Originally posted by morepower2 Common problem with early KA24's.
Ya...so what's the fix? New parts don't solve the problem. I don't really think anything is "fixable". Everyone says, "ah, that's just what they do" but that doesn't make it right. Unfortunately, even new Nissans demonstrate some valve chatter, so it's not likely there's a simple part that can be changed to shut it up!
Mine had the ol start up rattle from the time I bought it (75k miles). Over the summer I noticed it surging when I was in or around 3rd gear and doing a slow speed-say 30 mph. When I let off the throttle it would surge when decreasing RPM. I took it all apart and found the guide was broken and most of it was in the oil pan. With much help from this forum and about $200 I changed it out myself. Since then I have NO rattle what so ever. The truck can sit for a week and start up quietly. I use a Fram filter and Pennzoil. I think much of the Nissan rattle has to do with the timing chain. I had always assumed it was oil starvation, but after tearing it down and finding the valve train in such good shape I would have to say that it's probably your timing chain.
2003 Nissan 350Z 11000 mi
1993 Nissan Truck 133,000k mi
1999 Mercury Mountaineer 55kmi
1966 Ford Mustang 2many k mi
My guide and tensioner look brand new. So does most of the valvetrain. My chain doesn't have any slack in it -- at least when I removed the cam cover to check on it. Do you think my chain is that far stretched? The only time I get a rattle is after a hot start. Overnight or a week later, it starts quietly.
After a hot start or whatever it takes when yours makes noise, remove your oil cap and take something long and skinny and reach in there and see if you have any slack in the chain. I let mine sit over night (this is when my noise is the worse) and did this. When in reached in with a long skinny screwdriver i could move the chain a lot. I then started it (it rattled for about 3-5 seconds) shut it off removed the oil cap and checked it again to find the chain had no slack. Maybe there are several issuses with these engines? If mine was a strethed chain, wore chain guides etc... it should do this all the time not just after it sits for a period and the oil all drains. I am convinced that mine has a weak/malfunctioning cam chain tensioner. I switched to a higher quality anti-drain oil filter and it reduced my startup rattle to a second of noise compared to the 3-5 seconds i did have. Either way when i replace it i'm going to go with the whole timing kit because of all the work involved.
I've covered this issue in the past, but I'll repeat it anyway. The primary cause of the chain rattle problem is not the design of the guides, but it is the oil channel to the oil-fed timing chain tensioner. The tensioner consists of a plunger, spring, and body with an oil port. When the engine turns, oil is forced through the channel to the tensioner, which causes the plunger to push out and push the "slinger" guide against the timing chain, which takes up the slack. If sludge or debris gets into the oil channel, it will restrict the flow of oil to the tensioner, causing the insufficient pressure of the "slinger" guide against the timing chain, causing it to slack. The loose chain will then beat against the fixed guide on the opposite side. The fact that the early type guides were plastic didn't help and they would start to chip apart and/or break. If not for the slacking chain, these plastic guides would have been perfectly adequete. Later, Nissan upgraded the fixed-side guide by making it a metal guide with a plastic liner, which is a more durable design that the plastic guides, but still does not correct the initial problem, which is the slacking chain. Hardbodies from 95 through 97 have the upgraded guide, but can still experience the timing chain rattle if there is a restriction of oil to the tensioner, or, if there is low oil pressure. Before tearing down an engine, it is a good idea to install a mechanical test gauge and confirm proper oil pressure. If not, then this issue must be addressed first. During the replacement of the timing chain componants, it is important to clean out the oil channel to the tensioner. To do this, the tensioner and the oil filter need to be removed. Brake cleaner or carb cleaner can be sprayed into the oil port, which will blow out of the oil filter adapter. If available, it's best to follow with compressed air to completely clear out the oil channel. Then the front of the engine can be re-assembled. If this step is not taken, then it is very possible that the chain rattle will still exist even with new timing componants installed. In general, the timing chain and gears tend to wear very little on a properly maintained engine. That said, if an engine has well over 100,000 miles, I would probably just go ahead and install new gears and chain, anyway, while the front is apart. You should also check for any damage to the inside of the front cover. A new tensioner and guides should always be installed. As far as type of parts, you can't go wrong with genuine Nissan, but I would have no problem using aftermarket componants from a name-brand company such as TRW or Cloyes. Oil should be no thicker than 10W30 and 5W30 is preferred. If you have a KA24E with tapping lifters, this, to some degree, is "normal." If it is unusually loud, then the only fix is to replace the lifters. Some have been successful removing, disassembling and cleaning the lifters, but this is a long, tedious process. Use a quality oil filter, ie genuine Nissan or Purolator, and avoid overfilling, which can lead to aerated oil due to crankshaft whipping. Capacity on many KA engines is only 3.5 quarts, so check your owner's manual to be sure.
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