GMMTC Posted June 20, 2012 Share Posted June 20, 2012 I have an L24 in my 240z that had an oil leak. I drove it a few blocks with very low oil accidentally and it stalled out on me. I filled it back with oil and drove it 3 more blocks to work, but it was running like complete crap, it felt like it was really struggling and low on power. So I thought it was toast and towed it home. I bought a spare engine that was bare, so I pulled my engine. Then I pulled the valve cover off both engines and noticed mine looks 100x cleaner and has all new valve cover, intake/exhaust gaskets, etc. The "new" engine I bought has oil caked everywhere on the outside of the block, but I know it at least runs because I bought it off my buddy who drove his car for a season before swapping in a rb25det. I also noticed on my original engine that one rocker arm near the middle was knocked off to the side, the little notched retainer thing that sits on top of the valve spring was sitting randomly in the corner of the top of the head. I can't put the rocker arm back on right now because the cam lobe is facing down. My question is could this be my only problem or is this a sign of more severe damage. Is there an easy way to check? Other than my engine looking cleaner, the other issue I'm having with swapping my "new" engine in is that there appears to be this vacuum tube out of the engine block that has a large hose clamped and runs into the top of a tube that connects the two sections of my intake manifold. You can see it here with the large opening and small opening that was capped off. Now my "new" engine has this removed, so I can't seem to figure out how to swap this tube thing over to the other engine block. I'm wondering if anyone has any suggestions, or can I just plug this hole in the middle of the picture in the block and plug it on the intake manifold without any issues? Or is my original engine not as messed up as I first imagined and would I be better off to just put that back in the car? Let me know any advice or suggestions you might have, thanks! Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 20, 2012 Share Posted June 20, 2012 That tube is the PCV tube. It should just twist and pull out of the one block and press in to the one without. Looks like you might be getting ahead of yourself. You've bought another engine and pulled the old one and you don't know what you had before or what you have now. You could have done a compression test with the old engine in the car. Probably still could with the engine on blocks and the transmission and starter re-installed. You'd want to put the little notched retainer thing back on first though. Were you revving the crap out of it when it started running bad? That might explain why the thing, whatever it is, came off along with the rocker arm. The How to Rebuild book by Monroe is worth buying. $14 at Amazon. It covers the PCV tube and everything else. How to Rebuild Your Nissan/Datsun OHC Engine: Covers L-Series Engines 4-Cylinder 1968-1978, 6-Cylinder 1970-1984 [Paperback] Tom Monroe (Author) Quote Link to comment Share on other sites More sharing options...
Z Greek Posted June 20, 2012 Share Posted June 20, 2012 The "notched retainer thing," sounds like the lash pad. With the cam follower "knocked off to one side," that cylinder was completely dead, engine would have been low on power from this alone. It was probably making a hell of a racket too. Look very closely at the cam and cam followers on all cylinders. Also make sure the spray bar is intact. Now that the engine is out, it is very little work to put it on an engine stand, flip it over and pull the pan off. Pull off number 6 rod cap (furthest from the front) and look at the condition of the bearing, and rod journal. If it looks good, you may want to pull a few more and examine just to be sure. Keep the caps in order, they are numbered, and the numbers must line up when re-assembling. If it looks bad (deep lines, copper showing through, etc), it will need major crank work. Take a picture and post it. Many good engine guys on this forum, from a few detailed pictures, any one of them can tell you whether to do a minor repair on your head and put it back in, or go to plan B. Good luck! Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted June 20, 2012 Share Posted June 20, 2012 If you plug that hole in the side of the block you will blow all you're seals because of the crankcase pressure. Just pull out you're old one and gently tap it into the new engine. Don't worry about the little capped off side hose, just leave it like that. That notched retainer thing is the lash pad as stated above, and it was probably running like crap because you were only firing on 5 cylinders. If you revved the crap out of it while it was off you could have potentially bleached a cylinder by flooding it with gas that never got combusted. That lash pad popping off could be a sign of something worse. When I got my friends ZX running after sitting for 5 years it ran fine for a week, then when we filled up the tank with fresh gas it knocked some goo/crud in the tank loose which clogged up everything and the headdropped a valve and what you experienced happened, a lash pad popped off and started to rattly like crazy. It completely wrecked the valvetrain and we ended up sourcing a new head to rebuild. Since you already have a new engine just swap it in, get the car running and then autopsy the old motor later. Quote Link to comment Share on other sites More sharing options...
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