Any Suggestions

[MTT]

I have a 90 240sx. It has 150,000 miles and was running great until a couple of weeks ago.

It sounds as though the oil pressure is down because there some serious tapping sounds coming from the engine.

There is plenty of oil in the engine.

I am not sure how to diagnose the problem.

Any suggestions would be appreciated

[I am Technoman]

an oil pressure test around 12 psi at idle and 55 psi at 4kyou can tap it at the oil sending unit

[MTT]

Thanks for the tip!

[Aries]

sounds like THE timing chain tap...deadly...hope it is just an oil pressure problem...

[MTT]

It is not the timing chain, I had the timing chain replaces last year. Its sounds much worse than the timing chain rattling.

[bruinbear714]

If you changed out your timing chain because the guide broke off and ended up in the oil pan, most likely it got melted and re-hardened up on your valve train where it is cooler.

If that's the case, then you will need to pull out your rockers and rocker arm and clean out the passages because it will block oil from reaching the rockers, hence, the knocking. This is the KA24E we're talking about right?

[MTT]

Yes it is the KA24E.

The mechanic that replaced the timing chain last year said he dropped the oil pan to clean out the pieces from the nylon idler.

Maybe the idler broke again but it does not sound like the timing chain is rattling.

How difficult is it to clean the oil passages on the valve train.

[bruinbear714]

Yes it is the KA24E.

The mechanic that replaced the timing chain last year said he dropped the oil pan to clean out the pieces from the nylon idler.

Maybe the idler broke again but it does not sound like the timing chain is rattling.

How difficult is it to clean the oil passages on the valve train.

If you pull off your valve cover and give each of your rockers a little tug, you will see which ones are loose/losing pressure.

I bleieve there are about 10 10mm bolts holding down the two rocker arms. You remove those bolts, the rocker guides, and pull the shaft out. Then get some wd40 and clean out the oil passages on the arms.

Reassemble everything back with some engine assembly lube and torque down the bolts to the right specs (I don't remember what the #'s are).

What happens is if your timing guide broke and fell into the oil pan, the hot oil melted it and the plastic ended up on the valve train where it is a little cooler, cool enough to let the plastic harden again. This happened on my friend's 89 KA and we ended up pulling out the two arms to find that they were clogged with little pieces of plastic that used to be a part of the guide.

[MTT]

Thanks for the advise. I will have to give it a try.

Is there a premanent solution for the problem with the nylon guide?

[SSS]

Unfortunately i don't think there is unless someone has fabricated/engineered a replacement piece.

[JNM240]

Yes there is a fix. In 1994 Nissan redesigned the peice with a metal bracket on the backside of the . If you are replacing your timing chain, get a updated kit. Basically, just check the auto parts store, Pep Boys had my updated kit.

[SSS]

I suppose Nissan Australia don't have that same part?

[bruinbear714]

Yes, there are timing kits for the KA24E engine. They include the cam sprocket, the crank sprocket, the chain, the guides, and the oil seals on the timing cover. It should cost around $130ish

[JNM240]

They should, since Nissan themselves redesigned the peice. Autoparts store kits should include the chain, updated guide, tensioner, cam and crank sprockets. Just walk in and ask to see the kit. If the guide is only plastic, its the old one. If it has a metal backing, its the new one. My kit even had a note saying that it was the updated kit and when Nissan updated it. Good luck!