[ddouglas77]

OK, I got the crank pulley replaced, timing marks are where they should be, minus the cams are off by just a couple of degrees, but the noise persists. It sounds like a rod or main, but goes away when: You let the clutch in-noise almosts disappears, noise goes completely away between 1K-3K RPM, reapears at 3K, then disapears at 3.5K, but engine won't rev above 4K. I got it above 4K briefly, noisey, and surged a bit. The noise reappears directly after accelerating when the gas peddle is let go of, will go away when clutch is pushed in. Even if clutch is in, noise appears at 3K RPM and above. What is going on?

 

[ddouglas77]

Noise gets less noticable when engine is warmed up. I'm thinking rod bearings now. The preignition problem more than likely over wore a rod bearing, especially when it would have occured at over 6.5K rpm. Any advice still helpful, even if you're not sure, anything is better than silence from the experts.

 

[Alfisto Steve]

If pushing in clutch lessens noise I would check end play in crankshaft first as thrust washers maybe worn/damaged.

 

[ddouglas77]

Is it possible to drop the oil pan with the engine in the car?

 

[John M]

Yes it is. But I wouldn't attempt to make any repair to the block with the engine in the car. Just drop the lower pan and inspect it for bearing shavings. It'll look like you struck copper if its a bearing. Shreaded throughout the pan. Also the drain plug magnet will likely have tiny filings surrounding it. To test for rod bearings, you can also pull plug wires one at a time while the engine is making the noise and see if the noise goes away with any cylinder electrically dead.

Best Regards,
John M

 

[John M]

One more thing David, do a compression test to rule out the top end.

Best Regards,
John M

 

[ddouglas77]

Now I'm getting scared...
I can drop the pan and inspect for shavings and test thrust play of the crank (with someone holding the clutch in) and throughly inspect each rod and thrust washers. No repairs, but better diagnosis.

 

[ddouglas77]

One more thing David, do a compression test to rule out the top end.

Best Regards,
John M

I know you know your sh*t, but wouldn't a compression test just tell me if I had a leaky valve? If a piston pin is broken or cracked, etc... the piston should still be able to seal up good, until enough damage is done to egg shape the liner. I already inspected piston tops, no marrs, no indications of hitting anything and best yet, no metal shavings.

 

[John M]

Do a compression test first. It'll tell you if you are hearing a bent valve. If compression good then move on to the plug wire test. This way you can all but rule out rod knock. If it fails that...in other words knock quits with plug wire removal, then drop the lower pan and look for shavings. If you find shavings, the block will need to come out.

The upper pan can come out to....but by the time you take the motor off the mounts and raise it...you are just better to pull the motor. You will not be able to make the repairs to the crank with the block in the car.

The ultimate question is the condition of the crank journals and the block. The cost of parts in regards to bearings is dirt cheap. The cost of machining to fix a damaged crank.....and finding a machine shop that knows what they are doing are the real hurdles if it comes to that.

On the compression test....you won't have any at all if its a bent valve. You can rule out a piston by adding a cap full of oil to the top of the piston. Cap as in the lid to the quart bottle of oil. This will effectively seal the piston leakage to rule out the upper end. Unless a piston is holed, it'll push some compression although low with broken rings. Piston pin isn't a weak part. I'd be very surprised if the pin/rod connection is the issue. If there was trouble there you would find scoring of the cyl wall from the pin traveling back and forth. Scoring would show perpedicular to the line of flow.

Best Regards,
John M

 

[ddouglas77]

Unfortunately I'm flat broke, so this will have to wait till payday when I get paid and do a free tool rental from Autozone (I'm flat broke, I down have the security deposit $ needed). I can do the spark wire check now though, as that is a freebie. Thanks John, I'll let you know what I find out.

 

[Erik]

If pushing in clutch lessens noise I would check end play in crankshaft first as thrust washers maybe worn/damaged.

Or dropped out. Better take the sump off and check thrust washers, bearings etc.

Good luck
Erik

 

[ddouglas77]

Individually cut off the cylinders, noise was still there. So I took off the coil wire, killing all cylinders, noise was still there while cranking, but when I put my foot on the clutch, noise disappeared, let go of the clutch noise came back. I can not get any play out of the crank, thrust washers?

 

[Stan Murray]

loose flywheel?

 

[ddouglas77]

loose flywheel?

Your guess is as good as mine, I'll keep that mind. John M is enroute to help problem shoot this.

 

[Bobcatmo]

Thrust (throwout) bearing or loose fork???

 

[ddouglas77]

Thrust (throwout) bearing or loose fork???

Why would that cause a noise with the clutch in or at and at different RPMS? Not disclaiming you, just picking your brain...

 

[Bill S]

loose flywheel?

I think that's a good call, Stan. Flywheel bolts have been known to shear on an over-revved engine. Seems somewhat consistant with the variety of symtoms, too. Even though it would require transmission removal, that would probably be the best-case scenario for David. We can hope!

Bill

 

[ddouglas77]

I'm all about the best case scenario, but could you provide detail why this would cause the symptoms at hand?

 

[Alfacliff]

stepping on the clutch pedal a little releases tension of the clutch plate to the flywheel, allowing it to shift position if the bolts are sheared.
cliff

 

[Peterv31]

Don't take anything apart yet! get a big screw driver, get under the car and
pry the front pulley towards the engine block, then have someone push on the clutch pedal and see if you can see the crank move forward. .010 to .015 should be ok, shop manual will give exact amount but just see that movement is not excessive.

Transmission brg could also cause noise when clutch engaged

Pete in VA