Random cold start/idle rattling

[Badassbanshee]

Ok guys I have a 98 4.0 Explorer with 202k that has a horrible rattle/chattering noise upon initial startup and idle. After driving the truck for 5 to 10 minutes the rattle almost completly subsides at idle and can only be heard faintly around 2500 rpm or more. It isn't consistant with engine rpm and really only varies in intensity.

I have half assed probed around with a screwdriver in an effort to pin down the source of said rattle to no avail. I believe it is coming from the upper left side of the motor in the vicinity of the timing chain. I have read about the timing chain guide issues with this engine and suspect the noise is the chain rattling on the guides from either a tensioner failure or strech.

Only thing that I don't get is that the noise dosen't change with engine rpm. I am not opposed to changing the chain, tensioners and guides but would prefer not to on a guess. Was hoping some of you guys have ran into the same rattle/clatter and could confirm my suspensions of a timing system issue...

Thanks in advance!

 

[RandomNerd2000]

Timing Chain guides are failing, if it's not every single, you've probably had one bust that hasn't made it's way down to the oil pan. Best thing to do IMO, is pull the lower oil pan, remove any plastic guides you find there, and get yourself a good drop in, and do any upgrades you want to on that one. You are aware of what doing the chains/guides on a SOHC entails, aren't you? There's a chain on the back that requires engine removal.

 

[Badassbanshee]

Yes I am aware of the rear timing chain. If the guides were bad wouldn't it rattle all the time though? Was thinking about changing the tensioners in hopes to fix this without removing the motor...

This truck was pretty neglected when I got it but over the two years I've owned it I've worked out most of the issues and it actually runs and drives damn good for being 19 years old. I'd like to keep it on the road but just don't want to keep fighting a loosing battle on a 500 dollar truck

 

[RandomNerd2000]

Well I've been told that occasionally they'll break but take time to fall out due to the fitment of the guides inside the engine, and the coming and going rattle is them getting out of line, and then getting back in line. That's how it is with my 01, it's a beautiful truck, it really is, it's a 4.0 though and has TC lockup issues I've been looking at, it's the OEM trans, never been out, the same goes for the engine, it's got 193K, the PO drove it in the ground, and it shows. I love it and hate to junk it, and can't afford to, but it's stupid to pour money into it. I'm doing my V8 project soon since this 01 replaced a rolled 99 I have, and then after that, I might look into getting a V8 donor for the 01, since few things would be nicer than to see the 5.0 in there, and though I'd have 2 V8s then, the 01 is going to be my college driver to keep the miles off my V8, so the miles are gonna really rack up since the college I'm looking at is a 35 minute drive one way.