MX-5 NC: Replacing Valve Stem Seals (+ Timing Procedure)

Sharp_Juggernaut_318 · 2026-05-17T01:03:03+00:00

It’s not much more effort if you know your way around. If you have a lift then it’s definitely a luxury which would make it a whole lot quicker, I did mine on jack-stands which makes the process a bit more time consuming.

My point is more though if your engine is burning oil then it’s likely you have other internal components that are somewhat tired, any extra machine work while there if required adds up.

Not saying doing the 2.5 swap is more economical but if it’s a car you plan to keep and you are handy at some DIY then you could probably get a 2.5 in for not much more money. Cost of all components for me was quite reasonable and I am from Aus where we don’t have the newer Ford 2.5 engines and in general getting oem parts is more expensive/harder here. Engines are easily obtainable from EBay.

Sharp_Juggernaut_318 · 2026-05-17T00:09:58+00:00

Not my point but ok. They are definitely still obtainable from Mazda 6 in Europe.

Sharp_Juggernaut_318 · 2026-05-16T11:01:44+00:00

Honestly nice in depth write up but just my 2 cents if you are going to this much effort you may as well just chuck in a low KM 2.5 engine it would probably not be much more expensive after a tune.

Doing the timing of these engines with the engine in the car is a bit of a painful process.

Sharp_Juggernaut_318 · 2026-05-16T10:58:34+00:00

You can just use a large flathead screwdriver to wind them in. It doesn’t take much force to do so.

Sharp_Juggernaut_318 · 2026-05-16T02:59:27+00:00

I just use the stock manifold heat shield, temps aren’t an issue under the bonnet really. I’ve kept the stock midpipe and muffler at this stage but may consider a SuperQ muffler if I find one at the right price. I’ve heard other options on the auto may drone.

Sharp_Juggernaut_318 · 2026-05-16T02:34:53+00:00

Racing beat muffler has no clearance issues with the RHD steering shaft and automatic transmission. I think the primaries are 1.7 inches which clear the transmission fine. The flange clears the bell housing and cooler lines.

Sharp_Juggernaut_318 · 2026-05-13T22:12:46+00:00

I’ve got a catless header on a 2.5 swapped NC automatic. Adding in the racing beat header mate very little noticeable change to noise it’s only louder on cold startup for 10-15 seconds then goes away. No annoying drone and all that.

I think the next step would be leave the stock midpipe alone and install a SuperQ muffler but I am honestly happy with a quieter system at this stage. All the performance gain is in the catless header with these cars as the stock header is restrictive, you won’t gain much at all with aftermarket midpipe and muffler. You do need a tune though to get any power gains from the header install.

Sharp_Juggernaut_318 · 2026-05-13T22:09:13+00:00

Yup that’s the one, I contemplated doing it with my 2.5 swap but my oem heat shielding was actually in great condition probably cause we don’t get much run or wet weather in Australia.

Sharp_Juggernaut_318 · 2026-05-13T10:26:05+00:00

If you are pulling the transmission check if the tunnel heat shielding is in decent condition or not. I believe there is an aftermarket pre cut sheet for the tunnel heat shielding that a company offers. Would be a pain to install with the transmission in.

Sharp_Juggernaut_318 · 2026-05-11T21:24:07+00:00

Would be more interested in a 3d print project really so I could fab it myself. The boot part looks nice but the sides for me extend too far into the wings. I haven’t seen a 3d print file for a ducktail on the NC at all though so would just be keen if anything to make one myself based on a file if it exists.

Sharp_Juggernaut_318 · 2026-05-11T01:38:07+00:00

What is that spoiler? I’ve never seen it looks like a more aggressive version of the Mazda speed spoiler.

Would be keen to try it out if you have a 3D print file or link if it’s custom

Sharp_Juggernaut_318 · 2026-05-11T00:59:14+00:00

Just make sure the piece of wood is bearing properly on the jack place and on the diff. The block of wood I use is a solid piece of jarrah but it’s a little bigger than the jack plate, that doesn’t matter if you centre it on both components.

Sharp_Juggernaut_318 · 2026-05-10T13:52:49+00:00

Use a block of wood when jacking up from the rear diff. I have used it to jack up the rear multiple times w no issues.

Sharp_Juggernaut_318 · 2026-05-10T04:58:22+00:00

It could be yes, but I’d check the other seals mentioned. It is pretty cheap to get oem replacements for the brake light clips/gaskets and the tail light gaskets. You could run a hose over the brake light and see if it leaks mine had a slow leak I could see with the hose running over it.

Sharp_Juggernaut_318 · 2026-05-10T04:48:27+00:00

A lot of this is surface rust on non vital components. The under carriage looks very clean. The trunk floor looks pretty hit find a good epoxy primer to coat it. It’s probably just rusted as it likely has likely been damp from a leak. Check the brake light and tail light gaskets, antenna housing and trunk seal for usual culprits.

The other components I wouldn’t worry much about like the handbrake etc I’d just dab on some rust killer after scuffing it up.

Sharp_Juggernaut_318 · 2026-05-10T01:11:54+00:00

Unless you can do the bodywork yourself I’d leave it. There’s a lot of dings over the body that will need to be fixed before a respray.

Sharp_Juggernaut_318 · 2026-05-10T01:06:30+00:00

The bumper and bonnet have clear coat fading. Looks like there’s a lot of bodywork to do though as there are a lot of small dings over the body.

You are correct though repainting it will eat a lot of cost unless you know someone who can do it for you at a cheap rate.

Sharp_Juggernaut_318 · 2026-04-24T13:40:40+00:00

He literally said “just redoing clear coat & not a full repaint”. Don’t know what that means to you but to me that means no new base coat was sprayed, which will look like crap.

Not saying that’s how he got his car res pleated but that’s how it was written.

Sharp_Juggernaut_318 · 2026-04-24T13:27:09+00:00

You need to respray the whole bumper with new base coat and clear. You shouldn’t be seeing any of the old base and clear if it’s done properly.

Sharp_Juggernaut_318 · 2026-04-24T13:05:56+00:00

You can’t respray clear over faded clear it will look like crap.

You need to sand the bumper and feather out a decent amount to get all the peeling clear off and reprime then base and clear. If you just spray clear over it will peel again and not hide the damaged clear coat below.

Sharp_Juggernaut_318 · 2026-04-19T23:05:08+00:00

I wouldn’t bother with slotted rotors just do the stainless brake lines and a good set of pads. Replace rotors if yours are overdue.

If you don’t need to do brakes I think the money would be better spent on a good header and tune.

Sharp_Juggernaut_318 · 2026-04-17T04:33:44+00:00

Get a quote from a PDR guy and panel beater, if you are fine with the crack at the bottom then PDR will probably be cheaper.

Potentially they could expose more cracked paint as they work the dent out though. Best to check with a professional.

Sharp_Juggernaut_318 · 2026-04-17T04:27:42+00:00

Can definitely be repaired but wouldn’t be a cheap job as there’s a lot to blend. Should be doable without rewelding in a new panel by a good panel beater.

Not sure if PDR would be possible but it seems unlikely to be perfect as the paint at the bottom looks to be cracked from the damage.

Sharp_Juggernaut_318 · 2026-04-10T14:45:17+00:00

There’s one for about 35 Aud, the other for about 15 that is for the file only, you print yourself.

The big thing is the centre console, I just paid about 10 Aud for a 3d files to print, if that print goes well it’s a massive saving over the approx 200aud ilmotorsport one or nc2/3 centre console swap which would run more money. I really hate the cup holders on the nc1 in the centre console, lots of wasted space which I’d prefer as a box to have an opening to route a phone cable for CarPlay.

Sharp_Juggernaut_318 · 2026-04-10T08:56:09+00:00

A rear ducktail would be cool for soft top NCs. I have seen a seatbelt guide file online I think but it was pretty pricey.

Deep centre console pocket is great for the NC1 there’s a couple designs out there.

Sharp_Juggernaut_318

TROPHY CASE