Dreaded 4.0 SOHC rattle? Help!

[ErockSteady]

Hello everyone.

Here's a video (sorry for the bad quality) of my engine running. 98 EB w/ only 86k miles. Is the noise (particularly at the beginning) my timing chain(s) rattling? It's loud, but only occasionally. Oddly, it only does this when warm. I originally suspected the catalytic converter(s).

http://www.youtube.com/watch?v=TELWmpmDmW0

Thanks!

 

[2000StreetRod]

uneven idle?

It sounded to me like your idle speed is uneven in addition to the rattle. Have you ever replaced the upper and lower intake manifold gaskets? Have you checked for broken/loose vacuum hoses? This link may help: Intake manifold vacuum lines

My timing chain rattle (broken rear guide and broken primary tensioner) was noisiest at cold start before oil got to the chains. This link may help: Timing chain rattle resolution process - SOHC V6

 

[ErockSteady]

It sounded to me like your idle speed is uneven in addition to the rattle. Have you ever replaced the upper and lower intake manifold gaskets? Have you checked for broken/loose vacuum hoses?

I was hoping you'd chime in 2000! I've been doing a lot of research on this site and you seem like one of the resident experts on these matters. Yes, my idle speed is definitely uneven. See my thread about it here. I do suspect the manifold gaskets and/or other vacuum issues (I also have RPM flare and stumbling idle with very cold outdoor temps), but the odd thing is that it the uneven/surging idle only behaves this way when warm and under NO LOAD (i.e. in park or neutral). When in gear or with AC or defrost on, the idle drops a bit and smooths out. When I unplug the IAC, the issue completely goes away, and it idles fine (albeit lower). I've cleaned the IAC, but that has not helped. I don't know if that means I have a bad IAC, or if unplugging it just masks the issue. You can read all about my zillion questions on that thread ;-)

My timing chain rattle (broken rear guide and broken primary tensioner) was noisiest at cold start before oil got to the chains.

Yes, it would seem that most all people have worse timing chain rattle at cold starts and cold engine temps. Mine is only when warm, and is very intermittent, but pretty loud! I'd say it does this rattling about 20% of the time. Very odd! It seems like it's coming from the back of the engine compartment and/or underneath the rig, but I can't pinpoint it exactly.

This Explorer has been babied it's entire life. 1998 and only 86k miles, synthetic or syn blend changed religiously every 3k miles, and no hard driving whatsoever.

 

[2000StreetRod]

2 or 4WD?

If your rattle is timing chain related I suspect it to be due either a failed primary (crankshaft to jackshaft) chain tensioner or balance shaft chain tensioner. If you have 2WD you can eliminate the balance shaft chain tensioner as a possibility. The original primary tensioner was inferior and failed quickly. The 2002 and later design is greatly improved.

I suggest that you make sure the rattle is not from a broken cat shield mount by listening thru a long tube while laying on the ground next to your vehicle. Then make sure the rattle is interior to the engine by removing the serpentine belt and running the engine briefly (less than 1 minute) when it normally rattles. Once you're confident it's internal, then pull the upper intake manifold and valve covers and inspect the left and right cassettes. You need to replace the upper and lower intake manifold gaskets but I would delay that until you identify the source of the rattle.

 

[ErockSteady]

Thanks so much for the help. I will do as you suggest!

My rig is 4wd.

One thing that's throwing me off about this rattle is that it's quite infrequent, and only when warm. Seems to be the opposite of when most of these motors rattle due to timing chain issues. I have not listened to the exhaust with a tube or stethoscope yet, but I've crawled under there when running and banged around, and everything seems tight. At least on the outside, nothing is rattling around.

So I can actually get at the left and right cassettes with the intake off? I thought I needed to pull the motor. Or is that just for the chain in the rear?

Any idea about why the uneven idle would smooth out when the IAC is unplugged? Would this indicate a bad IAC, or just masking the real issue?

Thank you!!

 

[2000StreetRod]

inspecting for failures

. . . One thing that's throwing me off about this rattle is that it's quite infrequent, and only when warm. . .

A balance shaft chain can rattle at any time if the tensioner is broken. A primary chain usually rattles at engine mid-range if the tensioner is broken.

So I can actually get at the left and right cassettes with the intake off? . . .

With the valve covers removed you can usually identify a broken rear chain guide and sometimes a broken front chain guide. Removing the oil pan and examining fragments often reveals what's broken without removing the front timing cover. With the age of mileage of your vehicle if you have broken timing chain related components I would guess both the balance shaft and primary chain tensioners are broken.

Any idea about why the uneven idle would smooth out when the IAC is unplugged? Would this indicate a bad IAC, or just masking the real issue? . . .

Since you have a lean code for both banks there is probably an intake leak(s) somewhere. Intake leaks are small and have the most affect when the engine is idling under minimal load. An uneven idle under no load could be due to a loose primary chain allowing the timing to vary. Another possibility is varying fuel pressure due to vacuum fluctuations in your return type fuel system. I suggest ignoring the idle speed fluctuation until you determine your timing chain status.

 

[ErockSteady]

Thanks so much! Looks like I have some work to do. Man, and here I thought I was buying a reliable low mileage vehicle from my dad...

 

[ErockSteady]

So after driving my Ex more over the last month, I've got an update. I've determined exactly when it rattles, and under what circumstances. Very strange...I can't wrap my head around it. Perhaps the following details would give someone a clue as to what this would point to?

I hear the loud, intermittent rattle ONLY when driving it until warm, shutting it off for 5-10 minutes, then starting it again. While idling, it rattles. It's not a consistent-with-the-RPM chatter, like I hear on other 4.0 SOHC youtube videos. Mine is an on-again, off-again, clanky sound (watch video in my original post).

I can start my rig and drive it for 50 miles. No rattle whatsoever. Not at start, not at idle, not under load, nothing. Only after shutting her down, waiting for a few minutes, then starting her back up do I hear it. Then, it pretty much stays rattling for as long as she's running. Sometimes she quiets down after 10+ miles.

Does this sound familiar to anyone?

Also, does anyone know a mechanic in the Pacific NW area who knows a lot about these early 4.0 SOHC motors? I've contacted 3 local mechanics and my local Ford dealer to ask for a quote to pull the motor and do all the timing chains and guides, and they all act like they've never heard of this problem with this motor. One guy said it's a great motor, and all it probably needs is a tuneup. The Ford dealer had no idea what I was talking about when I asked him about "the timing chain rattle problem" with these motors.

Thanks!

 

[koda2000]

it's only a great motor when it hasn't started making timing chain noise (or after you replace all the related parts with upgraded ones). to do the front and rear chain repairs you're looking at around $2200 parts and labor. your truck isn't worth much more than that. if your Ford dealer hasn't hear of the problem it's because they're no longer used to dealing with the issue. it was/is very common with the early SOHC engine. if you want to keep the truck, look for a used 2005 Mustang SOHC long block with relatively low miles. you might find one for around $400-$500, but you'll still need to pay the labor to have it installed. my advice is to run it into the ground and scrap it. if the noise just started, you could have 30-40K left in it before it grenades. i don't know what prices are like where you live, but where i live you can find a 2000-2001 V8 with less than 120K for less than it will cost you to repair/replace your V6. with regular maintenance the V8 will go 300K+, have more power, a stronger transmission and get pretty much the same fuel economy.

you could try just doing the M0012 kit, which replaces the tensioners, guides and adds an oil restrictor tube, but if you're got a lot of miles on your engine your chain cassettes are probably starting to break up. that's where the majority of the expense of repair comes from as the engine has to be removed to replace the rear cassette/chain. in my opinion that isn't worth it for a 16 year old vehicle.

 

[ErockSteady]

thanks koda2000!

The problem is that I just bought this rig for $3,500. It's a 98 but it only has 87k original miles, and it's been babied. It's in mint condition, and I have all the service records and receipts. The oil was changed religiously every 3k miles, as well as the tranny fluid every 30k, etc etc. I didn't do proper research on this motor before buying. Therefore, I'm into this thing for $3,500, and now I'm worried it's not gonna last.

What do you think of the video posted in my original post? Pay attention especially to seconds 4-7 and 12-20. Sound like timing chain noise to you?

 

[koda2000]

my internet connection is very sketchy this afternoon, so i doubt i could make it through your video. i'm sure someone else will offer an opinion. i understand about not doing your research on the SOHC. that's how i got into these trucks, when my daughter bought a 2001 SOHC with chain noise (at least she didn't pay much for it).

if your truck is otherwise cherry and only has 87K on it - as far as saving your truck, your cheapest option would be to try the M0012 kit. if that doesn't help, look for the '05 Mustang motor swap. it won't have the balance shaft, but most don't think that's a big deal. i've never actually heard anyone explain why the 4WD engines have this shaft anyway. installing a reman engine will run you even more than the the chain repairs and i wouldn't waste any money on a salvage yard engine unless you know it has the updated parts.

BTW i believe the reason you hear the noise after running and restarting is because the oil is thinnest when warm and it drains out of the 2 hydraulic chain tensioners once it sits for a while. you should also make sure you use an oil filter which has a anti-drain back valve (like a Motorcraft filter or better). using a slightly heavier full synthetic oil also helps. with only 87K, i'd try the M0012 kit. most believe the tensioners should be replaced every 75K anyway. while you're at it consider replacing the upper/lower intake manifold gaskets (another problem area with these engines) can cause lean codes, hard starting, idle flair, uneven/high idle.

 

[ErockSteady]

your cheapest option would be to try the M0012 kit

Thanks again koda! I have the M0012 kit sitting in my garage waiting to be installed ;-)

I'll probably replace the other tensioners too, since the M0012 kit only comes with one. The intake gaskets are part of that kit, so that's a good thing. I'm also having some idling/vacuum problems, so hopefully the kit kills two birds with one stone.

Either that or I take it to a dealer while it's nice and shiny and brand new looking with its 87k miles and my file folder of all the service receipts and see what they give me for a trade

 

[koda2000]

Thanks again koda! I have the M0012 kit sitting in my garage waiting to be installed ;-)

I'll probably replace the other tensioners too, since the M0012 kit only comes with one. The intake gaskets are part of that kit, so that's a good thing. I'm also having some idling/vacuum problems, so hopefully the kit kills two birds with one stone.

Either that or I take it to a dealer while it's nice and shiny and brand new looking with its 87k miles and my file folder of all the service receipts and see what they give me for a trade

i hope you can get it straightened out, because the dealer isn't gonna want to offer you much for it, or keep it on his lot, regardless of how new and shiny it may look. it's just too old and their job is to give you as little as possible for your trade-in and get as much money as possible from you on whatever you buy. good luck!

 

[2000StreetRod]

internal or external rattle?

What have you done to determine the source of the rattle other than make a video?

 

[ErockSteady]

What have you done to determine the source of the rattle other than make a video?

I've crawled under the rig while running and placed my ear as close to the cats/exhaust as possible, as well as tried to locate the sound in the engine bay. I do not have a mechanics stethoscope, so I cannot pinpoint the origin, but the sound is the loudest underneath near the back/bottom of the motor. I plan on picking up tubing or a stethoscope, but haven't gotten around to it yet.

My only cause for reposting before doing the aforementioned exercise was to add the data I've gathered from driving it every day for a month. Again, only when hot, and only after shutting off for 5-10 mins and starting again. With the first start of the day (or after a long period of sitting), I can drive 5 miles or 50, and it won't make a peep.

 

[kevinspann]

I would consider replacing the tensioner.

http://www.youtube.com/watch?v=P4N5E_RfYpE

A video is easier to find to explain...his symptoms are opposite of yours. It seems like it's stuck? Or the guides are already broken and rattling around. If that's even the case. Hard to tell from the video. Sounds like you need an IAC possibly as well.

 

[rb142]

If you don't have a stethoscope, you can do mostly the same thing with a long screwdriver, or a copper tube, or something like that.

If you hear the sound mostly from the bottom/back of the engine (that's where mine was), it is likely the rear cassette. That is the one that fails more often, and it requires pulling the engine to fix.

 

[2000StreetRod]

disconnect the belt

A worn water pump bearing rattle can be intermittent. If you can rock the pulley using the fan blades then replace the pump. The pulley on the harmonic balancer can separate from it's inner section. Check it for correct alignment. I suggest disconnecting the serpentine belt after engine is warmed up and run the engine for no more than a minute. If it still rattles then you've eliminated the water pump, power steering pump, A/C compressor, alternator, belt tensioner and pulleys, and possibly the harmonic balancer.

It is very difficult to isolate an engine internal noise because it echoes off the walls of the block. I used a length of flexible hose and a mechanics stethoscope to try and isolated my start up rattle. I decided it was coming from the left (front) cassette but when I removed the valve covers and front timing cover I found a failed rear (right) cassette and failed primary (crankshaft to jackshaft) front chain tensioner.

 

[ErockSteady]

Sounds like you need an IAC possibly as well.

I just put a brand new IAC in, and the surging idle persists. Probably a vacuum leak issue. Once I replace the intake gaskets with the 00M12 kit, we'll see where that gets me.

Thanks for the input everyone! I'll disconnect the belt as StreetRod suggests to eliminate all belt-driven components and go from there.

 

[4pullingGM]

I've had to replace a couple of harmonic balancers on the sohc, they had a weight that was bonded to it and it came loose and would roll around as it rotated. That made more of a knocking sound than a rattle though. It still made noise with the belt off. Something to look at anyway. Good luck!