snap ring on Oberdorfer

[wingman]

I did a search, but didn't find anything specifically on this.

When I exchanged the impeller on the Oberdorfer, it was missing the snap ring under the brass washer (it was also missing one of the washers).

To get the snap ring on, it appears that you have to pull the main impeller shaft 1/8 inch or so out from the engine to expose the channel on the shaft that the snap ring fits into. Is that the correct assembly?

If the shaft is pushed in all the way, the channel is buried in the impeller.

[KWKloeber]

You didn't search hard enough! 

Look at the TechWiki > Engine > Cooling topic.

My entry re: the correct-clip explains what to do with it (deep six) and why.

[Stu Jackson]

Ken's right.  I just did a search on "+snap+ring" and found this:

https://c34.org/bbs/index.php/topic,7974.msg55346.html#msg55346

[wingman]

Thanks guys! Maybe because I was originally searching on circle ring!

Ok, now one of the brass washers was also missing, which is obviously easy to replace. Was running for quite a while without the inner washer...

[KWKloeber]

Wing,

There is no particular issue with removing the shaft if needed, either.  REPLACING it is somewhat touchy.
Lube the end w/ SuperLube and carefully slide/twist it in, so that the leading end goes into and past, without knicking, the two rubber seals.  Twist until the male tang seats in the female fork on the end of the camshaft, and voila.

As far as the inner washer - pop quiz.
What value do you see in it?  i.e., what function does it serve with the impeller on the shaft and the shaft installed through that washer into the pump body?

-ken

[wingman]

As far as the inner washer - pop quiz.
What value do you see in it?  i.e., what function does it serve with the impeller on the shaft and the shaft installed through that washer into the pump body?

Ken, ok, I'll bite. I was looking at the washers like they were regular washers that you might use with a bolt. But maybe the washers are designed to support the impeller on the shaft, but missing the inside one isn't critical?

As a non-engineer I assume all the bits and pieces have a reason to be there even if I don't really know why...

[Jim Hardesty]

I assume all the bits and pieces have a reason to be there even if I don't really know why...

You are a wise man.

[KWKloeber]

As far as the inner washer - pop quiz.
What value do you see in it?  i.e., what function does it serve with the impeller on the shaft and the shaft installed through that washer into the pump body?

Ken, ok, I'll bite. I was looking at the washers like they were regular washers that you might use with a bolt. But maybe the washers are designed to support the impeller on the shaft, but missing the inside one isn't critical?

As a non-engineer I assume all the bits and pieces have a reason to be there even if I don't really know why...

Wing

I'm glad you asked!  It goes toward your replacing it with a plain'ole washer.  I doubt you would find an off-the-shelf washer with that OD, ID, and thickness anyway.  However, the short answer is, there's no harm installing it or the front washer, but you don't need them. 

Read on, if you're interested why (i.e., Stu's "How does a wristwatch work?" answer.)


***
The impeller has essentially zero fore-aft movement.  Why?  The impeller vanes ride against the back of the cover and against the body of the pump.  So it's fixed - it cannot move fore-aft.

Two things limit the pump shaft fore-aft movement -- the impeller and the engine camshaft.

The shoulder machined into the shaft rides directly on the metal hub of the impeller (i.e., the brass center with the flat in it.)  That limits shaft forward movement. 

With the shaft pushed all the way "in," the other end rides against the front of (and fits into the female fork on) the camshaft.  That limits how far aft the shaft can move (the camshaft is why no cir-clip is needed on the shaft.)

The shaft passes through the back washer (it simply floats free.)   So along with the front washer and the cir-clip, the rear washer is unnecessary -- they do not contact the pump body, cover, shaft, or cir-clip.)  Owners have run w/o those washers for hundreds of millions (not thousands) of impeller revolutions.

TMI?

-k

[Ron Hill]

Wing : You don't need the snap ring ("C" clip).  Look at the inside of the pump.  The impeller sit in the cavity and cannot move forward.  Then you install the cover and the impeller is captive. 

The only time I envision that the "C" clip is necessary is if you were to run the Oberdoffer with the cover OFF!!!???


A few thoughts - One VERY Gooffy!! 

[wingman]

Ok, I'm convinced those parts aren't needed even though Moses L. Oberdorfer may be rolling over in his grave.