Re: Looking for the "Key" to impeller key installation
WOW,
Remarkable. I've never experienced anything like this forum. THANK YOU ALL. I've built automotive racing engines with good results. That was insufficient background for the undertaking of re-building a small outboard. On the issue of my difficulties with the cooling impeller installation, I am sending special thanks to several men who were helpful. I'm also including at the end, a few things I did that employed their knowledge and also worked for me.
First, I apologize to those who were discomfited with my use of "Sir" in my addresses. To you guys, I was drafted as an E-1 in the middle of the Viet Nam conflict, I served E-1, E-2, PFC, Spec 4, Buck Sgt, Staff Sgt, (then sent to OCS) 2d Lt, 1st Lt, Cpt and Commanding Officer. I even address my girfriend's father as "Sir", just a built in reflex on my part. Sir is honorary, not a reflection of rank or duties or anything else.
The good news. The impeller is in, is fully functional and my I.R. meter shows engine temperatures well withing operating ranges at all speeds. This would not have been the case had not:
Charlie B suggested emory cloth on the main propeller drive shaft and warned me about the risk of grease deteriorating rubber.
Lots of Boats shared his good idea about using a sharp punch to get an interference fit for the "key"
emckelvy referring me to a helpful old post to the forum
right coast Rob warning be about force being an indicator that something wasn't right
Scatty suggesting silicone to hold the key in place
AMD Rules for emotional support, guidance on patience and enough interest to request a picture of the engine
Laddies for pointing out that a mark on the prop driveshaft to identify the center of the milled Key slot would help and for warning me that the process would take a "few tries". Laddie please define "Few"....
From my own experience should anyone in the future read this thread, I'll add some things I did to make the repair possible for me:
I used a case hardend "splitter" chisel to crack the old impeller bushing apart at the thin part centered on the key, being careful to not harm the propeller drive shaft or the key. The engine is from 1967, nothing less would remove the old impeller bushing.
I used compressed air to clear out the debris in the impeller housing feeds and outlets. Air stream directed up through the water inlet.
I chucked the top of the splined end of the prop driveshaft into an electric drill and spun the shaft inside a tensioned loop of emory cloth to clean up the surfaces involved with the impeller.
I wrapped the flexible "paddles" of the impeller with carpet thread, paddles correctly angled, tightened them down to fit easily during installaton, then snipped the thread and removed it after installation. Rotating the prop shaft aids removal of the thread remnants. Note, the prop shaft rotates clockwise when viewed from above, the alignment angle of the paddles is apparent.
I cleaned the keyway to surgical standards!! Helped a lot.
My fingers are way too large to be of any use in putting the key into place. I used some more carpet thread and a tiny drop of superglue and accelerator on the convex side to serve as a "handle" to get the key into place to interlock with the impeller bushing. The thread split aduring assembly and was easily removed after installation.
"RTV Blue" is impervious to water. A tiny bead between the mating surfaces of the impeller housing should function wel as a replacement for a Mercury gasket that seems to be made of "Unobtanium" as the base material.
Locktite Blue used on all fasteners.
I close this post with my most sincere thanks to all who guided me, informed me and encouraged me.
Gary
