Timing Chain Guides...(Not the usual questions)

[Mikel]

Ok, I've read a million times that the KA is bad about killing timing chain guides and rattling. I just bought a 89 Coupe with the KAE with the infamous timing chain rattle. I pull it into my shop, pull off the cam cover and check out the timing chain...looks fine. The guides aren't worn at all, and the tension is great. Nothing looks to be broken, worn, missing, or in any other way faulty. What gives? The noise is definately coming from that area, it does it more or less all the time, gets worse at around 3000rpms.

The only thing I can think of is that is was low on oil by about half a quart, and it's an horrible need of an oil change. Maybe the old oil + low oil was causing the tensioners to act up?

[orion::S14]

Or the pump is old and worn out, so you have bad oil pressure as the RPMs rise.

That'd be my guess.

How many miles...???

No matter, get an oil pressure gauge on there and report the findings to us.

- Brian

[NismoSilvia270R]

yeah mines got real bad valve tap.

bad oil. i agree with the check on oil

[aznpoopy]

unless u have a dohc swapped into your car, im guessing u have the sohc...

from i remember, the SOHC timing chain rattle is different then the DOHC timing chain rattle. its also a much more serious problem. not sure (as i dont have one) but i think the guides on the sohc were plastic. the tensioner would get weak, causing a slack chain and the plastic guides would proceed to get munched into little plastic bits. slack chain can jump teeth and munch valves, tasty!

the 240sx.org FAQ section has a bit more info on it.

[twitchy]

i change the oil religously in mine KADE

i have the rattle, im going to get the VC gaskets and take the damn guide out soon and ill let you all know if it helped. If that doesnt fix it, im going to sell the 240 and buy a 2005 Z06.

[amolao]

Yes he is saying hes got an 89 and a KAE, thats SOHC.....I was you I will replace the oil pump, I hear stories of people using a 280Z (supposely fits perfec...) for better performance.... If still the same replace chain and tensioners, no questions asked......but there is a good chance that is the oil pressure....

[Mikel]

Yes he is saying hes got an 89 and a KAE, thats SOHC.....I was you I will replace the oil pump, I hear stories of people using a 280Z (supposely fits perfec...) for better performance.... If still the same replace chain and tensioners, no questions asked......but there is a good chance that is the oil pressure....

Actually, I think I've found a parts car with a good KA24DE, problem solved.

On the KAE, I changed the oil and it quieted down a lot. I think my diagnosis was pretty much correct in that the low oil level and old oil weren't making enough oil pressure to tension the chain properly. The only problem is that I think it's jumped timing. Anyway, I'll probably just swap to the twin cam engine untill I do the SR swap.