FastWoman

My '78 280, designed for the 60A alternator, had a rather small line (MAYbe 10 ga, protected with an 80A fusible link) from the alternator output in to the battery. Moreover, the line connected through 2 or 3 crimp junctions inside the wiring harness. There were a couple of melty/charred areas as well. All in all, the electrical path was inadequate in 1977 as it rolled off the assembly line, and it had become grossly inadequate with the ravages of time. I replaced that mess with an 8 gauge wire, to an 80A maxifuse, to the battery, with no crimps. Conservatively I might have gone with 6 gauge, but a full 60A pull seems brief enough for the 8 gauge. Your 240 is 7 years older and was designed for a smaller alternator. You can't possibly have beefier wiring than I had in my stock 280. I would bet that's where your problem lies. Give your alternator a beefier current path to the battery, and you shouldn't see as much voltage sag.

Hey, you think CAR buffs argue about filters? Try photographers! To use a protective filter or not... Hmmmm.... That said, while I'm still trying to liberate all the PO's crud from my engine, I think I like the sound of the Wix filter, with its graduated filter element. I think I'll make the switch the next time around. Per the great page 74L28Z linked to: "These appear to have a depth gradient filter element, which uses cotton fibers to progressively trap smaller particles as they get deeper in the filter. This helps maintain good flow as the filter gets plugged." (I like that.) And if Tiffen made oil filters and not just lens filters, I'm sure they'd be a lot like Frams.

semi-sphere rubber plugs: You mean like a small rubber boot at the end of a wire, where it makes a connection? The rubber dome simply covers a terminal post. You'd simply pull it back to reveal the post. Some of them are going to be crumbly. If they are, they're not doing much anyway. Your car will run fine without them. You can protect terminal posts with a thin layer of grease if you wish. metric tap and dye set: Available from Autozone -- about $15 I listened to your video, but I can't tell much from it. I suppose I hear random missing. I'm sure it's much different in person! I think I hear some hard puffs in the exhaust. Does the exhaust blow rather hard at idle -- much harder than on an engine that's running right. If so, then you're probably running lean. the buzz: Probably a body rattle. Honestly, just ignore it. Pay more attention to fuel pressure. the AFM connector: It's built very much like the injector connectors, with a little wire clip that runs around the outside. Use a small flat-blade screwdriver to catch the tip of the wire and stretch it back off of the connector. Be careful not to let it drop, or you'll have a hard time finding it! thermostat housing: Really not very labor intensive, as long as your bolts turn freely. You don't even have to take the radiator hose off. It's one of the easier jobs on the engine. To keep everything in perspective, you really have to be methodical in your approach. Right now you're swinging at a pinata. Since you have the AFM open already, do this simple test: Warm up your engine as far as it warms up. Idle it. Gently nudge the AFM mechanism with your finger. Can you make the engine run much faster when nudging it in either direction? If so, then you really do have a fuel mixture issue of some sort. My guess is identical to cozye's -- a lean mixture. However, without knowing the outcome of this test, it's only a guess. If your mix is wrong, the diagnosis will take a more methodical approach. You're really going to have to follow diagnostic steps like cozye and I have laid out. First and foremost, you're going to have to make certain you've got everything other than fuel/air delivery right. Once you've reached that point, we can take a more reasoned approach to getting your engine running right.

Thanks, Bonzi. Mine is of unknown origin, but it inserts under the weatherstrip too. The pads were loose when I bought the car. Please let me know whether that bottom louver bows somehow after you've got the thing installed. OK? Maybe it's just the nature of the beast.

Ah, not for me. I don't like the look. However, there's some really good photography on that page. Kudos to the photog! As I was looking through the shots, I was thinking, "Damn, this is some good stuff. Looks professional." Sure enough, it is.

Thanks! OK, I'll just keep doing what I'm doing then. My plan is to progress from light/penetrating lubricants to heavier ones. (I did try the motor oil at first, but it wouldn't penetrate.)

Hmmmm... Well, it depends on where it's measured. I suppose if you measure at the top of the radiator (where the water returns from the engine), that's probably true. Another way to check for a stuck thermostat might be to monitor the radiator water as the engine is warmed up from cold to warm. If the temp starts climbing immediately, when the engine starts running, then the thermostat is open. If the thermostat is operating normally, there shouldn't be any water flow through the radiator until the engine warms to its normal set point, at which time the thermostat will open, and hot water will flow into the radiator.

What Cozye said about the throttle switch. (Good idea!) You can also pull off a vacuum hose to see whether the engine runs better (faster) or worse (slower). Better means your mix is too rich. Worse means your mix is too lean. He's also right that you need to resolve the thermostat issue before proceeding further. I have to differ with the thermometer in the radiator water idea, though. The thermostat regulates how hot the water is inside the engine. The radiator water will be at entirely a different temp -- probably much cooler. If I were you, I'd go ahead and pull the thermostat out and test it in a pot of hot water on the stove with a thermometer. (Drain a bit of coolant before unbolting the top of the thermostat housing.) Once you've tested the thermostat, order in a new gasket from Autozone, and if you need it, which you probably will, order in a new thermostat along with it. Also while you're at it, it sounds like your oil pressure sender is bad. It's easy to fix. It unscrews from the side of the engine block, just next to the oil filter. Replace it, and you'll magically see more oil pressure. (They read low as they tire out, or at least that's been my experience.) BTW, before you reinstall these things, be sure to clean all the old gasket material off the thermostat housing, and wrap the oil pressure sender threads with teflon tape (available at the auto parts store or your local hardware store). Keep a positive attitude! You can do it! Girl power!

Your bold-face questions: Disconnecting electrical stuff before connecting up a fuel pressure gauge. My attorney would tell me to tell you you ABSOLUTELY HAVE TO DO ALL THAT STUFF. However, I don't personally do this. I just make certain I don't turn the ignition key and energize the fuel pump while the fuel system is open. My own safety measure is that the key goes in the ignition only when I'm testing something. When I'm done testing, and before I put my fingers into the engine or crawl under the car, the key goes in my pocket. However, this is only how *I* do things. For you, I'd officially recommend following the conservative advice of my attorney, if you know what I mean. The spark plug wire test is done while the engine is running. Before you start, make sure all your spark plug wires are easy to pull off. Then start the engine and let it warm. Then grab a spark plug wire and pull it to see if the engine slows down. If the engine slows (and perhaps chugs), then the cylinder was firing correctly. Replace the plug wire, and move on to the rest. Precautions: Wear rubber gloves, and don't put your fingers too close to the tip of the spark plug wire. You don't want to complete the circuit. Also be VERY CAREFUL not to get too close to any moving parts, especially as you get towards the #1 cylinder. Some people will point out this method is hard on the ignition system. They're right, but that doesn't stop some of us from using it. A better method is to buy a device you can put inline with the spark plug to short it to ground (??? I think). An even better approach is to pull loose an injector connector instead. No fuel = no fire. However your connectors are probably brittle/crumbly and might easily be damaged in the process. (They should probably be replaced. You can order some off of Ebay. You need to know how to solder electrical connections, use heat shrink, etc. -- not rocket science.) Other matters: Your vacuum is very low, but you know that. You should ideally have a reading of 19 at idle, but cozye and I are running about 18 on our engines. You should probably pull at least 17. You might be running lean. However, you're probably getting ahead of yourself. Your vacuum confirms that you have a problem. Now how to diagnose it? I'd have to refer you back to my original approach. First, make certain you have no vacuum leaks. Your engine is properly timed, which is another important step. Also make certain all of your cylinders do something (by pulling wires). If you have a compression gauge, you might want to verify that you have normal compression in all of your cylinders. All of this will establish that your engine is mechanically sound and that your problem is a fuel delivery issue -- probably fuel/air mixture. You've worked your way through the EFI bible and have verified that all your sensors are good, so you're quite far along. AFTER YOU'VE DONE ALL OF THE ABOVE, pull the black cover off of your air flow meter. (It's sealed with caulk, and you'll eventually need to re-caulk to reinstall it.) Make sure the mechanism moves freely, with no binding. Measure the voltage at the wiper connection (that center contact) with a mechanical volt meter (ignition on) to be certain it varies smoothly when you move the mechanism back and forth. Now with the engine idling, nudge the little counterweight mechanism a bit clockwise and then counterclockwise. Does the engine run much faster when you move it either direction by a very small distance (maybe 1/8") and much slower when you nudge it in the other direction? If so, then your fuel/air mix isn't optimal. If it runs better when you move the assembly counterclockwise, then your mix is too lean. If it runs better the other way, your mix is too rich. I think once you've gotten to this step, we'll be able to help you figure out where to look next. Oh, finally, a note about the engine magically running well one moment and then the next: That's often something electrical -- a contact that sometimes fails and is sometimes good. Make certain all of your connections are clean and free of corrosion, including the one on the bottom of the air flow meter. Also clean the carbon trace and contacts underneath the air flow meter cover plate. One more note: I've rarely seen a car older than 10 years that doesn't have multiple fuel issues. They can often work against each other, so that when you fix one problem it makes the engine run worse. Don't worry about it. Just go with it, and keep fixing problems as you find them. Eventually the engine will run great. Peace back at'cha! (Too little of it nowadays.)

Reviving an old thread: I've been nursing my door stop rollers along for a long time now, squirting them occasionally with penetrating oil, hoping that they would get better with use, and that the crap would eventually work its way out of them. The problem is that mine like to freeze in place (no doubt due to rust), so the detent arm slides and grinds on the frozen roller. That's not good. I once bought a truck whose PO neglected this part, and the metal fatigue had broken up the door's sheet metal around the door hinge. I had to have the door welded back together. So has anyone figured out how to get lubricant into these things without removing the doors and rebuilding the hinges? I'd be grateful for any easy solutions.

K&N! Very nice filter. I've never had a problem with the Jiffy Lube type shops. However, if you want the job done with your motor oil and filter of choice, and especially if you want to do something like a motor flush, it's generally better to do it yourself.

Wow, a lot of issues addressed here! Answers to questions are generally much longer than the questions themselves. Anyway, I'll take a cursory stab: First of all, timing on an electronic ignition engine (like yours) is remarkably stable over time (as long as you tightened the set-bolt at the base of the distributor (pictured in your righthand photo). Once you've got it set right, I doubt you'll ever have to re-time it again. You can raise your idle speed by adjusting the big screw on top of the throttle body. However, if your idle speed isn't as high as it was, something else is probably wrong. You could have a clogged fuel supply. That would probably be evident in the fuel pressure under the conditions at which the engine isn't running correctly -- in your case at idle. It could be an ignition problem, but usually ignition problems are more evident at high RPMs, when output demand is higher. Put your timing light on each of your spark plug wires to see whether there are any "skips" in the flash pattern. Your idle shouldn't sound like "blub blub." That's what a V-8 engine sounds like -- the classic (V8 burble). Instead, the exhaust on an inline 6 engine should have a smooth, low-pitched "hum," for lack of a better word -- more like a very low note on a tuba than something from the Dukes of Hazard. On a poorly running engine, there may be occasional misses, where a puff is missing, or where the engine shoots out a puff that is much harder than the others. If there's a regular and rhythmic chug, chug, chug, then that indicates a specific cylinder that isn't firing. You can find it by pulling spark plug wires one by one. If/when you pull one one that makes no difference to the running of the car, that's your dead cylinder. It could be either an ignition problem (e.g. fouled spark plug, bad spark plug wire, short to ground), an injector that's not firing (no electrical contact, clogged, malfunctioning), something wrong in the valves, or even a blown head gasket (in which case you'd probably notice lots of other awful stuff too). If the missing is randomly timed, and if misses are somewhat infrequent, then you could have sticky valves, particularly if the car has spent a lot of time sitting or has been poorly maintained. You can free up sticky valves with a Sea Foam treatment or an engine flush (Gunk). People often have very strong feels that you shouldn't flush your engine, but it's always worked well for me. Sticky valves also get better with regular use. Probably a more likely cause of random missing is an incorrect fuel/air mixture. Contrary to my expectations, I could still smell a hint of gas in my exhaust when I was running much too lean. That's because of the misses, when the lean, unburnt fuel/air mixture is ejected into the exhaust. When this happens, I think the mixture detonates in the exhaust, causing a hard puff, but it burns very inefficiently, resulting in the hint of gas smell in the exhaust. If your engine is running too rich, the smell of gas in the exhaust will be rather strong, and you may see some black smoke, especially on full-throttle acceleration. If your engine is running too lean, the exhaust will blow too hard, with occasional hard puffs. A better way to diagnose fuel air mix problems by reading your spark plugs. Do a google search for "read spark plugs." You'll want to install a fresh set and run them for maybe 100 mi before reading them. There are MANY reasons why you might have the wrong fuel/air mixture. If you read through my "what next" and "purs like a kitten" threads, you'll see all I did to diagnose and correct my own fuel mixture problems. Aside from suggesting general areas to look, it's hard to make more specific recommendations. You're going to have to do a lot of sleuthing on your own. My advice is to do the following: 1. Make absolutely certain your intake system has no more vacuum leaks. To do this, remove the air flow meter from your car -- 3 bolts on the base, two possibly crumbly boots (replaceable through MSA), and a fat electrical connector at the base that has a small spring clip that must be opened with a small screwdriver to be removed. Stuff a yogurt cup into the boot going to the throttle body. Now pull the brake vacuum line and HVAC vacuum line (the small one beside it) from your intake manifold. Connect a clean hose to the brake vacuum fitting. With your finger covering the HVAC vacuum fitting, blow through the hose to "inflate" the intake system. It should take maybe 10 or 15 seconds for the pressure to start declining. You'll be able to feel the rate of leakage. Now do the same thing without your finger over the HVAC fitting. You're introducing a known leak by doing this, and you should feel the pressure decline quite a bit faster (e.g. a few seconds). If the first test seems quite a bit tighter than the second, you probably have no vacuum leaks. Of course don't forget to test the other direction to see if you have leaks in your HVAC or brake system. Once you know your intake is tight, then... 2. Use both your factory service manual and the "fuel injection bible" (downloadable online) to troubleshoot your system. 3. In addition to a fuel pressure gauge, buy a vacuum gauge. It will tell you quite a lot about how efficiently your engine is running. ... and yes, what Cozye said. Correct all known issues as soon as you discover them, or else you'll be running around in circles. Even though the bad thermostat shouldn't make your engine run badly, it will prevent you from diagnosing the engine at normal operating temperature. It can be a lot of work, but you should end up with a nicely running engine. Good luck!

And sorry for the thread-jack, but is the louver at the bottom supposed to be bowed? Mine is, and the two I see in the above pics are too. Bonzi Lon, is your "new" bottom-most louver bowed? I can't figure out how to straighten mine, but maybe they're just that way.

BTW, a tip to any of you trying to figure out how to mount the thing without the proper double-adhesive pads at the bottom (the super-thick kind): Use black 5200 caulk instead. You can't just build up multiple layers of the ordinary double-side adhesive pad material. It will come loose. My louvers came with the adhesive partially given way, and this was the only method I could find to re-stick it.

Well, you've already seen enough pics to know what it looks like, so it's pointless to upload my own. I used to really hate the look of louvers until the 70's ended, and then I sort of missed them. I bought a '75 280Z in 1983, and it came without louvers. I thought it looked better that way, so I didn't add any. Now, many years later, and long after having sold that car, I bought my '78 280Z, which came with louvers both on the rear and on the quarter windows. My first thought was whether I should remove them. I pulled them off, but them on, scrutinized, head-scratched, and concluded that I'd keep the rear louver but ditch the ones over the quarter windows. The ones on the quarter windows were cheap plastic and did nothing but obscure the view and make the car look less aerodynamic. They also chopped up the clean lines of the body and roof. The ones on the back, though, weren't all that bad. They GREATLY cut glare out the rear window, protected the interior from sun, and kept the cabin cool. What's more, they were a throw-back to that cool late-70's look, for better or worse -- Saturday Night Fever, disco, polyester leisure suits, etc. Rather than turning my nose up at it, I decided to embrace it. My '78 came out the very year all that started, and I felt it should wear the rear louvers proudly. Besides that, the additional horizontal lines sort of complement the projected front bumper of the 280. BTW, I saw a disco mirror ball Christmas ornament and thought briefly about hanging it from the rear view mirror as a lark. However, good taste got the better of me.

The 280 is probably the better daily driver for reasons stated. It also has that mid/late 70's look that not everyone appreciates (but I do). In addition to all of the above points raised by Dave and Leonard, I believe the carbureted fuel system of the 240/260 is more vulnerable to the corrosive effects of ethanol gasoline than the EFI fuel system of the 280, as the EFI has no ventillation ports to let in atmospheric moisture.

You're throwing quite a few new parts at this issue! A better approach might be to diagnose the problem thoroughly when the system is acting up. When you can't start, measure your battery voltage with a multimeter. Is it low? If so, it might be the battery, alternator, or voltage regulator. Jump-start, and test further. If your voltage is good, then what happens if you jump a small wire directly from your battery to the little terminal on your solenoid? Does the starter crank? If so, then your starter is good, and the problem is somewhere in the wiring. When your engine runs, is your voltage up to maybe 14.5 V? If not, it might be the alternator. Keep a loose eye on your ammeter to see if you unexplainably go into discharge. If you find alternator problems, it could either be your alternator or the wiring from the alternator. Look for corrosion. Also look for corrosion beneath the insulation on the secondary wire coming off of your pos battery post, and look for a crumbly fusible link. Going through my own car, after I purchased it, I did find a number of electrical problems. I did have to replace the alternator because of a bad regulator (high voltage), but otherwise I had about a half dozen issues with the wiring -- all of them from corrosion.

Koalia and Mgmoreau, check out Ebay auction 350416194155. That's cheap! I have one, pulled from my 280, but I'm saving it for a while. I replaced it with a fully automatic aftermarket antenna.

That's what I did on mine. Just be sure to file the head of the bolt smooth, so that it doesn't wear at the brake switch. A tiny dab of grease is a good idea too.

PS Now that I think about it, I suppose the tapping sound could be the manifold against the nut/bolt.

Zed, Gary, the loud tapping sound is metal against metal, or at least it was on our 318 inboard (#1 cylinder -- front left -- isolated on the exhaust riser, sort of like the #6 on the L26 exhaust manifold). I doubt the noise could have been made any other way. I figure with the gasket gone, the manifold probably hovers in very, very close proximity to the head, so it wouldn't take much movement for the two parts to clatter. The sound travels through the boat, somewhat like a prisoner tapping morse code on the water pipes. (The motor/transmission mounts are solid, not rubber.) I'm not saying all (or even most) exhaust leaks sound this way, but rather that a loud tapping sound can be due to the manifold banging/clattering this way. Ed, the rear-most cylinder is probably the most common location for exhaust leaks in the L24/L26/L28 engine. You should look for the soot, like Gary suggested. You can also feel for leaking exhaust, but be careful. I suppose another way to check for exhaust leaks might be to use a vacuum cleaner discharge port to back-pressurize your exhaust (cool, non-running engine). Then you can feel all around the exhaust manifold for air leakage. Incidentally, I had an interesting "EGR" issue with my Z. I had exhaust leaks adjacent to intake leaks, so my exhaust was being sucked back up into the intake. THAT was interesting! Ed, I have to say I'm surprised nobody knows how to work on Z engine with a Holley. Geesh! It's not like it's a spaceship or anything. I guess mechanics nowadays need OBDII diagnostic codes to fix anything. Maybe you need a mechanic who's at least 45 years old, preferably at least 50. Either that, or you need a mechanic who works on classic cars. Even someone used to working on old Camaros and Mustangs should be able to figure your car out. That said, I'm finding that the Holley isn't an easy carburetor. I just rebuilt the one on our boat and was frustrated by it popping a couple of fuel leaks that had to be brazed closed. I'm still waiting on a little piece of rubber that wasn't in the rebuild kit -- the accelerator pump check umbrella thingie that I've estimated is literally worth at least 3 times its weight in gold. (No kidding.) Compared to other carbs, the Holley isn't an easy beast. It's cheap to buy, but you pay for it later. I don't think I ever want another. An Edelbrock is a nice piece of equipment, though.

Ed, I doubt any pieces of the exhaust gasket could fall into the cylinder. If your exhaust gasket is the problem, the noise would be from the manifold banging against the head. An exhaust puff flexes the manifold outwards, and then it swings back in and bangs the head. You definitely want to be SURE you have an exhaust leak before attempting a replacement of the gasket. I just did mine, and it's not for the faint of heart. All I needed was ordinary tools. And yes, you have to take the intake off as well. You are likely to encounter frozen bolts and studs. You may need a blow torch to break some of the corrosion loose, vice grips to turn any broken studs, and possibly even a drill and bolt extractor set. You just have to do whatever it takes. If you're a religious person, prayer might help too. If you're not, and maybe even if you are, you'll have a great opportunity to expand your four-letter vocabulary. Once you've gotten everything off, you'll need a metric tap and dye set to clean out the threads and a new stud/bolt kit from MSA. Also try to find some nickel anti-sieze compound to apply to the studs. If you opt to have a mechanic do the work, it will cost. I was quoted $800 by the local Z specialist. It might have been worth it in hindsight, except that he wouldn't have changed out the old studs (which is a lot of the work). I ended up with a much better job by doing it myself. You can read about my adventures here: http://www.classiczcars.com/forums/showthread.php?t=39833 ... and then here: http://www.classiczcars.com/forums/showthread.php?t=40234 But again, make CERTAIN that's what you need to do before unbolting your manifolds! Make certain you have an exhaust leak where the manifold bolts to the head. Good luck!

Not sure about the backfire, but a loud knocking noise (sounding like a valve going very bad) CAN occur when you've blown out the exhaust manifold gasket, and the exhaust manifold is banging/clattering against the head. It happened on our boat once. I thought the salt had finally gotten the best of its ancient engine, but a replacement of its exhaust gasket made everything right. See if there's a massive exhaust leak between your head and manifold. If so, I bet that's the source of the noise.

If you cruise down the highway in your top gear and then floorboard the accelerator pedal, does the engine RPM increase without the car going any faster? If so, then your clutch is slipping and would need rebuilding. Otherwise, there's no way for a car with a manual transmission (in gear) to slow down without the RPMs dropping. When you say "start to" slow down, do you mean that you don't really lose speed (at least not enough to see on your speedometer), but you just momentarily lose a bit of power? If so, it could be any number of engine problems. It would be hard to be any more specific than that.

A spatula is great to pry against too (to protect the paint).