Rattle at higher RPMs. Chain?

[eightynine4x4]

89 2.9l 4x4
85K miles (I think)
Not referring to basic low speed/rpm ticking. Yep I have some ticking, but it’s steadily improved as I’ve been working on lots of stuff over time.
But since the engine is now quieter and I can hear subtle sounds, and also since I can comfortably drive it at higher speeds of say 55-60, I’ve started to get concerned about a particular sound I’m hearing when the engine is pushing higher RPMs like 2600 ish and up, especially during long up-hills. So I back off the throttle and cruise uphill at 35-40 to be safe and it sorta goes away. But going back down hill it goes completely away, so it seems that it’s caused by being under heavy load.
It sounds kind of like a tambourine would sound, if you only had one or two discs of metal on it instead of a few dozen. So, like a piece of metal shaking. It’s not louder than the ticking, so it doesn’t sound like immediate doom, but it doesn’t sound healthy.
Does the 2.9L even have a timing chain that is serviceable? Or is it one that needs to just be replaced and that’s it?
Or could this just be exacerbated lifter ticking?

 

[Dirtman]

The timing chain on a 2.9 is replaceable but as it's not a over head cam engine it's just a very short chain with 2 gears and no tensioner. They do not wear out very often, not that they can't but they can often last for the life of the motor.

As I'm sure you are aware 2.9's have notoriously noisy lifters though so that would be my first assumption. But it could also be a bunch of other stuff like an exhaust leak, a cracked flexplate, a broken cat shell, since it happens at high rpm under load it could also be the engine pinging/detonating. It's pretty much impossible to diagnose a noise over the internet.

 

[eightynine4x4]

I'm leaning towards it being the lifters just behaving even worse under the more intense workload. It sounds like it's coming from the same place in the engine as the more basic lifter noise.
Cat is new, exhaust is almost all new. Never looked into the flex plate so have no idea about that so will do some homework.
As for the lifters being the cause, it makes me want to just open up the top end and at least take a look at things. I don't really know how lifters are structured but under high speeds it sounds like one or two of them are loose, like a segment that is supposed to be securely bolted is a little bit loose and rattles a little bit under high pace workloads. And since the lifters already make some noise, I would like to at least look at the culprits to see if there's anything obvious to be corrected in general.
Is lifter inspection a matter of just popping covers off and visually checking things out? Maybe removing some tubes above it to get access?

 

[Dirtman]

To inspect the lifters you need to remove the valve covers and intake manifold. Then remove the rocker arms and pushrods to pull the lifters out of the valley. The famous 2.9 tick comes from a few problems, it's a flat tappet cam that just wears poorly, oil issues that cause the lifters to fail to "pump up" leaving the valves loose, and the need to periodically adjust the valves. I would pick yourself up a Haynes manual, or a dedicated 2.9 engine manual and read up before taking anything apart. Doing an engine flush and adding ZDDP to the oil can help quiet down the noise in some cases though. But at the end of the day 2.9's just have noisy valve trains... The sky is blue, farts stink, 2.9's tick...

 

[eightynine4x4]

To inspect the lifters you need to remove the valve covers and intake manifold. Then remove the rocker arms and pushrods to pull the lifters out of the valley. The famous 2.9 tick comes from a few problems, it's a flat tappet cam that just wears poorly, oil issues that cause the lifters to fail to "pump up" leaving the valves loose, and the need to periodically adjust the valves. I would pick yourself up a Haynes manual, or a dedicated 2.9 engine manual and read up before taking anything apart. Doing an engine flush and adding ZDDP to the oil can help quiet down the noise in some cases though. But at the end of the day 2.9's just have noisy valve trains... The sky is blue, farts stink, 2.9's tick...

Agreed!
I’m not here to start the 16268th thread about ticking 2.9 lifters, nor look for new additives. ( I did do a flush and it was risky but worked out well ) I’m just trying to gauge if the tambourine sound at high rpm could be something more severe than ticking that will suddenly just pop and kill my engine or me.
I think I’ll soon dedicate a day to take this stuff off the top and at least see if anything appears crazy. I have the Haynes and always follow it !

 

[ecgreen]

I had a rattle between 2500 and 3000 RPMs. Swore it was lifters. Turned out I was missing a bolt on the thin metal backing plate between the tranny and engine.

 

[eightynine4x4]

I had a rattle between 2500 and 3000 RPMs. Swore it was lifters. Turned out I was missing a bolt on the thin metal backing plate between the tranny and engine.

Is this plate visible from underneath? Easily inspected?

 

[ecgreen]

Is this plate visible from underneath? Easily inspected?

Yep, look between the engine and tranny by the starter. It was missing one of the bottom bolts. Its a long shot you have the same trouble, but worth a look. The plate looks like this:

 

[eightynine4x4]

Yep, look between the engine and tranny by the starter. It was missing one of the bottom bolts. Its a long shot you have the same trouble, but worth a look. The plate looks like this:
View attachment 62446

Well what’s intriguing is that some ticking noise definitely seems to come from underneath too. Stepping outside the truck and peering under, there is a metallic light banging sound a lot of the time. I’m going to inspect this ASAP.

 

[gaz]

89-4x4,

If you don't resolve your noise source on that spacer plate, pop of the valve covers, discover how incredibly filthy and laden with soot and sludge.

Completely clean and inspect:

-valve covers
-rockers
-push rods
-rockers arm shafts (especially inside)

If determined 100% serviceable;

-increase the size of the oiling holes in the rocker arm shafts and rockers

Follow the lifter preload installation instructions while reinstalling the upper valve train then report your findings ..)

No matter what, all these procedures should be done and will yield improvements while possibly resolving your noise.

 

[eightynine4x4]

Yep, look between the engine and tranny by the starter. It was missing one of the bottom bolts. Its a long shot you have the same trouble, but worth a look. The plate looks like this:
View attachment 62446

So i've finally inspected this spot and found that the thin flexible plate does seem to separate around 1/8" for a whole lower section. Pics below. First one clearly shows the gap.
I'm confused what the purpose of the thin plate is though, at least in this section of it. I thought i had discovered a wide open problem but in fact i saw that there's already a huge curve shaped gap in the thin plate piece just above it (shown in other pics), so it can't possibly be sealing something right there. Or is it?
My plate doesn't appear to have the same shape as the one pictured by ECGREEN. Mine has that curved gap.
It's tough to tell if screws are missing and this is a problem, or if the plate is just sorta old and bent but this has no impact on anything.
I've recently started noticing kind of a fuzzing / spitting sound from underneath in this area but that could be because i've quieted so much other clammer in recent months. Maybe this loose thin plate is simply vibrating causing the spitty sound, or maybe they have nothing to do with each other.

 

[gaz]

I believe we are addressing the proverbial "dust" cover. Yours was out of shape when installed and left uncorrected. It is not a sealed surface, just keeping out unwanted stuff.