Captain Obvious

I believe the intuition is correct. The highest of the forces should be compression straight down the rod. And after all, one mm off the diameter is only a half mm off the radius (about 20 thousandths for us US folks). I'm no engine builder or materials science guy, but my seat of the pants engineering says I wouldn't be concerned about taking off .020 of material. Anyway, I know it's academic because you're not ready to try to tackle a job like this, but if you were, you juuuuuust might be able to get that on your lathe. The FSM says the rods are 5.13 inches "center distance", and I assume they're taking center to center between the two bearing surfaces. With the big end lower cap off, you just might be able to swing it. (Get it... Swing it?) Haha! I kill me.

Never heard anything about it, but wanted to ask... What's the swing of your new lathe? You might be able to do this yourself if you decide to go that route.

And later in the lube section it says that the pressure relief valve in the pump limits the pressure at 80psi. With those data points, I consider 70 psi at 3K warm to be just fine for an engine with a well done fresh bottom end. Now, if the pressure was like 90 psi at idle when warm, then I'd be a little more concerned about the bearing clearances, but this one sounds like a non-problem. Diseazd, I know you're not worried anymore, but if you do another turn around and decide you're worried about it again, I'd be happy to trade for my engine!

Well, considering the alternatives, that's awesome news! I am surprised that the failure was enough to actually stall the motor while it was running. I was figuring that it was straining and squealing, but finally locked up good while stationary. Also surprised there wasn't shrapnel. Anyway, awesome news. So I went back to the very beginning of the thread where you were questioning your oil pressure numbers: "My 71 240Z (L24engine) runs 75 lbs. of oil pressure at 3000 rpm." Don't know why I didn't mention it before, but I'm not sure I would have ever even called that a problem. You get 75 lbs at 3000 RPM (when hot, I assume)? So what? Sounds like a healthy bottom end to me. I assume it drops off at idle? I've seen the "10 psi for each 1000 RPM" tossed about, but my understanding was that was a minimum before you needed to do something about it. Not what you could expect on a new healthy motor. Frankly, if I had a freshly rebuilt bottom end and only got 30 psi at 3000 RPM, I'd be disappointed.

Haha! He said the motor is fine. There are clearly some clutch parts that are completely FUBAR, but the rest of the motor is fine. Frankly I'm surprised there wasn't a more spectacular failure with shrapnel. I'm guessing it was squealing like a pig and he shut the motor down. The front of the throw out bearing and a bunch of pressure plate fingers were all liquidy hit in spots from the friction and once it stopped turning, everything welded together before they cooled

Been a while since I messed with oil pumps, but IIRC, the turbo oil pump is longer to accommodate internally longer rotor gears. In other words, you might be able to tell that from the outside?

Wouldn't matter what gear the tranny was in. The fault was upstream from there. My interpretation is as follows... Throw out bearing was installed incorrectly, and as such, was always loaded. Problem is, they're not designed for that. They're designed for intermittent loading only (when you push the clutch pedal in). Throw out bearing worked for a while before seizing internally. Now the front part don't turn no more and the disk which is supposed to spin with the pressure plate is now sliding against the fingers. This caused the front part of the throw out bearing to get so hot that it welded to pressure plate fingers. Front part now stuck to what wants to rotate. Rear part never rotates. Something's gotta stop... Or give.

Good step forward. Now you'll have to crawl under the car. I can't stall you anymore. PS - Nice pics!

So on the good side, your motor is fine. On the bad side, you still have no explanation for your high oil pressure, right?

Whew. Good! I was hoping I was remembering that right. All I remember was that I was having a heck of a time measuring the ratio on a diff out of the car. Nothing was making any sense until I locked one of the axle flanges in place.

Glad to help and I hope it does in fact help! So one more detail about the JIS screws vs Phillips. I've not reviewed the mechanical specs for both, but I've found that it often helps to take a small amount of material off the very tip of your typical Phillips screwdriver in order to get a better bite on a JIS screw head. In other words... I've found that Phillips screwdrivers bottom out in JIS screws before they are fully engaged because the tips are "too pointy". With something that small, a couple passes of the screwdriver point across some sandpaper ought to take off enough material to allow deeper engagement. Couple strikes straight across some 320 grit? Thanks for the link back to that thread and the only other thing I could add is that I managed to get the air duct off and back on, so it's at least possible! So you can wrestle with the screw or you can wrestle with the duct.

If you've got both wheels off the ground, this might not work. I think you have to insure that only one wheel can spin or it doubles the ratio because of the differential function inside the gear case. You'll need to block the other wheel to prevent it from spinning in order to use this method. Either jack up just one side or use a wheel chock or something to block the other side wheel from turning?

Two things that might help... First is that the screw LOOKS like a Phillips head, but in reality it's not. It's a JIS (Japanese Industrial Standard) screw that's very similar to Phillips, but slightly different. Most of the time they're close enough that you can use typical Phillips screwdrivers on them without incident, but there are times when a Phillips screwdriver will smear out the JIS screw head. Second thing? If you're just trying to replace the upper bulb and you've already got the tach out, can you reach in through the hole left by the missing tach to get to the top speedo bulb? You might not have to pull the speedo at all? (Also, can you post a link to that thread where I was talking about the cable before? I remember the thread, but can't find it.)

You always need an alignment after replacing bushings and the alignment guys are supposed to adjust things such that the steering wheel ends up at perfect 12:00 when the alignment is done. Problem is it's not always that easy to accomplish and they're in the business of making money. And important to note that pulling the steering wheel off the column and changing it's position is NOT the correct way to adjust to 12:00. The steering wheel 12:00 position is supposed to be accomplished by adjustment of the tie rod ends, not the steering wheel to column positioning. So, bottom line is that the alignment guys didn't get it quite right and if it bothers you enough, you should take it back to them and tell them about it. But be aware that it's not always easy for them to get the steering wheel perfect, and I would cite two possible reasons. 1) Accumulated looseness in the whole system from steering column bearings all the way to the wheel bearings and everything in between. 2) The sticky friction of the urethane bushings that you just installed. They're in the business of making money and probably won't want to spend four alignments worth of time getting your car hair splitting perfect.

Wow. That sucks that you had to pull the head just to get the pencil stub out. I've not done that, but I did drop a small bolt down the plug hole in one of my cars once. First attempt at retrieval was a magnet, but that wouldn't grab it because it kept getting stuck to everything else in there. Second attempt was with a shop vac and a small diameter piece of tubing stuck down the hole. Taped the small tubing to the end of the large shop vac hose and went blind fishing. Worked like a charm. That would have worked on your pencil too if you could have gotten ahold of one of the ends instead of the middle somewhere.

There's something I've been meaning to bring up with regards to your A/C install and I kept forgetting. Seeing this post again reminded me. You're looking for a Fast Idle Compensation Device (FICD) to boost your idle while running the A/C. That's the correct part to use. BUT... I don't see any reason why you couldn't repurpose the throttle opener servo instead to do pretty much the same thing. Instead of connecting the actuator hose to the vacuum control valve, you could run a tube over to the A/C vacuum switching solenoid instead. So here I've been trying to show you what the is FICD this whole time, but the more I think about it, the more I think it might actually be easier to find a throttle opener servo diaphragm instead. It's not the RIGHT part, but I think it would work and it's probably much more plentiful. I think every Z from 70 through 74 had one. Even the ones that didn't come with A/C.

Good luck. Sounds like Murphy is luring you into his trap..... You absolutely know that this problem is going to come back again at some time in the future, don't you? At the most inconvenient and inopportune time, right? When that happens, take some more measurements and come back here for some help if necessary. In the meantime, work on the next hottest fire!

I'm not so sure. I wouldn't think it would go intermittent. I would expect once and done. That link runs a bunch of other stuff as well including all the dash gauges. There would be other effects. On second thought... Wait a minute... You said the tach dies also?

No, no... It's great info. I was just adding some additional info to make things, ummm... "easier"? That FI combo relay system is a pain in the butt. I think it's a lot more complicated than it really needs to be, but I wasn't there when they designed it. The diode is between pins 36 and 76. Pin 36 is the fuel pump control from the AFM and pin 76 is the fuel pump control from the START signal. The diode OR's those two signals together so that either of them can power the fuel pump. In normal use, the signal from 76 is used first while cranking, and then once the engine spins up to speed and you stop cranking, the signal from 76 goes away, but by then the signal from 36 takes over instead.

Zed Head, About the info you posted above... Yes, you are right that there are actually FIVE fusible links on the EFI cars with the fifth one coming directly off the positive terminal of the battery. That's the one you identified as #4 in the sketch. But... That fifth link (item number four) runs the injectors and a bunch of other stuff related to the FI system, but it doesn't power the fuel pump directly. It DOES supply power to the AFM switch, so it does provide the primary side control power for the AFM signal once the car has stopped cranking, but other than that it has nothing to do with the fuel pump. The fusible link that directly runs the fuel pump and the AAR is the driver's side rear link located in the fusible link blocks. Also note that the link that runs the fuel pump and the AAR is the one in the schematic you posted. Also interesting to note that the other FI link (item number four) that comes right off the battery is not shown at all on that schematic. Haha! Don't mine me... I'm just trying to make things more complicated by making them simpler! On edit - I fixed an overextended statement I made prior.

I posted this in another thread where there seems to be fuel pump issues, but it's probably applicable here as well. So are you familiar with the numbers on the FI combo relay? Here's the pin numbers related to the fuel pump and AAR: - Pin 73 is power from the battery. Should be hot at all times.- Pin 76 is the control signal from the ignition switch. Should go hot only in the START position.- Pin 36 is the control signal from the AFM. Should be hot only when the AFM is passing air.- Pin 74 is power output to the fuel pump. Should be hot in START and when the AFM is passing air. The system works like this... Power comes from the battery through the driver's side rear fusible link to pin 73. When either control signal (pin 76 or pin 36) goes hot, the relay connects pin 73 to pin 74 which then goes to the fuel pump. So when either in START or when the AFM is passing air, pins 73 and 74 are connected together and that sends power to the fuel pump. So in your case, one or more of those four pins isn't working properly. Either because of a wiring or connection problem or a problem inside the relay itself.

The fuel pump control side of the FI relay does have a fusible link between it and the battery. It's the driver's side rear link of the four on the wheel well. If you've got 12V on both sides of that link while the problem is occurring, that's not the problem. So are you familiar with the numbers on the FI combo relay? Here's the pin numbers related to the fuel pump and AAR: - Pin 73 is power from the battery. Should be hot at all times.- Pin 76 is the control signal from the ignition switch. Should go hot only in the START position.- Pin 36 is the control signal from the AFM. Should be hot only when the AFM is passing air.- Pin 74 is power output to the fuel pump. Should be hot in START and when the AFM is passing air. The system works like this... Power comes from the battery through the driver's side rear fusible link to pin 73. When either control signal (pin 76 or pin 36) goes hot, the relay connects pin 73 to pin 74 which then goes to the fuel pump. So when either in START or when the AFM is passing air, pins 73 and 74 are connected together and that sends power to the fuel pump. So in your case, one or more of those four pins isn't working properly. Either because of a wiring or connection problem or a problem inside the relay itself.

Haha! CHIPS! I was thinking that the portion of the ECU case where the connector mates is an aluminum casting. I bet if you dropped it wrong, you could chip it.

I posted this in another thread where there seems to be fuel pump issues, but it's applicable here as well. The AAR (you know what/where the AAR is?) is wired in parallel with the fuel pump. You can pop the connector off the AAR and probe the connections inside to see the same signal that the fuel pump should be seeing. Put a little noid light across those two terminals if you get energetic. Something you can see easy from the driver's seat. So just like the fuel pump, the AAR should have 12 volts across it's two terminal connections: - any time the key is in the START position, and/or - any time the key is in the ON position and there is air flowing through the AFM. So, if you've got power to the AAR at the correct times, you're looking for a bad fuel pump or connection to it. But if you're not getting the correct signals at the AAR either, then you've most likely got a problem with your FI relay. Would be interesting to see what happens when your car shuts off from lack of fuel. If the AAR still has power but the fuel pump has stopped is a different issue than both the AAR and fuel pump losing power at the same time.

In case you want one other thing to check before you climb back under the car to take a closer look at the fuel pump... The AAR (you know what/where the AAR is?) is wired in parallel with the fuel pump. You can pop the connector off the AAR and probe the connections inside to see the same signal that the fuel pump should be seeing. Put a little noid light across those two terminals if you get energetic. Something you can see easy from the driver's seat. So just like the fuel pump, the AAR should have 12 volts across it's two terminal connections: - any time the key is in the START position, and/or - any time the key is in the ON position and there is air flowing through the AFM. So, if you've got power to the AAR at the correct times, you're looking for a bad fuel pump or connection to it. But if you're not getting the correct signals at the AAR either, then you've most likely got a problem with your FI relay. Just thinking it's easier to check for that signal standing up at the front of the car instead of laying on your back under the rear of the car. And, unfortunately, rossiz is correct that his trick with the oil pressure signal won't work for your year. That only works on 78's.