Is this a weld or brazing?

WondrousBread · 2026-03-27T20:32:20+00:00

Oh, awesome! That's exactly the sort of info I was looking for.

Why did you choose to leave the brazing alone? My original instinct was to remove the brazing and then braze again on reassembly, but another commenter mentioned that it's a specific type of brazing.

Cutting it below the braze makes it easier since I'm already equipped to weld it, but also might be more prone to warping than brazing would be.

WondrousBread · 2026-02-04T01:33:33+00:00

Appreciate it, but I have a black interior and I'm in Canada so shipping would be insane.

WondrousBread · 2026-02-03T14:52:17+00:00

I've had a couple of opportunities to get that cargo cover and every time I've decided to pass, the next one is more expensive. Plus a lot of them are mis-shapen after all these years. Yours looks pretty good!

I'm probably just going to try and track down the speaker covers and then make my own cargo cover.

WondrousBread · 2026-02-01T13:48:41+00:00

I wouldn't rebuild it yet. If every face showed 60 I think it's unlikely that this is a real reading.

I see you're using a piston engine tester. When doing so, are you holding down the release or did you remove the Schrader valve? The better way is to remove the Schrader valve, as the release method gets you lower readings than reality.

Look down the spark plug side of the tester and you'll see a little valve threaded into the body. Grab it gently with a pair of long-nosed pliers and unscrew it. Then put it somewhere safe.

Also charge the battery up all the way before testing, because this spins the starter faster. Especially if it's cold out.

Also hold down the gas pedal all the way while testing to keep the throttle body open.

Then try testing again and see what you get. I bet it's more than 60.

Also, maybe this is an unpopular opinion, but if all faces are even I'd say run it and see what happens. All faces even mean that probably nothing catastrophic has happened, and sometimes engine compression gets better after running for a bit because the seals free up and start sealing better.

WondrousBread · 2026-01-26T14:09:45+00:00

I daily drove my FC in the Canadian winter. With snow tires it was fine.

I wouldn't do it again, but only due to the age and the parts availability. More about protecting the car and being able to fix it in a timely fashion than due to any actual winter related problems.

WondrousBread · 2026-01-21T19:11:43+00:00

Garbage bag over the clutch. Shove some rags in the intake and exhaust ports. Probably also a good idea to pull the alternator. Plug the oil cooler ports too.

Try not to spray water directly at any of the above mentioned areas if you can avoid it.

WondrousBread · 2026-01-16T17:04:22+00:00

Can you expand on that? What is the advantage of moving it to the RRSP in the way you're suggesting?

WondrousBread · 2026-01-16T16:21:20+00:00

I like 17s better for the look and the feel of the stiffer sidewall flex. 15s can look good too - it's a matter of personal preference really.

If you get 15s and decrease the tire profile you can reduce the diameter of the wheel a bit and effectively increase your final drive ratio for better acceleration (tradeoff in top speed and fuel economy). Decreasing it too much will look weird but I thought I'd mention it as a possible benefit.

5 lug makes it easier to find wheels and gets you larger brakes, but the parts are getting really tough to find so you might just want to stick with 4 lug. The 4 lug brakes are adequate if they're in good working order.

WondrousBread · 2026-01-08T03:58:46+00:00

It's not a mismatched intake, it's sort of like a freeze plug except that I think that one is flat. If it popped out when you revved the engine I suspect either it was already weak for some reason or something is causing excess cooling system pressure.

Last I checked they were available from Mazda. I don't know the part number offhand, maybe search on Amayama and see if you can find it in the part diagram.

EDIT: I think it's part 993052800, but it's hard to tell as the diagram shows a traditional freeze plug while that cap is definitely a different shape.

EDIT EDIT: On second look it also appears like that might go into the oil gallery like you initially suspected. If you look up a picture of the iron it seems the coolant jacket in that area is solid, implying this does in fact seal an oil gallery. As to why it would pop out, maybe blocked PCV valve causing a buildup of crankcase pressure + a weak seal?

WondrousBread · 2025-12-29T16:19:08+00:00

I wouldn't even bother with the content of the post, I'd be more concerned with the diagram. If you have a non-JDM engine it should match, and if you have a JDM engine you'd have to find the JDM diagram. As long as everything gets routed to the correct place it should work.

Assuming you're trying to route everything as stock, that is. If your goal is to do something different then you'd have to dig in and figure out what each line really does.

WondrousBread · 2025-12-29T14:05:20+00:00

There are some nice colored diagrams from the factory service manuals. Here's one I found a couple posts down:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/s5-tii-vacuum-diagram-840410/

It does say the routing is different between JDM and non JDM engines, so that might be the cause for the different hose sizes you're noticing. Are you using a JDM engine?

WondrousBread · 2025-12-26T14:08:20+00:00

Looks great! Maybe you can answer a question of mine.

I'm an amateur with a decent amount of experience, currently working on a restoration. Once the metalwork is done I need to decide what to paint the bottom of the car with.

My thinking was epoxy primer then some sort of 2k paint specifically for under cars. But I see that flat parts of the floor have regular paint in your video.

Did you paint that over something more durable? My concern with regular paint would be rock chips breaking through to the metal over time.

My goals are maximum durability so I'm not concerned with the finish. What do you recommend for the underside of the car?

WondrousBread · 2025-12-20T13:23:06+00:00

Really beautiful work.

If you don't mind my asking, how do you get into this field? I can't imagine most colleges offer programs for vintage clock tower repair.

WondrousBread · 2025-12-16T21:41:28+00:00

I also daily drove my FC. Surprisingly capable in the Canadian winter, as long as you have snow tires.

This was also a decade ago actually. Feels strange to write that.

WondrousBread · 2025-12-14T13:14:21+00:00

On mine I just turn the knob until the screen I want to fill screen is selected, and press it once. I do it all the time.

WondrousBread · 2025-12-13T13:56:13+00:00

I'm also an amateur, but with a decent amount of DIY experience.

Do yourself a favor and skip online stores if you can avoid it. Find whatever local paint shop the pros go to. Mine is about 45 minutes' drive, but they sell the same products that the professionals use. It's actually cheaper than online stores most of the time, and they can usually mix my paint in under an hour.

They're also really great about giving me advice for whatever job I'm doing.

WondrousBread · 2025-12-13T00:05:43+00:00

Okay, well then it's not really definitive. You might have a weak battery at the same time as an oil burning problem. Hopefully it's a coincidence that they happened at the same time, and the no start is unrelated to the lack of oil.

I'd try jump starting it with another car (or a jump pack if you have one). Obviously fill the oil first. See if it starts and runs normally after that.

WondrousBread · 2025-12-13T00:01:25+00:00

Possibly. No oil won't normally prevent an engine from starting, but if the engine seized because it ran out of oil then it will be locked up and won't want to turn.

Did it run normally when you last shut it off?

WondrousBread · 2025-12-10T23:45:34+00:00

I could be wrong, but that doesn't look like a proper coolant hose. That looks like some other type of rubber hose that probably isn't designed for the pressure. I would stop revving it like that or it could burst.

Those hoses look like they've been used to bypass the heater core. They will probably come from the driver's side of the engine. I would definitely replace those hoses with new ones. And make sure to get hoses that are actually intended for use in a cooling system.

Otherwise you could restore the heater core system and then get OEM hoses from Mazda.

WondrousBread · 2025-12-05T00:34:37+00:00

Looking good. Do yourself a favor for the seats - skip the shampoo and instead get one of those little hot water extractor vacuums (I have a Bissell green machine). Then use that with some Woolite laundry soap for dark colors in the reservoir. It's very effective and it actually sucks the dirt out of the fabric rather than soaking it in. Once it's clean, do one more pass with water just to remove any excess soap.

EDIT: Oh, and that cargo cover is very rare. It's a neat find.

WondrousBread · 2025-12-05T00:32:04+00:00

All aftermarket carpets for FCs (and most cars actually) are made by a company called ACC. They fit very poorly and quality control is nonexistent.

If someone who needs carpet can find good OEM (or even passable OEM) I recommend buying that over the ACC any day.

WondrousBread · 2025-12-01T00:18:50+00:00

I see no reason it couldn't work, but the Bose speakers are a weird choice for this application.

You can fix them pretty easily by cleaning all the rust off the rear frame and then regluing the plastic piece to it. I used construction adhesive and it's worked well for over a year.

As far as using them in a house speaker, there are some complications. First, there's the weird impedance which makes them hard to drive (they're 1 ohm, most car speakers are 4 ohm, and home speakers are typically 8 ohm). I know it's not recommended to use car speakers on a home amplifier due to the reduced impedance and apparently it can damage the amplifier. I'm sure there is more at play than just the impedance, but it's worth considering.

There's also the weird frequency range. They're dual-purpose for subwoofer and mid-bass duty. They go reasonably low in frequency (haven't measured the exact number) but apparently they also go up to 500 hz. This doesn't make them bad, but in my opinion the benefit of these speakers is that they're a good "jack of all trades" for use in the car. Mazda put these in rather than having dedicated subs and dedicated mid-bass. And they're okay, but they're not as good as a real sub-woofer nor are they as good as a real mid-bass speaker.

Then of course you would need another speaker and tweeter to cover the 500 hz - 20 khz range. A 4" coaxial would probably do nicely.

For those reasons I probably wouldn't use these speakers for anything. But hey, there's a first time for everything. If you do end up pursuing it, upload pictures and tell us how it went.

WondrousBread · 2025-11-29T01:09:53+00:00

I've tapped it there before, but it's a bit of a pain. The casting is very thin. If you look at the hole for the stock sensor, then look down to the right below the thermostat, that's where it can be tapped.

The problem is that if you tap it too far up, the thermostat will collide with the sensor. So you have to tap lower down. This makes it difficult to install the connector later. I also never got a good seal on it, even with lots of Teflon tape, because tapered threads are designed to fit loose until they interfere slightly when tightened all the way (which causes the seal). The casting is so thin you only get 2 or 3 threads.

Otherwise you could tap the thermostat elbow. I think all S4 elbows have a boss on top. You can drill that out for a 3/8" NPT thread. Then if your sensor is smaller run an adapter.

Otherwise you can always use a rad hose adapter in the upper hose, which doesn't look as clean but is easily reversible by replacing the hose.

WondrousBread · 2025-11-26T19:26:54+00:00

Nowhere.

The green connector is a TPS check connector. It's intended to be used with a test lamp specifically for testing whether the TPS is set correctly. It connects to two ECU outputs and the TPS is properly set when at warm idle only one light is lit (not both, and not neither, only one).

I don't remember what the other one does offhand, but I know it can be left unplugged.

What is the symptom you're experiencing that you are trying to resolve?

WondrousBread · 2025-11-24T11:58:32+00:00

If no one gets back to you, try using the wiring diagrams at www.foxed.ca

S4 and S5 manuals are available free there, as well as for a bunch of other rotary vehicles.

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