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Discussion Starter #1 (Edited)
I have a ka24e that when cold, will seem to knock at around 2500-4000 rpms. And this is about 30 seconds of being run. I am going to replace the timing chain this sunday coming, and do the clutch as well. The truck has 156xxx miles on it. IT doesnt make that knock sound at idle so i was HOPING it was just the chain banging against the cover due to the high oil pressure on the broken guide when the engine is cold. Give me your ideas. Like i said, it only does it when accelerating after just being started. Also if you rev it up in neutral you can hear it. 40 degree weather and lower. After a minute of running, it quits doing it. I'm hoping its not a rod bearing starting to go bad, but if it is, I was thinking of just investing in a new motor seeing as the number one cylinder has 15% leakdown. thanks guys. 1992 hardbody 2wd. I also am aware of the timing chain rattle. The rattle usually only takes place when first started and when the engine warms up.

I do rag on it from time to time, so i wouldn't be surprised if it is what i'm fearing.
 

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If it quits after it's warm, it may not be a big deal. The oil is thicker and it's common for a engine to be noisier when it's cold. Sometimes the hydraulic lifters sound terrible on cold mornings, but after it's warm it fine. This is nothing to worry about. A lot of engines have a small ticking noise even after they are warmed up, this is normal valvetrain noise. You can really hear it if you are idling near a brick wall with the windows down. (like a drive thru, the sound reflects off the wall making it more audible)

15% leakdown is probably OK. A good rule of thumb is less than 20%. A more important question is where is the air going??? There is a procedure for a leakdown test that will narrow down the issue. Again this shouldn't be a big deal.

Be sure to use the correct oil 5w30 and a filter with an anti-drain back valve(Fram Tough Guard, Wix, there's plenty out there). If you have kept up with the oil changes properly (which means there should be no sludge build up anywhere, and especially around the seals) synthetic oil seems to quiet the engine down a bit, but it's OK with Conventional oil.

Changing the timing set is a good idea, but I wouldn't do it unless the rattle got bad. If it goes away after warming up, it's probably OK. If it does rattle really bad on a cold start for more than 3 or 4 seconds, I'd change it.
 

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i believe that timing chain has a spring loaded tensioner againd the guide on the right side of the engine it keeps constant pressure on the chain so it it was a broke or missing guide or anything else to do with the timing chain the noise would not go away you would hear it all the time
 

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Discussion Starter #5
I was planning on changing to mobil one synthetic 10w30 tomorrow. And i was going to use a purolator pureone oil filter as well.

I doubt with the high miles that little change in weight would hurt it. We put our ears to the oil fill, and have concluded the leak down is coming from the rings. Number 4 cylinder only has 4% leak down. Yeah, even if it is a rod bearing, it isn't serious yet. Probably worn out I guess. The timing chain rattles like hell when you down shift after the engine has warmed up. And while accelerating a rattle can be heard. I definately think it is time to change it. I don't want to have to pull the head and replace valves on such an old motor. In the future sometime, I would like to swap to a ka24de and turbo it. SHould be a fun experience. There aren't many hardbodies sitting on 300HP. THey are light as hell. This worn out sohc ka rapes civics all day long. So I would like to see what a turbo dohc can do.

I was wondering if there are any mild cams for this engine? maybe boost the power output a little more than in it's worn out state.
 

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It sounds like you may have low oil pressure which could be caused by several factors. Worn rod/main bearings. Plugged up oil filter. Dirty oil pickup. Most of the time it's the oil pump which may be worn and not producing the proper oil pressure/volume. The KA24E oil pumps were notorious for not lasting long.

You can check the pressure very easily by installing a temporary mechanical oil pressure gauge. You would remove the oil sensor which is located next to the oil filter and install the mechanical oil pressure gauge in it's place; you may need to get an 1/8 BSPT to 1/8 NPT adapter to hook up the gauge.

With the engine fully warmed up, the pressure should be as follows:
idle - at least 11 psi
3000 RPM - 60 to 70 psi

If the oil pump needs to be replaced, it's easy to do so on a KA24E as it bolts on externally.
 
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