Aloha everyone, got another question about the ol' 4.0. So I have a valve train noise at startup that has some interesting conditions associated with it, I'm wondering if anyone has had this problem before.
At startup on a cold start, there is a series of ticks coming from under the passenger valve cover. The pattern is timed. 1, 2, 3 ,4. Tick, tick, tick, silence, repeating and it is rpm dependent. I have isolated it to the valve train with a stethoscope and ruled out injectors. If I use the clear flooded engine routine to prime the oil to the top end it won't tick on startup 99% of the time, it's only on a dry cold start. The ticking goes away as soon as I'm driving under load and doesn't return until the next cold start. The sound is loud enough to hear from in the cab or outside with the engine running.
I have looked over the diagram for the valve train, and noticed there are 4 cam shaft bearing or journals, and based on the pattern and symptoms I'm thinking that there could be slop in the cam bearings allowing movement until oil pressure tightens things up via the hydraulic lifters. I would love to hear any ideas about what I might have missed.

 

Assume 4.0l OHV engine, 1990-2000 Rangers

More likely to be a broken spring inside a lifter
Until there is oil pressure the springs inside the lifters keep them tight, no "ticks"
When spring breaks or gets weak lifter will "tick" until oil pressure takes over

Yes, one side of engine's rockers is feed from center cam bearing, and the other side from the other center cam bearing
I think front center feeds passenger side and rear center feeds drivers side
So yes, as engine gets more miles oil pressure to rockers and lifters can go down

You can run a 40w oil and add Marvel Mystery oil, these can reduce "ticking" on startup
But doing the Clear Flooded engine on cold start really helps the most, with the larger bearing gaps in a high mile engine you WILL get more oil draining back out of lifter and rocker passages, so they need to be refilled by cranking engine over without starting

Just FYI, you have to pull off the heads to change the lifters on the 4.0l OHV

 

Duh, sorry, it's a 2004 so sohc engine.

 

That's a different oiling system so can't really help with that, never looked at it that much

 

So I'm curious if anyone has replaced just the hydraulic lash adjusters and followers on a sohc. From what I have read in the service manual, it says I can use the valve spring compressor and relieve the spring tension on the follower, then just wiggle it out. Using this method, could I replace all 12 followers and lash adjusters without having to muck around with the cam bearing caps or cam timing? It looks like the followers nearest the sprockets might be blocked by the larger bearing caps. If anyone has gone through this I'd love to hear your results.

 

This noise is likely to be your timing chains are coming loose. These engine are famous for that. What happens at startup is it takes oil a few seconds to add pressure on the worn out chain tensioners. You can replace both timing chain tensioners and make sure you keep your oil full and run synthetic. It will help but you will still need to replace timing chain guides which is a very long process.

 

Thanks, I'm aware of the timing chain issues with these engines, but I don't think that's my current issue. It's a 2004 model, and the chain tensioner are less than 6 months old. The noise isn't a rattle, it's a very specific tapping rhythm that is coming from under the passenger valve cover. I'm planning to pull the valve covers and drop the lower oil pan here in a couple days, I'll post pics and update when I do. Obviously if there's plastic chunks down there I'll know my chain guide took a dump. More likely it's the hydraulic lash adjusters that are having oil pressure/spring issues. If I prime the engine with oil by using the clear flooded engine routine, it starts up with no noise and if its been driven and shut off it will start with no noise for an hour or two until the oil drains back out of the adjusters. My fear is that when I get in there and throw a micrometer on the cam I'm gonna see more slop than I'd like.
I'm still very curious to hear from anyone else who has done a hydraulic lash adjuster and roller follower replacement on the sohc. I have all the tools and the service manual, it just seems too easy. I feel like I'm overlooking something.