Taptaptaptaptap

[Merlot]

When I purchased my '5 about 18 months ago, it had some tapping from the engine. I replaced the oil with Mobil 1 0w40 and this got rid of the problem. However, 12 months later and approx. 2,000 miles and I'm getting the tapping noise for the first 2-3 minutes when cold. Thing is, there seems to be no pattern to it - it'll do it about 20% of starts, but not always under the same conditions - sometimes when the ambient weather is warm, sometimes when cold. I cannot recreate it under the same conditions, it just appears at random.

I would have thought it would tap when the weather is colder - thicker oil?

It is due an annual service anyway, but just checking to see if this randomness is normal?

[Quick silver]

My Mk1 has an occasional clatter on start up, but only once in a blue moon........might have something to do with being started when stood on a gradient?

[todd69]

Common problem, had it on 2 of our MX5's

Just do a flush and oil change again

[Monumental]

Having had similar problems recently I've read up on this and it seems like the tapping is very common from a cold start, especially if it's been idle for a while (which seems likely given your annual mileage)

If it goes away after a few minutes I don't think it's an issue, especially if you're about to service it anyway.

spelling edit

Edited by Monumental on Friday 31st July 17:46

[dg45]

Quick silver said:

My Mk1 has an occasional clatter on start up, but only once in a blue moon........might have something to do with being started when stood on a gradient?

mine parked on slope too ,bit noisy sometimes when reversed in but not as bad when driven in forwards .

[A2Z]

I get this sometimes, in fact I had it today. Past the usual few second tapping on startup I got a persistant tapping at idle, rising with revs. I too only did about 2000 miles last year and it has been laid up for a month whilst on holiday. Took it out today and once warmed up had a thrash down the back roads. Noise went in about 10 mins. It seems to happen if the car has been stood for a few weeks. Due an oil change shortly though.

[Merlot]

A2Z said:

I get this sometimes, in fact I had it today. Past the usual few second tapping on startup I got a persistant tapping at idle, rising with revs. I too only did about 2000 miles last year and it has been laid up for a month whilst on holiday. Took it out today and once warmed up had a thrash down the back roads. Noise went in about 10 mins. It seems to happen if the car has been stood for a few weeks. Due an oil change shortly though.

Mine happens randomly, it'll do it when only parked up overnight in my garage sometimes. As I said in my OP, it'll probably do it in 20% of startups.

Whilst I'm sure it'll go away with an oil change, I was wondering what causes it to tap? The oil in my car is 0w rated at cold and is only 2,000 miles old!

[Firefox1]

Merlot,
Take a look in the garage section on Miata.net under engine section, it has a very comprehensive description on how to clean them and why they stick. Mine start to stick after about 3k mile with but it clears within about 5 seconds. Recently it got progressively worse to the point that it took about 5 miles to clear, I tried the Wynns HLA treatment which was okay for a couple of weeks. Yesterday I used Wynns oil flush and changed the oil, for the past 4 years I've used Havoline semi-synthetic, but Morrisons are not going to stock it any more,they only had the synthetic so at £16:99 I thought I'll give it a go. I started the car about half an hour and the HLA's were completely silent. I should add that mine is a 1.8 R Ltd daily driver for 100 mile a day commute so my annual mileage is 10 times yours.
I know yours is a limited edition as is mine but don't be afraid to use it, mine is on 196K kms and after 4 years of MX5 ownership both a 1.6 this one it's one of the things that make the drive to work worthwhile.

[Monumental]

Merlot said:

I was wondering what causes it to tap?

Try this: http://www.mx5oc.co.uk/forum/forums/t/6212.aspx

Or just search for 'HLA' in any of the MX5/Miata forums. Then you realise you're far from the only person with this issue!

[Merlot]

Firefox1 said:

Merlot,

I know yours is a limited edition as is mine but don't be afraid to use it, mine is on 196K kms and after 4 years of MX5 ownership both a 1.6 this one it's one of the things that make the drive to work worthwhile.

Not afraid to use it at all, I've just been walking to work and using the car for social only! However, moving in a couple of weeks so mileage will jump up (a bit) to 7,500 or so PA.

[maser_spyder]

Hydraulic tappet issue, normally happens when it's been laid up a while, or you have a hydraulic tappet or two on the way out.

Cheap and relatively easy to replace if you're doing a cam belt change, won't do any damage in the meantime, nothing desperate to worry about.

There's some specialist tappet stuff out there that's supposed to solve the problem by flushing between oil changes, normally gets mixed reviews but might be worth a try, it's cheaper than mechanical work for sure.

Google 'hydraulic tappets' for a better idea of how they work, there's a good wiki on them!

Hope that helps.

[Merlot]

I understand the cause of the tapping, what I don't understand is why it won't always do it under the same conditions.

For example, 12 hour lay + cold start @ 20 degree ambient temp all other conditions being same. Will tap sometimes, but not always.

[maser_spyder]

Merlot said:

I understand the cause of the tapping, what I don't understand is why it won't always do it under the same conditions.

For example, 12 hour lay + cold start @ 20 degree ambient temp all other conditions being same. Will tap sometimes, but not always.

Depends where the valves stop when you turn off the engine.

If you have a faulty tappet, it may empty itself of oil if the tappet is 'open' when the engine stops, and won't fill up for a few seconds at least (or a few minutes if you have an oil filling problem). Tappet down on engine stop won't give the same effect as the oil won't leak out. Or the other way around.

Normally, if you were going to replace them, you would replace the whole lot together, as it's very hard to work out exactly which one will be causing the problem and they're actually pretty cheap.

They're not really worth replacing unless you have a tappet rattle when normally running hot, and even then, it's irritating more than a serious problem.

[TwistingMyMelon]

TBH they all seem to do it, I'd put up with it, its an old but good engine design and this is just a "characteristic". I find these cars love to be used and laying them up/doing small milages can almost be counterproductive

Mine does it every so often, i either gently increase revs to 3k and it stops or if I'm feeling more mechanically un-sympathetic I'll just turn the engine off and restart it and noise gone.

First port of call would be change the oil, even tho it is only 2k old, oil deteriorates over time, I think that could be a factor in your case.

I find avoiding short journeys, revving the crap out of the engine (when warm) and changing the oil (with good quality fully syn) and filter every 4-5k miles helps avoid the problem, although sometimes it rears its head for a few seconds on startup.

[skinny]

Merlot said:

Whilst I'm sure it'll go away with an oil change, I was wondering what causes it to tap? The oil in my car is 0w rated at cold and is only 2,000 miles old!

it's also a year old and therefore due a change. 2000 miles of stop-start cold weather driving *for example* will be a lot harder on the oil than 8000 miles of consistent long journeys