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drnittler
02-19-2007, 07:54 PM
Hi, Some questions: On my 289 V8 the other day I was driving my Lark. I heard some banging and the oil light came on (rapping like a slapping or ??). Anyway I turned off the car and had it towed. Later on I started the car and it would start and idle. When I would rev it up it was a bit noisy, but not as bad as before. I am at a loss to guess the problem.
Stuff that was done:
Two years ago I needed to repair piston 7 and the valves. The repair had 2000 miles on it. The block has been cleaned out, timing was perfect, oil clean etc etc. I checked that piston 7 had compression and it did. Oil pressure starts at 50-60 and goes to 20-30 when the oil is warm. I put a oil gauge on it and pressure comes up and it good. Some times it acts a bit out of time but the distributer had not moved, the rotor was ok moves etc. Nothing seemed to be binding.
Ant thoughts are appreciated to save this stude.

David G. Nittler

John Kirchhoff
02-19-2007, 08:43 PM
Boy, that sounds like a bad rod bearing to me. Were it me, I sure wouldn't run it any more until until I could drop the pan and see what's going on. If it is a bearing, the reason it sounds less noisy when cold is because the oil's colder and stiffer. Oil pressure is realitive...on a worn engine it could have worn but ok bearings and have 20 pounds but a good tight engine could have one ruined bearing and have the same pressure. The thing is, you don't know what the pressure was before the noise started, it may have been much higher. Concerning the oil light coming on, I know this sounds stupid, but it does have adequate oil in the crankcase doesn't it? When very low on oil, acceleration or decceleration can slosh the oil forwards or backwards and starve the pump intake momentarily. What repairs did you do to #7 piston? Depending upon what it was, that could possibably give a clue to what's going on. Other things can make bad sounds also, but the rod bearing would be my first guess without actually hearing it.

whacker
02-19-2007, 08:54 PM
I agree with John, but before you go to all that trouble you should check the simple stuff. Do you have a loose fan blade? Are your motor mounts intact? Has something found it's way into your bell housing that could be hitting the flywheel? How about your fuel pump cam, is it bolted down tightly? Not a bearing going out on the waterpump? Check the simple stuff first.

drnittler
02-20-2007, 04:43 PM
Thanks for the help so far. Let me give better details. Two years ago a valve keeper broke and caused the valve to go through the piston. (#7) I also messed up the cylinder head. So I replaced the head (Used from Steven Allens), The piston, rings bearing and so on. I had a machine shop check the head, ground and or replaced valves etc. Put it together, a mechanic made all the necessary adjustments valves timing and etc and the car ran great for two years). (The oil pressure was ok). I will check if other stuff is ok and tight. If I find out of the rod bearing is bad, should I go ahead and replace them all? Can this be done with the oil pan off and not the cylinder head?).Anyway thanks for the help. Dave

David G. Nittler

John Kirchhoff
02-20-2007, 06:21 PM
I don't think you can buy just one rod bearing and even if you could, I'd never replace just one on an engine that's seen very much use. Too much work replacing one to not replace all of them. I've never replaced rod bearings in a Stude engine while still in car. I'll have to refer that question to those more experienced in that arena.

When you had the valve problem, did anyone check the connecting rod for straightness? Considering the problem, if any of the people involved knew the details of what happened, they should have checked or at least told you to have it checked. She hit pretty hard to barf up the head and punch a hole in the piston and that could have bent the rod ever so slightly. That would cock the bearing on the crank journal causing uneven loading on the bearing. Hopefully it will be something else, but if worse comes to worse and it is the bearing, look to see if the bearing is worn on one side only. If so, you'll want to pull the head and remove that piston. Rods can be straightened, but I'm sure someone on here has a rod for less than what a machine shop would charge. Keep us posted.

drnittler
02-20-2007, 07:22 PM
The rod appreared to be straight and did not bind. I am trying to remember if I replaced the rod or not, probably not. opps.

David G. Nittler

John Kirchhoff
02-21-2007, 11:34 AM
Most bent rods are so slight that you can't tell with the naked eye. You're looking at thousands of an inch. If you do remove the pan, check the bearing as I said. That should give you an idea. If the bearing is ok or worn evenly, the rod is likely ok.