318 just started knocking???

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Golden Scamp said:
The plugs are oily, so where is this oil coming from and does this mean I have seals or rings that are not doing their job? Also, this knock is seems low in pitch, not like a tick form the valvetrain but more like a bump bump bump from lower in the motor.
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It could be rings or valve seals.
 
Golden Scamp said:
The plugs are oily, so where is this oil coming from and does this mean I have seals or rings that are not doing their job? Also, this knock is seems low in pitch, not like a tick form the valvetrain but more like a bump bump bump from lower in the motor.
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I have heard that low thud knocking , it wouldn't do it until the engine warmed up, as the oil got thinner and began losing viscosity , it would get worse. nothing I did from outside the engine would cure it. pulled it out , took the pan off and found one loose rod nut/bolt. it had finally beaten the rod bearing into submission. I never lost oil pressure. I replaced that one rod and cap, new bearing, put it back together , and it ran another 50K
 
I was afraid of the rod scenario, but I'm thinking this is what we may have here. Is there an easy way to turn the rotating assembly in the motor if I drop the pan and try to go at it from below to check those bolts? There is almost no circumstance in which I plan on pulling the motor here. I would just like to be able to rotate everything around and check from underneath.
 
Golden Scamp said:
I was afraid of the rod scenario, but I'm thinking this is what we may have here. Is there an easy way to turn the rotating assembly in the motor if I drop the pan and try to go at it from below to check those bolts? There is almost no circumstance in which I plan on pulling the motor here. I would just like to be able to rotate everything around and check from underneath.
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if there was enough clearance between the journal and the bearing (or lack thereof) , you could have someone on the crank bolt moving it back and forth while you are looking for a rod that isn't moving right away, or , one that you could actually shake and it would rattle. you would have to have a ton of clearance for that to work , and I would imagine , you would have one hell of a knock if that was the case. I am going to say that you don't have that kind of clearance. IF it were ME, and I was not able to pull the engine, I would pull the pan , pull the oil pump, take off one rod cap, bump the journal away from the rod, measure that rod journal , and order a set of 8 rod bearings , and replace them all. get a new oil pump while you are there. chances are good that if you have one going , another will follow , if this is an older engine. I didn't read the last page before posting here lol

if it is in fact a rod bearing , you do not want to run the engine one more second so you are not trashing the rod or journal associated with the knock. if you find a bearing that has spun or that has become so thin the journal is beating up on the rod , you will have to replace it. worst case is that you spun a rod bearing and the journal would be wasted, but I have a feeling , since the knock is not that pronounced, and by your description , that you will be ok. I guess what could be worse is that you go through all that and find that wasn't the problem . the only other bottom end knock I can think of , would be a wristpin. I suppose it could be piston slap but that's not quite an actual knock
 
once my rocker shaft bolts arrive, and i get that mess sorted out, I can actually get to the bottom of this. From what ive been reading, it really does sound like a rod. Don't know if this motor has ever even been torn into. I'll update next week once I've pinpointed it. Thanks again for all your advice.
 
If the knock is comming from one cylinder wrist pin or rod bearing, start it up and pull one plug wire at a time. When you change the knock sound you found the source.

The misprint for rocker shaft bolt torque has been in a few aftermarket books for years now. I've never heard of this misprint in a factory service manual before. Anyway...
Correct is 18 ft. lbs. not 30. Too late I know. Good luck with it.
 
63VALIANT*KISS said:
thought about doing this myself bonds! do u have to take the rocker shaft off i worked on a golf cart engine and removing the pushrods i could pull the rocker arm up and pull the rod out. could i not do the same one by one on my 318?
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Yeah, it can stay on, but not tight. It's not worth keeping in place and it's extremely easy to remove the shaft, the bolts and spacer washers under the bolt heads in one deal. If you just grab them by the front and back end with the bolts completely unthreaded, pull them straight up and off, let the rockers rotate upsideown and put them in the valve cover, to the side as you work.

There is no way you could safely move the rocker arm without prying on something you shouldn't.

They are five bolts that need loosened and tightened by hand, in a sequence. It takes less than two minutes to undo them. Putting them back on by letting the longer valve side of the rocker arm simply use the top of the valve spring retainer to guid all 8 rockers back into place, upright and plop the bolts back in the holes.

Golden Scamp,

you could buy a cheap, automotive stethascope. They work extremely well for finding the source of a knock.

If you don't find any bent pushrods, you could put the system back together, button it up and take the stethascope to the sheetmetal parts first.

If you hear something from the top end of the oil pan with the wand, it could be a rod or main bearing that is spun. Don't give it a lot of RPM. Just diagnose it from idle.

If it sounds like a pushrod, but you don't find anything, it could be a trashed lifter or camshaft.

The stethascope is an easy and cheap way to determine if you need to do some major overhauling.

One other thing that hasn't been mentioned is checking your oil for damage.

Metal will not show on a dipstick. It falls to the bottom of the pan and into any low areas of the engine, like down in the lifter galley up top, in pockets in the cylinder head, etc. If you did hurt the cam, you will see some of it in the filter element.

If you are up to the task, you can drain the oil, remove the filter, stab it and cut it open with tin snips. The element will be dark with carbon, but you should be able to see some metal. If you use a magnet and pick anything up from the filter, it could very well be a flattened cam lobe and trashed lifter.

If you see metal flakes that are lighter in color and the magnet doesn't pick anything up, it could be a bearing problem, in which case RedFish's suggestion of pulling one wire at a time on the distributor cap, while it's running (wear gloves) will tell you if it's a rod bearing and which one is slapping, every time the engine fires on that cylinder. Removing spark takes load off of that piston and the noise goes away, if it is a bad bearing, rod or journal.
 
replaced rocker bolts, started it up, and no knock. Just disappeared. Added oil couldn't have hurt but the noise is gone. I'm going to slowly walk away from this one and hope that it doesn't return.
 
Did you let it warm all the way up? Still gone? I am glad you got it fixed.

Ok guys easy to find which rod is knocking for next time.

Start the car and then pull each spark plug wire off the spark plug 1 at a time listen if the knock goes away, if it doesn't put the wire back on and move to the next cylinder. When you pull a wire off and the knock goes away or changes......... You found your cylinder that has the knock!
 
Golden Scamp said:
replaced rocker bolts, started it up, and no knock. Just disappeared. Added oil couldn't have hurt but the noise is gone. I'm going to slowly walk away from this one and hope that it doesn't return.
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I take it the bolts arrived?
 
If it is a rod bearing knock it will return. The rod bearing failure of #5 in the slant 6 engine is a good example of a rod knock that would come and go a couple of times before that rod exited through the left side of the block.
This post doeesn't mean I'm pesimistic or betting against you, just saying...
Keep your tow truck drivers car onboard.
 
I'm guessing it was a stuck lifter of sorts. Unloading them and putting it back together may have let them depressurize and bleed down. You may consider doing an oil change with a low detergent oil and zinc additive. That should help.
 
I do live in a state of pessimism and would bet my knock is still there and really came out bc of being a quart low. Water pump looks to be leaking now too. Gotta love it. Probably just slash the asking price and hope somebody gets it who has the time.
 
At least a water pump is a relatively quick and painless fix...I think I only paid about $40 for a brand new pump a couple years ago...
 
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