Help ID-ing this rattle

[seabiscuit]

I haven't had a death rattle before at start up or any time. This rattle started suddenly after driving on freeway for 25 minutes. Luckily I was able to hear it when I got off the freeway and was on quieter surface streets to my brothers house.

Sound is loudest at the timing chain inspection cover while running (using the long screwdriver to ear test). There are no marks on the "L."
Rattle increases with RPM's.

I took this video before the sun went down as I waited for the tow truck. I didn't want to chance driving on it for another half hour home. I won't be able to inspect further for another day or two; so in the meantime I thought I'd post here for help.

Any ideas? Direction?



Disclaimer: I've never physically heard an actual "death rattle" audio. Is this what it sounds like?

[jrusso07]

Hmmm, death rattle that I experienced always goes away when oil pressure is up...and it isn't as "ticky" as what you have. Never heard it be so consistent and prolonged. Death rattle is more "rattling noise" as chain scraps the evil L.

Making WAGs maybe a valve tick, or maybe a valve guide in #1 has dropped down toward piston? I assume the frequency of the sound increases with engine speed?

[JT68]

Sounds very regular&consistent to me, not so chainlike.

Suggest:
First remove the fan belt to rule out an odd alt/alt-fan/waterpump/fan issue. ( not real likely, but certainly possible)

If still there with no accessories running, lift the VC and look closely at the front most rocker arms.

What happened to the VC? Did this engine break a chain previously? J

[Gregs672000]

Ya, that's not the typical sound of chain slap on the L. But it's so fast at idle it does not sound like a rocker arm to me which I think would be more of a clear tap tap sound, but it is hard to tell. It's so fast that it does sound like something going round and round like a chain moving fast. I'm with Jt, remove the fan belt to get the pump and alt out of the mix. Look all around the outside of the engine... I had a loose bolt on my non-stock fan shroud that briefly fooled me once. Remove the valve cover and inspect the tensioner and make sure it has movement and is not chewed up. Check for any bolts on the upper guide that may have backed out some and could hit the chain (?). Inspect the chain, halfway broken link? (total guess). Check your rockers to make sure they haven't thrown a lash cap (I've had that happen before too... could be it, will be obvious). Pull the plugs and inspect, then have a friend spin the engine with the plugs out and the coil wire off so you can watch the rockers and look for anything unusual, or to ID the culprit.

Only other chain issue I can think of would be the lower chain and guide. The guides tend to break or to otherwise come off (per Rallye Roadster) and while they usually end up in the pan it could be that it is sitting in a bad spot. No way to really tell, though you might have a better idea with the valve cover off and spinning the engine with the starter. NOTE THAT OIL WILL LIKELY BE SPRAYED AROUND BY THE CAM WHEN YOU ARE SPINNING THE ENGINE WITH THE VALVE COVER OFF, SO BE PREPARED WITH RAGS LAID OUT.

[seabiscuit]

Thank you for all the suggestions. I first tested the fan belt accessories and sound continues. Inspected the area and found all parts intact. Chain looks ok.
I did find some metal that was abnormal. The photos have two different locations where it seems the chain contacted bolt heads and the mounting metal it secures. It appears that the metal the bolt fastens to is knurled over the bolt heads. Unfortunately I never looked this closely at these points before the noise started so I'm not absolutely sure it wasn't like that previously. Anyone seen that before?

I think it might be part of the upper chain guide mount and the other is below the inspection hole. I'm not sure what part that is.
I can't get a better look below this. What's the next step to look lower in this assembly? Would an inspection camera help?

Thank you again folks for your help.

JT, I got the car with the repair already done on the VC so I'm not sure of the exact history. I've always assumed the chain broke. There's chain damage on the top of the "L" (not below) that's been there since I got the car so I think he salvaged as much as he could when rebuilding after the break.

-Leo

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[Gregs672000]

The pic of the chain tensioner (large metal block) is correct, as that is a lock plate that is formed around the bolt to keep it secure. I use locktite instead. The other bolt is concerning. I wonder if the chain is tensioning properly or has stretched to the point of replacement.

Gotta run, I'll look again later.take more pics in general.

[spl310]

The bolt losing it's head is a sign of impending chain failure.

[fj20spl311]

It could also be one link of the chain failing, that is one of the little plates swinging loose. Pull the plugs and rotate the engine over by hand a examine the chain closely.
I think its time for New gears and chains......Many just do chains. I think that's CRAZY.

[boxcar]

Sounds more like valve train. Check your cam for heat tracks and check your number 1 intake and exhaust valve lash.

[Gregs672000]

Agree with above about the bolt. I do wonder if the tensioner has lost pressure. There is a very small hole that feeds the tensioner and a paper gasket that seals things up. It's really an unusual place for the chain to be loose, as the tensioner should take up the slack and not allow that much chain slop, especially on that side. That's what makes me wonder about the function of the tensioner.
This is what I would do: As indicated, spin the engine by hand (plugs out) and inspect the chain for broken links that are slapping. If none found, actuate the tensioner by hand so you can feel what it feels like when there is no oil pressure to it... it's pretty light and should slide back and forth easily. With the plugs still out and the coil wire disconnected, spin the engine over at least 20 counts or more with the valve cover on and with the inspection plate slid back on (neither need to be bolted down) to get oil pressure to the tensioner, then remove the valve cover and see what the tensioner looks like (should be extended) and then push back on it and it should be more resistant than before. The oil pressure bleeds off via a hole in the tensioner foot. You can do this several times to check pressure if you're not sure it's reached the tensioner. If the tensioner is the same, then that suggests something has plugged the feed hole or the gasket is leaking bad enough to not pressurize the tensioner, allowing for chain slap.

From there, if the tensioner is not functioning, then remove the inspection plate, stuff a rag under the cam gear etc such that nothing can fall into the engine by accident, bend back the tabs of the bolt locking plate and remove the bolts with a 10mm socket. Then carefully remove the tensioner, noting that it has a spring but it's not super taunt and probably won't fly off. Inspect the gasket, inspect the oil holes in the block and tensioner. With the tensioner in your hand, plung it back and forth and it should suck through the hole in the back. You'll hear it and feel it. I don't recall if there is a fitting on the block for where the oil feed hole is, but see if you can see any blockage there. Little pieces of things, like silicon gasket maker end up in little places. This is a guess but you have nothing to lose.

If a problem is discovered and fixed and you're reinstalling it, you will need to purchase or make your own new gasket that is exactly like the original and does not cover up the oil feed hole, and use no gasket sealer. I would ditch the lock plate and use blue locktite on the bolts.

One then would have to wonder about the longevity of the chain due to it striking that bolt.

If the tensioner is working as designed, then the chains and likely the gears need to be changed out, which can mean pulling the head, exhaust and intake, oil pan, rad, alternator, front pulley, water pump and replacing all the associated gaskets. May be possible to do without pulling the head etc, but it will depend on what it has for studs vs bolts on the front cover to oil pan fasteners (it is probably possible to pull the front cover to oil pan studs, which would help allow this whole project to be done without pulling the head), and may require pulling the water pump studs. Regardless, a several hour job that requires a couple special tools depending on what's needed (head bolt Allen head socket, stud puller, maybe a gear puller for the crank dampener, dye to clean head bolt holes, torque wrench, etc). You can do this with patience and some general mechanical knowledge if you follow instructions, and we can help if you dive in.

We'll cross bridges when we get there...

[JT68]

You have not found the problem yet. Both the tensioner bolt and the "lower" bolt (actually one of the upper
guide bolts), both have lock tabs on them-do not appear damaged...at least to my eye

[JT68]

Suggest you look very carefully at all the rocker arms and springs.

[jrusso07]

Agree with JT, the bolts don't look damaged as that is the locking plate (which is typically replaced after one use). Again, sound you recorded does not sound like chain noise. I will guess a missing lash pad or lash settings are way off on one of the cam followers/rocker arms. Could be a valve stuck open?

[JT68]

Agree with JT, the bolts don't look damaged as that is the locking plate (which is typically replaced after one use). Again, sound you recorded does not sound like chain noise. I will guess a missing lash pad or lash settings are way off on one of the cam followers/rocker arms. Could be a valve stuck open?

yep, lots of things coukd cause this, several are listed above add destroyed rocker, bent valve, broken spring--sounds mostly like valvetrain to me//


try this, remove spark plugs and have someone turn the starter for you. watch the chain& look& listen to the valves and rockers. best, j

[Gregs672000]

The lock plate looks chewed up to me. Could be from reuse I suppose.