loud knocking noise at lower rpm need help please

[Big Blue 84BJ60]

just took my truck for a 2hr drive and close to the end of the trip the water temp rose up to warmer but not into the red i noticed this after a sudden loss in power i backed off and the engine cood back to normal some of the power returned but not all when i got off the highway i noticed a knock from 1500rpm -600rpm/idle the knock is faint above 1500rpm i had a some guy say it sounds like a valve let loose (ideas what he ment by that) i thought bad valve but no real excess smoke mabey a little more not much though help any ideas?? thanks in advance

[crushers]

well
a bottom end knock gets worse the higher the rpm so i doubt it is a bearing.
sudden increase in water temp and loss of power doesn't sound good. i assume it is NA.

some more questions:
any change in driving conditions when this occured?
where you towing anything?
what was the terrain like?
have you checked the water level since you got home?
have you checked the oil for water contamination?
what colour is the smoke?
how much smoke at start up and what colour?
did you just fill the fuel tank recently and if so how soon after did this start happening?

[Tapage]

Go under your truck and let you buddy go from idle to 1500 rpm ( and more ) and let us know if the sound it's loud under the truck ..

I bet on piston .. sorry.

[Big Blue 84BJ60]

the 3b has a turbo

the terrain was fairly flat when it happened revs at aboot 2750rpm
wasnt towing
coolant at the same level
oil down a hair no water contamination
smoke at start up is black/grey but when i rev it a little its greyish white???

the noise is comming from the top end it still can be heard under the truck but its louder when you stand over the engine could it be the fuel pump or injectors both 1 an 2 i can feel the ticks vibration through the fuel lines more so #2 fuel line

[crushers]

crack the injector lines and see what happens (besides getting srayed with diesel fuel). does the sound go away?
Yes? injector needs rebuilding
No?
then it might be a chunk of prechamber bouncing around.

did you just fill with fuel recently? did you run to the bottom of the tank?

[Tapage]

Originally Posted by crushers

then it might be a chunk of prechamber bouncing around.

good Shot Wayne ..

[roscoFJ73]

Originally Posted by Big Blue 84BJ60

the 3b has a turbo


smoke at start up is black/grey but when i rev it a little its greyish white???

the noise is comming from the top end it still can be heard under the truck but its louder when you stand over the engine could it be the fuel pump or injectors both 1 an 2 i can feel the ticks vibration through the fuel lines more so #2 fuel line

Try bleeding #2. The metal fuel line may have a hairline crack or maybe there is a problem with the delivery valve for #2 on the pump.
Check carefully for leakage

[Big Blue 84BJ60]

i bled no 2 line and the noise quieted a little but didnt go away

fuel is good

[cruiser_guy]

Originally Posted by crushers

then it might be a chunk of prechamber bouncing around.

I've been there. The noise of a precombustion chamber bouncing around is quite distinct (not at all quiet).

If there is a noise like that I think I'd be strongly tempted to pull the head and check. The alternative is not very pleasant at all!

[crushers]

IF it is the prechamber then damage to the piston, cylinder walls, head, (possible con rod bearing) valves has already occured. the engine is toast and will need a rebuild.

[Big Blue 84BJ60]

i dont think its a piece of a precup i had 3 mechs look at it 1 says injector nailing one says its a valve and the other says both

what does injector nailing sound like ?

and what would make a valve clap real loud?

[rchalmers3]

Dude,

Sounds serious. I recommend you pull the injectors and base seals and stuff a boroscope down the injector holes to confirm there's nothing hammering the combustion chambers. You really don't want to run the motor any more than you have to to deduce the failure.

Has anyone seen wrist pin failures on therse motors? This might explain the symptoms described, but killing the cylinder should make the noise quiet down completely.

Besides pre-chambers, I have seen (on gassers) some inocuous carbon chunks come off a piston and make hellacious noises. Make you think the motor was lunched. Only took a small amount of calibrated water ingestion to break up and pass the carbon.

Not saying this is your problem, just saying....

Rick

[rchalmers3]

Valve clap....broken spring? Loose adjuster? Worn lobe? Should see compression anamolies: Low pressure, slow to build pressure with a valve related failure.

Rick

[Big Blue 84BJ60]

thanks all for the replies i will pull the valve cover and injectors tommorow to see if i can see anything wrong and after that pull the head i guess

[Big Blue 84BJ60]

pulled the oil pan and there are a few pieces of tin or aluminum smaller than baby finger nail and what looks to be some rubber/silicone oil seal but the bottom end looks good as for the head havent pulled it but i pulled out the injectors and the two closeset to the fire wall look like they have over heated because there is blueing/heat coloring near the tips. Also after reinstallation the nock is a little louder could injectors make a noticeable nock

[Tapage]

Yes .. but not it's diferent a injection point sound than a piston sound for example ..