# KA24DE valve shims and adjustment



## himilefrontier (Jan 21, 2003)

Has anyone adjusted the valve lash using the shims that are required as per the FSM? My KA24DE has some valvetrain noise and I figure it may be time to do it seeing as it is a solid lifter engine and it has never been done. It had a extremely mild intermittent miss at idle and I have checked the compression( it was very strong), replaced the cap, rotor, PCV valve( PITA!!!) breather filter, plug wires, plugs ( NGK V power properly gapped), air filter and all of the other tune up parts I could think of. I have never replaced any of the engine's sensors and it has 247,000 one owner miles. I have also done almost all of the repairs and service since it was out of warranty ( transmission rebuild is the one exception) myself so I know what has been done to it ( not alot!). I have heard that valve lash problems could cause some idle issues and am starting ot think that's what's up with it. It pulls strongly in all 5 gears with no hesitation and still manages the same 23 MPG city it has gotten since I drove it off the dealer's lot, so I doubt it's a computer related issue. It's a minor issue, and I'm just curious as to how much money I am looking at for the shims, etc and weather or not it's worth doing now, or if I should just do it when I rebuild a 240SX engine for it ( I wail on it and I think it will eventually break a rod bolt).


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## nissanmadness (Sep 18, 2006)

You mentioned alot of things that you replaced, which is good, but how about a fuel filter and injector service? Check your catalytic converter too, for partial blockage. How about the timing chain and tensioner. I once had an intermittent miss like yours, turned out to be a loose electrical connector on the #3 injector. Worth a try.


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## azrocketman (Oct 5, 2005)

You indicated a miss at idle. A true miss would probably trigger a "check engine" light. Is the light illuminated?

Steve


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## BTF/PTM (Oct 19, 2006)

Generally, doing the valve lash on the bucket/shim engines is very impractical for us backyard mechanics, and it's mostly a cost issue. The shims are precision pieces and are very expensive, to the tune of $4 - $9 each depending on the engine and size. The only way to adjust the valves in a single day is to have a complete set of these shims handy, and there's the big impracticality. You could choose to check the lash, find the ones that are loose and their corresponding excess clearance, remove/measure the existing ones with a micrometer and then order just the shims you need, but that process can take as long as two weeks if you have to wait for the shims to arrive. You'll also need a micrometer if you don't have one already, and then you have to learn how to read it accurately. If you can afford to have the truck down for as long as two weeks and you are already equipped and skilled with a micrometer and all the tools needed to remove the valve shims from the buckets (there are special tools for that too), you could save a lot of money by doing the valves yourself. Otherwise, it's worth the money to have a shop do it so you know it's done right and you know that if anything isn't done right it will be taken care of.

When you say there is a miss at idle, are you referring to what sounds like a spark plug not firing, so you get that light "puff" sound periodically from the tailpipe? Quite often that noise is actually normal in high-miles engines, that sound is caused by the engine valves not seating completely. As long as it's not happening constantly, I wouldn't worry about it. However, if the symptom is more extreme, it might be the stuff listed in the other posts.


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## himilefrontier (Jan 21, 2003)

The Fuel filter has been changed at regular intervals and the injectors have never been out of the engine, but I do run injector cleaner in it regularly. If the cat was clogged, it would likely have an adverse effect on fuel economy but the fuel economy has stayed the same since new. I stay on top of that so much that I can tell the time of year they change to RFG in my state by the slight drop in MPG due to the oxygenated fuels.Throttle response is also still very crisp all the way to the fuel cut, which it sees at every 1-2 shift( 20-30 times a day). Well, I shift 1-2mph before it, because I don't think it's good to hit it and shock the drivetrain.


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## nissanmadness (Sep 18, 2006)

It is a good practice to run injector cleaner in your fuel. But, if the injector coil is starting to break down, no amount of cleaner is going to help. Have the engine scanned and have them check resistance values, etc.... It may be time for a set of injectors. Remember you have almost a quater of a million miles on your engine.


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## himilefrontier (Jan 21, 2003)

nissanmadness said:


> It is a good practice to run injector cleaner in your fuel. But, if the injector coil is starting to break down, no amount of cleaner is going to help. Have the engine scanned and have them check resistance values, etc.... It may be time for a set of injectors. Remember you have almost a quater of a million miles on your engine.


Yeah, I know but it's expensive and I don't know anywhere to take it except the dealer and they want alot to check things out. I am thinking it may be a worn throttle shaft hole in the throttle body because of my experience with an older Quadrajet on a Chevy 350 with a similar problem and a new engine. I plan to check it next week when I get time and them think about having it bushed by a carb shop if that is the problem.


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## nissanmadness (Sep 18, 2006)

You could look in the phone book for injector service. Most carb shops can do them too. Dealers are not your only option, but it is your choice to go where you want. But I would have the engine scanned before I did anything. And get a printout if you do. It's nice to have a reference.


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## himilefrontier (Jan 21, 2003)

nissanmadness said:


> You could look in the phone book for injector service. Most carb shops can do them too. Dealers are not your only option, but it is your choice to go where you want. But I would have the engine scanned before I did anything. And get a printout if you do. It's nice to have a reference.


I'll probably just try my DVOM and refrence the resistance values against my FSM when I get around to it. It's a really minor annoyance that 95% of the people who ride in it never even notice. It doesn't spit out the tailpipe , I can just barely feel it in the shifter. If I have to spend over $100 for an annoyance right now, it'll be the worn out driver's seat or the door strikers which have lost their rubber causing the doors to rattle slightly over hard bumps.( This month I replaced the steering wheel, window channel rubbers and added sound deadener to the doors to make it more quiet/less old feeling, and had the transmission rebuilt a few weeks ago too)


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