# Top end knocking -- suggestions?



## isb360 (Apr 6, 2005)

Hello,

My 1990 Stanza XE has developed a "knock" or "rap" in the top end after being on the highway for a while. If I coast to a stop at the end of an off-ramp, it will sound like the lifters are dead and there is some valvetrain rapping. After a couple of minutes of idling, it goes away. I am suspecting possibly a blocked oil passage, but am not sure.

One thing to note: last two oil changes, I put in a can of the "engine flush" liquid, followed the directions on the can, and hopefully flushed out 212k miles worth of crap. 

I am wondering if I knocked some piece of junk loose in the engine which is now interfering somehow with valvetrain oiling.

Thoughts? Suggestions? Words from the wise?

Thanks
Tim


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## stanza man (Sep 15, 2005)

I had the same problem with my 1990 nissan stanza, I would turn the car on and I would hear this loud ass knocking sound around the valve cover area; I would also hear it when i would accelerate to about 50 mph. the knocking sound means that one of the lifters is going bad. one mechanic told me that it was the timing chain but that was just a bunch of b/s. as a matter of fact as im typing this message my stanza is in the process of getting another engine with low milage. i didnt even pop the hood and as soon as the mechanic heard the knocking he straight up told me that i need another engine because the engine is on its way out so my advice would be to replace the engine; my engine ran at $1000 but im sure you could find one cheaper or you have an alternative: get an engine rebuild, it will cost way cheaper.


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## rowdy-GTi (Jul 3, 2005)

Engine flush isn`t good for high mileage engines. Flushing oil is your best bet which is super thin oil you fill up as normal after a change and let idle for 10 mins or so then change for the proper oil.


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## isb360 (Apr 6, 2005)

rowdy- GTi, I had some reservations about using the engine flush too because just as likely as it is to flush the crap out, it is also likely to flush small chunks of sludge into small oiling holes/return passages, etc. I probably won't do that again.

As well as the lifter(s) going, my thought is that occassionally something is preventing the lifter from staying pumped up and that the constant high rpm (medium strain on valvetrain) is bleeding the lifter dry. Then after a few minutes of idling at lower rpm and low strain on the engine, the lifter can pump back up with no problems.

Are a set of lifters expensive?

Tim


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## Macc (Jul 4, 2005)

ISB I have the same car (90 XE). For a long time I had the lifter tapping and just ignored it thinking it was just due to wear from 126k. Finally, a couple of months ago I had to replace the cam. As part of the repair I had to remove the rocker arms. At that point I had the same thought as you thinking that some debris might be clogging the oil ports. Well, to make a long story short, I took each rocker from the arm and removed the lifters from the rockers and cleaned them (also blowing out the channels of the rockers). Since then I have had no noise at all and was amazed at how much better the engine sounded. I can't say that I saw any debris in the channels nor when I blew them out but it sure made a difference. I don't know why it made a difference but do have a few hypothesis; (1) Since the lifters have a check valve, maybe the oil that that was in them was old and possibly compressible somewhat (I don't know, just a theory). (2) I don't know how to word this but if you disassemble a lifter you will see that it is kinda like a piston in a sleeve that slides into the rocker. Anyway, maybe by having new oil in there the piston sleeve part holds compression better. Hope that makes sense! (3) Finally, even though I didn't see any debris, maybe there was microscopic debris in there holding the check valve somewhat open. In addition, I will throw this in there also. I obtained a used cam at a salvage yard. While removing the cam from one car I examined the rockers on it (and two other cars) to see if any of them had oil port blockages. To my surprise some of them did. The blockages I saw were right where the oil goes from the arm into the rocker (decreasing the port by maybe 50%). It looked like a carbon deposit. Keep in mind the oil channels are smaller than the diameter of pencil lead. Like I said, I didn't see any blockages in mine, but after seeing those at the salvage yard it is possible. 

If you decide you want to give this a try post back to let me know and I will give you some more detail and tips on how to disassemble the lifters. Note; before going this route you might want to check your oil pressure and make sure it is good. Good Luck!


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## isb360 (Apr 6, 2005)

Macc,
Excellent post, thank you! Although I would debate the compressibility of used oil given it needs to act hydraulically, you have given me valuable information. I will disassemble the rocker assemblies, soak them in parts degreaser, bake them dry, relube, and reinstall. A key point to your post for me was the boneyard parts you went through that had partial oil passage blockages. Debris can get in there. 

I replaced the timing chain/tensioner/guide/oil pump cover/oil pan a few thousand miles ago and I am thinking 1) I stirred up some debris that although I thought I cleaned, I didn't, and 2) I have used the engine flush stuff a couple of times and it is likely that I flushed some caked-on deposit(s) loose and now they are kicking around in the top end of the engine.

If you could give me some lessons learned from rocker disassembly, as well as a rough time estimate, I would appreciate it.

Thanks
Tim


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## Macc (Jul 4, 2005)

Are you wanting info on removing just the rocker arms and the rockers from the arms or are you wanting info on removing the lifters from the rockers?


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## isb360 (Apr 6, 2005)

Macc -- sorry for delay in responding, I was on a business trip.

Info on removing rocker arms, rockers from arms, and lifters would be appreciated.

Thanks in advance.

Tim


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## Macc (Jul 4, 2005)

The following steps are how I removed the lifters, cleaned them, and reinstalled them. Doing everything took me a full day. The only reason it took that much is that it is a little tricky removing/installing the clips that keeps the lifters in the rockers. Everything else is simple and once you get the knack of that it goes rather quickly. I don't know how much you 
know as to how the oil flows up to the lifters but it goes something like this. 
It comes up through the cam brackets (alongside the bolts), goes into and down through the arm, up into and through the rockers, and down into the 
lifters through narrow passages. There are no seals or anything just metal to metal contact. If you haven't changed the oil recently I would recommend doing so before beginning this. Anyway, here are the steps: 

1. Set engine to TDC.
2. Remove rocker cover. At this point take a good look at how 
everything is put together and oriented.
3. Loosen rocker arm bolts in the proper order (opposite of torque 
sequence) but do not remove them from the arm. Note; right where the
distributor shaft goes into the block there are two smaller sized bolts 
that hold down the cam bracket but do not go through the rocker arms. 
There is no need to remove those in order to remove the rockers/arms. 
But, that particular cam bracket has sealant under it so that oil will not
leak out towards the distributor and if you have never removed it you
might want to while you are there and reseal it with RTV or something to
prevent a future oil leak. But, be careful and don't use too much so that 
it doesn't squeeze out onto the cam area. I could not find, and was told 
that there is not, a torque value for those two bolts but some people told
me to just snug them down, but not too tightly, cause that metal is
somewhat soft (don't use the rocker arm torque values). The reason I 
point this out is that if you ever do get some leakage there it is alot
of hassle to get to it as you will see.
4. Now simply lift up on the whole arm assembly and set it at your work 
area. Then do the same with the other. 
5. To remove the rockers simply slide the pieces off of the arm but 
before you do take a good look at everything and make sure they go 
back on the way they came off. In particular note what is the top and
bottom of the arms themselves and the way they are oriented on the 
engine. Its best to set everything on a table in the proper order as 
you remove them. Note; don't worry about how each component is 
spaced on the arms cause each piece will automatically space itself
due to those metal pieces between each rocker and the arm bolts.
6. Now you are ready to remove the lifters from the rockers. If you 
look where the lifter part goes into the rocker there is a circular clip
about 1/16" below. In order to remove it I used the pointed end of a 
a safety pen and a real thin pen knife to manipulate it out. 
Sometimes the lifter is pressed rather hard against the clip and makes
it tough to get it out. You can't just press the lifter in because it
has a checkvalve that prevents the pressure from releasing. But, I
found that if you take an air compressor and blow air in where the 
lifter goes into the rocker and then try pressing the lifter into the 
rocker with pliers (doing this multiple times), eventually the lifter
will move slightly into the rocker just enough so that you can remove
the clip and then the lifter can be simply pulled out. Two words of 
caution. One, when you go to pull the lifter out of the rocker take note
as to how the pieces are oriented so you will know the correct order to
put them back in. Two, there is a small spring inside the lifter so when 
go to remove it do it in an area so that if it falls or springs out you will
not loose it. Note, the following four pieces are in there; two cylinder 
type pieces, one spring, and one thin metal circular disk. 
7. Now simply clean the pieces with a solvent. Make sure all ports are clear
and clean and examine the checkvalve (ball and spring) for proper 
operation. Its best to used compressed air to blow them out. Don't
forget to clean the ports in the arms, rockers, and cam brackets also. 
Then let them dry. 
8. Now you are ready to put the lifters back in the rockers. Wipe a little 
oil over all pieces. I don't know if this is necessary but I filled the 
cylinder part where the spring goes with a little oil to kind of preprime 
(fill) them. The only problem with doing this is that sometimes I had too 
much oil and I could not push the lifter in far enough to intall the snap 
ring. So, I had to pull the lifter back out, press the checkvalve (ball) 
with a pointed object in order to remove the suction while pulling the 
checkvalve cylinder out, empty some oil, and reassemble. If this doesn't
make sense it will when you disassemble everything and see how the 
parts work and go together. It sound tough to do but it is really pretty
easy. 
9. Once all of the lifters are back in the rockers you are ready to reassemble
everything. Coat the arms with oil and simply slide the parts back onto
the arms in the proper order. Then put the Bolts back into the holes and
lift the whole assembly. Now, slowly lower the assembly onto the engine
using the bolts as your alignment guide. Once on, begin tightening the
bolts using proper torque procedures. The recommended torque range 
is 37 to 41 foot-pounds. 
10. Now, pour a little oil over the various parts and install the rocker cover.
The recommended torque for the cover bolts is 4 to 8 foot-pounds. At
this point the installation is complete but there is one more step.
11. Anytime the lifters are removed/installed there is a process to get them
fully pumped back up. To do this simply start the engine and let it
idle at around 1500 rpm for around 15 to 20 minutes. Some say it should
idle at more like 1800 but mine worked out fine at 1500 for about 15 
minutes. When you first start the engine the rocker/lifters will clatter
like hell (for several minutes) and you will think you did something wrong 
but don't worry. After about ten minutes the noise will begin to subside 
and will continue to do so more and more until there is none. Note; the
time values could vary by many minutes. At this point everything is
done. I hope I didn't leave anything out. 
I assume you have a chilton book etc. for the torque sequences but if you don't, or you have any questions, post back and let me know. Either way post back when you get done and let me know how it turned out. Good Luck!


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## isb360 (Apr 6, 2005)

Good stuff Macc, thanks! Beyond the procedure you laid out, the tips about do's and don'ts is very helpful. There is a fair chance we'll have passable weather this weekend, and if so, I will try to dig into the car on Sunday. Strangely, I am a little worried about the fuel injector wiring harness because it is brittle and if you so much as breathe on it wrong, the injectors misfire and the car runs like sh!t. From when I did the timing chain, I know you need to shove the FI wiring harness aside to pull the rocker cover off. I will have to be careful for sure.

Thanks again.

Tim


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## Macc (Jul 4, 2005)

ISB360 sorry for the chopped up reply. Not sure what caused that. I copied it to (and from) wordpad. In an earlier post you asked how much the lifters are. As I recall, I think they were like $24 apiece (but I could be wrong). Whatever the price was led me to try the process I've described first. Alot of people I questioned about the lifters (radio call-in car shows etc.) said that once they start making noise all you can do is replace them. Well, I didn't necessarily believe that. Once you get in there you will see that there is alot of little passages and that it would only take a small particle to cause problems. Especially the lifter's checkvalve. If something is holding that open, then the lifter will never stay solid and will tap. I do have one caveat. I would allow two days to do this in case you have a tougher time reassembling the lifters than I did (unless you have another car). I do have one question for you since we have the same cars. If you would (when you work on your car), look on top of the transmission (the flat part) directly below the coil. There is a tube that comes out of it. Attached to this is a piece of vacuum type tubing that comes up (maybe 16") and then has a piece of metal tubing that curves over and downward just hanging in the air. Is that some kind of vent for the transmission or is it supposed to continue to something. I noticed that yesterday and I'm curious. Good Luck, let me know how things turn out.


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## isb360 (Apr 6, 2005)

Macc, I have a 5 speed, not sure what you have, but I will take a peek and see if I can locate the tube you are talking about.
I am also going to contact a local Nissan dealer to see if they have any recommendations for "special tools" for removing the snap rings, etc.


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## Macc (Jul 4, 2005)

I have an automatic. Thanks anyway. Boy, now you have me curious as to whether there is a tool for that. I can't imagine how it would work. I did think of one other thing. You might want to have some really fine emory cloth (say #400 or higher) in case you need to polish up some of the lifters. When I did mine I did have a couple that had minor scoring. Remember, they are basically like the piston in the engine and can score. But, I wouldn't over do it. Let me know how your venture turns out.


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## Macc (Jul 4, 2005)

I made a mistake in the torque values that I posted above. I often use the Newton-meter values in addtion to foot-pound. When I posted the Nm values I accidentally identified then as Foot-Pound. The correct torques settings are 27-30 foot-pounds (or 37-41 Newton-meter) for the rocker arm bolts and 2.9-5.8 foot-pounds (or 4-8 Newton-meter) for the rocker cover bolts.


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## isb360 (Apr 6, 2005)

Macc,

I think the conversion is 1ft-lb = 0.737562N-m. I dug into the car this past week. Rocker assemblies came off very easily. I ended up not disassembling the lifters from the rockers. Instead I let them drain for a few days by putting them "upside down" and then used a c-clamp with a thin piece of wood to prevent scoring of the lifter face and broke free all the lifters so they freely moved in and out against the internal spring. They were all frozen in place, even with no hydraulic pressure on them.

Then I dunked rocker/lifter assemblies and the rocker shafts into a fresh 5-gallon pail of parts cleaner for 14hrs or so, then let them dry. I reassembled everything, inspecting best I could to make sure there were no clogged passages.

Car started and idled 15mins before it quieted down, but sounds good now. I haven't taken it on a long enough trip to simulate the "bled down" lifter noise I was hearing before, but I will let you know when I do.

Interestingly, the same local Nissan dealer that happened to have an oil pump cover in stock also had a complete set of rocker/lifter assemblies on the shelf, for $27 and change each. If I still have some noise, I might buy just the ones I think are making the noise. While at the dealer I took a peek at the FSM and it mentions not to disassemble the rocker/lifters. I am impressed that you took the time to pick those small circlips out of there. I would not have had the patience for something like that.

I really appreciate your help and guidance. Will keep you updated.

Tim


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## Macc (Jul 4, 2005)

I did some checking and the correct ratio is 1 N-m = .737562 ft-lb. The N-m values are alway larger than the ft-lb. I don't think your lifters were frozen in place. The reason they seemed like that is that they did have a hydraulic resistance pressure (when you pressed on them) due to the check valve in them (The oil goes in them, but doesn't go out. That is how they stay pumped up). The only way the oil could get out is if the check valve is bad (worn, stuck open etc.) or the lifter surface is worn just enough to let some oil squeeze by. This might not make since but if you saw the parts you would understand. Like I posted earlier, the only way I could get them to go into the rocker was to repeatedly blow some air where the lifter goes into the rocker and then push in on it. Eventually the lifter would go in more and more. I guess since they were used some of the air got in them and somehow it was moving the check valve (a little ball) an letting some of the oil out. I doubt it could be done with new ones. Anyway, out of curiosty, did the FSM say why you shouldn't disassemble them (probably so they can sell new ones). Also, did they say anything about how (or have a tool) to remove the snap rings. I did my lifters almost a month ago and they still sound good. Hope they stay that way! Good Luck on yours!


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## isb360 (Apr 6, 2005)

Hi Macc,

The FSM only showed a picture of a rocker/lifter assembly laying on it's side with a giant "X" through it and a little note next to the diagram saying "Do Not Disassemble". Accordingly, it doesn't provide any means to remove the snap rings in the lifter assemblies. I took a look at a brand new one when at the dealer and if I push really hard on the lifter, it moves in against the spring.

I had first thought the little "ball bearing"-looking thing on the top of the casting was another check ball, but I believe now that it is merely a plug for when, during manufacturing, the passage through to the rocker shaft was drilled. There is no LOS (Line of Sight) from the inside, so it was probably drilled from the outside then plugged with the small steel bearing. 

There is a very small hole on the top of the lifter cylinder, opposite side from the lifter piston. I noticed when I turned them upside down that oil very slowly seeped out of these holes. What I did then was turn them all upside down and left them for a couple of days to let all(some?) of the oil out and was then able to free them up.

So far, all my previous symptoms of running fine, but rapping after getting off the highway seem to have gone away.

The guy at the parts counter commented to me that the KA24E engines are particularly happy with very regular oil changes, i.e. the top ends are sensitive to having sludgy or old oil. My mother-in-law always did 3k oil changes, so I am thinking that the engine flush I used washed some crap into one or more of the passages, partially restricting them, as we'd previously discussed.

Tim


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