sore rattle

[scoty]

Right guys ..... I have a 1997 4.0 v6 sohc with 165,354 miles on the clock i have just bought this truck as its imaculate inside and outside and a kinda purple colour metalic and i liked it lol ... On startup its quiet but runs eraticly but ok once you drive off .. Once you drive 100 so pluss yards a rattle apears which is like a tick kinda rattle but loud enough for everyone to hear it and louder under load ... However it goes away when the engine reaches operating temprature and ist quiet as a mouse ... Its from the front of the engine but i cant quite pin point it .. Its strange its not there on startup or when heated up ... Any ideas guys ? ... Any help or advice would be great thanks.

 

[koda2000]

rattle sounds like the beginning of the dreaded "timing chain death rattle" (very common on this engine). it usually appears at startup and around 2200-2500 rpm. you could try replacing your left cam chain tensioner (including installation of the oil restrictor) but at some point the noise gets much worse and then your looking at a $2,500 repair job which includes engine removal. as far as the rough running, that's also common to these engines and is usually due to intake manifold o-rings (not too bad a job) or could be due dirty IAC or MAF sensor, but intake o-rings are very common problem. i know i'm freaking you out, but you can drive it many thousands of miles as it is (probably 10's of thousands). if it comes to it, you can replace the engine (long-block) with a low-mileage '05 mustang 4.0L SOHC engine for less money.

 

[scoty]

... it dont rattle on start up till it starts to warm and is there till it reaches running temp then the rattle is gone and the engine is quiet with no noises at all .... would this still happen if its the tensioner thats away ????

 

[koda2000]

the tensioners (there are 2) are hydrualic and after about 75K the springs inside get weak. until the oil pressure comes up, they don't put enough tension on the timing chains. in your case the tensioners are probably not the poblem. the timing chains are kept taught by "timing chain cassettes" with plastic guides. on the older design cassettes the plastic wears out and breaks up. once the plastic is gone the chains start running on metal parts and get loser, hence the rattle. at some point the metal parts break and then things get really ugly until complete failure. i suggest you search this forum for more on timing chain treads. there are 100ths of them.

 

[scoty]

right i investigated a bit today .. started her up from cold and let her tick over but she was spluttering and sounded if she had a miss and blowing exhaust but slowly settled when warming up .. no rattle till 5 min of ticking over then a wee bit rattling for maybe 15 seconds and ive narrowed it down to ... around the pulley to the right of the thermostat housing and if you remove the oil filler cap and listen in through there you can hear it clearer .. but once she is heated up no rattle at all ..... i need to find and fix it as its quite a sore rattle not unlike a pully being knacked but i dont think its the pulley.. there is not a single oil leak from anywhere and a full service history with her ...... any ideas or do you guys still think the timing chain ????? thanks

 

[koda2000]

yes. sorry...

 

[scoty]

do you think i would need to replace the guides or would just replacing the tensioner possibly rectify the problem ????

 

[koda2000]

well, as it doesn't rattle at startup, replacing the tensioners probably won't make a difference, but they're cheap (relatively speaking) and not that hard to change. from what i've read, you should plan on replacing the tensioners about every 75K anyway and if you're replacing the cassettes you should replace the tensioners too.

but hey, from what you describe you needn't rush to do anything until the noise gets much worse. my '01 xls w/160k+ sounds like a diesel engine and has for the last 30k. i don't know how much longer it'll keep running, but when it dies i'll see if it makes sense to swap in a newer motor. i'll have to decide if it makes sense financially.

 

[scoty]

Can i replace the guides and tensioners on the front of the engine and cure the problem .. Can it be done without messing about with the timing ? ... Also is there anywhere you would recomend for the stuff i need to buy as in tensioners and guides for the front of engine ????? Thanks guys and im in scotland in uk

 

[koda2000]

it is possible to change the front timing cassette with the engine in the vehicle. special tools are required to keep the cam timing correct. in the U.S. this job costs about $750. i have no idea what it would cost to do in the U.K.

my final thoughs on this subject are that i'd just drive it as is. it could take years for it to get any worse.