Not too long ago I noticed a faint knock, maybe a tick. Kinda sounded like the injectors. It would become more noticeable if the motor had no load, like doing a consistent speed. I thought maybe a lifter needed adjustment. Not too long ago I tore the motor apart to install a cam.

Tonight I pulled next to a twin turbo 300ZX. The guy was doing about 25 MPH. That's just a little too fast to throw it into 1st and not fast enough to throw it in second. Well, I threw it in 1st and stabbed the go pedal. The car kinda lost power when I was high up in the RPM range (maybe bounced the rev limiter - I didn't look at the tach, I was watching the 300). So I don't really know how high the RPMs went, but they were up there. After a couple more races with the 300 ZX, I headed home. I noticed the knocking had gotten louder.

Should I pull the oil pan and tug on the rods or could it be a lifter? It knocks when it idles, when I accelerate, but not when I floor it.

[This message has been edited by SCCA FIERO (edited 02-08-2003).]

I would start praying to god its not the rods Ive never heard a lifter knock so I cant be sure but Ill tell you the sound of a spun bearing rod knock is one of the most mood killing sounds youll ever hear, its a real dull thud kinda knock, mine only knocked at like 2300-2500 rpm but when it did you knew it maybe someone else can be of more help

Sounds like same symptoms Iv'e got.
Give me less than 24 hours and I will let you know what my knock, knock is. I'm replacing bearings and installing new HP oil pump.
One of our forum members suggested pulling one spark wire at a time and listening to see if there was any change in the noise.
I was told that a change in sound indicated a spun or bad bearing was possable.
I will let you know tomorow.
jetman

If it's excessivly loud it's a rod bearing. I just went through this with my DOHC. Mine started very faintly and within a few miles (maybe 10)got really bad. I was driving it really hard the morning it happened. Pull the pan now and check, In that short distance I ruined my crank(I babied it home after it got louder too). $1728 later, I'm picking up the new balanced and blueprinted shortblock today. The price inclued gaskets and reworked heads. Your 2.8 should be cheaper.
Good Luck and let us know.

Banzai !!!!!!!!

Usually a knock from rod is when you rev it up from idle. Lifter will knock thru all the rev range, or even go away when you rev it due to higher oil pressure. Sometimes just an exhaust leak can be mistaken for either too.

My experience with a spun rod bearing was that the knock became more pronounced and louder when the motor was revved above 3k or anytime load was applied. Whatever it is, the sooner you get in and find it the better off you'll be. If it is a rod you don't want to wait till the piston comes through the side of the block. I tore the top end off prayiing it was in the top end but it was a rod bearing. By going ahead and tearing it down it looks like the block has sustained NO damage. Was not so with a 318 I had, was driving it to my brothers to swap in a 360 when the piston and rod came through the side of the block, not pretty!

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http://www.geocities.com/fierorulz/

The car was smoking a litte when I popped the deck lid. Looked like it could be coming from the forward exhaust manifold. The knock sounds like a metallic knock though (not any pinging, just sounds like solid objects not agreeing with one another).

I also have problems with my car idleing and keeping oil pressure at low RPMs. And a Miller-Woods turbo kit is pushing 10 psi into the motor.

I bet my motor is toast - just my luck

If it is, then I plan to build a 2.8 to go along with the turbo. The season starts the 23rd and my car is FUBAR

yeah....thats a spun bearing
low oil pressure comes with that too, so it gets worse QUICKLY. If a lifter or rocker is that noisy, it usually makes the motor run uneven from the one valve not opening as much. check the dipstick for bearing chunks. might just be a silvery paste by now. valve cover arent to hard to pull up, wiggle the rockers. turn the crank. smoothly if you can. when the piston of the spun bearing changes direction from up to down, alot of time you can feel the thunk of the crank (which is also the knock you hear @ rpm).
time for a 3.1 stroker crank

Take the oil filter off,cut it open and spread out the paper,i think you are going to find LOTS of ground up metal in it.If you only find a few minute specks here and there there is no need to take the engine down. Good luck.

Easy way to tell if it's a rod knock.

Get the engine to where it make the noise and pull the wires from the dist cap one by one. If the noise stops or significantly changes when you pull a wire then it is a rod bearing.

The reason being that the cyl with the knock will stop knocking because you are removing the fire for combustion thus pressure on that cyl.

I've used this method for years and it's almost foolproof. Good luck....hope it's a lifter.

Phil

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87 FIERO GT 2.8 5spd
0-60 in 6.8 seconds!

I warmed up the motor and pulled the plug wires one at a time. The knock never went away.

Maybe it is a lifter, but can they get louder? Do they unadjust themselves even more? That might also explain my idle.

Where can I get those deflectors to run my car with the valve covers off?

Another way to check is tale a broom handle, cut it to about 3ft. put your thumb over the end, touch your thumb knuckle to your ear and the other end to different parts of the engine. Acts somewhat like a stethascope.