What does a compression check tell you?

[Finz250]

My 08 with 78k miles has been making the rattling/ ticking noise at the start of acceleration and up to about 1500rpm. Took it to the dealer twice. The first time was a quick check for codes - found nothing. The second time they said they checked everything they could and that it was normal injector rattle. They did compression checks on all cylinders and said it looked fine. They cut the injectors off one at a time and found two that were a little louder than the rest - but all worked fine. My question is this - would a compression check indicate any valve train problems? Although the truck runs fine - I just cant get the thought of this noise being a valve, lifter or rocker arm problem. Has anybody else had any experience with this??

[sinner6.0L]

A compression check won't usually indicate any minor problems with the valvetrain. There are too many variables that don't allow for very precise measurements.

What cylinders did they indicate may be a cause for concern?

[strokinpower]

mine has made this noise since I got it and I had head gaskets and new heads done so I'm sure if something was wrong they would have seen it then but nothing was ever said and it still makes the noise. My dealership also said it was normal.

[Turbostang500]

The only thing a compression test does (still major info) is tell the tech how well each cyl is sealing (valves, rings, and head gasket).

What you are concerned with would not be indicated with a compression test.

Loose components in the valve train would cause noise so if it would help you to be more at ease, you could pop the valve covers off and feel for and loose rocker arms. Maybe trying a feeler gauge between the valve and rocker arm. I think but not sure, that engine has hyd lifters so everything should be tight (not able to slide a feeler gauge in between).

I could be wrong so take this advise for what its worth. I havent been in the 6.4L.

[Finz250]

Sorry sinner - just saw this - They said no cylinders showed any signs of concern. According to them all is well. 4 diesel techs at 3 dealerships have all said its a normal noise. Injector cackle is the term they're using. I've put about 1000miles on it since I've noticed it including pulling a 36' camper. Power is fine. SO beats me?!? Guess I'll just drive it.

[gmw33]

Is your truck completely stock?

[STROKMII]

If you really want them to find out whats wrong with your engine have them do a Cylinder Leak Down test....

[Finz250]

The truck is completely stock. I've had it at 3 different service dept and they say they have done all diagnostics and all checks out. I've been told they're not going to tear down the engine for a sound they consider normal and no loss of performance - which i understand but if there is something wrong- it would be nice to know.

[gmw33]

We have a stock 08 F450 CCSB and a Deleted/Spartanized CCSB F250, Stock truck you really cant hear much as far as injector rattle goes but its definitely more of a diesel rattle sound than a ticking....it is a diesel engine and these things do make some noises. Best thing I could see is maybe drive another stock 6.4 and see if its comparable.

Spartan truck on the other hand and to be expected, loud injector rattle under moderate acceleration with the hotter tunes.

[kaya@bernhausen]

at our shop we've noticed quite a few 6.4's in which the pivot at the end of rocker arm would wear excessively. it seems like a common problem with them. on one, the pivot was completely worn off and the rocker arm was pounding directly into the valve bridge.
on another vehicle, the rocker arm blew apart.
keeping in mind that the material that wears off the pivot and, on advanced deterioration, the rocker arm itself, is getting into the engine. one of the possible causes could be the fuel dilution in the oil