328 over rev engine knock

Before we pull the engine out of this bad boy, does anyone have a better idea. Looks like somehting on the bottom end, but it does not sound like a connecting rod knock.

So far we have,
Compression check OK,
Valve springs OK
Valve Guides OK
Cams OK
Top of pistons OK
Pull oil pan, no debris

Engine must run over 500 RPM's before you hear the knock. Knock seems to be coming from cylinder #3 on the rear bank.

Any adivse would be appreciated,

Kelly

 

Olso check the cam drive bearings, It happened to me last month, It sounded like you said....

 

Does it knock on acceleration or deceleration? Deceleration would be piston wrist pin, acceleration could be a number of things.

 

knocks mostly all the time

 

does that engine use hidraulic lifters???

 

Solid mechanical lifters.

Could be a streached rod bearing bolt resulting in a rod knock.

What exactly happened?
These motors should be okay to 9000rpm.

 

How about shifting at redline out of 3rd and down shift to 2nd when you should have up shifted to 4th. I would say that is around 10,000 or 11, 000

Kelly

 

I would'n tend to think it is a streched rod bolt. That would allow the bearing insert to spin on the crank, or at the least, move around a bit, thus losing oil pressure. You would have known it by it getting a lot worse alllready.
How is the oil pressure compared to before? The same? Probably not crank or rods then.

Piston? They can break a skirt of, in one chunk, and it would slap, sounding like a knock, but not necesarily much debris. It would be more of a slapping, or sharp sound.

The Small end of the rod may have opened up, which would also sound like that, but usualy they don't react that way. They just come apart.

A wrist pin bore in the piston, haveing been pounded oversize, would sound very much the same, and once again, no debris.
Best to drop the plate and spend some time looking over what you can see, before making any judgement calls. A bore scope wil help a lot. turn it over slowly, or better yet have someone else turn it so you can watch the parts move willl help diagnose. Note the pistons travel. It should be smooth in its travel while the crank is being turned. You might spot a problem that way.

While they are good bottom ends, and can flash breifly a long ways beyond redline, they can break.
In any case, it sounds like a teardown is in the future, sorry!!!
Kermit

 

Did you break a valve spring? I had something that sounded like you describe once.

Cheers
Warren

 

once on my car(land rover) there was a cracking sound only under deceleration and it was a cracked crankshaft right on the rod, i didn't know what it was and i rode the car for a full month before it broke in half

 

Well, its looking like speculating isnt going to solve your trouble's. If the motor started making noise after bing overrevved, just pull it put and go have a look. One possiblity could be a bent rod.

 

Hey, did I forget to mention it could have been worse? I recall reading a story about back when they were testing the Dino engine. Some test driver came down into a turn and missed a shift. The engine made a nasty sound and the car limped back to the pits. The mechanic told him to keep it running as he wanted to look at it before it was shut off. Well, the right rear 1/4 of the block was gone, as were one or two cylinders, while the crankshaft was spinning away throwing out the remains. Tough motors.

 

Drain the oil and look at it.
If you spun a bearing, there would be alot of metal in the oil.

 

Just a quick check to do before you remove the engine. Start the engine and bring the revs up till it starts knocking,then one by one remove each fuel injector wiring plug on each clyinder. If the noise goes away on one particular clyinder,then its your big end bearings. Give it a go,if your keen? Cheers

 

It has CIS so no injector wiring to pull. Maybe he could do the same test by removing a spark plug wire one at a time?

 

Will a Ferrari engine even run under 500rpms? All 6 of the Ferraris I have owned idled around 1000rpms!

 

Ok,sorry,my bad. That will do it but. Just have to stop the power stroke/cycle of the cylinder(no fuel/no spark) Doin that will not put pressure on top of the piston to hammer it back down the bore and then in turn,no load is being put on big end/connecting rod bearings! Works a treat!