NAC: Need help fixing my furnace - Found problem

[Cody Forbes]

YAY! Yesterday I got off work a bit early and got to get under the house 
during daylight hours to give it a go. I figured if I shut the tank valve 
off and shut down the power the damned things already broken ... may as well 
tear into it.

I found the screen that was mentioned by a few of you very quickly, and 
found it clean as a whistle. So I decided to dig further. I got down to the 
business end of the pump - it's identical to a 5cyl Audi engine oil pump, 
just teeeeeny tiny. Everything looked good, outer gear spun freely, but then 
I noticed that so does the inner. The inner gear of the pump should be 
driven by the motor and should NOT free spin. So I dig deeper. I found the 
optical sensor that a bunch of you mentioned and while I was there made sure 
it was clean, it was. Then I found the culprit. Theres a drive coupling 
between the motor and the pump. Each has a different sized shaft with a flat 
spot to key it to the coupling. Well the coupling is plastic and the keys 
had simply worn out of it. The motor was turning, but wasn't turning the 
pump. I got a replacement coupling today for a couple bucks, but haven't 
installed it yet.

Ironically the weather turned warm today, was in the 70's and is supposed to 
stay 60's to 70's for a while.

Thanks for all the support and info everybody!! Special thanks to Bob Myers, 
Mike Claire, Huw Powell, Wylie Bean, David Conner, Randy, Nick in OH, Peter 
Orban, Scott by Boston, and even big-wig Dan Simoes (both for suggestions 
and for providing the medium for my questions!!). Once again it's quattro 
list to the rescue ;-).

-Cody Forbes
http://www.5000tq.com
'86 5k noT noQ
'86 5k noT noQ - Parting Out
'87 5ktq
'87 5ktq - Fast. Really Fast.