Timing Chain . . . Yes, Another One

[elbles]

Hi,

I have a 1990 240SX with a newly rebuilt KA24E installed, with around 1,000 miles on it now. I thought all was well with it, aside from a stupid EGR problem, until a few weeks ago I started to hear what I thought were the injectors. The more I hear the sound though, the more I'm convinced it's the "marbles in a can" timing chain issue. It seems really prominent at idle (which is a little high, at 1,000 RPMs, but that's probably my IAA valve, from what I've read), and seemingly goes away above 1,500 RPMs. Obviously, this is something to be looked into further, but any ideas as to what exactly it is? Tensioner or guides? Both? I'm hoping that it will be covered under warranty, but I'll definitely be supplying the parts this time myself, considering that the company who rebuilt the thing can't seem to stop using old, outdated and obsolete parts. :-( Thanks, in advance.

[victor90]

Hey Check to see if the tensioners are the old ones...there are two different materials that were used... the old ones were recalled due to degradation way back..... there is a technical service bulletin for it from nissan... I know , same happened to me after an expensive repair .... i used to have the scanned tech bulletin but not anymore. its a design problem that was changed and alll original nissan owners recieved a letter of notice( not Recall) way back ....lates

[elbles]

Hey Check to see if the tensioners are the old ones...there are two different materials that were used... the old ones were recalled due to degradation way back..... there is a technical service bulletin for it from nissan... I know , same happened to me after an expensive repair .... i used to have the scanned tech bulletin but not anymore. its a design problem that was changed and alll original nissan owners recieved a letter of notice( not Recall) way back ....lates

Thanks for the reply. I've read about the old and new tensioners, but is there any easy way to tell the two apart? Can you tell the difference simply by pulling the valve cover, and looking at it from the top? It really only seems to be prominent at idle, and it's not at a constant volume. Pretty strange, if you ask me. My dad listened to it, and he thought it sounded like something in the valve train, so who knows. Thanks for the reply though, I appreciate it.

[ricebike]

you can't really tell from taking the valve cover off...

the old ones were just plastic... the new ones have a metal backing to them... I have both since I told the mech that I wanted the old parts back,please.

http://www.geocities.com/Motor...n.htm

thanks to the guy in the FAQs of http://www.240sx.org

[elbles]

you can't really tell from taking the valve cover off...

the old ones were just plastic... the new ones have a metal backing to them... I have both since I told the mech that I wanted the old parts back,please.

http://www.geocities.com/Motor...n.htm

thanks to the guy in the FAQs of http://www.240sx.org

Thanks, I've seen that site before, but it only mentions the 1989 models, though I'm aware 1990 models were affected as well. I took a mechanic's stethoscope to it today, and it was definitely coming from the front cover, and to me, it sounded like it was coming from the left side (passenger side) of the engine, which, IIRC, is where the tensioner is. I would find it hard to believe that an engine with only 1,500 miles on it would have broken guides (although it might be possible with a KA ;-)), but could it be the tensioner? The noise varies in intensity with seemingly no pattern to it. When I first got it back with the new engine, it had 10W-30 in it, and we had some cold (0-10 degree) mornings, and it rattled a little then, but only on startup. Now it does it quite often at idle (though not always), and goes away as RPMs increase. Could it be due to low oil pressure at idle (if the tensioner is actuated by oil pressure)? Sorry for the long post, but with over $5,000 into my 1990 240, it's the last thing I can risk. :-(

[ricebike]

good point; only way to check is to attatch a gauge n check out the pressure. but w/ a rebuild, that should have been done from the gitgo.

well after hooking it up, warm to norm operatin temp..

idle speed: ~11psi3,000 rpm: ~60-70 psi

good luck!

[elbles]

Thanks again for replying. I will probably test the oil pressure, to rule that part out, but my mechanic suggested 10W-40 oil might help out with the problem, which might make sense since I can't recall hearing this noise with the 10W30 in it, other than when starting it cold. We'll see what happens I guess . . . if this one dies, I'm parting the car out, and getting a 91+ plus 240, beating the crap out of the engine, and putting a SR20DET into it, which is probably what I should've done with this car in the first place (believe it or not, same cost as a rebuilt KA :-(). If only my dad would've let me at the time . . . only now does he say I could do it. :-( Thanks again for the reply, I'll try it out. Hope your weather is as nice as it is up in New England . . . dry, twisty roads make for fun in the 240. :-)

[ricebike]

hey here's the part where they also cover 90 SOHC...

http://www.geocities.com/Motor...4.htm

KA24E TENSION SIDE TIMING CHAIN GUIDE BROKEN

APPLIED VEHICLES:1990-94 Truck (D21)1989-90 204SX (S13)1990-92 Stanza (U12)1990 Axxess (M11)

i've done my timing chain set in 1999/ 143K miles... didn't do the oil pressure gauge thing yet since there weren't any noises after the job... well, exhaust manifold leak & 2 bolts stripped.

y was your's done soo soon? wasn't it covered under warranty back then?

[elbles]

hey here's the part where they also cover 90 SOHC...

http://www.geocities.com/Motor...4.htm

KA24E TENSION SIDE TIMING CHAIN GUIDE BROKEN

APPLIED VEHICLES:1990-94 Truck (D21)1989-90 204SX (S13)1990-92 Stanza (U12)1990 Axxess (M11)

i've done my timing chain set in 1999/ 143K miles... didn't do the oil pressure gauge thing yet since there weren't any noises after the job... well, exhaust manifold leak & 2 bolts stripped.

y was your's done soo soon? wasn't it covered under warranty back then?

The engine in my car needed to be replaced because of rod bearing failure, or so it seemed. From what I could gather, the old engine had a all new timing chain and cover put on, likely due to the fact that the old one was pretty much destroyed when the old chain wore a hole in it, and let coolant into the block. I noticed a noise when I first looked at the car, but I dismissed it as being lifters. It wasn't. :-) So, one day, on my way to school, was half a mile away, and stopped in traffic, and I go to first, let the clutch out, and . . . nothing. Stalled, dead, wouldn't start. After 2 weeks and $3400, it was back on the road. As you can probably tell, I don't want it to happen again. ;-)

[WAbernethy]

Here's a shot of the metal backed timing chain guide from my car. Just finished getting it all back together the other day. I swear, it feels like it has so much more power now after replacing pretty much the entire valve train and cleaning the head up. Oh well, hope this helps.

[elbles]

Thanks for the picture, it helps out quite a bit. I'm probably going to try to take the valve cover off this weekend, to see if I can see any obvious problems. The noise has really just started to bother me, along with the immense amounts of water leaking into the hatch when it rains (or when I wash "Christine", haha), along with the front tires wearing on the inside (these cars have camber adjustments from the factory?), it's starting to annoy me. :-(

I do have a question though . . . how hard is it to remove the front cover, and is there any benefit to doing it? I know the timing chain job itself is tedious and long, but if the chain and tensioner are in good shape, could I mess with the guides with just the front cover off? Easy to do? I have the FSM, but it's downstairs, and at 12 in the AM, I'm too lazy and tired to go look tonight. ;-) Just looking for voices of experience, not something that the FSM can necessarily give me . . . thanks again.

[red240ne]

i finished my timing chain job earlier today. you won't be able to see anything with just the valve cover off. don't even bother.

you have the same exact side effects I was having. All of my sensors were good, but for some reason it would always idle around 1500rpm in neutral.

It was a PERFECT idle tonight. If you were going to go to the trouble of taking the timing cover off, then believe me, you'd want to go ahead and replace EVERYTHING. The gears, chain, tensioner, guide, and any seal.

[elbles]

Thanks for the reply. The only reason I asked about possibly just doing part of the whole timing chain assembly is because the engine is only 2 months old, with ~1,500 miles on it. My guess as of yet is that the tensioner is defective (noise goes away after idle, and presence/intensity varies at idle). The company that I bought the engine from does provide a warranty, and cover everything on parts, but only $450 in labor costs. I'm going to have to argue with them about having it all covered because this thing is only 2 months old, and it's already making a noise I fear could destroy this engine like with what happened to the old one. :-( Thanks again for the reply though . . .

[elbles]

Just to follow up, I took my valve cover off today, just because a look in the FSM made it seem as though I might be able to see a few crucial things. First off, the guides appear to be the redesigned part (metal backing, still plastic or nylon against the chain though), and the tensioner was working when I applied force to it (it took some effort to do, but it quickly came back out). There was a lot of slack on the driver side of the chain, but turning the camshaft pulley a bit helped remove it from *that* side. Rattling on startup still, but I don't hear the noise at idle; I doubt very much that the problem is "fixed", but the next time I hear the noise at idle, I'm pulling the cover again, it seems you can tell quite a bit with just that off, at least on the KA24E. Any ideas?

[WAbernethy]

About your idle problem; Does it idle normally after coming to a stop at a light or something and then creep up to 1500 rpm or does it just drop to 1500 right away? Mine creeps, or at least it used to. The Nissan dealer ran a "diagnostic" and told me that the IAV was bad. After taking it out and cleaning it/checking the soleniods, it still did the same thing. Now, I just unplug it and set the idle manually w/ the screw on the side. I've tried everything and can't figure out what's making it happen. Everything else seems fine so I'm just letting it slide for now. You having similar problems? Got any ideas?