How to inspect a used Cobra MX46SPB — UK guide
Cobra mowers punch above their weight on price-to-feature. The MX46SPB combines a Briggs 500E engine with a rear roller for stripes — at £100 less than the equivalent Mountfield. Used examples are good value if you check the right things.
Before you go
Bring: spark plug socket (16mm), torch.
Cobra dealers are thinner than Mountfield — confirm there's one nearby for parts before paying premium money.
1. Cold-start the Briggs 500E
Three primer squeezes, full throttle, pull. First or second pull when healthy.
Won't fire = stale fuel or carb. Easy DIY fix. Knock £25 off.
Smoke at idle = engine top-end wear. Walk away.
2. Test the drive
Engage on a slope. Should pull cleanly without slipping.
Slipping under load = drive cable stretched. £18 fix. Knock £30 off.
3. Inspect rear roller (stripe quality)
Cobra MX46SPB has a steel rear roller. Spin by hand — should turn smoothly.
Clicking bearings = £18 generic bearing kit. £40 off.
Roller surface gouged affects stripes. Light marks OK, deep grooves no.
4. Steel deck check
Lift and inspect underside. Cobra decks rust faster than Mountfield in salty coastal areas.
Surface rust is fine.
Rust through the deck (visible holes) = walk away or 60% off.
5. What to pay in 2026
2018–2021: £140–£200 mid-condition.
2022–2025: £220–£320, sometimes with warranty remaining.
Knock £30 for any: stiff drive cable, primer hardened, missing service stamps.
Knock £80 for any rust through the deck.
FAQs
Cobra vs Mountfield SP46 — which is better used?
Identical engine (Briggs 500E variant), similar build. Cobra is £30-£50 cheaper used. Mountfield has the wider dealer network and slightly better resale. Either is a sensible buy.
Where do I find Cobra parts?
Cobra dealer network is run by Henton & Chattell. Less dense than Mountfield/Stiga but most garden machinery dealers can order parts within 48 hours.
Is the rear roller actually worth it?
If you care about stripes, yes — non-roller petrol mowers can't produce them. If you mulch or just want grass cut, save £30 and get the MX46B (no roller variant).
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