Chevy 250 Cid engine problem...UPDATE

For those of you who are interested I have an update as to my problem with a 250 chevy engine.

My original post:
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I have a pickup with a GM 250 Cid engine, 6 cylinders – carburetion.

About a week ago it suddenly started running badly and then I noticed the oil pressure gauge dropped to zero. I immediately shut the engine off and towed the pickup back to the ranch.

A couple of days later I had time to look at it and started it. The oil pump immediately had the required pressure but the engine still ran badly – like it was out of time. I retimed it (it was okay by the way) and started it but it still ran rough.

I took the compression in each cylinder and all were even and within specification. I removed the pan and looked at the oil pump and it was fine.
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The problem turned out to be a broken push rod. It had broken off the tip of it which is about 3/16".

I guess it had just enough movement to allow the valve to move just a little thereby giving a passing compression test.

What gets me now is the loss of oil pressure. Could the broken lifter have caused the momentary loss of oil pressure?

Thanks everyone....

Mike

• The original thread...

Thanks! So that"s the common link between the oil pressure and the rough running. I never had something like this ever happen so the symptoms caught me off guard. Well everything now is running back to normal and I"ve learned something.

Thanks everyone for the help. I really appreciated it.

Mike