Engine Diagnostic Help Needed

[[email protected]]

My mechanic is trying to diagnose some noises and a few other things with my engine and I need some help as he is not real familiar with the LSX, but knows normal LS engines very well.

 

I need to know what the oil pressure would normally be, if it would normally have a solid lifter cam, and which valve cover gaskets are used so we can order the right kind.

 

The engine is also making noise that he describes as a tractor like mechanical ticking sound. It has made this sound since I have bought it, but now that one of the cylinders is throwing a code and it is losing a fairly large amount of power we want to try and figure out if it is normal and if it is not what to do to correct it. My knock sensors have both been throwing codes and he thinks the engine is loud enough on it's ticking to set them.

 

Any help would be appreciated, I'd like to get this all figured out soon.

[Mr.Scary]

try suggesting a bad lifter

[1BAD2K]

The lsx is a normal ls engine. My ls6 idles around 38 oil psi. I would also check lifters.

[shawnss]

Can you get a sound clip? might help some out. does the ticking go away with more RPM or get louder? my last 6.0 was right around 40 lb of oil pressure at idle. but being yours is a built motor a lot of guys go with a high volume pump. is it a injector tick? some injectors are loud. is it hit and miss or all the time. theres so many things it could be.

Edited August 31, 2013 by shawnss (see edit history)

[[email protected]]

I don't have any way to get a sound clip at the moment as it is at his shop. It does not go away with more RPM, you can hear it coming down the exhaust at all times, cannot really tell if it gets louder since the exhaust is so loud itself. The oil pressure in the truck is around 20lb, so we obviously have an issue there.

 

Thanks everyone for the ideas,

[BlueAKSSS]

Is 20lb the idle oil pressure? That is a bit on the lower side from what most LS engines run at but possibly still acceptable I would think as long as it rises from there with engine RPM. Keep us updated!

 

BTW- I'm enjoying the parts I bought off your last truck!

[sprayed99]

ticking or knocking? oil pressure being that low is a concern.

 

Not having it on video is a tough one for all of us. I had a similar issue a long time ago with a 6.0L and it was a main bearing.

[JC03SS]

I'd almost say a sticking or mabe a collapsed lifter. I had that prob once

[silverado_ss_04]

sounds like lifters to me, i would start off by replacing the lifters since its a pretty easy job.

Edited August 31, 2013 by silverado_ss_04 (see edit history)

[[email protected]]

I am not sure if you can pick up what it sounds like in these videos, but these are the exhaust videos I made when I had the exhaust changed out.

 

http://www.silveradoss.com/forums/topic/81224-exhaust-videos-with-new-rear-dual-exit-and-electric-cutouts/

 

I will try to go in and get a couple of new clips of the sounds as soon as I can.

 

ticking or knocking? oil pressure being that low is a concern.

 

Not having it on video is a tough one for all of us. I had a similar issue a long time ago with a 6.0L and it was a main bearing.

It is a ticking sound.

[sprayed99]

Heres a thought. pull the valve covers and see if you have a rocker that is loose. Now with a bad lifter the rocker should be very very loose. If so you would need to pull the heads. replace the lifters and inspect the cam as well. You will also need to pull the oil pump can check the pressure valve for debris. Low oil pressure can be caused by trash in the relief valve.

[[email protected]]

The mechanic checked out the rockers yesterday and said everything there looked and felt good, I will pass on the info though.

[sprayed99]

The mechanic checked out the rockers yesterday and said everything there looked and felt good, I will pass on the info though.

The it is not a collapsed lifter.

[misterp]

Easy things a competent mechanical can spend a morning doing and ascertain exact condition of the motor, non-invasively with simple tools:

 

Using an OBD-II tool, command the PCM to do both an ignition and injector kill test - this will pinpoint weak cylinders.

 

Perform a cylinder leakdown test - this will tell you exactly the condition of the rings and valves. I am a BIG believer in cylinder leakdown testing.

 

Listen to the valvetrain using a "mechanic's stethoscope" - put the tip of the probe in the roof of each intake port, you will hear literally the valvespring action, and valve seating... what you are listening for is any valve that sounds different from the others, this is how you easily find a broken spring, dampner, or even burned valve; you will also possibly hear the injector firing too. Repeat this putting the probe on each header tube, to listen to exhaust valvespring/valve action. If you've got broken valvetrain this will quickly pinpoint the affected cylinder.

 

Remove the accessory belt and run the engine for 60-90 seconds, just to be sure the ticking isn't coming from the power steering pump, or A/C, or water pump. (Don't laugh, I've had it happen!!) Don't run the engine for long without a water pump, but you can idle it long enough to rule accessory drive as either a factor or not.

 

"ticking" can be a split/cracked spark plug insulator (I've had it happen, MidnightRidr found it for me lol). It can also be the spark jumping inside the boot from the wire to the spark plug terminal/tip.

 

Mr. P.

[Cramer]

Since the exhaust was just installed I would check that out. A ticking sound can be an exhaust leak at the flange causing a misfire code to pop up. This can lead to a burnt valve or detonation if enough carbon build up is in the chamber. Use the stock header gaskets if you take them off. Also like Mr.P said about a broken isolator on the plug or burnt and arching wire.