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Not good news, still fails CCT#8 after LL8 replacement.

1K views 13 replies 5 participants last post by  clydesdale 
#1 ·
I ran a CCT after 15 miles and I still fail #8. I believe the truck still has the intermittent knock as well. Everything went well with the injector replacement, except that it still fails and I believe it still knocks. When I started the truck a plume of white smoke came out, and then it smoke for a short period and cleared up. Everything seems ok.
The compression in that cylinder was 375 when the motor was totally cold and off for 24hrs. What do you make of this? The truck runs fine, but I don't like not passing the CCT still. Words of wisdom?
 
#3 ·
I had driven about a total of 25 miles since I made this post and it still knocks. The thing I don't like is that when I first started it, then knock was gone. It does seem like the knock comes in after the truck warms up. Any thoughts. I will drive it more, if that is what is suggested.
 
#6 ·
The crank times seem back to normal. It took much longer to start after the injector swap and then right after the first drive which was only 5 miles. After a 20 mile drive, the crank times seemed more normal.
I did not go in for the recall, so I should still have the black cps.
How do I check my low psi oil?

My fuel pressure is set at 62-63. Should I bump this up? I posted about the knock 4 days after the RR, which was 1.5 years ago. The knock has gotten worse and I think it is gone when the motor is cold, but comes in as the truck warms up.
 
#8 ·
That is sort of what I am worried about. But, I get my oil analyzed and it comes back great and I just got a sample back about 1k miles ago. My rotational velocity at idle on #8 reads 3% and it is about 0% on the others.
 
#9 ·
I did about the same as you. Installed itp rr kit and I was able to hear the ll injector knocking slightly louder than before. I have since installed a new alliant ad injector. After installing the injector once the air was out I had a knock that was much worse than before. My truck also reacts the same way. Until the engine is warmed up the knock is not there. I have not performed a cct test on my truck and my compression is higher than yours at 425 psi on all cylinders.

My truck still is not perfect, as in I can tell that number eight is firing harder and the truck vibrates more than it used to at idle.

The only thing that I have done that has 95% of the knock is to run the fuel in the head from the rear of the head to the front of the head. Although it may or may not solve your problem.

If you think it may be a mechanical knock, rev the truck to 3000 rpm in park and turn the key off. Listen for any knocking.

Aaron
 
#10 ·
If you have any other questions I will help as much as I can.

Have you done anything so you are absolutley sure which cylinder is causing the knocking sound? Like unplug the injector while running.

At what rpms does the knock occur, how much load, what speed?

It could be something like air in the fuel from the suction side or a loose fitting or hose.

Any unusual smoke other than at startup after injector install.

Aaron
 
#11 ·
No smoke, seems to run fine.
The knock seems to be there only at idle.
I have an airdog, so hopefully the air is solved.
I have not unplugged the injectors yet.

How did you do the compression test? Was the engine cold or warmed up? Thanks
 
#12 ·
My engine was completely up to tempurature and I did the drivers side head first. It was still hot when I was done. I also had all of the glow plugs out.

The knock was most obvious on mine above an idle. The engine up to tempurature and accelerating from a stop up to about 1100 rpm I could hear the knock. If I power braked the engine from just above idle to the same of 1100 rpm.

The only time I could hear it at idle was parking the truck after a long drive. While steering with the ac on and backing into a parking spot, throw it into park and for a few seconds you could hear Knock Knock Knock Knock.

Also if the ICP sensor was unpluged with the engine hot.

Aaron
 
#13 ·
What did you conclude in your situation?
I just drove it, no knock at all until the oil hit about 170-175, then I hear it consistently. While driving it, it seems fine.
 
#14 ·
Kainers, my low pressure oil pressure, taken at the hpop reservoir was 40 when cold and 22 with 190 degree oil, at idle. It went to 45 when I brought the rpm to 1800 when cold and went to about 35 when warm. Are these good numbers?
 
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