timing chain

[slidewaysAZN]

i just bought a 91 240sx coupe and i have the "marble in a tin can" problem....do you guys know what excactly is the problem and if the parts are hard to find and is it expensive to have done?

[dickie]

1. what kind of experience do you have with mechanic-style work?

2. what kind of experience do you have with the 240sx ka24de?

if the answer to those is, "not much," consider taking your car to a shop for a diagnostic. that rattle is usually indicative of worn timing chain issues.

some people will tell you to remove the upper guide, which is easily accessed by pulling the valve cover and looking at the chains and immediately over them. if you have a rectangular plate over them, there it is. DO take it off and look at it, chances are you will see some scoring/gouging.

lazy/broke owners will just leave the guide off because it probably stops the rattle noise from occurring. this is fine if you don't mind replacing all your valves when the chain snaps and they all bend.

if you want to prolong the life of your motor, i suggest having the chain, tensioners, and lower guides replaced. seeing as this is NOT a minor service, it will end up costing you over a grand in parts and labor to do.

its not something i would advise a beginner to do since you will be removing several other parts to gain access to the chains.

good luck.

[glitched]

I do believe there is also mediatary step between those 2 options of removing top guide and replacing all parts.

if removing the top guide doesnt help, find the guide in the how-to's on how to remove the lower guide as well. while you have that cover off you can also inspect the tensioner and clean off any sludge that is hampering it.

I've already removed the top one on mine for a slight improvement, my next step, probably this weekend, is to remove the lower one and inspect the tensioner.

If that doesnt fix it, the motor will be drivin till it pops. new motor is more bang for the buck.

[dickie]

dude, why are removing the lower guide? under no circumstances should that be removed, according to Nissan...

plus there is no "improvement" to be gained from removing the top guide, only keeps the chain (which has expanded from wear/bad tensioner/etc...) from making contact with it.

removing guides is not a solution, more like procrastination :P

just depends on how well you maintain your car/how long you want your motor to last.

[slidewaysAZN]

alright cool i wont remove it i'll take it to a local shop and have them check it out...thanks

[glitched]

Dude, i dont know what im talking about, only following the How to's http://www.nicoclub.com/articles.php?id=105618

But now that i re-read it, the directions say to remove guide 2, but up top says to not remove lower guide ?

*EDIT* nope i had it right hte first time. there are 2 guides on the upper chain that you remove, You DONT remove the guide for the lower chain.

the lower one is the one making the most noise, and if it gets chewed up more it could break apart and cause more damage.

I meant improvement as in little less rattle noise

[dickie]

that guide is wrong . thanks for letting me know i will take care of it!

i was going to remove mine back in the day but i was advised by several sources that it would be a bad idea and cause my chain to lose tension and screw up my motor. glad i learned that early on!

replace the chewed-up guides and replace your tensioner too. although mine was okay visibly, i was told to replace it anyways and when i got my new timing kit i saw how wrong i was when i was planning on leaving it in.

[glitched]

Check it out closer, there are 3 guides. 2 for the top chain one for the bottom, remove the top 2, leave the one at the bottom.

[dickie]

i know how many guides there are. the only one people remove is the very top one. removing the others is NOT recommended.

i learned this when i pulled my motor apart, and checked into it thoroughly.

[glitched]

Where is the actual nissan article?

[dickie]

there is no actual nissan article apart from the fsm. my info came from 2 Nissan techs at the dealership, corroborated by a former Nissan dealer tech that has been running his own nissan-exclusive shop for 25 years as well as 2 mechanics at another shop that specialize in nissan/mazda repair.

oh yeah, the parts distributor i got my timing kit from echoed their statements, when i asked them about removing the guides they set me straight.

good luck on whichever way you decide to go though.

[glitched]

WEll I know you found your problem but for future searches and what not I just checked the TSB records and found this:

98-092 11/15/1998 Engine - New Timing Chain/Front Cover Service Procedure

NOTE :The two chain guides for the upper timing chain have been deleted. Discard the two chain guides and their bolts during any service to the timing chain

Looks like both upper chain guids are to be removed...

zerothread?id=153669

[gingerbredman]

so you dont replace the chain/s itself just the tensioners and guides? i remember seeing somewhere the chain is a "nonservicable" part or something like that, would it need to be changed also? i need to do something about mine quick :o

[dickie]

you replace the chain, and you SHOULD be able to find an all-inclusive (or mostly inclusive) kit for replacement through your local dealer or parts retailer. if not, check wholesaler websites like worldpac to see what you need...