to have to explain this a little differently... water doesn't go into the inlet, but comes out the exhaust????

chiefalen · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Thats going to be my phrase all day today.

I use to say it all the time.

Sea beaver · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

When its completed il post some pictures. With the muffs on the inlet side and the engine running it does not go up to engine it just comes out of prop hub. So it is escaping somewhere. Same as when i put water down from the inboard side of the system (not the wet/exhaust side) instead of coming out the inlet grate it goes out the exhaust. It is a alpha 1 gen1 leg. It has been rebuilt awhile ago by previous owner but ive took it on as a project. The engine will run same as car but with exhaust cooling. same as lombardini marine generators etc. I am just wondering if it is possible that it has been rebuilt wrong as water shouldnt be able to go up inlet and come straight out exhaust without visiting the engine first.! Thanks in advance

achris · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Going back to your original post... Water should not flow passed the pump without it running, in either direction. If you put water on the leg intakes, water will only be pumped to the engine when it is started. If you put water into the inlet side of the colling system of the engine, then water will run out of the exhaust... That is normal.

Again, back to the original post... What problem are you getting? Is the engine overheating?

Chris..........

Sea beaver · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Hi, The problem is with the muffs on, engine running, there is no water getting up to the inlet to cool the exhaust. The water is just coming out of exhaust. Even with a few revs on to help "draw" the water up to the inlet it makes no difference. How is the inlet linked to the exhaust? I thought they were seperate passage ways?

Thanks
Ben

Chris Hays · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Sea beaver said:
Hi, I have a problem with one of my legs!!

Do you need a doctor?? LOL .................... (Sorry):redface:

achris · Oct 17, 2008

Re: Mercruiser Alpha 1 pump problems

Sea beaver said:
Hi, The problem is with the muffs on, engine running, there is no water getting up to the inlet to cool the exhaust. The water is just coming out of exhaust. Even with a few revs on to help "draw" the water up to the inlet it makes no difference. How is the inlet linked to the exhaust? I thought they were separate passage ways?

Thanks
Ben

Ben,

You appear to have an 'off the menu' cooling system setup... Without drawings and photos it will be impossible for us to give you any direction...

Chris...

Fishermark · Oct 18, 2008

Re: Mercruiser Alpha 1 pump problems

Like Chris said - when you start modifying things it can be difficult to diagnose - especially for someone who hasn't seen what you have done.

With that said, if no water is coming up from the leg and is simply going out of the exhaust... my best guess would be that perhaps someone somehow made a mistake when trying to mate the lower unit with the upper unit. When trying to install the water tube it missed the upper pocket? That's about the only thing that would make sense given what you describe.

Don S · Oct 18, 2008

Re: Mercruiser Alpha 1 pump problems

The engines are cooled by bigger radiators and bigger fans,

I know previous owner had the leg reffitted and i think it was done by monkeys???

??????????

Sea beaver · Oct 18, 2008

Re: Mercruiser Alpha 1 pump problems

Ok, thanks for all the replies. had the leg off and the problem was many things. The pump hadnt been fitted correctly. meaning it wasnt sealing to the inlet and just letting water out the prop hub. Also the impeller was the wrong way round. And to cap it off the pipe linking the pump to the top of the leg had cracked. So after a quick clean up. fresh gaskets and few other parts. job done. my home made water cooled exhaust runs perfectly. Took the boat up the river and got 14kts with a water temp of 78 c round my fresh water cooling system. not bad. now onto engine 2. Thanks for all the help.

Bondo · Oct 18, 2008

Re: Mercruiser Alpha 1 pump problems

Ayuh,....

I'm sure that I can speak for the Whole Gang here at iboat's forums,....

We absolutely Must see some pictures of this craft,+ Especially it's driveline/ cooling systems.......

Sea beaver · Oct 18, 2008

Re: Mercruiser Alpha 1 pump problems

As soon as i have the other engine in and its all tidy and neat i will post a load of pictures. Its been an interesting project so far. I will keep you updated!

Mercruiser Alpha 1 pump problems

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