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View Full Version : SR timing chain: Can upper guide be removed?



SOHC240
08-06-2002, 03:43 PM
Well, what do you guys say? Is it like the KA24DE in this respect?

Thanks,
Marshall

uiuc240
08-06-2002, 03:47 PM
hmmmmmm...i've been wondering about that top guide too! i seem to notice a bit of noise/vibration coming from that region. hopefully wayne or yury or jeff or mark or greaser or some other SR guru will know the answer (there are others, and i'm sorry if i forgot your names at the moment http://forums.freshalloy.com/ubbthreads/images/icons/frown.gif)

Eric

AZ_Dave
08-06-2002, 03:55 PM
I'm not trying to get you in trouble...but you asked the same question in another recent post...which i tried to help you out on, or atleast offer a bump.

SOHC240
08-06-2002, 04:29 PM
I realize I asked twice, but this post is much more specific because I think this is qutie possibily an answer to my problem. The other post is much more general, and people looking for info on, or having answers about the chain guide may not look in the other post. If the mods feel this irrelevant they will delete this post. That's up to them.

I do thank you for the help in the other post though.

Marshall

phase2
08-07-2002, 01:14 AM
Yes it can be removed, although it causes no harm to leave it in there. SR chain tensioner is fairly good compare to the KA which gets weak over time and would slap against the upper guide.

It's there for protective reason 'if' the chain happens to break.

9591
08-07-2002, 02:04 AM
'If' the chain breaks, the only thing the guides will protect is the chain cover. Meanwhile, there're a whole passel of bent valves and aggravated pistons crying for attention. Probably, the guides are there to protect in case of a tensioner failure, which would be more likely than an outright chain break, anyway. The guides, in this scenario, might keep the chain from jumping off the gears, thereby preventing catastrophic bad stuff.

Agent_S13
08-07-2002, 12:41 PM
Just to clarify in this topic tho, the SR is belt-driven right? There's no timing chain in an SR?
To make it somewhat related to the responses - I would think there wouldn't be a problem w/ the guide because its guiding a rubber belt, right? It won't make the noise a metal chain would on a metal guide (metal against metal). Its a great question cuz I don't think anyone's ever brought this up, I just wanted to know if the SR is belt-driven instead of chain. http://forums.freshalloy.com/ubbthreads/images/icons/laugh.gif

-Aaron
'91 240sx coupe

uiuc240
08-07-2002, 12:54 PM
the CA motor uses a toothed belt
the SR motor uses a chain

Eric

Hollywood
08-08-2002, 12:28 AM
Just leave it! Why do you want to mess around with that anyway?

Hugh
08-08-2002, 10:53 AM
You don't want to remove the top guide. Imagine you are at 7000 rpms and the chain is spinning faster than you can comprehend... the tensioner starts to give a little slack under all the pressure, and the chain jumps a tooth.

Maybe its ok, but its gonna run funny. You open it up again to see whats going on... and it jumps again. All the valves smash into the pistons... meltdown of the head.

Not cool. I would leave it on there. Nissan rarely puts anything on they don't have a use for.

uiuc240
08-08-2002, 11:41 AM
from an email from Demon:

"that vestigal guard has been present on datsun/nissan motors since the U20's introduction in '66, and it does nothing but cause trouble. it is removable."

i'm going with him because he knows his [censored]. and i don't mean any offense by that 1bad.

Eric

Hugh
08-08-2002, 11:43 AM
It's cool. I'll leave mine on http://forums.freshalloy.com/ubbthreads/images/icons/wink.gif

oberkill
08-08-2002, 05:31 PM
They can definatly be removed. I dont think you have to worry about the chain jumping, at least on the intake side. There is not enough room for the chain to come off of the sprocket. If you have ever had one apart you know you have to pull the sprocket off the intake cam to get the chain off. Hypothetically it could jump on the exhaust side as there is plenty of room on that side for it to come off I just doubt it would. That being said I dont remove them because if the tensionor did decide to crap out I want to hear it as soon as possible and if that top guide is there you will hear it!

Alan

Hugh
08-08-2002, 07:36 PM
If the tensioner is starting to fail, your chain will jump. I watched this happen myself recently.

Hollywood
08-08-2002, 09:41 PM
I'm with 1bad 100%. Maybe nissan puts them on there engines for all these years because that's the same engineering behind the engines all these years. The timing chain system is a design, not a flaw.

But do what you got to do.

oberkill
08-08-2002, 09:55 PM
Which side did it jump on? It may jump on the Exhaust side but it physically cant on the intake side. There is not enough room between the sprocket and the head to get the chain out. Like I said I wouldnt remove it either but I dont think I would be all that worried about removing it.

Alan