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Old October 19th 05, 05:12 PM
Steve
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Default BB 366 - rockers clatter; oil pressure but no oil at rockers

This is why oiling the top end through the pushrods is a bone-headed way
to do it. The engineers that insisted on oiling through the rocker
shafts (Chrysler, Olds, Cadillac, etc.) were a few notches brighter than
the pushrod guys.

Short burst operation over a lot of years is a good way to crud up the
insides of an engine, and those small passages through the pushrods are
prime candidates. I once pulled apart a Ford 302 that had done years and
years of short-operation work on our farm, and the darn thing had *ONE*
open pushrod on the driver's side, all the others were filled with sludge.

My guess is that the long trip freed up a lot of goop in the engine and
added a collapsed lifter to the problem. New lifters and cleaning out
the pushrods will probably get things back in shape, though the bearings
may have taken a beating from crud passing through them as well. Be sure
to break in the new lifters as though you were breaking in a new cam
(first 20 minutes should be sutained at no less than 1500-2000 RPM, and
use a good break-in lube on the bottom of each lifter) or else you may
wipe a cam lobe in the process.




wrote:

> I'm back with an update. Thanks for all the help so far. I tried
> losening a couple of the rockers with the motor running as suggested
> but it didn't work; still no oil even after 30-60 seconds of running
> like that. I also hooked up a trusted mechanical oil pressure gauge
> and found that I do have 50psi at cold idle, so I'm ruling out oil pump
> and any serious bearing trouble.
>
> Here's a little background that may help the experts. This all started
> when I took the truck on a trip much longer than we normally use it.
> Typically, on the farm, it doesn't run for really more than 30minutes
> at a time, but I was helping my brother move and had to drive it on a 3
> hour trip, including some highway. On the way, after about 2 hours, I
> started hearing a ticking in the motor. It's hard to describe the
> noise; it was louder than the tick that comes from a loose rocker, but
> not as loud and deep as a connecting rod problem. It's frequency was
> dependant on RPM, but the noise did not get louder if the motor was
> revved up; it just ticked faster. I had no idea what the cause was,
> and since I was far from home anyway I figured the motor was toast and
> I tried to make it as far as I could. It made it the rest of the way
> to his house and back, running the same way.
>
> I started working on the motor and found the spark plug on the #5
> cylinder was smashed flat on the end, and that with a new spark plug
> the piston was not working right; it skipped and removing the spark
> plug wire from that spark plug made no difference in how the motor ran.
> I pulled the valve cover and found only a tiny amount of oil flowing
> down the rockers when it was running, went farther and pulled the
> drivers side head and found the exhaust valve on #5 was broken - 1/2 of
> the outer ring of the valve was gone and the piston dome was pretty
> lumpy. No pieces inside.
>
> I had the head checked and fixed, put it all back together. Now the
> motor runs very smooth, but the loud ticking is still there. With the
> motor running, I loosend the rocker on the #5 exhaust valve, and the
> noise got less and less; with no tension on the pushrod tube (it just
> going up and down but not compressing the valve, it was almost gone -
> the loud ticking noise (normal valve ticking was going on though cause
> it was loose). As soon as I slightly tightened the rocker the ticking
> started again. I pulled the intake off but everything looks ok, but
> what do I know?
>
> So - what does this mean? Can hydraulic lifters go bad and cause this?
> Could a bad lifter keep oil from going to the top of the head?
>
> Oh, and by the way - when I took the distributor out I think I know
> where the idea about the distributor came from. The channel in the
> rotor housing that passes oil from the pressure port behind it to the
> lifter ports on the side is not a consistent shape; one side narrows
> down and is much smaller than the other side. I think if it was in 180
> degrees backward it could impede the oil flow, but it didn't look like
> it would block it completely on my engine. It was in 'wrong' from what
> I could see - the narrower restricted side was towards the oil pressure
> port in the block.
>
> Tomorrow I will replace the lifters and spin the oil pump with a drill
> to make sure oil is getting up there. If that doesn't work I do not
> know what to do next.
>
> Thanks again.
>

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