Pushrod popped out of rocker arm
Had this truck come in with a vibration complaint. As soon as I was in it bringing it into the shop I felt the miss. Put the scanner on it and sure enough Cyl #3 was dead. Did a relative compression test and and confirmed #3 was at fault and low comp. Fired up the wps500 and captured a cyl waveform attached. Given that I had 12 psi of vacuum cranking and exhaust seemed to be opening I figured something was up with the intake valve not opening. So I pulled the cover off and sure enough the pushrod for #3 intake was out of the rocker.
I am assuming that the lifter failed and stuck fully compressed but I am wondering if anyone has come across this and if I should be looking beyond a failed lifter at an oil supply problem or something else perhaps? Any thoughts would be great. Thanks guys.
I've seen carbon build up on intake valve cause rocker arm to fall off
Absolutely check your cam as well. These are known for wiping the lobe off the cam.
Hi Stephen, A lack of maintenance can cause scrubbed guides. Also using low grade cheap fuel will gum up the valves and cause sticking. These problems will create issues that will cause a pushrod to un seat. Check for the push rod to be bent. If it is not put it back in and change the oil with synthetic to help with better lubrication. Verify the basic valve operations to make sure the lifter…
2010 Ram 5.7L plugged pushrods. Intrestingly, the old school compression gauge was measuring 190psi of cranking compression, which was higher than the rest.
The intake valve closes sooner due to the wiped out lobe and this increases compression pressure. John Thornton has a very interesting class on this very thing.
In this case, the intake valve never open to begin with. Intake Manifold off, looking down into the cylinder head port, you could see dead bugs. Anyone guess how they made it so far. I remember a post on iATN about the subject, seeing compression scoped over time, the first cycle built good compression, because it already started with air in the cyclinder, and possibly drew some passed the…
Possibly look with a bore scope and see if the valve seat is sticking out at all. I'm not sure if the 5.7 has that issue, but I've seen some older dodge motors have that happen.
Cam problems are a bit too common in this engine as are weak or broken valve springs.
Most likely worn cam lobe due to seized lifter roller bearing. Very common on these 5.7s
Thanks for all the responses fellas. Checked the pushrod and seemed ok. Attempted to re-install but the lifter had collapsed and there was still roughly a half inch of clearance between the rocker and the spring. Decided to drop the oil to look for metal debris for signs of cam damage but it came out surprisingly clean. Talked to the customer and we're going to pull the heads off and do all the…
Stephen, before you tear down, you might want to check for cam and lifter part availability? We have run into shortages of those very items.
Thanks David, Not surprising to hear at all. I have been having issues with the chevy 5.3 parts as well as I have one of those torn down as well. Any recommendations on OEM or Aftermarket or just get whatever is available? I know I have heard with the 5.3 to stick with oem on the lifters or look forward to a comeback.
Hi Stephen, I recommend going with a Jasper reman with a good warranty (important), otherwise go with all OEM cam and lifters. Other parts may be from other companies, but don't take chances on the cam and lifters.
I haven't checked on the lifters for the Mopar 5.7's in recent months. I do know there were enough stories about aftermarket lifters from trusted colleagues, that I was scared away from using them in this application. Having said that, I feel the most likely source of the failures is assembly practices by us in the field. We just are not able to be clean enough to ensure these finicky &…
Hi David, I will add, drop the pan and clean the pick up tube real well. I have had a lot of issues with Dodge trucks, especially short trip and poorly maintained ones. I pulled a lot of pans over the years. Some actually had a depression where the pick up screen set in. Guess where all the carbon debris collect, in that depression area? Also cleanliness is super important with any internal…
Excellent point Glenn. Do the shops with the gravel and dirt lots have a name for the air quality I wonder? Maybe they call it “break in compound”? Or planned failure programming? LOL
There is a special tool that aids in holding all the pushrods in place, while installing the rockers. With the engine still in the vehicle, it can be a real pain, unless you have an extra set if hands. Just FYI
Thanks Kevin, I noticed that in service info and was fiddling with them pushrods as well. Looks like it could be fun without it.
Work on these every day and the 4.7 with an overhead cam using a follower would drop its follower when valve seat drops out partially . 90 percent of the time it’s from a partially dropped valve seat or someone reassembled wrong and popped out at start up . I have seen a cam lobe on hemi ground to a circle and not drop a pushrod . Also I have occasionally seen cracked rocker on shaft but should…
So I got the heads off the truck. Turns out The lifter bearing failed and eventually hammered the pin until the ears that hold it broke off leaving the lifter just floating there. Found the rest of it in the bottom of the pan. Also the intake lifter on the next cyl had a bad bearing as well.