ghardester

Last week I did a WOT high reving pull on my car. Shortly after that I heard a new rattle in the valve cover area, not the usual piston slap which I am well familiar with, a new rattle that increases with RPM. I had to drive it to work and back for a few days with this rattle present.

After reading every thread I could find I diagnosed bent push rods. I know that this is usually caused by a missed shift on a manual and mine is A4.

So I just pulled out all the push rods and the top ball end that hits the rocker arms on some are scored, like they were scratched with emery cloth. Both ends should be smooth. These seem to be the ones that are slightly bent. Nothing drastic but a slight wobble rolling them on the smoothest surface I can find.

My question: is this scoring an indication of a bent push rod and a result of my driving it after they were bent? Or is the scoring on top of the push rod a sign of something else?

I had 4 scored/bent on the passenger side and 1 on the driver's side. I am now waiting on parts and will install new push rods next weekend.

There were no other problems other than the new rattle, no misfires, codes, etc. Changed the oil and there was nothing on the magnet, poured the oil through a bath towel and found no metal filings.

Are slightly bent push rods apt to have scoring on top?

farmington

iTrader: (14)

after they bent they became essentially shorter a little, hence the rattle.

ghardester

I have one more push rod install related question. Everything is going back together in 2 days. Probably a stupid question.

The pivot rails that the rocker arms sit on when bolted down have GM lettering and a few other symbols. On both sides of my 2002 LS1 engine these rails were installed with the lettering upside down. Factory engine that has never even had the valve covers off, I am sure.

These rails appear to fit in either way, lettering right side up or upside down. Of course I am going to put them back exactly as they came off.

So my question is, are these LS1 engines built by robot machines that may sometimes grab the part and install the rail with the lettering up and sometimes with the GM upside down?

It just seems odd that the rails would have the printing upside down on both sides. Anyone recall the lettering orientation on the rocker arm rails when they first opened up the valve covers on their virgin LS1?

ghardester

Well it wasn't the push rods. None were obviously bent and I showed the scuffed end to my guy at the local hot rod shop and he said that was probably just normal wear for the 97,000 miles I have on the car.

He listened to the noise and said it isn't the lifters and did a "huh, that's odd". The noise is near #6 and #8 on the passenger side of the engine. His shop is always backed up for 2 or 3 weeks so I put the car in my garage and take it back to him on the 5-21. They are the best shop in my area and will find and fix the problem.

The puzzling thing to me is that the car runs just fine like it always has, from idle to cruising along at 70 mph. No lights, no codes, no misfires, no performance issues at all. Except for the noise. You can hear the noise under the car too, like someone is tapping on the exhaust with a little hammer.

Maybe it will be exhaust related and I will have to tell my wife, "honey, he says we have to take all that stock **** off and put headers and a new exhaust on." That would be awful.

Or it is going to be something nasty and expensive internally.

Darth_V8r

iTrader: (4)

I don't know how much this will help, but here goes...

To diagnose a bent push rod, I would put one end in a drill and spin it. If you see the exposed end wobbling, it's bent. Also a good way to check valve stems for being bent. I've seen plenty that didn't look bent that were found to be bent by spinning them. Don't just eyeball it and assume it's ok.

To me an exhaust leak sounds more like an annoying rhythmic 'tick' than a rattle or a hammer sound.

joeformula

iTrader: (11)

A bent pushrod sounds much louder than an exhaust tick.

Darth_V8r

iTrader: (4)

That's my point. OP said that it sounds like somebody tapping on the exhaust with a small hammer. An exhaust leak would just be an annoying tick, which it looks like he's hoping is all it is.

I've seen plenty of things that looked straight until you spin them.

ghardester

It is going to the hot rod doctor May 21st. I will keep posted as to the cause. I hate it when people never show back up to reveal what the issue was.

I changed the push rods, none were obviously bent. Noise still there. Made m appointment at the only shop I trust, and we will see. He listened to the sound and said it wasn't lifters. So I do not know what would make a clattering sound on the passenger side, on an engine that still runs just fine with no engine codes or misfires.

We will see.

Chris25

iTrader: (1)

Easiest way to diagnose a bent push rod is to put it on a piece of flat glass and roll it slowly.

RabidStreetRacer

iTrader: (1)

Exactly what I was taught by a local machine shop

Chris25

iTrader: (1)

And honestly if the push rods and rockers look fine Id be worried about a spun rod bearing. They can spin and oil pressure and everything else will run just fine. Have you drained the oil yet ?

ghardester

Yeah, that's what I am afraid of.

It was due for an oil change so I changed the oil the day after the noise started, nothing on the magnet, I laid out an old bath towel and poured the oil through it and did not see any flakes or anything unusual. Like panning for gold but I did not see any color. The noise still sounds on top of the engine and I would think a rod bearing would sound more internal, but I don't know.

It's a daily driver, never raced, occasionally given a hard pull from a start, like I did right before the sound started. 97,000 miles and less than 10k per year, Mobil 1 changed early Spring, late Summer, and late Fall.

The guy's shop I am sending it to is the best around that's why it takes weeks to get an appointment, we will see. In any case it will get fixed. I am now driving a Ford Focus for Crist's sake!

ghardester

Well here is the result. There isn't anything wrong with my engine, it's fine.

One of that cats broke free and is making all the noise. The guy at the shop was only able to tell once he got it up on the lift and listened to it from below.

New Y pipe and cats and it will be fine! I decided to just fix it the stock way rather than pull all that crap off and go with headers and new exhaust at this time.

Sure sounded like engine/valve or rod noise to me. But I am much relieved that the engine is fine.