UPDATE: DIESEL EXPERTS! Look here!

I posted a few days ago with a nasty engine knock. Drained the tank sump, fuel filter housing, and replaced the fuel filter hoping that I had a water related problem. I did get SOME water out, but not as much as I expected.

I messed around with it some last night and found that it would knock and miss at lower RPMs while belching black smoke on each miss. It runs fine 1/3-1/2 throttle up to WOT. I put a healthy dose of Diesel Kleen to it and ran the hell out of it for about 3 hours. It ran like a top, after of course knocking after start-up.

I did not shut it down to a low idle, but cut back on the throttle to cross the creek on the way back home and the knocking/missing started again, but sounded a little different with a 6-9 ceatane rating boost. Got the RPMs back up and it cleared out, no smoke or noise.

Either I have an injector not seating/leaking/stuck or the injector pump is failing? Would these be the route to go? I know injector OH is MUCH cheaper than an injector pump OH, but are either at fault? Runs fine flat out, but knocks like a MFer at lower RPMs...

Thanks,

CT

IF IT IS SMOKING WHEN IT IS MISSING,CRACK(LOOSEN)EACH INJECTOR LINE 1 AT A TIME AND SEE IF IT STOPS SMOKING AND /OR MISSING,OR CHANGES TONE.THAT INJECTOR IS PROBABLY BAD.DO NOT RUN IT LONG MISSING AND SMOKING BAD, OR YOU WILL NEED A PISTON.MARK

Simple easy test is to take all lines off of the injection nozzles, crank engine over and look to see which one shoots compression out of it.

Charles: Haven't changed my mind, other than it may be something else mechanical loose. After roughly 100,000 hours of diesels under my care and control, all I can say, something mechanical is broke, out of place, worn, etc.

Fuel problems don't hang around that long, they either get fixed or quit first.

Charles, Something is broke inside that engine. I would start by pulling the head and looking for a busted sleeve. If you don't see anything there look at the lower end. Could be a wrist pin bushing. Either way you are playing Russian Roulette everytime you start it. You are driving a grenade. A fuel problem would not start that suddenly.

Sounds like a bad injector or injector cup. A sleeve would have disengrated by now and would not clear up with RPM, it would just make more noise with higher speed. You say its a knocking/missing sound? what does it sound more like, a mechanical clunk or just a miss. A knock and a miss are quite different and could result from different causes.

Thanks for all the suggestions. I am leaning towards an injector(s) or the injector pump. A diesel is far simplier than a gasoline engine. All a diesel has is more/less fuel, more/less air.

When starting and idling it starts randomly knocking. This knock dosen't sound metallic. It sounds like a real heavy fuel knock like pre-detonation on a gasoline engine.

The only way this makes sense is that when running at higher RPMs, the injector is hosing it to it the cylinder and being burned. No smoke, no miss, well it has had a light miss for years... Idle down and it starts knocking like a MF'er.

If an injector were stuck, not seating, trash, broken spring it would be flooding that cylinder causing black smoke and a heavy spark knock? Could the injector pump be related? The injectors, pre-cups, and pump are all OEM from 1962, never touched in 47 years. Has about 5000 hours on the clock.

If it were a piston pin or sleeve I feel it would have gerenaded long before I ran it 3 hours yeaterday with a 6 foot cutter in 6 foot high weeds at about 2000 rpm. But it still acting up at idle.

I think I'll try removing the lines and turning it over. If I do that, I am going to have to bleed the system... What would it cost to overhaul 4 injectors.

CT

If it makes you feel any better my 560D has in excess of 20K hours on the clock(s). She's fuel knocked at idle for as long as I can remember. Injectors have never been rebuilt and we've had her since the day it came home from the dealership in 63. Pump has been gone through though... Engine could use a rebuild... Even has the original head on it... though that's been rebuilt a few times.

I too would be looking at the fuel system as suspect.

A leaking nozzle will knock like crazy, so easy to check because you just have to pull the lines off nozzles,(commonly refered to as injectors) crank engine over a few times and observe. Good ones will not push any compression out at all, shot one will shoot right out and worn ones may push a little out, and you don't have to bleed anything, just screw them nuts back on. Have seen many drop the pintle from nozzle tip which can give you both a fuel knock and a mechanical knock from it becoming imbedded in top of piston. Be interested to see what you find, could be any of suggested remedies.

I am fully convinced that I have a failed injector and it is leaking when at low RPMs. I called around and found two diesel shops that will clean, repair, rebuild my injectors. Depending on condition of injectors and parts needed they will cost $15-$60 each, I am doing all four. The guy did tell me that it is getting difficult to obtain the parts for these as CNH has obsoleted some parts. Is this true?

Any advice on removing the injector assembly? What about the precup, should I bother with inspecting and replacing if eroded? I have been told that removing the head and driving it outward is easiest. I would like to do all this with the head on.

Thanks again,

CT