Namerow

Try loosening the nut with an impact wrench. Sometimes the combination of shock and vibration is effective in backing off a Nylok nut.

My depth gauge 'pointer' is actually a metal strip measuring about 3/16" across, with a square profile at the end. As someone else has pointed out, the bottoms of the holes are conical rather than square. That means that the tip of my depth gauge would have sat slightly short of the very bottom of the hole at its centre. If you use a piece of wire as a depth gauge, you measurements may come out 1 or 2mm longer than mine.

There's nothing like a good mystery story... As luck would have it, I have in my workshop a fully-reconditioned, stripped-down L24 block sitting on an engine stand. I also have a depth gauge! What I discovered is quite interesting... The block has 7 head-bolt holes along each side. The depth of all of the holes along the passenger (right) side of the block is 26.5mm Things are much more interesting along the driver (left) side. Numbering from front to rear, the hole depths are as follows: 1. 32.0mm 2. 29.0mm 3. 25.5mm 4. 32.0mm 5. 26.5mm 6. 32.0mm 7. 28.5mm These measurements should be considered accurate to +/- 0.5mm. Nevertheless, there's a substantial variation along the passenger-side. Why is this? I'd have to look at the head casting (not convenient). However, I expect that height of the bosses for the head bolts have variations as well. You also have to take into account that there are three different lengths of head bolts (the parts manual calls them 'S', 'M', and 'L'). They may have different threaded lengths, too, but I don't have a set conveniently available to check this. It seems to me that -- properly assembled -- each head bolt should end up with relatively full engagement of its threaded length. If you get their locations of the S, M, and L bolts mixed up, you may end end up with problems. I can't find any info in the L24 FSM. It only offers this cheerful note: 'Three different types of bolts are use (So be careful when in installing).' My Haynes manual does have a bolt diagram -- although it says there are only 2 different bolt lengths - 'Short' (S) and 'Long' (L). With that noted, Haynes says: Passenger Side: all 'S' Driver's Side - from front to rear: L - L - S - L - S - L - L Maybe Tom Monroe's book, Rebuilding Your Nissan/Datsun L24 Engine' offers more detailed info. Unfortunately, I've misplaced my copy. As a first step, I suggest that you use a depth gauge (or a 'calibrated' piece of wire) to ensure that all of the hole depths in your block are about the same as my measured depths. I'm pretty sure that they will be. It seems inconceivable that just the tip of a bolt would break off at the bottom of its hole. If one of these bolts snaps off, it's going to happen at the top of the threaded part, not half-way or three-quarters of the way down, so you should be able to clearly see the top of the broken bolt sitting at or slightly beneath the top deck of the block. BTW, all of the bolt holes are blind. That is, none are open at the bottom to some other water/oil passageway.

Perfect. Now I have the full picture!

Interesting. It's promoted by 3M as a cut-off wheel, although they say in the spec sheet that it's suitable for cutting and grinding. There are 4 sizes (diameters) offered, each with its own centre hole size. The 3" disc you're apparently using has a 3/8" centre hole. Does your die grinder have a 3/8" chuck, or do you use a step-down mandrel to adapt to a 1/4" chuck?

I don't think you're likely to be able to source these new as stand-alone items (unless Zeddsaver comes through). Instead, they'll probably come in the form of used items from someone with an unwanted, beat-up seat. If I were such a person, I'd offer to either sell you the whole seat for $25 (you pay the packaging and shipping, so add $100) or I would invest my labour to recover the clips and dispose of the rest so that I could sell you the clips for $25 (you pay the packaging and shipping, so add $25). Alternatively, @zKars probably has a cache these (used), ready for sale and instant delivery. My guess is that his price will be $25 .

@240dkw That wire sounds intriguing. Unfortunately, it looks like the manufacturer only offers it in 11-lb spools (Cdn $130 plus tax & shipping from KTS Tools). That's good for commercial shops, I'm sure, but it represents a lot more welding than I need to do (or at least a lot more than I'm hoping I need to do ). Other members with more ambitious build programs may want to try it out, though, so thanks for the tip.

@SledZ Can you be a little more specific about the '3M weld grinding wheel' that you use? They have dozens of products that fall into the weld-grinding category. Do you have the 3M product number or name?

Make sure the threads on the studs and nuts are clean before you start. Maybe also spray lightly with WD40. The easier you can get those nuts to finger-tighten, the less annoying this job will be (and it can be really annoying).

Not me. However, the VIN is within 400# or so of my own 5/70, so I'm more interested than usual. Low-miles (perhaps) and looks 'rust-free-ish' (perhaps). Driver's seat look very good. Original? Dash pad appears crack-free, but I suppose it could be a cap. No under-car photos, so there's potentially a lot left unknown there. The thing that caught my attention is that the car still wears 90% of its braided hoses in the engine compartment (even the heater in-out and brake vacuum hoses -- and that's rare to see). The upper and lower rad hoses didn't make the cut, of course.

I guess I assumed that he performed the head 'rebuild' work without removing it from the block. If not, it would indeed be hard to understand how the broken bolt wasn't spotted the first time the head was off. Of course, there's always the possibility that it was spotted (and ignored) -- or that it was broken during re-assembly (and ignored) -- and that's why the car burned 2 quarts of oil in 100 miles. For the time being, though. let's give youztheclue the benefit of the doubt and assume that the bolt was broken by someone else.

I can't help but wonder whether this situation would respond better to big heat and big torque. As in, welding a nut onto the top of the stud and then putting a wrench on it. IIRC, @grannyknottalked about this in another thread a couple of years ago when the topic was extracting a snapped-off manifold stud out of the cylinder head. Something about the merits of using an oxyacetylene torch rather than a MIG? The difference here is that we have a large-diameter stud (bolt shank) that's seized inside a cast-iron engine block (vs. a small-diameter stud seized inside an aluminum head). Whereas it's the galvanic action of dissimilar materials that typically creates problems with steel fasteners getting stuck in alloy castings, for a head bolt it's steel-in-iron so I would think that the causes for the locked threads would be simple air (oxygen)-generated corrosion (unless the block has a micro-crack and coolant (water) has leached into the stud threads -- but let's not talk about that). In my (limited) experience of removing cylinder heads from high-mileage L24's, the head bolts take a lot of torque to break free and some of them really pop when they give way. Looking at the threads after the bolts came out, they appeared 'sooty' but not really crusty-rusty. I think that part of the problem with these head bolts getting stuck in the block is that they were installed at the factory without any lubrication so as to get accurate torque readings during tightening. Having said all that, I will repeat another story that I wrote about previously. In my area of the world (on the fringes of a 7-million pop. Canadian city), I discovered a contractor who provides the new-car retail industry with specialist services for extracting frozen fasteners from customer cars. That's all he does. He told me that there a certain model years for certain higher-end car brands where a key fastener (e.g. suspension mount) is chronically frozen, hard to get at, and often snaps off during attempted removal. That's where he makes his money. I hired him to get the snapped-off studs out of my Z's cylinder head (still mounted on the engine, in the car) and it was one of the best $120 I ever spent. He came to my house, rolled a tool caddy out of his truck, sized things up, and had the job done (without using any heat) in 10 minutes tops. Cheating? Maybe. Depends on your threshold for potentially-painful outcomes. You might consider looking for a comparable specialist in your area. The service managers at your local Benz, BMW, Audi and Volvo dealers might be able to help you find one.

Maybe I'm missing something but, from your photos, it's not obvious how that trim piece can achieve any left-right position other than what's determined by the two mounting screws. That suggests that what you've got is the way it's meant to be. Maybe a 280 owner can verify. Are you sure that the HVAC lever assembly has been correctly installed/aligned?

I think I might have the answer for you... https://www.belmetric.com/stainless-castle-nuts-c-3_558_1376/cn8ss-castle-nut-stainless-steel-p-8342.html?zenid=3j9n5fjlbd4p3hntj7jub44nl5 Looks to be a lot shallower than what you bought, although maybe not quite as shallow as the Nissan OE item. I've bought from Bel-Metric before. Good vendor, good products, great catalogue. BTW, if all else fails you should maybe pay your local Nissan dealer a visit. This might be a PN that's still available.

Lots of useful info. Thanks very much. Now to the next question: What processes and/or chemicals do you recommend to prepare the welded area for primer and paint?

What are members' recommendations for tools and abrasives to dress down MIG weld beads? For reference, I'm talking about stitch welds on sheet metal. The typical combinations I've seen suggested are: 1) angle grinder/flap disc 2) mini die grinder/2" sanding disc Abrasive grade recommendations I've seen are 36-grit to start and 60-grit to finish. I'm curious to hear thoughts on which combination(s) works best.

That was an impressive amount of bondo on that door. I suppose someone considered it easier than trying to align the door with the rocker and the door pillar. There's an interesting build thread on the Ferrarichat website that details the restoration of a 275GTB that had been bought for $$$ and was being restored to make it worth 10 x $$$. The 'before' photos show a car that looked ready to compete in a concours. However, when the shop started to strip the body for a re-paint, they discovered that the entire nose are had been re-sculpted with bondo. Almost an inch thick in some places! The work of an artist, to be sure. Re your Zkars replacement door, are you going to replace the metal in the mirror mount area? That seems to be a chronic corrosion area for these doors.

Interesting. If you look at the consumer-driven stats for the auto industry's products (J.D. Power, Consumer Reports, etc), you find that vehicle reliability has been on a steady and significant improving trend over the past 30 years. Here's an irony for you to consider: Back in the 1960's and 1970's, your vehicle's structure would basically disintegrate after about 5 - 10 years, leaving you with a bunch of perfectly good parts and sub-assemblies attached to an undriveable vehicle. In 2019, the parts and sub-assemblies crap out at the 5 - 10 year point, leaving you with a perfectly good structure that isn't worth keeping because of the uncertain cost and frequency of parts replacements. The vehicle manufacturers are under intense scrutiny over vehicle reliability. For that reason, the vehicle OEM's put their attendant OE systems and parts suppliers under a similar amount of scrutiny. However, the aftermarket parts suppliers are under no scrutiny whatsoever. The only people who tend to know whether a particular repair part (or part manufacturer) is unreliable are the service professionals (who will talk) and the parts supply wholesalers/retailers (who probably won't talk). This because they see such a high volume of incidents. As individual car owner/consumers, we're not in a good position to avoid buying bad stuff. Although it's not a guarantee, I think that the best practice is to stick to well-known brands, even if they cost more (and they almost certainly will). Although many of these manufacturers now have factories in China (and Vietnam, Taiwan, the Philippines, and South Korea), I'm inclined to think that they exercise a higher level of quality control at those plants than would be the case at the generic manufacturers' facilities. Electronics are a special subset of this issue. You can hide a lot of bad quality in 'black box' device without it being evident at the time of installation. Name-brand manufacturers have QA/QC programs and add the cost into their pricing. Generic manufacturers, I suspect, have no such programs.

I had my 70 Z's brake m/c sleeved and rebuilt a couple of years ago at a cost of Cdn $275. A problem I encountered at the time was finding a rebuild kit (the design of the pistons, etc for the early-model m/c is quite different from that used for the later cars). The brake rebuilder that I used operates a big business and has been around for many years, so they had the parts in stock. That was in 2016. Maybe a new stash of rebuild kits has surfaced since then with one of the Z aftermarket suppliers. If not, be sure that you're happy with the condition of your seals and pistons before you invest any time in sleeving the casting.

They're pretty smart when it comes to finding a comfortable place to live...

So you spun up the tube and cut from the inside until the spring perch broke loose? How did you avoid having the perch and the separated part of the tube create a jam when they dropped free?

Side mouldings are gone, too (a good thing). That suggests it's been re-painted.

But PN 55490-E8300 (the weight) doesn't seem to appear in the parts manual. Those add-on rubber washers don't appear to be listed either.

A lot of this discussion about design changes is starting to sound familiar. There's another Topic somewhere from about 2 years ago that has an extended discussion with lots of photos. Re your photo of a car with no lower rubber washers fitted to the MB, it's hard (but not impossible) for me to believe that Nissan would have decided to put the wavy rubber washers on the top rather than the bottom of the MB end mount. After all, the diff weight should be forcing the MB down, not up. That said, I don't understand why the MB bar in the photo is jammed up against underside of the car. Possible answer: The owner used the diff as a jacking point. As a result, the whole diff/MB assembly got pushed up against the wavy washer and got stuck there. Let's assume for the moment that maybe there is only one of these rubber washers fitted at each end of the MB. If that's the case, it makes more sense to put them on the bottom of the mount rather than the top. By the way, that's the way it's depicted in the Parts Manual diagram. What makes more sense to me, though, is that the wavy washers should be fitted to the top and the bottom of the MB end mounts, so that they're put into a slightly pre-loaded state after everything has been tightened up in assembly. In the parts listings, I see four different iterations of the 'Stopper - Differential Mounting'. In every case, the manual specifies 2 uppers and 2 lowers. I don't know exactly what to make of the arrangement shown in your photo. Maybe someone with an unmolested early Z (is there such a thing?) can chime in.

TS71-18 describes a cobbled-up fix that Nissan came up with to address complaints from owners about powertrain noise in Z's with automatic transmissions. It largely consisted of hanging a big-arse weight off the back to the diff casing. It also doubled up on the number of wavy rubber washers at each of the 4 places where these are located. It's interesting to note that the 'teeth' of the new, add-on washers appear to have been designed to interlock with those of the original washers. That would have really stiffened things up. Although I haven't checked the parts manual, I doubt whether this dealership service kit ever made it into actual production. Nissan probably found a more elegant way to solve the problem with the auto-trans Z's (different final drive ratio, maybe?)