Engine "Rattle"

[ptomat]

I have a 1998 Ford AWD Explorer with the 6 cyl 4.0 SOHC engine (approx. miles 144k)

In the last couple of months I started hearing a rattling noise from what appears to be the lower part (rear?) of the engine when I start it up after not driving it for a while (such as first thing in the morning). After it warms up/is driven a little bit, the noise will go away & will reappear when there is a time gap in between driving.

I'm wondering if it has something to do with a dirty/clogged oil pan screen?

Any input would be appreciated...Thanks

 

[fast_dave]

ptomat,

From what I've read on this forum, here's what is sounds like you're experiencing.

Search on this forum for "4.0 SOHC Timing Chain Cassette".

Pretty well documented issue with your engine.

Hope that helps -

 

[koda2000]

Ahhh, the dreaded "timing chain death rattle". If it's only doing it at startup you may be able to fix it by just replacing the hydraulic chain tensioners. The springs in the tensioners weaken with age. There's also a noise abetment kit (Ford 00M12) which includes new tensioners and a plastic straw/oil passage restrictor which is supposed to help the oil from draining out of the tensioners. Also a good idea to always use an oil filter with an anti-drain back valve.

BTW, If you have the V6 engine, you don't have AWD, just 4x4. Only the V8 came with AWD with no 4x4 option available.

 

[Tech By Trade]

Welcome to the club,
Here is a helpful guide. A little newer, but these engines didnt change much over their production span.

http://www.explorerforum.com/forums/showthread.php?t=278100

 

[Mike65]

ptomat, welcome. I have a 99 Sport with the 4.0 SOHC & it was having the rattle on cold start up then goes away. I have since replaced the rear hydraulic tensioner & it reduced the noise by about 1/2. This weekend I will be replacing the front one & hopefully it will eliminate the rest of the noise. I got them online from Rock Auto, r/s front pt#-95586 - $33.99, l/s rear pt#-95587 - $39.79.

 

[ptomat]

Thanks to all for your replies (koda2000 - thanks for the correction as well on the 4WD/AWD])
So, I was previously somewhat familiar with the rattle. Bought the truck second hand 3+ years ago with 110k miles on it & had the front tensioner(s) replaced by a Ford dealer (removal of upper/lower intake manifolds + installation of a volume reduction plug into left cylinder galley) after I found out it was originally a Ford recall issue.

If I understand the reply(s) as well as the embedded URL from TBT correctly, it sounds like the engine would have to be pulled in order to get at the problem if it's a problem other than a recurrence of the original problem fixed 3+ years ago.
I neither have the capability personally nor the money to have worked performed which includes pulling the engine. Besides, the truck itself is probably not worth as much as the expense of this potential (labor intensive) repair.

What is the absolute worst that could happen?
- Is it that the engine would just not run from one (or both) of the timing chain(s) jumping time?
- Is it dangerous to drive?...either around town and/or on the highway (65+mph)?
- I've changed the oil regularly (3k miles) since owning it - I've recently been substituting 1qt. of Lucas Oil Stabilizer for 1qt. of oil each time it's changed. Will it last (to some degree) & for how long if I just keep doing this?

Again,
Thanks for any/all feedback or input

 

[C420sailor]

If I understand the reply(s) as well as the embedded URL from TBT correctly, it sounds like the engine would have to be pulled in order to get at the problem if it's a problem other than a recurrence of the original problem fixed 3+ years ago.

Yep, unfortunately.

What is the absolute worst that could happen?
- Is it that the engine would just not run from one (or both) of the timing chain(s) jumping time?

Chain jumps teeth, valves and pistons have a not-so-little how ya doin'.

- Is it dangerous to drive?...either around town and/or on the highway (65+mph)?

No---just be mindful that it may leave you stranded one day. BUT for a little frame of reference...

Mine started with symptoms like yours at around 110k (rough guess). I didn't know any better, so I didn't do anything to remedy it. In hindsight, I should've replaced the tensioners. This job isn't that bad (a full day to do both for the average wrench) and doesn't require pulling the engine. I kept driving the truck until it became a regular thing. It was always worse in warm weather, sounded like a diesel at idle, and sounded like someone dumped a bag of marbles in it around 2200rpm. I drove that engine to 202k---so nearly 100,000 miles past the onset of symptoms. It was still running well when I swapped the motor out, but it sounded absolutely heinous. A mini-teardown revealed that while the rear tensioner/cassette was working 4.0, one of the front cassettes broke off completely and was sitting in the oil pan. The tensioner was fully extended and doing its best to keep the slack out of the chain. I am honestly surprised it never jumped teeth. As always, YMMV.

- I've changed the oil regularly (3k miles) since owning it - I've recently been substituting 1qt. of Lucas Oil Stabilizer for 1qt. of oil each time it's changed. Will it last (to some degree) & for how long if I just keep doing this?

Can't speak to this. I don't believe in adding anything to oil. I changed mine every 3-4k with Valvoline Max Life and Motorcraft FL1A filter---but I don't want to start an oil war.

 

[koda2000]

Our first SOHC Explorer (purchased by my daughter and her boyfriend with no input from me) had bad TC rattle at startup, at idle and when driving. I hated hearing the noise with the starting flare. I have no idea how long it had been rattling, but I suspect a long while. It ran for quite a few thousand miles (60K+) before it finally jumped-time and died. At that point we junked it and replaced it with a V8 Mountaineer. Love the trucks - not a fan of the SOHC V6.

If you're going to continue driving yours without at least replacing the chain tensioners, I strongly suggest you drop your lower oil pan (easy to do and you may be able to reuse the gasket) to remove any pieces of tan plastic that may be found there. These are broken pieces of your timing chain cassettes. They can get sucked up and clog the oil pickup screen, which cuts of the oil supply/pressure to the engine. It like your engine has a heart attack (not good). When/if this happens your oil pressure gauge needle will start jumping around wildly. My daughter's oil pressure gauge once bounced so hard the needle ended up on the wrong side of it's stop. You may also find gritty material on the bottom of you oil pan. This is metal that is getting worn away by your timing chains flailing around. These particles can also clog the oil pickup screen, but will do so more slowly over time.

I'm seriously considering replacing my chain tensioners in my '01 Sport Track as preventive maintenance. I found no broken plastic in my oil pan, so my cassettes are apparently still in tact. My son-in-law's '97 Sport has over 250,000 miles on it (on a rebuilt engine) and currently has no timing chain noise.

Unfortunately, replacing broken timing chain cassettes is cost prohibitive, complicated and labor intensive on a vehicle which is approaching 20 years old and replacing your engine with a used one is not a good solution unless you rebuild it before installation. I guess it comes down to how much you love your truck and how much time/money you're willing to put into it.