knocking noise from sr20det

[Neil]

ya socket/breaker bar works too

[blackmagic]

alright well i had to fix a boost leak first but i got that taken care of and now i have the valve cover off and im not seeing anything wrong yet. its about 100degres outside right now with humidity level up the yinyang and no cloud cover so im taking a 5min. break before I end up lookin like a lobster.how much are the rockers supposed to move. i only messed with one so far but it only moves side to side a tiny bit. i did take my chain guide off though so who knows mabe thats what it was the chain does feel like it has a little bit of slack. where is the second chain guide i heard somone say its on the bottom? bottom of what?

[Neil]

Ahh.. Check on the underside of your valve cover. Does it look like the chain has been hitting it? Unlike the service bulletin for KA24DE's, that guard between the cam sprockets needs to stay in place.

There are 2 more guides and they are both behind the oil pump cover. Looking at the front of the motor, to the left there's a curved one that pivots at the bottom, that's the tension side. There's another guide on the right, and it is straight.

It is possible that if you only recently started hearing the noise that your chain tensioner is starting to go bad, and the slack is allowing the chain to flap and make contact with the underside of the valve cover. Luckily the tensioners are very easy to replace. It looks like a cap held in place by two 10mm bolts just below the cylinder head on the left side. Nissan has revised their design like 3 times since the early '90's. USDM SR20DE's use the same piece so if you order one for a G20 or something it'll be the right part.

I'd recommend replacing it anyway even if it ends up not helping your ticking problem. They operate with oil pressure and age/sludge will prevent them from applying enough tension on the chain.

As far as the rockers are concerned, I think a tiny bit of side to side movement is okay but if you find any pivotal movement, as a result of any gap between the pad that makes contact with the cam and the cam itself, then that would describe what I was thinking the sound could be. Then again, that's probably an unlikely scenario because supposedly if the rocker is allowed to float at all it will immediately dislodge itself and ruin the valvetrain. which would be why aftermarket rocker arm stoppers exist, since increasing the redline without upgrading valve springs introduces the risk of valve float.
Modified by Neil at 9:27 PM 9/15/2008

[blackmagic]

alright well i looked at the guide and i can see 2 lines in the shape that the chain would be so it has hit the guide now the other 2 guides your talking about look fine to me. the chain does have slack though the more i rotate the crank the looser the chain gets then it tightens up a bit. do i have to remove the front cover to replace the guides? O and i checked the up and down movement on the rockers and there is none so im in the clear for that i guess. The chain guide is the only thing wrong so far that im seeing then theres the gay valve cover bolts keep stripping and pissing me off im gonna have to go buy some bolts and just make my own valve cover bolts.

[Neil]

A little wear in the guide is normal, the pad is only plastic. I'd definitely put it back in unless it's worn through to the metal bracket.

you do have to remove the oil cover, and most likely the head, to get at the other two guides. I wouldn't worry about them unless you have the motor out for a complete rebuild.

and the chain will have a good amount of slack without the motor running, since the tensioner operates mostly with oil pressure. I edited my above post to mention that the tensioners do go bad from sludge buildup and I'd recommend replacing it if you want to make sure there's no excessive chain slack when running the motor.

[blackmagic]

alright well im putting the valve cover back on the head so I can get back to where im staying. Ill let you know if it changed anything if not then next time i pull the valve cover off ill drop the guide back in. Ill be replacing my head gasket pretty soon cause im running my gt28rs turbo and im sure the stock one wont hold for to much longer. so when i do that ill go ahead and get them tensioners done to.

[blackmagic]

alright this sucks. i got the valve cover on and started it and same noise. so i guess its not the timing chain and if it is the i dont know what its hitting and i tried moving each rocker and nothing.But hey i fixed the boost leak so its not all that bad haha. im almost ready to just buy another motor and swap it out. and just try to figure whats wrong with this one then fix it and sell it. the only thing i realy like about this motor is it has good compression

[Neil]

Did you put the upper guide back in?

[blackmagic]

no remember i said ill just leave it out to see if it fixes it and next time I pull my valve cover off ill put it back in. What else should i look at... this is confusing cause I can hear the noise at the head and not at the block with the mechanics stethoscope. AHHHHHH

[Neil]

I know. I was kind of just messing with you because you put the valve cover back on without it and seemed to be surprised that nothing changed

When was the last time you changed your oil? Did you use anything besides a quality 10w30? I was doing a little searching and supposedly if the noise quiets down with a fresh oil change then it can mean the "coating on one of the lifters" is wearing thin... though I'm skeptical of the knowledge behind that comment. I also read a suggestion that the oil squirters in the head may be partially clogged and are not lubricating the moving parts properly.

I watched your vid again and it doesn't seem to be running rough at all.. just noisy.. I wish I were more intimately familiar with the valvetrain to make a more educated guess. Maybe you can steal a few minutes of time from a tech at the local Nissan dealer and see what they have to say? All SR20DE's have the same head guts, fundamentally... There's a chance he may know what it is right away.

[Neil]

I know you already said there's no play but I was poking through the fsm and found this, 4 hundredths of an inch isnt very much movement..



When you get back under the valve cover just double check the way it says to. If you find that sort of play you'll have to take the cams out, which is a good time to consult the FSM for the how-to and torque specs for reassembly.
Modified by Neil at 4:49 AM 9/16/2008

[blackmagic]

alright well i thought whats there to lose might as well take it off cause i didnt see anything else wrong next time I pull the VC off ill check out the lash adjuster. As for the mechanic these mechanics here in palmbay dont do anything that they dont have to but ill give it a shot. The car doesnt run bad at all its very very quick at 12lbs of boost. i just raced against 3 other cars in a time attack. 1 was a sr20 with the gt28R from the s15 another was an rb25det and the other was a honda integra gsr with built head and i came out the fastest by 14sec. after adding all are times up. so im not loosing power from this. so idk ill try your ideas though. thanks
Modified by blackmagic at 10:49 AM 9/16/2008

[blackmagic]

alright so i took the car to nissan and asked the guy what he thought it was....he did the exact same thing in the exact same order as me. He thought it could be the chain then he thought the rockers then the lash adjuster and then he also said try putting some mystery marvel in the vaccum line cause it could be carbon buildup.....i realy dont think thats what it is. So anyways im thinking its either the chain or the lash adjuster needs to be bled. so next time im in the head ill check it out.

[boriquaS13]

I would be looking at that chain tensioner. I don't think it should bleed of and loose tension on the chain. I have a nissan 200sx se-r it has the sr20de now when it reached approx 50,000 miles it had a rattling sound in the engine around 1500rpm light load, I took it to nissan because it was still under warranty it ended up being the timing chain tensioner they put one in and the noise was gone. Just a thought good luck

[blackmagic]

thanks im going to do that when i pull the head off to put a new head gasket on.

[Neil]

Just get the tensioner now. There's no reason you have to wait until you pull the head to do so, and it could very well solve the noise problem.

It + gasket isn't more than $100 (got mine for ~$80 from everythingG20.com), and it takes 10 minutes to replace.

[blackmagic]

I thought you had to pull the chain and replace that to...

[Neil]

nope, it's installed from the outside of the motor, and is located directly above/behind the water pump pulley.

Luckily the tensioners are very easy to replace. It looks like a cap held in place by two 10mm bolts just below the cylinder head on the left side. I'd recommend replacing it anyway even if it ends up not helping your ticking problem. They operate with oil pressure and age/sludge will prevent them from applying enough tension on the chain. Modified by Neil at 9:27 PM 9/15/2008

[exhsturbine]

thats what happened to mine (as i described on the last page, how my chain guide broke). my tensioner failed and soon after i had a loud rattle and then the guide broke. it is real easy to replace, and you may as well. if this is your problem better to fix it now before you get an even bigger one like mine.

[blackmagic]

I ordered it and i looked and see it yeah that looks super easy to fix not even 10 min. thanks we'll see if it works

[Narciso]

Hi guys!! Yeah this is my first post here. I have been searching forums for people with this same problem. I was just wondering if you fixed your noise problem. If you did, can you tell us what you did to fix it?

I had a knocking noise on my last engine that turned out to be a rod bearing. So I got a another one and upgraded a few things to include a Tomei timing chain and head gasket. When I swapped my engine in, it did not make the knocking noise. It started after it got tuned. Here is what I did.

1) Rev until the noise came (2500rpm+) and unplugged/plugged the coil packs one at a time. Noise was still there. This means the bearings are still good. If the noise was gone then the rod would just float since there is no combustion. I tried this test on my last engine and piston 3's rod bearing were the culprit.2) Bled the lifters. There was no air in them to begin with but since they were out, I bled them again. I did this 3 times. The first time was to check and the next two were because I thought using a heavier oil would help. 3) Checked the rockers, timing chain guard and timing chain guides for scraping marks. Scratch free.4) Switched out the tensioner. Noise still there.

This is what I'm going to try next1) Check the oil squirters to see if they are clogged. If they are fine, I have another set so I can make the holes bigger on them.2) Buy new lifters and rockers. Not solid lifters though.

Sorry if I am jumping on your thread. I figured it would be better than starting another thread with the same problem.

[blackmagic]

no im still waiting on the timing chain tensioner to come in it was on back order for like 2 weeks im pissed. i woulda just bought it from somplace else but the payment already went through and i didnt want any kinda trouble. I was driving the car 2 days ago and dumped the clutch and screwed up what ever it was more it started making more noise at any load other than idle. it sounds like ticking from the chain so im hoping thats the problem. i pulled the valve cover again and im gonna check evrything out again but idk. im hoping i havnt bent a valve yet. what would a bent valve sound like???? cause last night i had the car idling and i could hear a knocking/ticking noise at idle i doesnt sound like rod knock though.

[Narciso]

Alright. I took the oil squirters off and ran some parts cleaner through it. I found that the majority of the holes were clogged. I know it was mentioned on this thread before so thanks to whoever posted to that. However, it did not fix my problem. Since they were clogged, I figured that the lifters were starved of oil.

I bled the lifters again and I also noticed that a few of the slots that the lifters sit in were low on oil. The holes on the oil squirters that were clogged were also on top of the holes that were low on oil. I don't know and I will do some research to find out how lifters go bad. Either way I will buy new ones along with hydraulic lifters, stock guides and shims.

I figure since the chain is fine, the tensioner is good and the valves are straight, the last things to change are the rockers and the lifters. BTW I'm running Apexi 260 IN/EX camshafts. The rockers could be slapping the camshafts. If that doesn't work then it has to be the bottom end. But not necessarily the bearings however the thought will be kept in the back of my head. I will post to let everyone know if it works.

[Neil]

Hi Narc. Kudos for your thorough investigation!

The additional cam lift of your 260's shouldn't make the head any louder. The rockers should ride on the lobes the same way they do on the stock cams. They should with heavier valve springs, anyway... but if stock springs were re-used then any unusual sound you'd hear from running higher lift cams would come from valve float causing a valve to get munched and/or rocker to become dislodged. That's obviously not your case, though.

Keep up the TLC. I'm sure you'll find your sound. FWIW though, I thought my tensioner was good too until I replaced it.

OP, a bent valve wouldn't make a sound. It wouldn't move in its guide and you'd either not make compression on one cylinder or you'd have a broken rocker. Either way you'd know something a lot more serious was going on.

[Narciso]

I forgot to mention that when I drove it, the sound did not speed up or slow down. It was a constant ticking. At higher speeds it would become quiter or seem to go away at acceleration but as soon as I back off the gas a little, it would come back.

Any ideas?

[blackmagic]

alright so i got the part and put it in but must have screwed up the timing a little cause i tried starting it and the car started then just started to die then died. so im tired and its pitch black outside right now so ill wait till tomarrow to check it out some more. its prolly off 1 tooth cause i did hit the chain a little on accident.

[blackmagic]

ok guys well it was off one tooth i found a thread and found out the notches on the cam gears are supposed to be 10oclock intake side and 12oclock exhaust side the exhaust side was between 11 and 12oclock so i moved it started the car up and bam started like a champ. i reved it up and the noise is still there. i didnt bolt the valve cover down cause i wanted to make sure that the problem was solved. its not so i did an oil change and looked at the oil and it doesnt look like any metal is in there at all how big are the pieces of metal supposed to be. cause there could have been tiny fragments in there but i didnt see them. this is realy getting old cause idk what else to check. any more advise would be awsome anything else i should try before the valve cover is bolted back together and i just put another damn sr in there.

[Narciso]

I had some friends look at it and they ran a test. They replaced my lifters and my rocker arms with some fairly newer ones. At least newer than the ones I had. They called me and told me that the noise was reduced. He then told me that my camshafts had scratches on the lobes and that they should be smooth and shiny like a mirror. He recommended that I buy new camshafts. At this point since progress has been made, I am willing to do it since those camshafts are over 3 years old.

[blackmagic]

that sounds like a waist of money you coulda already bought a head for less than you have spent. if you buy new cams. Now i got the valve cover on and tightend so i can start it and had the motor running and pulled the coil pack plus 1 at a time and the 1st 2 plugs stop the nocking noise when pulled out. so im guessing its rod nock now so i just bought a longblock i can just drop in and i can work on the other motor fix it and sell it. cause i just cant have my car being out of commision.

[Narciso]

It's not costing me a lot. For what I do with this engine and car, it's worth it. Sucks to here that your bearings are bad. Good luck with the rebuild.