Hi everyone,
I’m having an issue on cylinder 5. After ruling out the usual, I did a compression test; had low compression. So I did a leak down test, used 100psi, had about 5% loss. Pulled the valve cover, found the pushrod for the intake valve not sitting in the rocker arm cup. Would this be a bent pushrod or did it lose it’s place some how? Rocker arm felt tight to the valve spring, spring looked ok as far as I could tell although couldn’t get a great look since the spring has a retainer thing around it. Should I just replace the pushrod or do you think I need to continue to look for what caused it? I never really got this heavy into mechanical repairs, trying to figure out why I would have low compression if it was just a bent pushrod. Wouldn’t the spring hold the valve closed, and I would still show up fine with compression?

Not sure if this has any merit.. I did an oil change a week before this occurred, also got gas the day before.


2005 Dodge Ram Hemi 5.7
150k miles




‘’Thanks,
Mark

 

Mark, good job on the troubleshooting.
Bent pushrod is definite possibility, then question is, "what failed in system?" Was it a material failure of the rod itself? Possible but unlikely. Bent rod/unseated rods can occur because of loss of lash.
Somewhere between rocker, spring, pushrod, lifter, cam there was a failure. I think most likely culprit is a collapsed lifter, but purely a guess.
What I would do: if you still have your old oil, send it out for an analysis. That will tell you if you have excessive wear, particularly with cam lobe.
Then I would take a look at procedure for removing the head. If oil sample is good then proceed with removing the head. Intent is to replace the lifter and pushrod.
Lifters come in brackets of four. You should also order new pushrod, gaskets and head bolts.
Some other smart people will chime in here also.
Certainly you could reseat the pushrod and set lash and hope for the best. I think more work now will be better in the long run. Throwing a rod can be a disaster so doing full job is safest.

 

Get the rocker shaft off for more inspection. Compare the valve height of the involved valve as compared to others.

 

Maybe jumping the gun a little....some hemi's were known to drop valve seats. IF this happened. ...piston hit valve bending it and jamming it in the valve guide...push rod ends up bending trying to open jammed valve. Hopefully not the case and you find an easier repair.

 

5% leakdown indicates that both valves are actually closed, and they are seating just fine. Compression is rather low, so I would more expect that one of the valves isn't opening..... a pushrod being in the wrong spot would certainly cause that. I would more suspect a stuck valve, or failed lifter.

 

Thanks guys for all the replies! You guys gave me more to think about.

Is there any test I can do for the lifter before pulling the head? With the rocker arm removed and a new pushrod inserted; if I turn the engine by hand would I be able to tell if the lifter is bad? Also any suggestion to test for a sticking valve? Would I be able to see an issue with it by pulling the intake manifold?

 

You could re-seat the current pushrod, set lash, then turn the engine by hand and observe valve action. You can also disable fuel pump and turn engine with starter.
If valve is not moving, there could be several causes. Worst case is a wiped out cam lobe.
At this point I recommend you download the FSM if you don't have it already, and, start watching some youtube videos. The FSM has excellent troubleshooting steps, and there are some very informative and well done videos on Hemi valves (also some poor ones, but you will spot those right away). A forum can supplement your knowledge, but some self study is critical here.

 

Jrsick,
I have been watching videos and doing a lot of reading.. I guess I was looking for a lazy way out.. Took your advice from above, and doing the more work now to say me from other problems later.

Pulled the head today, worst part was undoing the exhaust manifold flange bolts, took a good two hours for the one bolt that was fighting me. I’m going to replace the exhaust manifold while I’m at it. Found a stuck lifter. Also going to pull other head and replace those lifters and pushrods.

 

Nice work on getting the head off. Everything looks good on the top end.
Finding the sticky lifter is a relief because it means your camshaft is probably fine. If you have a borescope you should take a look at the cam lobe that the sticky lifter was riding.
How did you know it was sticky, was it collapsed?
How many lifters are you going to replace? I recommend assembly lube for the new lifters.
Seafoam on a rag works well for removing carbon.

 

Thanks,
The cam lobes looked fine from what I could tell, I scoped each one. All the rollers felt fine and smooth on the lifters. Thought I just pulled head and lifters for nothing, then I noticed on the back side the one was sitting lower then the rest. (Not sure if picture shows it great).

I replaced all 8 on that side and all new pushrods, I’m planing on doing the same on the other side as well while I’m at it.

‘’Thanks for the tips!

I’m ready to install the rocker arms on this side.. I see dodge has a special tool to hold the pushrods in place on the intake rods.. is there a trick to do it without it? Also my rocker arm sits up about a half inch if I have a pushrod properly seated, ( I double checked the pushrods were installed in the correct location)I didn’t try tightening down the bolts as I don’t want to snap anything.. is it because cylinder 1, the piston is to the top and if so is it ok to hand turn the crank to lower it? I see in the service manual it says not to rotate/crank the engine, so not sure how to proceed.

Thanks!