Before jumping in and taking things appart in the cold and the rain I thought I would run my symptoms past the group because I'm sure someone has seen this before (and yes, I did check the search function Ώ]). The engine has started making a hollow knocking noise proportional to engine RPM but only around idle. Blip the throttle just a bit and it goes away completely. If you give it a good rev it won't make a sound until its been idling for a couple of seconds. So far I've:

+ (re)done the clearance on the all the valves (they were okay to start with)
+ checked valves for opening (no dead lobes)
+ gone over the exhaust manifold and collector with a fine tooth comb (no cracks, blown gaskets, loose brackets)
+ checked the compression (155-155-150-155)
+ changed the oil (no metal bits, no water)
+ looked at the coolant (green and oil free)
+ changed the transmission oil for fun (M41 long shifter, also clean)
+ used a metal bar/chunk of fuel hose to try and isolate the noise.
It doesn't seem to be coming from the waterpump, alternator or top of the valve train, otherwise the exact source of the noise eludes me.

I'm suspecting the gears for a couple of reasons. First, it was commented that these can produce knocking noise at idle which goes away with revs due to the oil pump loading up that end of the cam ΐ]. Then I remembered that about a month ago, and for no good reason, I had to retime the engine because it lost a bunch of power. Turns out, it decided it wanted to run at 0dege BTDC. I reset the base timing and went back to driving it.

Any of these symptoms sound familiar? Am I naively hoping for an easy fix?

Thanks

Joel



Ώ] I now know more than I even want to know about the availability of steel gears, the advantages thereof and how the big gear is not compatible with the crankshft gear.

ΐ] http://www.brickboard.com/RWD/?id=679466 (symptom 3) An author much better informed than I, but, it's always good to double check.