Ok my car has a light slapping/tapping sound that is constant whether on start up or on a lond drive. Had issues with tappets on my previous mazda 323f but this sounds slightly different, almost like a quiet diesel engine! Only had the car for a week but changed the oil and filter and just stuck some NGK iridiums in but nothing is helping. Car has done 47000 miles so dont think its wear on the little end, or pray not, but cant work out any other reason. Tappet noise usually ceases when you’ve had a run out but this almost chugging sound continues consistently. P.S it increases in frequency in proportion to revs.
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I would do as Geoff as said , it may even need to be done for a couple more services, but have you checked the tension in the timing belt, if it is a tad loose it can give belt slap.
Sounds like she is in need of a good service, what air filter is on her ,cat and zorst?
Bit more info on year, model etc will help us buddy.
Is it a Mk1? Only the Mk1 has hydraulic tappets, which respond very well to a dose of Wynn’s hydraulic lifter treatment if just changing the oil doesn’t help. FWIW, the only oil that my Mk1’s tappets were happy with was Mobil 1. I tried Castrol Edge but they rattled every time I started the car.
So - I’d dose with the Wynn’s stuff and then change the oil and filter with Mobil 1 0W40 a couple of hundred miles later.
If it’s a Mk2 or Mk3, the tappets are shimmed and rarely give trouble since the contact area is so large. They can be re-shimmed at high mileage but it’s a fairly large job and you won’t know the size of shims needed in advance.
Just as a matter of interest it is possible to fit mk2 tappets for mk1 engines as I have sold a few sets for thios reason.We have old scrap engines we keep for parts only so ideal for this.
The Mk1 tappets (HLAs) rarely wear out; normally it’s just that a little hole in them gets clogged up and then the engine runs with noisy valve clearance until the oil manages to force its way in and the clearance reduces to zero. There are occasional tales of collapsed HLAs requiring replacement (where they won’t hold oil at all), but not many.
Hydraulic tappets were really popular in the 80s but hardly anyone uses them any more. They were a good idea, but a bit expensive and probably not suited to modern 18,000 mile oil changes.
The bucket-and-shim solution is pretty much maintenance-free as well; the old type of rockers with a threaded adjustment had such a small contact area that they needed adjusting every 6,000 miles on some cars. I remember doing them regularly on my K10 Micra. On that car they had to be adjusted HOT (thanks Nissan), so I got pretty quick at whipping off the “frying pan” air cleaner and the rocker cover.
The car is a MK2 1.8, year 2003. The vehicle has nearly full service history apart from the previous year and like I said I have just changed oil, filter and plugs (not that plugs will change anything) so she should be up to date service wise. I will check the timing belt but it seems louder in the cockpit and sounds like it is the dashboard side of the engine. When stood outside the car you cant really hear it. Will give it another oil change soon and swap to some mobil 1 0w40 fully synth I think.
Bottom end wear is almost unheard of on MX-5s, although I suppose a previous owner could have lugged the engine up hills at 1000rpm and turned the bearings oval.
I believe the valve clearances can be checked without removing the cams, so I’d have that done. Different oil won’t have much effect on the Mk2 type of valve lifters.
