engine and drivetrain Rod knock, piston slap, or something else?

[Guest_anonymous]

22 hours ago, TobyB said:

 

Seriously, have you even pulled off the plug wires one at a time to see what happens?

 

t

 

[Mike Self]

One more thing to check--valve adjustment...a really misadjusted valve can cause a pretty pronounced knock, and all it takes is for an adjuster to work itself loose so that you have way too much space between the adjuster and the valve head.  While that's usually more pronounced on a cold engine, it's worth checking--there may be something else loose under the cam cover--and you'd feel pretty foolish pulling and tearing the engine down only to find out it was a problem in the valve train...

 

mike

[Columbo]

Thanks Mike!  I got the car in my garage and a clean workspace finally.  I plan on removing the valve cover to and check what you suggested.  Next I plan to remove the plugs, move each piston past TDC and carefully push down on the piston with a screwdriver to see if I can detect any play.  I'll also check for loose nuts on the alternator and everywhere else.

 

I've also been reading up on what's involved in removing the oil pan just in case I have to get to a rod bearing.

 

I appreciate the help everyone.

[Columbo]

Welp, I think it's #2.

 

I pulled the plug wires one by one (each time shutting the engine off before pulling) and then reved the engine.  The knock isn't there when the #2 wire was pulled (or at least not nearly as loud).  

 

I have never pulled an engine before and to be honest, find it intimidating to do so.  So I guess I'm either jumping in with both feet and pulling it or going to try to attempt to get at it by pulling the oil pan.  As posted earlier, there is no metal in the oil or in the oil filter for whatever that's worth.

 

 

 

[ray_]

Well...

 

The motors come out pretty easily. Not many wires, a few bolts and hoses, and done!

 

You can do a bit of reading and either drop the subframe, or pull the motor from the top. Removed the distributor cap in either case, first.

 

... You did pull the valve cover for a look, right?

 

Cheers,

[Fatherof3]

Automatic or manual?

[Columbo]

It was an automatic but was converted to manual long before I bought it.

 

I did look around the valve train and nothing is out of sort.  I was thinking about starting it with the cover off to be certain the knock isn't coming from the valve area but didn't want to spray oil everywhere.

 

Any suggestions are still welcome.

[jgerock]

Prefacing this with "I am not a professional mechanic" and "can guess with the best of them"..

 

Does it have A/C?   One local 74tii owner attended a concours event earlier this year and his engine started knocking just after his arrival.  Several folks (including me) listened to his engine while it was running and we all had our own suggestions.  I borrowed a long screwdriver and held it to various engine parts while it was running (other end held to my ear with a cupped hand).  I guessed it was related to the A/C system and not a rod or other engine knock.   The owner had it towed to a place where it was inspected and they found the A/C idler pulley was bad.  A replacement pulley eliminated the noise.

 

Check the easy stuff first (I got REALLY lucky)

[PaulTWinterton]

While you have the valve cover off, check the valve clearances for #2 cylinder.  Check them all for that matter?  Good to eliminate that variable.

 

 

 

 

[TobyB]

You won't spray much oil running with the cover off, at idle.  The chain's the worst. 

I've done it to pin down noises...

 

The #2 plug wire is pretty suspicious, I think.

 

And yes, you can often hear a bad rod bearing - pull all 4 plugs, roll it over by hand, and

rock it back and forth past top dead center.  If  #2's your problem, you'll HEAR it klonking around.

If it's bad.  And it sounds like it is...

 

sorry.

 

t