Has anyone had what I call fuel knock in a '94, it sounds like what I have heard in larger diesel engines due to timing or bad injectors. Eversince I own this truck it has had a bad rattling sound at idle. I have checked the bearings and found no issues, I guess I need to check timing and see. Just wondered if anyone else has heard of something like this. Thanks
If it were me I would crack each injector line with it idling. If the noise decreases or goes away with a certain line cracked, you know you probably have an injector issue with that cylinder. If that were unfruitful then I would look into the possibilities of timing and such.
I have tried to loosen the injector lines and had no luck. Pulled the timing cover to check for the kdp, fixed that while I was in there and still have not found the root of this. I have rerun the valves, just to make sure that the lash was correct. This motor has always sounded different than my last truck, but the oil pressure keeps going from 20-40 psi without any sort of reason. The truck runs great and pulles good, I can even live with the oil pressure, but the rattling this engine is making (like to pieces of thin metal banging into each other) is about to drive me crazy. The torque conveter bolts came loose one time and sounded just like this, and my first thought was of that. This noise happen so bad for few seconds the other day, it sounded more like a gas engine that was tipping the valves. Maybe that will make somebody's bell ring, because I am ready to pull it out and put my other motor in this truck.
This problem is why I joined this site. I am having the exact same problem. Sounds like a nut rattling around on a copper tube. I have been all over the engine bay and just as above checked the valve lash, twice in one week just to make sure I did it right. I have a G56 so no torque converter bolts. I have no loss of power, no excessive amount of smoke. I will look into the Tork Tek. Great site. I have learned much in short time. Thanks.
Just a thought but I've seen this twice. Had a 5.9 in a Case with oil press troubles and rattling, the oil pickup tube had broke and was sucking air an rattling against the oil pan. The other time a 3406 Cat started knocking and when I loosened # 2 line it stopped, so replaced inj and it still knocked. Figured it had spun a bearing so we sold the truck with bad engine. The guy that bought it yanked it out put another in and sold the engine for cheap,that guy pulled the pan to check the bearings and found a broken oil pickup tube that had been hitting the pan, he put a new tube in and it's still running today.
Thanks guys for all the input on this. We had a death in the family and I have not been back to it. Did pull all the rod bearings this time and found one that is questionable.
Well finished the in frame today and a lot of the noise went away. How ever, while I was letting the engine run at high idle, I loosened the injector lines, and found that #4 cyl is not pulling it's weight. Cricketo99 was right about this one. Now just need to do some more digging and find out if it is in the pump, or the injector. The fuel just sprayed from the line, where the others just leaked out with a noticeable engine rpm drop. So more searching the forum and doing some thinking. Thanks all, at least now I know what is in the bottom end.
You could pull the injectors and have them pop tested. I believe most shops that deal with IP's will do it fairly cheap. That would tell you what condition all your injectors are in and also if #4 is related to the injector. However if you wanted to do things on the cheap you could swap injectors with #4 to see if the misfire follows the injector. Is there bad blowby from your engine? That would indicate compression getting past the rings which could cause a no fire situation.
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