'68 mustang ww/289 rebuilding

[philman]

wife's mustang started running rough, running hot.found cylinder #7 was not firing properly.decided it was time to pull engine, when I took off the oil filter to remove left motor mount I found the oil filter had no oil in it, none, no residue, nothing.I had changed the oil and filter when wife was complaining of running rough.guage oil pressure indicated normal.motor is in shop for a rebuild.any ideas??

 

[sammyb]

Wow, this might be a question for the few Mustang gurus here, but my vote is for a clogged oil passage...I wonder if there's a big metal shaving or something blocking?

Was there ample oil in the pan/on dipstick?

 

[Steve]

I would concur with Sammy. I had thought that a buildup of sludge might be responsible for the blockage however.

 

[Guest]

Yikes, that would certainly scare the heck out of me. The 289 is a pretty tough little motor but, like any other, not without good oil flow.

I'd have to take a guess at this as well. Sounds like it could be a clogged passage. You said the motor was running rough, was there any valve chatter or anything like that that might indicate that areas of the motor were not receiving good oil flow? Just curious to know what you mean by running rough, like just the miss or something else? I would be worried about the running hot part. If you had a miss in #7 that alone shouldn't cause it to run much hotter. Maybe a little but not near overheating hot. Were you able to figure out what was causing the miss? Another consideration, the oil pumps in these motors have a spring loaded high pressure bypass valve built into them. Maybe that has gotten stuck one way, which would bypass oil flow from the filter. These valves keep the high pressure cold start oil from going to the filter so you don't blow the thing off. If the valve is stuck that way oil will never get to the filter. Usually they stick closed though, and you end up blowing the filter off the motor. Never seen one stick open but I guess it's possible, especially if a small piece of gasket or bearing has gotten lodged in there. The bore for the valve has clearances of only a few thousandths.

It sounds like there might be a relationship between some of the other symptoms you have described and the lack of oil to the filter. If this has been going on for some time without your knowing it unfiltered oil may have caused damage to other parts of the motor, mainly valve train and bearings. Be interesting to see what they find when they crack her open, let us know.