I'm thinking the motor is hurt

[Cowracer]

I pulled my friends 7500 pound boat from Kansas City to St. Louis. Ever since then, there had been a bit of a knock in the motor. It seems most noticable on a cold motor at around 2500 rpm. It sounds like a rod, maybe.

I didnt stress the truck too hard on the trip. It never saw over 1000 egt (pre turbo) and never got hotter than about 190. Oil pressure is good. It also seems to be a LOT of blow by if I pull the oil fill cap or dipstick when the motor is running.

I know I need new injectors, and I know that injectors can knock sometimes when bad. Do they sound like a rod, or is it something compeltly diffrent. What about the balancer? Can that sound like a bad rod when shot. God! I hope I dont have to tear into the motor.

Tim

[dieseldummy]

I would guess it may be excessive piston slap, indicated by the blowby and knocking. I just had something similar happen to me very recently. I hope you don't have the same problem.
Goodluck,
Justin

[ucdavis]

If your egt's & total temp readings are accurate, I'd say normal wear & tear & not damage from hauling the boat. 1000 egt & 190 coolant should keep stuff from breaking. Maybe a prior lead-footing experience that's just now showing itself?

[charliepeterson]

Maybe you just killed the injectors? If they don't spray well they'll just drip and could make noises. I wouldn't tear into the engine without a compression test first. I bet it's just the injectors.

[Cowracer]

True, it could be the hot-rodding chickens coming home to roost. If thats the case, I'll take my lumps and rebuild.

But first I will try new injectors. I have felt for a while that my truck is way down on low and midrange power. Above about 2500 it has plenty of whoop-ass, but below, it almost feels like it has a miss. The kennedy exhaust allows more noise out the end of the pipe, and between 1500 and 2500 the engine seems not to run a 'crisply' as above. Maybe (hopefully) and injector is not pulling its fair share of the load untill the revs come up.

I probably really need to check timing chain wear too.

Tim

[Polar Diesel]

does it miss at idle?

[tom.mcinerney]

Usually hurt HBs don't afford audio feedback {until crank craps-out}. But people have reported clanging/knocking from the crankshaft pulley, bolted directly to front of the HB. And this noise immediately precedes demise of crank. Once you manipulate one of these implements (by hand) it is immediately apparent how a little degradation of the component will threaten the life of the rotating assembly.
Suggest remove serp belt, maybe upper radiator shroud and fan ; rotate the crank pulley [which usually drives the other accessories ] by hand--it'll move a bit by design, as the outer pulley ring is guided by a bearing but torsionally coupled only by a 1" thick ring of soft rubber. {Some members check it from bottom vehicle with no dissembly. May be better}.
It should probably rotate 1/8"-1/4" by hand. The danger is if too loose (elastomer too flexible)in operation it will rotate until it hits cast stops beyond the designed acceptable torsion. This is when becomes destructive. The HB is suspect with high mileage, too; but usuall a silent killer, though i think i've read of some rings cracking, and departing accustomed paths....
good luck; keep posting.

[Cowracer]

The truck does not seem to have a miss at idle. Then again, with the electronic controls, even with a cylinder out, the PCM will just fuel it up to keep the desired rpm, so I dont know if it would show up. The 'miss' I think I hear/feel may just be nature of the beast for diesels. On a gas motor, it would surely get my attention, though.

On close inspection, the balancer outwardly appears to be ok. The knock seems loudest when i was following a slow truck up a long hill. I only hear the noise occasionally. Sometimes its there, sometimes not.

If I can find a way to get the oil pan off easily, I might just check the rod bearings for damage.

Tim

[bigmikestud]

Imagine that, I had the same problem occur driving back from St. Louis to Kansas City. I was pulling a heavy load of Hunter Engineering products-about 14,000lbs. My nasty knocking noise came from the pulley on the harmonic balancer. The noise would basically go away under load but at idle sounded nasty. My first thought was the harmonic balancer ($112). I had them bring out the pulley just for grins ($220+). You guessed it, the more expensive part. If anyone wants a digital picture of this E-mail me at: bmsp51@yahoo.com I'm taking it to the local Vo-Tech school for reference soon.