KA24E Engine Knoocking

[KA24Evan]

Ok so I am 15 and just bought my first car, 1990 Nissan 240sx SOHC. The

condition I bought it in is really good, only rust is under the mirrors and it will be fixed soon I will probably bondo it. Anyway to the engine, when I

start the car the engine makes a knocking noise immediatly, now my dad

says it could be the piston rods, bearings and the crankshaft. Does

anyone else have any ideas that might contradict this? I need all the help I

can get because I don't know much about cars but I want to learn. Thanks

for everyone who posts logical and helpful replies!

[seang]

Glad you came to a specialized website. First, let me say that your dad is generally correct here, those noises could be any of those things he said, but almost every ka24e has a dirty/sticky timing chain tensioner that relies on spring and oil pressure to work, so on start up they can rattle/slap around pretty loudly for a few seconds until it un-sticks. Is this the sound you're hearing?

Personally, I just start my engine and immeiately shut it back down, and then start it again so it doesn't just idle through it anymore. The original starter has held up to this repeated use for 2 1/2 years now, and it's going strong, (the truck has 140,000 miles). If the oil is dirty, then it sometimes takes re-starting it up to 3 times to quiet down, but oh well.

I would suggest just changing the timing chain, guides, and either thouroghly cleaning or replacing the tensioner. I happen to have a 1997 model ka24e in a pickup truck that came from the factory with metal backed timing chain guides. You have an earlier model that has plastic backed guides that can wear through and eat through the front cover into a water jacket, spilling water into the oil. Thankfully, I don't have this problem. If this is the sound you are hearing, and you do end up replacing the chain and its parts, then I suggest getting a kit for a 95-97 Nissan D21 Pickup 2.4 4cyl that has the metal backed guides, just for good measure. I have read about people who change the timing chain and guides, but retain the old tensioner, or don't clean it out. and the same noises start up again.

It's likely not a case of chain stretch, because the chain itself has no life span. It was made to last the life of the engine.

Modified by seang at 5:36 PM 9/22/2009

Modified by seang at 10:30 AM 9/23/2009
Modified by seang at 10:31 AM 9/23/2009

[KA24Evan]

Alright I will look at some timing chain replacements, but the knocking never does stop. I can drive the car around the block and the knocking will still be there no matter how long I idle the car. Thank you so much for the help and opening my eyes to different problems, I deffinitly want to get rid of the plastic back now.