Hi, all: Daughter's daily driver '87 4.0 rattles for about 5 seconds on startup.

After warming up, engine sounds like a gravel crusher around the valvetrain/head area at fast idle/moderate RPM.

Lifters were replaced about 30,000 miles ago. That helped some at the time.

Using Mobil 1 10W-30 oil with a Wix filter.

It's REALLY loud. How much longer do I have?

Engine is original with about 220,00 miles now.

 

Gravel crusher? Do you have black smoke smelling like fuel from the tailpipe? Did it run like this before the lifter change? The rattle can be normal in the cold weather, mine does it. are the valve springs in good shape.

 

It's 70* here right now. It always rattles on startup as I mentioned. Was worse before lifter changeout. Main reason lifters were changed was because several were losing their prime resulting in loud tap tap tap.

But it has not had the loud rattling noise at constant RPM until recently.

No black smoke, or smoke of any kind. It'll use about 3/4 qt oil in about 6,000 miles.

It idles and runs smoothly, no missing.

 

How's the oil pressure? Possibly weak oil pump so not enough oils getting to the head?

 

Yeah, I need to check that a little closer when hot. Upon cool start a little while ago, there wasn't really a rattle except at startup.

Generally speaking, idle and running oil pressure has always been within specs on this Jeep.

 

Check the bolts on your flywheel (flex plate) what err you call it... Mine loosened up on me one time while heelig and it sounded like a pop can

 

That's a good hint. But the sound comes from up top, under the valve cover.

It does it worse when warmed up. Not so much after startup.

 

loose rings
banging piston skirts
worn out piston pins
oil loss may be the rings I lose about half a quart of oil about every 400mi or so on long drives due to the rings.

 

I saw mentioned you can check the knock sensor by rapping on/by it. And listen for a change. I haven't tried it. Just fielding a thought. I gather the ECU will keep advancing the timing until knocking signals the knock sensor to tell the ECU to knock that off!

 

As mentioned, mine loses 3/4 in about 6000 miles.

I hope it's just a weakening oil pump. When I had the head off about 30K miles ago or so, there was very little ring groove and the walls looked clean then.

 

Can you post up a link to a recording of that? I did a "test flight" posting on U-Tube and posting the link to that, and it seemed to work OK without much hassle. I suppose "condenser mic" in your device might well deliver a misleading signal...but it's always fun!


That experiment, Here>. ( It's checking injector pulse..on #2.., with a bulb from a three cell mag light) Its missing with #2 's wires disconnected for the 4.5V Bulb? AW phit. its fine. Just with the camera on it's not steady because of the way I'm holding it. It's pulsing fine.

 

I'm away from the Jeep right now. Out of town. Will see if I can do that when I get back.

Thanks!

 

could be the valve springs with that mileage

 

Seems like it would get quieter when heated up, because the springs should expand some with heat?

Take up the "slack"?

 

Not if they are broken or cracked.