Valve Train Noise
 

It's been just over a week since my daughter's Grand Cherokee became part of the family, and it has been pretty busy. Among other things, I have been reminded that it's a 2000, not a 1999, which is what I've been saying it is. I blame that on too much time trying to keep a friend's '99 Land Rover on the road. (It may be a lost cause.)

So, I've been tinkering with the Jeep the last couple of days, as weather allowed, and the one problem I've been working on is noise in the valve train. I pulled the valve cover off (It is a 4.0, by the way), and first thing I did was fiddle with the rockers to see if there is any sign of collapsed lifters. Two or three rockers seemed a tad loose, but all the others were nice and tight. I fired it up and listened to it some more, and to watch the valve train at work.

I noticed that the rockers were not all getting oil, and it seemed like a couple of sets were taking turns getting lubrication. The dry rockers also happened to be where I was hearing the worst noise, at the #2 and #6 cylinders. #3 and #4 seemed to be taking turns getting lubed. I turned it off, and all rockers were nice and snug against the lifters. No lash.

So, I pulled the pushrods on the cylinders which weren't oiling properly and ran a wire through them to see if they were clean. I checked for galling and found all of them okay. I put them all back in place and cinched them down, and fired it up again. Oiling improved somewhat on #2 and #3, #4 was a lot better, but #6 never seemed to get quite enough oil, although there was some improvement. The noise (a rattle) got somewhat better.

While it was running, after it warmed up, I took a look at the oil gauge, and it was holding a steady 40-45 psi at idle. So unless the gauge is lying, it looks like oil pressure is not a problem. However, as I sit here writing this, I am now wondering if the screen on the pickup tube is partially plugged. That wouldn't help oil volume at all.

As for the oil itself, it needed changing, and it was overfull. When I drained out enough oil to run some motor flush through it, I noticed it felt like STP. I can't help but wonder now if the previous owner had decided that if one can of STP would help, maybe three or four would be better! :huh: For the record, I drained it this morning when the engine was cold, and it took forever to drain out. It was a good steady flow, with no chunks, but it was slow. I changed the filter and filled her up with 10W-30, and the noise is still there, though it does seem quieter. I got the stethoscope out and listened, and the noise is definitely inside the valve cover, though I could also here it (less loudly, of course) on the camshaft side of the engine.

Any thoughts, y'all?

It sounds like the lifters have collapsed.

The hydraulic lifter has an internal piston and check valve to pump the oil up to the rocker.

A small amount of carbon will bind the piston in the bore.

They can be removed, disassembled (compressed air helps for disassembly), cleaned, lubed and reassembled.

Well, that's the crazy thing about it. There is no lash when the engine is off. So unless they have collapsed in such a way that the lifters are still holding the pushrods where they are supposed to be, I'm not sure I agree. Even with the rockers which were a tad loose, I don't think I have a feeler gauge that would have gone between the rocker and the valve.
:dunno:

How did some rockers moved by these hydraulic lifters change from fine to being a "tad loose"?

Why is the oil fed from the pressurized oil galley on the side of the lifter not getting pumped up by the lifter piston in the lifter bore up through the unobstructed pushrod tube up to the rocker?

I may have been unclear, and if so, I apologize. They went from a tad loose to fine. In other words, they tightened up to where there was no lash at all. And it is the fact that the lifters seemed to be pumping up okay that has me a bit confused. I can't say I've seen this before.

You ARE aware that 4.0s rattle, right? It is a characteristic of the beast for the lifters to not pump up at idle enough to keep it quiet. What has amazed me is when I replaced my cylinder head, I put in new Sealed Power lifters as well. When it's cold, it rattles, BUT when it's up to temp, it doesn't!

I've been told the reason for the rattle is the oil feed holes to the lifters are small and don't supply enough oil at idle to keep the lash tight. I think that's why they recommend 5W-30 oil in them. When my WJ cleared 175K, I switched to 10W-30.

Yeah, I know they rattle, but this is much more rattle than it should have. While it does let up with higher rpms, it comes back as it approaches idle. It's loud enough you can hear it in the cabin with the doors closed. I'm going to pull the pan and check the screen on the pickup. That will be aggravating, but I will at least have that base covered.

Dave 1123, since my last post to this thread my warped sense of humor kicked in, and produced this way of explaining the noise and how I react to engine noises.

If it's a simple tickety-tickety-tickety, I don't worry about it.

If it goes tickety-tickety-tappety-tickety, I might get a little concerned.

If it goes tappety-tappety-tappety-tappety, it will cause my eyebrows to become knit, and I'll look into it.

However, the engine is going CLACKETY-clackety-CLACKETY-clackety!!, so I'm figurin' sumpin ain't right.

:icon_cheesygrin:

Gotcha, Dee. I'd be concerned too. I forgot to check back in the thread to realize you ARE familiar with this engine. Pulling the pan sounds like a last ditch effort akin to shooting yourself in the head to avoid capture. Have you used a mechanical gauge to verify pressure? Maybe adding Seafoam to the oil? I seriously doubt the pickup is plugged unless the whole engine is full of sludge. The pump itself may be failing, but a pressure check should show that. If it were mine, I think I'd replace the lifters (major job in itself) before I dropped the pan. But, your engine, your call.

Yeah, the engine I am familiar with, this kind of noise is something I haven't quite seen before. Unfortunately, I do not have a mechanical oil gauge, or I would hook it up and see what it says.

There is something I did not do while I had the valve cover off that I saw my dad do once, on an engine that had noisy lifters. With the engine running, he tried sliding a feeler gauge between the rocker and the valve stem (like you would with mechanical lifters) to see if there was any lash. He also showed me a trick where I could put a finger on a rocker as the engine was running to feel for any lash, but I've forgotten exactly how that trick works. :sad:

The engine does have some sludge in it, but I've seen a lot worse, like the Duratec 3.0 in our now-defunct 2002 Taurus. We bought the car new and drove it until the first engine spun a bearing. When the second engine blew a head gasket, already knowing what a bear it is to pull the engine in that car, I threw my hands up in disgust.

Is the pan on this vehicle really that hard to remove?

AFAIK, not really. You have to remove the front driveshaft, starter, and exhaust pipe. You may have to let the front axle hang for clearance. I just don't like working overhead and getting it sealed up again. IDK that much about them to know if it involves the timing cover or not. That was a PITA on a Chevy small block. I know on them, you had to reach in and unbolt the oil pump, but that may have been for lack of clearance. IDK, it's been a long time. We also had to turn the crank to get the counterweights out of the way.

You ought to see what you have to do to pull the pan in a E30 (1984-1992) BMW 325! It's almost easier to just pull the engine.

Get one at Home Depot or Lowes for less than $20, plus a handful of 1/8" NPT fittings and pipes to hook up instead of the oil pressure sender.

It should be part of any tool kit to take out any possible oil pressure confusion from the dash gauge or idiot light.

The pan isn't too hard to remove. I had to replace mine due to rusting through. It's pretty much remove the bolts and a rubber mallet to free it. I was able to squeeze it out without removing anything. I've heard some people just raising the block a smidge by the crank pulley for that extra bit of breathing room. Just be patient with it and your fine. It comes out by pulling it toward the back

It didn't look that hard when I was under it the other day, but I hadn't crawled all the way underneath. Thanks!