HLA clatter woes, I think...

[Monumental]

I’ve got a ’94 Eunos 1.8, which is great and will be subjected to a good track spanking once I’m confident that it might survive more than one lap.

The problem is HLA clatter as far as I can tell. I know that a lot has been written on this matter, but it mostly seems to concern those that experience it on start up or all the time.

I get it for about a second on start up and then it runs absolutely fine at normal speeds. Sweet as a nut in fact. The issues begin if you give it the full beans i.e. a couple minutes of >5k rpm on a quiet b-road. Then it starts to sound like a bag of bolts until it cools down, after which it sounds perfect again. This problem is completely repeatable. A good caning equals lots of clatter every time.

The history is as follows; I bought it a few weeks ago. Since the service history was uncertain I gave it a service. New oil (Mobil semi-synth 10-40), filter, spark plugs, air filter etc. I don’t recall having the clatter on start up before the service. I’m not sure about the response at high revs because before the service I had a leaky radiator and therefore took it gently.

I’ve read that fully synth Mobil 0-40 is the way forward. I can understand that the thinner grade will improve the problem on start-up but not sure changing the oil will help when it’s hot. Is synth really that much better than semi?

Or have I got an altogether more serious issue that’s going to need more than a flush and oil change?

Your help is appreciated, I’m dying to get this thing on track but obviously not happy to do so when it sounds like it’s about to go to engine heaven!

[MX-5 Lazza]

Mobil1 will be a slightly better oil but won't make a big difference to something lke this.
Make sure the oil is at the correct level.
Also make sure the spark plugs are correctly tightened. The noise could be one of them rattling around...

[Monumental]

Sorry, forgot to mention that I checked the oil level and it's fine.

I'll check the plugs, but they were tightened to the correct torque with a torque wrench so they are probably OK. Good thought though, hadn't occured to me.

[skinny]

it's unusual that the new oil would be behaving like that - you would expect that due to the fact it needs additives to keep its viscosity when hot, and these shear down becoming ineffective, it doesn't deal as well with heat as a synthetic, but that normally takes a bit of time to kick in - out of the bottle, they should behave kinda similar in the first few weeks at least.

the 0W will be better than the 10W on start-up just because it's less viscous at cold temps so the oil circulation is more rapid.

was it a genuine mazda filter, as sometimes this can make a difference?

[Monumental]

Yup, was a genuine Mazda filter.

[snotrag]

Mines the same too.

its had 3 oil changes in 10k miles, and it still does it.

Few seconds on startup, then usually chirps up as you slow down after a hoon or pull off the motorway (ie when its got hot).

Driving me fecking mad, its the only problem with the car.

[Quick silver]

Monumental & snotrag, I'd hazard a guess that the problems you both appear to be suffering more than likely eminate from the HLA's, mainly due to the fact it's intermittent.

I wouldn't be too worried unless the rattle became permanent because the engines are prone to HLA rattle on start up as standard.

I have difficulty getting my head around the oil scavange system on the HLA's, due to design & seals it appears to me that oil becomes permanently trapped in the HLA, not allowing fresh oil to replace old & there has been much discussed on this subject on Maita.net.

I managed to find 'carbon build up' as a possible cause for the problem on maita.net - the cause, symptoms & fix can be found here: http://www.miata.net/garage/tsb/s004_93.html

[Monumental]

I'm not worried about the start-up clatter, this seems to be normal on these cars.

The clatter when it's hot is a worry, if only because it sounds terrible. It's quite loud

I took a look at the miata.net TSB. It notes at the top that the MX5s affected are up to '93. Could my '94 also be affected or did they fix it for that year?

[Monumental]

I've been looking at Wynns Hydraulic Valve Lifter Treatment as something to try first, since it's cheap and doesn't require an oil change after.

Has anyone had any success with this stuff?

[skinny]

i'd try a decent oil first - don't need to do your filter again, just drain the old stuff out and put in some mobil1 0W-40 from costco - £25 and will be better than anything from wynns.

[Firefox1]

I tried the Wynns worked for about 4 weeks. Mine can be quiet for a week rattle on the way to work and not home, it seems to have become worse since the radiator split a month or so ago and the temperture went off the clock at 80+ leptons for a couple of miles. Being curious what mileage has your car covered, mine's a 94 R Ltd Eunos showing 195K Kms, I about 33K kms a year and change the oil every 10K oil is Havoline 10w-40 semi-synthetic. my old 1.6 had similar mileage but never peep out of the HLA's

[DennisTheMenace]

mine tap after a good ragging , had some fun with a z3 a while ago , lost me on the stright but pulled him in on the corners got to nunney catch services near frome and it was tapping like a bd to it steady for a few miles and it shut up , think it needs a good clear out although if you need new ones apparently kia use the same engine in some of thier old cars and the hla's are cheaper bought from them .

[Monumental]

Firefox, mine has done about 100k miles.

The Wynns treatment doesn't seem to have made much different.

Might try an oil change tomorrow.

[Monumental]

Today I am happy! I changed to the fabled synthetic Mobil 1 0-40W, preceeded by a engine flush.

Cold and hot clatter has completely disappeared. It's seems this wonder-oil has extra added placebo effect as I've convinced myself that it's revving more keenly to the limter and that the exhaust is extra burbly now.

Thanks for all the advice folks!