I have an '82 suburban with a 6.2 diesel. There is a knock in one of the pistons on the right side of the engine. It still runs ok but is lacking power and blows white smoke from right exhaust pipe. It smells like unburnt fuel. Does anyone know what's wrong? Edited by: War Wagon

injector is hung open, squirting fuel into cylinder. Crack lines individually with truck idling to determine which cylinder it is, replace the faulty one but having all 8 rebuilt would be best.Edited by: Texas Diesel Guy

Thanks Texas For the info. How would i go about cracking the injectors. Is this knocking harmful to my engine?


Owen

Loosen the conection at the top of the injector where the line conects. Diesel will leak out when it is loose enough.


Texas Diesel Guy is right, you should replace all 8 injectors with new or rebuilt ones to ensure they are all opening at the same presure to get the best performance.


I would think that any knocking in any engine is not good for it.Edited by: project 6.2L

BY listening to it I almost think it could be a bad wrist pin or crank bearing. This knock sounds bad like metal to metal.

I've been told by Peolple who listened to it that the piston may be slapping the head. Broken or bent pushrod. Do 6.2's have a cylinder sleeve?

A bad pushrod will not cause the piston to hit the head.



Have you tried cracking the injector lines yet? IIRC all it takes
is a 7/8 wrench, loosen the lines where they screw onto the
injectors. Check them one at a time.



Checking the injectors should be the <span style="font-weight: bold;">first</span> thing you do to diagnose this problem.

I'll Try cracking the injectors This weekend if I find some time. If that is in fact the problem it would save me a lot of time and $.

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Last night I cracked the injectors on the right side. The fitting that I loosened was 3/4 on the top of the injecter. When I did this Diesel would spit out between the fitting and the line. When they were open, rpm would drop. I assume this is normal. I'm not sure if anything changed or not. I think the knock may have gotten quieter. Mabee that's just wishful thinking.


A'm I lossening the right fitting? How long do I leave it open? What should the result be? If it is a stuck injecter what specificaly is the problem? Does this mean there's air in the injecter body? What should the engine rpm be when I a'm doing this. </TD></TR>
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RPM drop is normal because you are cutting the fuel to one of the cylinders.


If it is the fitting at the end of the injection line you are loosening then it is the right one.


I would probobly leave it loose for about 5 seconds to ensure all the air is out of the line and then tighten it back up. You do all of this with the engine running at idle. The reason air in the line can be problematic is that the air compresses and doesn't let the injector open.


The result should be that the injector will open properly with no air in the line. Air in the injector body should be dispersed be fuel pressure alone since not much air fitsin the injector compared to the injection line.


If it is an injector stuck open internaly the only thing you can do is replace it. It is not recommended that you disassemble it be cause it will not work proplerly again

You want to crack them individually at idle and listen for the knock to go away, when you find the cylinder that cracking the line makes the knock stop, you've found your bad injector.

I tried cracking the right side injectors several times. No results. The knock stays there. I listened to the noises more closely this time. When I take the air cleaner assembly off, I think I can here air blowing back up through the intake. This makes me think that I could have a bent or broken intake valve. What are your thoughts on that?


thanks,


Owen Edited by: War Wagon

Put your hand over the intake and you should be able to feel it suck and blow back if its an intake valve. Pull the valve covers, remove the rocker arms and pushrods and look for worn out parts. If you don't find any, but you did certainly feel/hear a bad valve, then that head needs to come off.


First thing I would do is to pull the injectors and have them pop tested, don't even tell them what your problem is and see what they about them. If they tell you one is hung open, then you've found your problem.

It's still on the trailer now, but when I get a chance I'll run it in the shop here at college and try to find just exactly what's wrong.

Pull all 8 for test/clean, injection shop here charges $8/ injector to do that, or if they are original injectors and miles are high reman injectors go for about $35 each.