Intermittent Engine Noise

[oilyman]

Hello, I am new to the site and very happy to be a member. Current project is a 65 Ranchero. Currently trying to diagnose an engine noise. Build date/mileage of our (mine and my son's) 200 is unknown. The Weber 38 and the Pertronix igniton really woke it up and we are looking forward to a complete rebuild as money allows. Recently a knock developed that is very intermittent. Usually noticed on a cold engine parked uphill in the drive, parked downhill the noise goes away??? The noise is not always present, but I have noticed when it is, it is in time with a timing light which to me means it is probably in the valve train. Although using a metal rod against the ear/engine the noise seems to be loudest near the rear throw of the crank. When I first heard it my thoughts were collapsed lifter. Any thoughts/suggestions would be most appreciated.

Thanks,

 

[JackFish]

Do you know if the engine has adjustable rocker arms?
Lifter noise is more of a ticking sound.
A knock might be a rod bearing or something bottom end related.

 

[CobraSix]

Easy, don't park uphill.

Seriously...

More than likely what is happening is that when you park up hill, the oil sump is sucking up some air and dropping oil pressure (sump is in the front of the engine) which is leading to valve train chatter.

Now, you may need to adjust the rockers as well and you may just have one slightly loose that is being exasperated by parking uphill with the slightly lower oil pressure.

Slade

 

[oilyman]

JackFish, CobraSix,

It has hydraulic lifters/non-adjustable rockers, engine has good oil-pressure, a non-smoker and doesn't use oil although it does leak about a quart between changes (3000 mi). I haven't noticed a difference in oil pressure up or downhill, and it doesn't always make the noise. Doesn't always make the noise, the first time I heard it, it was parked on level ground.

 

[oilyman]

Today I pulled the tranny, dropped the oil pan to replace the rear main seal (the only oil leak left), I went ahead and inspected all the mains and rod bearings, they appear to be the originals (all marked FoMoCo) and in good shape. I did find some damage to the flywheel ring gear but nothing I could identify as a noise maker :| . Oil pan was clean with no gremlins laying around the bottom. Tomorrow I'll mike the journals and if I see no surprises I'll probably go back with a new set of standard bearings.