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Knock on startup?

Michaeljp86

Michaeljp86

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Heres a video of the engine knock, you can only hear it for about the first 30 seconds. At about 12 seconds you can hear it the best. Seems to only be there at idle.

Anyone have any idea what is causing it?


http://www.youtube.com/watch?v=y6RueRjG_20

<iframe width="420" height="315" src="http://www.youtube.com/embed/y6RueRjG_20" frameborder="0" allowfullscreen></iframe>
 
Sounds good to me. The knock sounds like maybe an injector or a cylinder that is burning off the unburned fuel while it heats up...???

If I can figure out how to post a vid I'll post mine up for you & let you hear it, it scares me a little but it's been doing it ever since I cranked up the TDCO to -1.9. Lots of thoughts about what stress it is or is not doing if ya search. I have no idea if it's something I should really be concerned about...mine has 226K on the clock, so I guess that I am just happy that it's still going strong.
 
This truck never did this before, it started it last year some time and slowly got worse. My other 6.5 doesnt knock. Normaly the knock is worse then it is in the video.
 
Mine is now doing the same thing, if I plug it in there is no knock. That leads me to believe it is a glow plug in my situation.
 
I have noticed mine is more cold blooded then it has ever been. Maybe I should change the glow plugs and see if that does anything.
 
On mine I think it is just a bad GP connection, the Duraterms aren't that old. Right now it is low on my priority list.

Each day you could disconnect one GP and start it until you find the bad one if that is what's the problem. Easier than pulling them.
 
Ive never put plugs in it and I know the guy who had it before me never did. He only had it a little over a year but time is adding up on them.
 
If its a injector would cracking a line loose stop the knock if I had the kncoking cylinder?

I want to put insurance back on it soon and drive the beast.
 
You have a miss or uneven engine running when that knocking is going on. How long does it sit for this noise to be loud? Overnight or hours?

You also have a coolant leak at the upper radiator hose t-stat housing.

Miles on injectors? Take one out and have a local shop test one or a few.
 
WarWagon said:
You have a miss or uneven engine running when that knocking is going on. How long does it sit for this noise to be loud? Overnight or hours?

You also have a coolant leak at the upper radiator hose t-stat housing.

Miles on injectors? Take one out and have a local shop test one or a few.
Click to expand...

I seen the leak when I had the camera out, thats why I looked at it with the camera. I just put a HO water pump in.

Id say its more like over night when it will do it again. I think after almost all day it will knock but not as bad.
 
Im not sure on the miles on teh injectors, I dont drive it much so I havent put many on it but Ive never changed them.
 
Pull a couple injectors and have them tested. I had sticking Chinese injectors that were hard to start. What they do when the dump a stream of fuel I am not sure the sound, but, I have seen the carnage first hand.

Always check for air in the system by putting a clear hose on the IP. Run and look for a bubble stream. Stop the engine and see if a bubble collects. Leave it overnight and see if the clear tube is still full of fuel. Any air means you need to work on an air leak.

Overnight allows air to leak back through the injector and empty the injector line or put air in it. This gives you a miss on startup or long cranks and then a miss.

You have verified the lift pump is working?

What kind of glow plug does it have? You may be able to double cycle the ignition for more glow time if they are self limiting.
 
I can hear the lift pump running, it was pumping fuel fine last summer.

The glow plugs run for about 30-40 seconds.

Its supposed to be nice out today so Ill try and find some time to play with it.
 
You should also check the harmonic balancer pulley. With unbalanced injectors, is doing the same type of noise with a cold engine
 
Ive looked at the harmonic balancer last summer and also again a few weeks ago when I put on the HO waterpump. Unless Im looking at it wrong the balencer looks good to me.
 
I meant, harmonic balancer PULLEY (THE PULLEY), not the harmonic balancer(This is how NAPA name it). However if you check it not to long ago it should be good.I used to have the same type of noise at my 6.5 and this was the problem.
 
I'll go look at the balencer again, how do I know if there is something wrong with it? The rubber looked ok.
 
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