390 rod knock noise, have oil pan off - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
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post #1 of 21 (permalink) Old 07-20-10, 05:35 PM Thread Starter
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390 rod knock noise, have oil pan off

And now what should I check for? I moved all the rods on the crank and they easily move back and forth, but don't seem damaged. I don't see anything obvious at the piston end. There was no metal shavings in the oil pan. My pan was pretty mashed at the oil pump end from some yahoo using that as a jack point.
Background.
I didn't have this knock when i got the car. The automatic never kicked down, so one day I adjusted it tighter and went out to make it kick down and see where it would upshift, but it never did. I think I hit 5000 rpm before backing off. When I got home, I noticed the knocking sound at idle and rapid knocking when letting off the gas, when just standing over the engine. I used a hose to try and isolate the noise and it seemed like it was in the pan. I believe some time in the past I took the valve covers off and checked the valvetrain. I've got a few cars, so not sure about that one.

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post #2 of 21 (permalink) Old 07-21-10, 12:00 PM
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Re: 390 rod knock noise, have oil pan off

Sounds travel in engines, so isolating it is a bit of a task. If there is a constant knock, then it's more than likely mechanical. When you checked the rods, did you try to move them up and down (small movements) to see it it might be a wrist pin? did you check to see if the crank moves up and down? That's 1. When you took off the calve cover were there any of the rockers loose and not traveling at full extention, Lifter or cam lobe. That's 2. Did you check the fuel pump, when they start to go bad sometimes the arm will bang on the essentric. That's 3.
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post #3 of 21 (permalink) Old 07-21-10, 01:19 PM Thread Starter
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Re: 390 rod knock noise, have oil pan off

One of the rods seemed to move up and down a little. I need to remove all the spark plus so I can spin the engine around easier. Should I loosen up the rod bolts so I can push around more one the rod?
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post #4 of 21 (permalink) Old 07-21-10, 03:34 PM
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Re: 390 rod knock noise, have oil pan off

If the head is still on the engine then take the rod cap off the rod and pull it off the crank, then very easily, remove it off the crank, now, keeping the piston head in place pull up and down "very easy" on the rod. If the rod moves while the piston doesn't then you have a wrist pin problem.

If you need more room to do this turn the motor so that the crankshaft is out of the way. Be careful that you don't scar the crank with the rod bolts.
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post #5 of 21 (permalink) Old 07-22-10, 02:14 PM
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Re: 390 rod knock noise, have oil pan off

Sorry I cant add to your concern but I had a question myself. Would the fuel pump sound like a lifter going out. Would it be that audible. I've got a ticking going on in my motor but i stethescoped the entire top end and can't find it. When I crawl underneath i can hear it but can't locate it. This is driving me nuts. If it could be the fuel pump that would be awesome.
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post #6 of 21 (permalink) Old 07-26-10, 06:38 AM
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Re: 390 rod knock noise, have oil pan off

Have you checked the oil pressure? If it knocks when you let off the gas, sounds like a rod bearing has failed.
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post #7 of 21 (permalink) Old 07-26-10, 10:53 PM Thread Starter
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Re: 390 rod knock noise, have oil pan off

Quote:
Originally Posted by marengo View Post
Have you checked the oil pressure? If it knocks when you let off the gas, sounds like a rod bearing has failed.
Car does not have an oil pressure gauge. After I took the pump off, I turned it by hand and it felt tight and did move some oil out. Don't know how to test a pump out of an engine.
Hit a lazy streak. Need to get back under there and try all the good advice!
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post #8 of 21 (permalink) Old 08-02-10, 07:42 PM Thread Starter
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Re: 390 rod knock noise, have oil pan off

Computer died a hard death....
Got some inspection done.
Pulled the spark plugs and #4 and 8 rod bearing caps. #8 has some grooves in it. #4 looks ok. bearings are
=====================
B
Clevite 77
-----------------
3 99
CB 760P
.010
===================
With the rods loose, pushed up an down on those rods. No movement.

Spark plugs (Autolite 45) a mixed bag. 1, 3, 4, 5 and 6 a nice tan color. #2 was loose and oily-sooty. 6 did have some oily threads. 7 was dark sooty and 8 even darker.


Some photos:
Fairlane work
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post #9 of 21 (permalink) Old 08-03-10, 07:47 AM
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Re: 390 rod knock noise, have oil pan off

gpjed55

A fuel pump going bad would be more of a knock than a ticking, unlike losing a lifter or cam lobe where oil is essential, the fuel pump would have a weak or colapsing spring in the arm. Try a fuel preasure guage and if you have low preasure with th combination of a knock chance are it's the pump.

On the other side of the coin your ticking might be the cam or a lifter. check the valve train for full travel on each one. If there is a loose one that will be more than likely your problem. Check the cam lobe heights with a dial indicator to make sure they are within tollerances. A colapsed lifter is easier to fix than having to replace the cam.
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post #10 of 21 (permalink) Old 08-03-10, 08:52 AM Thread Starter
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took fuel pump out

It actually looks very new on the outside. I moved the arm and it is very firm/solid. Also took off the #1 rod cap. It's bearing is slightly grooved but not to where I can feel it like the #8 was. Checked tourque on all cap nuts. Good.
Going to take off the flexplate shield today and check those bolts.
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