HELP! KA24DE Lower Timing Cover Damage

[schredder]

Greetings,

I am working on a 1998 Nissan Altima. The lower timing chain broke and in the process has damaged what the manual calls the stoppers on the lower timing chain cover. I describe them as the three? aluminum fingers or posts that are cast into the lower cover that go underneath the crank sprocket. The manual says they are there to keep the chain from disengaging the sprocket.

These aluminum fingers, stoppers, or posts are pretty well chewed up. My question is... does just the spring tension of the chain tensioner provide enough tension to keep the chain from jumping timing before enough oil pressure is created?

I have talked to a couple of mechanics.. I can't seem to get a straight answer if it will be okay just to put it back together with the damaged lower timing cover.

One mechanic told me those stoppers or fingers are there in the case of engine kick back or backfire...

Bottom line, should I try and locate a used cover? A new one is out of the question at $450.

Thanks,

Chris

[Shabbernigdo]

Greetings,

I am working on a 1998 Nissan Altima. The lower timing chain broke and in the process has damaged what the manual calls the stoppers on the lower timing chain cover. I describe them as the three? aluminum fingers or posts that are cast into the lower cover that go underneath the crank sprocket. The manual says they are there to keep the chain from disengaging the sprocket.

These aluminum fingers, stoppers, or posts are pretty well chewed up. My question is... does just the spring tension of the chain tensioner provide enough tension to keep the chain from jumping timing before enough oil pressure is created?

I have talked to a couple of mechanics.. I can't seem to get a straight answer if it will be okay just to put it back together with the damaged lower timing cover.

One mechanic told me those stoppers or fingers are there in the case of engine kick back or backfire...

Bottom line, should I try and locate a used cover? A new one is out of the question at $450.

Thanks,

Chris

cant tell ya from personal experience or any thing but i would replace them just for the extra insurance if any thing else.

Why take the chance for completly screwing your engine when you could of prevented it.

[schredder]

Yes I would just like to replace the cover, but a used one is hard to find. I guess I need to check ebay tonight.

Thought someone on here would have some experience to share.

[liquid_cool]

well you can go 2 routes with this....those fingers are really there so the chain dosent damage the oilpump sump tube or the coolent inlet area if the chain breaks....if nothing else is damaged but those little ears..then they did there job..if your short on cash..you can slap it backtogether for now ...but i would at the least file them down smooth and clean it up first....now if ya have some coin in your purse...then i would look on ebay and get a new lower cover with a new oilpump and seal..and kill 2 birds with 1 stone..hope this sets thing strait in your mind..good luck..what ever you decide.

[schredder]

well you can go 2 routes with this....those fingers are really there so the chain dosent damage the oilpump sump tube or the coolent inlet area if the chain breaks....if nothing else is damaged but those little ears..then they did there job..if your short on cash..you can slap it backtogether for now ...but i would at the least file them down smooth and clean it up first....now if ya have some coin in your purse...then i would look on ebay and get a new lower cover with a new oilpump and seal..and kill 2 birds with 1 stone..hope this sets thing strait in your mind..good luck..what ever you decide.

Thank you for the response! My main concern is if there would be a chance of the chain jumping timing before oil pressure comes-up in the chain tensioners. I know that they are also spring assisted, but this spring tension does seem like much.

It worried me when one mechanic talked about the engine kicking back or backfiring when this could very well be a possibility when starting the engine for the first time and having to set the ignition timing.

I will check ebay tonight to see if I can maybe find a cheap used lower timing cover. However, I would really like to start putting this engine back together tonight. Can't wait to get this job done. Not an easy repair.

Chris

[liquid_cool]

if your going to get one off of ebay..around 120ish to 150 ish..then it might aswell be new..btw..the oilpump should come with it...as far as the spring tentioner holding up to cranking forces it does..with no issues...its under load when the chain would have a possibility of slippage..

[schredder]

if your going to get one off of ebay..around 120ish to 150 ish..then it might aswell be new..btw..the oilpump should come with it...as far as the spring tentioner holding up to cranking forces it does..with no issues...its under load when the chain would have a possibility of slippage..

Been thinking... I know dangerous! You said that the aluminum ears (there were four looked last night), are there to protect the oil pump sump tube. But, now you mention the possibility of chain slippage under load. If the ears are there and intact, shouldn't they prevent chain slippage?

Also, as I am sure you know, the upper timing chain cover also has what my manual (a chiltons.. sucks!) calls a stopper. It is in the shape of a half moon? What is its function? I can only assume it's to protect the upper cover from damage in the event of chain breakage.

Again, as I mentioned, the manual states these ears or stopper are there to prevent the chain from disengaging the sprockets. I can see where they would be beneficial when assembling the engine before installing the head so you can install the idler pulley and finally put tension on the lower chain. Unless I am doing wrong the order of assembly has to be lower cover, oil pans, cylinder head, install lower chain on idler pulley, then pull pin on tensioner.

I just hope the lower chain doesn't fall off the crank sprocket before I can get the idler pulley installed and tensioned.

Thanks again.

[liquid_cool]

Been thinking... I know dangerous! You said that the aluminum ears (there were four looked last night), are there to protect the oil pump sump tube. But, now you mention the possibility of chain slippage under load. If the ears are there and intact, shouldn't they prevent chain slippage?

Also, as I am sure you know, the upper timing chain cover also has what my manual (a chiltons.. sucks!) calls a stopper. It is in the shape of a half moon? What is its function? I can only assume it's to protect the upper cover from damage in the event of chain breakage.

Again, as I mentioned, the manual states these ears or stopper are there to prevent the chain from disengaging the sprockets. I can see where they would be beneficial when assembling the engine before installing the head so you can install the idler pulley and finally put tension on the lower chain. Unless I am doing wrong the order of assembly has to be lower cover, oil pans, cylinder head, install lower chain on idler pulley, then pull pin on tensioner.

I just hope the lower chain doesn't fall off the crank sprocket before I can get the idler pulley installed and tensioned.

Thanks again.

those little ears only prevent the chain from smacking critical area's when there is a chain failure...not when its under load from the tentioner....KA tentioners work like a hydrolic piston..when filled with oil under load..thay have allot of force to hold that chain in its place..i myself wouldent worry to much about the ears.....if its gona fail..they usually send valves throu your pistons anyways..or worse..throw a rod throu the block...if i were you..id take a good look at the chain condition and tentioner , guides ..make shure they ahve no sighn's of wear..if not..re-seal and have fun for the next 70k miles.