I had a separate post that leads into this one. I had an odd hammering sound coming from the injector lines on the CR. Took it to an injector/fuelpump shop today and they hooked up the scanner and individually checked each injector. They found that when they power down the #4 injector that the "PSSST PSSST" sound goes away. The tech said that I should have it flow tested cause he thinks that I've got an exhaust valve on #4 out or going out. He said that it should be under warranty since I have only 75,000 on the truck. Anyone burned a valve or had a similar situation to this?
Thanks
Scott

 

BTW I am showing no codes, and the truck is running the same as it always has with plenty of power. Oh yeah, I got mods.

 

Check the valve lash on that valve. That should tell you right away.

 

How involved is it to get the valve cover off and get to the rockers. I haven't had to get into a diesel valve cover before, only some 70's ford V-8's.

 

I wouldn't automatically say that it must be a burnt valve, How is the truck running? If you had a burnt valve there should also be a noticeable misfire. Doing a compression test would verify a burnt valve or other compression loss issue but it is a major pain to do on a diesel. Checking valve clearance probably won't tell you too much unless you found #4 to be extremely tight (not enough clearance) but chances are it isn't. Wouldn't hurt to check however. By killing the injector and having the noise go away could also indicate that injector is faulty or any number of other problems. Killing the injector was only the first step in the diagnosis as now you have confirmed that #4 is were the noise is coming from. Now it needs to be diagnosed what the cause of the noise is.

 

A burned valve on the Cummins is pretty rare until you get up around 150,000 miles on a 24 valve head and 200,000 miles on a 12 valve head. Even then a burned valve is most often accompanied by a broken valve seat.

The ability to power down #4 injector and have the noise go away would lead me to the conclusion that you have an injector failing. That is very common, especially in a common rail truck that has had the wick turned up a bit.

For grins I would spring for an oil analysis and look for unburned fuel in the oil. If it comes back contaminated that will cinch the injector as the problem. The other alternative is to pull the injector and have it tested, and you could do a compression test at the same time as you use the injection port as the connection point for the compression test anyway.

 

I have stepped on it a few times, but I was watching the gauges, and I have the defueling settings set conservatively on the commander. I have only boosted to 35 PSI once, but never stayed on it but maybe a couple of sec.s. I am suspect of the injector myself. The tech was talking about these valves as "rotating" meaning that they will turn around as they are opened and closed. After he turned the number 4 injector off and then back on the sound went away until he mashed down on the throttle a couple of times, then the sound came back. That was his reasoning for suggesting a burnt valve possiblity. He said that they have seen several of the 3rd gens. doing this though. Sometimes they get warrantied, sometimes they don't. I will do an oil analysis tomorrow since I have a local truck lube shop that has the analyzer.

 

Your tech sounds like he was on the right track, so with the additional information I would pursue inspecting the valve train for the exhaust side of #4.

Looking at your mods, I see you have done enough to easily spin up over the 3,860 rpm death point for the stock valve train on a 5.9. I would check one more thing after the oil analysis. These common rail engines will bend the pushrods fairly easily if they are revved up near 4,000 rpm.

The common rails are a bit of a pain to get the girdle and wiring loom out off and out of the way, but pull the valve cover and then loosen your rockers and remove the exhaust valve pushrod and roll it down a good clean sheet of plate glass. If it has a high side you will feel it and see it as a space between the rod and the glass.

If you have a bent pushrod replace it and then pull your rocker arm assembly for the exhaust valves and replace it too. Check the fasteners for the studs and make sure one is not sprung or working loose, too. The valve actuation arms are rather soft castings and will spring out of shape just enough that they will continue to hit the valve stem at enough of an angle that you can damage a valve stem and cause a valve to stick if you have been running high rpms.

 

I believe what you are saying, but I have never had the RPM's above 2300. I dont use this truck for sledpulling, or drag racing. It's my daily driver which I average about 800 Miles a week, the mods were simply for some added fuel economy which I do gain, but I only run the box on 60hp, but I don't run high rpm's. There again, that's why I got the Commander so that I can monitor myself as well as the truck from tearing anything up.

 

I would bet on a dropped seat before a burned valve. It has the same effects and it is obvious if you check the valve lash on number four that something is not right. I just went through this and ended up putting on a new head. I also had the problem on #4. Of course you should be able to hear it out the exhaust if this is your problem.

 

hrmmmm ... I think my truck may be doing the same thing. It's been doing it for a few months now. I didn't think anything was wrong but now i'm not sure after reading this thread.

 

I got my UOA done today, with 5,500 miles on my rotella T all of the parameters for the oil are below or at lowest possible measure of the analysis. Meaning, my oil is in tip top shape, still looks black, but can run another 3,000 and do another UOA! What now?

 

Ok, here's the verdict, and no whippin' me at the end of this one. Took the truck into the dealer after a stripdown of the mods. They check it over and went through their checks with the scanners, readers etc. Long story short they found no valves out of spec., no clogged injectors, and the PSSST PSSSST banging on the injector feed lines is gone. THIS IS BECAUSE YOU HAVE TO MAKE SURE THAT THOSE LITTLE BLUE CLAMPS ARE NICE AND SNUG ON THE INJECTOR LINES. I totally skipped checking these, but after $100.00 and knowing my valves are ok, and injectors are o.k. I don't mind losing $100.00 for that piece of mind...

 

Be Gentle.LOL

 

Glad to hear that it was nothing to serious...no bashing as it really does suck when you think something serious was wrong. The good thing is you now have a sense of relief knowing it wasn't anything too serious.