1977 MC-1 Single Impeller Blade Pointing Worng Way ?

[Rake722]

Dear forum,

I have on ald dog of a drive that is giving me some greif.

It over heated last trip out so I inspected the water pump only to find a single blade pointing the opposite
direction to all the others.

Replaced with a top half kit and impeller and the other day I ran her dry by accisdent so had another kit sent over only to find that the same thing had happened twice and the new impeller had one blade pointing the opposite way to the others.

That leads me to the following Q's

1) How can this happen ?

2) Would it cause an over heat or affect the cooling efficiency ?

3) How to avoid it happening again of course.

The prop spins clockwise, when installing I rotated the drive shaft clockwise whilst pushing the pump top onto the impeller to install it. I beleive this is the right way to do it.

Only thing I can think of is that the drive shaft needs turning anti clockwise - all but one blade self corrected but the manual says rotate shaft clockwise to install.

Any advise gratefuly received.

Thanks

Ron.

 

[Fun Times]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

Hi Rake722, Sometimes due to impeller housing design you may get a blade that comes to rest in the opposite direction. It's not much to worry about as it should right itself once it gets turning. It's not going to affect your immediate cooling efficiency.

 

[MikDee]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

Ditto, Look elsewhere if you have an overheating issue.

 

[Bt Doctur]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

Clockwise on the driveshaft is the correct direction.

 

[UncleWillie]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

Clockwise on the drive shaft is the correct direction.

+1
Clockwise on the Prop Shaft of a Right Hand Drive, looking forward into the rear of the prop.
Also, Clockwise looking DOWN at the Drive Shaft that the Impeller is mounted on.

 

[Bt Doctur]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

and clockwise for the reverse rotation too

 

[Rake722]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

Thanks for the replies.

Strange because before I replaced this pump and top housing I had run her dry for about 5 mins before noticing.

Then Once the hose was reconnected I noticed water coming out of the muffs even with the engine running.

I thought that was strange. Now with the new impeller the water no longer sprays out from the muffs implying the old one was not working well.

Observation shows no deterioration of the Impeller I ran dry and the blades return to original star shape and don't retain the bent shape from the housing.

I am really at a loss explaining why it was not sucking enough water before replacing it.

Thanks again
Ron

 

[MarkSee]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

.......Observation shows no deterioration of the Impeller I ran dry .........I am really at a loss explaining why it was not sucking enough water before replacing it.

That impeller you refer to is the one that had no water for a full 5 minutes? If so, that is amazing.

Maybe there was air being sucked into the impeller housing thus reducing the amount of water being taken in?

Mark

 

[Rake722]

Re: 1977 MC-1 Single Impeller Blade Pointing Worng Way ?

Hi Mark,

Yes I have often heard people say that running these dry for more than 30 seconds means sudden death to the impeller.
Having seen this one after a good 5 mins dry I dont understand why.

There was no deformation, blades kept their elasticity and no delamination from the center.

Never the less I have replaced it again.

Regarding sucking air - yes it will have been when the hose popped off but once reconnected with a full pressure flow
water could be seen to be spraying out from where the muff ears met the outdrive over the pickups. Once the impeller was replaced this was no longer the case and the muff ears were dry implying that there was indeed a problem but what that problem was beats me.