Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

[Rake722]

Hi all,

Finally my 470 runs. Turns out the starter was the cause of all my problems.

Loaded the new one - started first turn of the motor.

Me jumping for joy forgot that it was in gear and went to inspect the tub which was by then empty and white smoke billowing from the impeller intakes.

So I gotta change the impeller on a pre alpha leg.

Is there a how to or any advise please ? Can I just drop the lower part of the leg ?

Many thans for any pointers.

Ron,

 

[Eric 3.7LX Alpha 1]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Here are a couple of videos for you check out, let you know what you are up against

Seperating the Upper Gearcase from the Lower Gearcase
http://youtu.be/kfpasFN_g8w

and another
Mercruiser water pump removal and repair video
http://youtu.be/0QC6_j2_wmA

and also check this out: Good Download here VVV
How To: Replacing Merc Alpha style impeller
http://forums.iboats.com/showthread.php?t=387864

 

[Rake722]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Thanks Eric,

I'll have a look now.

All I have is the impeller - will I be able to complete without gaskets and seals etc ?

 

[achris]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Thanks Eric,

I'll have a look now.

All I have is the impeller - will I be able to complete without gaskets and seals etc ?

You MUST replace the gaskets... .You want to risk an engine for the sake of $2 worth of gasket?

The question I do have, how long was it running without water? If you had smoke for the water intakes I'd say quite a while.... While you have the lower off replacing your smoldered impeller, take a look up into the bottom of the upper unit. You'll see a plastic cover that the copper water pipe goes into... If that shows ANY sign of melting, then it will need to also be replaced. The gasket leaks and when there's normal load on the engine (in the water) exhaust gasses get forced into the cooling system... .and the engine overheats... Not a good idea for the 470s....

Chris.....

 

[Rake722]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Chris - thanks,

My local shop didnt have any gaskets as we are UK based and not alot of parts around here.
Is there any alternative to a gasket ? sealant or anything as this is out holiday weekend and no boat unless I get this fixed tomorrow am.

Well I just rebuilt the carb and initially I thought it was fuel based white smoke but looking at the impeller intakes there is whiteness around the holes so I assume its the impeller smoke ???

I'd say she was running for 2 minutes.

Any help wpuld be great. Its go / No go for this weekend.


EDIT - just watched the video pposted and it seems the gasket goes on the lower half of the pump housing.

If I only replace the impeller and dont remove the lower housing - is that a get out of jail for free or am I just being desperate and stoopid ?

 

[achris]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Desperate... Once you remove the pump housing (not the base) there are a pair of gaskets that go either side of the plate... You can't get away with not replacing them.... And do the look up at the water pocket cover too... 2 minutes without water is well and truly enough time to fry it... Use a good torch when looking...

Chris........

 

[Rake722]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Thanks mate.

Looks like the boat is grounded this weekend then.

This is so frustrating after having a week of 25 degrees C and a non runner, I now have a runner but no impeller kit.

Hmmm, I wonder if there are any mer kits in Wales where we are going. Might ring Llyn Marine and see, if so I can take the boat and my tool kit and do this job on the camp site.

Its the only option left.

Found this one too that shows a different pump housing -

http://www.youtube.com/watch?v=jXq35NOX8kw&feature=related

Thanks again.

Ron.

 

[Bt Doctur]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

That video is for the GEN II type drive,not the Alpha that you have. You want a full pump kit including the base. You also want to check the water pocket cover for leakage from the overheat.

 

[Rake722]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

I'm such an idiot for rushing and leaving the thing in gear.

I didnt even get to see the 50 gallons of water being displaced in a fraction of a second - would have been a class photo if my son had been standing behind it !

Thanks all - lessons leanrt here and more to come when I get the kit.

 

[achris]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Just down having breakfast (I'm currently at work) and it dawned on me.... Stupid for not realising it at the outset... :facepalm: You will have smoked the entire water pump, not just the impeller... The housing, the cup, the plate and the base... You need to replace EVERYTHING!!!

Sorry to be the bearer of such bad news... If you take the boat and the tools to Wales, don't forget drive oil!

Just a quick question... Why in a tub, why not on muffs... Would have saved you all this grief... And why were you able to start it in gear? Have you got the neutral safety switch bypassed? Bad boy, that's a bit naughty!!!

Chris.........

 

[Rake722]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Hi Chris,

Guess you are right. Should have used muffs.

I'll leave the boat here the weekend. Forecast has changed for rain so not worth the bother.

Regarding the neutral - this boat is new to me and I now know the swich is bypassed. PO must have done it for some reason. Gotta figure out how to restore the safety.

Thanks again

Ron.

 

[stonyloam]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

I'm such an idiot for rushing and leaving the thing in gear.

FYI that does not matter, the driveshaft that turns the impeller turns anytime the engine is running. The engine needs cooling water -in gear or not. You may want to check your exhaust shutters too.

 

[stonyloam]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Hi Chris,
Regarding the neutral - this boat is new to me and I now know the swich is bypassed. PO must have done it for some reason. Gotta figure out how to restore the safety.

The only reason I can think of to do that is that the throttle only button is not working. Give it a try, push in the button and see if you can move the control without engaging the prop.

 

[achris]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

FYI that does not matter, the driveshaft that turns the impeller turns anytime the engine is running. The engine needs cooling water -in gear or not. You may want to check your exhaust shutters too.

Because it was in a tub of water, not on muffs, when it fired and ran in gear it threw all the water out the tub... :facepalm: And he didn't have a hose running into the tub to replenish...

 

[Rake722]

Re: Haleluja followed by Arrgghh Shoot. - Merc 470 impeller melted

Yep but we took her appart and mininal melting. The impeller was in good working condition. I found that the seal in the water intake upper leg had been caught by the copper pip and half of it was blocking the water passage.

This was the main reason for the lack of circulation.

The only melted thing was the guide ! Made new gaskets found a new seal and off we go.

Thanks for all the help.


Ron.